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1
Silva, António Sérgio, Aurora Carvalho, Pedro Barreiros, Juliana de Sá, Carlos Aroso e José Manuel Mendes. "Comparison of Fracture Resistance in Thermal and Self-Curing Acrylic Resins—An In Vitro Study". Polymers 13, n. 8 (11 aprile 2021): 1234. http://dx.doi.org/10.3390/polym13081234.
Testo completoAbstract (sommario):
Thermal and self-curing acrylic resins are frequently and versatilely used in dental medicine since they are biocompatible, have no flavor or odor, have satisfactory thermal qualities and polishing capacity, and are easy and fast. Thus, given their widespread use, their fracture resistance behavior is especially important. In this research work, we comparatively analyzed the fracture resistance capacity of thermo and self-curing acrylic resins in vitro. Materials and Methods: Five prosthesis bases were created for each of the following acrylic resins: Lucitone®, ProBase®, and Megacryl®, which were submitted to different forces through the use of the CS® Dental Testing Machine, usually mobilized in the context of fatigue tests. To this end, a point was defined in the center of the anterior edge of the aforementioned acrylic resin bases, for which the peak tended until a fracture occurred. Thermosetting resins were, on average, more resistant to fracture than self-curable resins, although the difference was not statistically significant. The thermosetting resins of the Lucitone® and Probase® brands demonstrated behavior that was more resistant to fracture than the self-curing homologues, although the difference was not statistically significant. Thermosetting resins tended to be, on average, more resistant to fracture and exhibited the maximum values for impact strength, compressive strength, tensile strength, hardness, and dimensional accuracy than self-curing resins, regardless of brand.
2
Arif, Wafa, Nosheen Fatima Rana, Iqra Saleem, Tahreem Tanweer, Muhammad Jawad Khan, Sohad Abdulkaleg Alshareef, Huda M. Sheikh et al. "Antibacterial Activity of Dental Composite with Ciprofloxacin Loaded Silver Nanoparticles". Molecules 27, n. 21 (24 ottobre 2022): 7182. http://dx.doi.org/10.3390/molecules27217182.
Testo completoAbstract (sommario):
Resin composites have been widely used in dental restoration. However, polymerization shrinkage and resultant bacterial microleakage are major limitations that may lead to secondary caries. To overcome this, a new type of antibacterial resin composite containing ciprofloxacin-loaded silver nanoparticles (CIP-AgNPs) were synthesized. The chemical reduction approach successfully produced CIP-AgNPs, as demonstrated by FTIR, zeta potential, scanning electron microscopy, and ultraviolet-visible (UV-vis) spectroscopy. CIP-AgNPs were added to resin composites and the antibacterial activity of the dental composite discs were realized against Enterococcus faecalis, Streptococcus mutans, and the Saliva microcosm. The biocompatibility of modified resin composites was assessed and mechanical testing of modified dental composites was also performed. The results indicated that the antibacterial activity and compressive strength of resin composites containing CIP-AgNPs were enhanced compared to the control group. They were also biocompatible when compared to resin composites containing AgNPs. In short, these results established strong ground application for CIP-AgNP-modified dental composite resins.
3
Encalada-Alayola, J. J., Y. Veranes-Pantoja, J. A. Uribe-Calderón, J. V. Cauich-Rodríguez e J. M. Cervantes-Uc. "Effect of Type and Concentration of Nanoclay on the Mechanical and Physicochemical Properties of Bis-GMA/TTEGDMA Dental Resins". Polymers 12, n. 3 (6 marzo 2020): 601. http://dx.doi.org/10.3390/polym12030601.
Testo completoAbstract (sommario):
Bis-GMA/TTEGDMA-based resin composites were prepared with two different types of nanoclays: an organically modified laminar clay (Cloisite® 30B, montmorillonite, MMT) and a microfibrous clay (palygorskite, PLG). Their physicochemical and mechanical properties were then determined. Both MMT and PLG nanoclays were added into monomer mixture (1:1 ratio) at different loading levels (0, 2, 4, 6, 8 and 10 wt.%), and the resulting composites were characterized by scanning electron microscopy (SEM), thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA) and mechanical testing (bending and compressive properties). Thermal properties, depth of cure and water absorption were not greatly affected by the type of nanoclay, while the mechanical properties of dental resin composites depended on both the variety and concentration of nanoclay. In this regard, composites containing MMT displayed higher mechanical strength (both flexural and compression) than those resins prepared with PLG due to a poor nanoclay dispersion as revealed by SEM. Solubility of the composites was dependent not only on nanoclay-type but also the mineral concentration. Dental composites fulfilled the minimum depth cure and solubility criteria set by the ISO 4049 standard. In contrast, the minimum bending strength (50 MPa) established by the international standard was only satisfied by the dental resins containing MMT. Based on these results, composites containing either MMT or PLG (at low filler contents) are potentially suitable for use in dental restorative resins, although those prepared with MMT displayed better results.
4
Hampe, Tristan, Andreas Wiessner, Holm Frauendorf, Mohammad Alhussein, Petr Karlovsky, Ralf Bürgers e Sebastian Krohn. "Monomer Release from Dental Resins: The Current Status on Study Setup, Detection and Quantification for In Vitro Testing". Polymers 14, n. 9 (27 aprile 2022): 1790. http://dx.doi.org/10.3390/polym14091790.
Testo completoAbstract (sommario):
Improvements in mechanical properties and a shift of focus towards esthetic dentistry led to the application of dental resins in various areas of dentistry. However, dental resins are not inert in the oral environment and may release monomers and other substances such as Bisphenol-A (BPA) due to incomplete polymerization and intraoral degradation. Current research shows that various monomers present cytotoxic, genotoxic, proinflammatory, and even mutagenic effects. Of these eluting substances, the elution of BPA in the oral environment is of particular interest due to its role as an endocrine disruptor. For this reason, the release of residual monomers and especially BPA from dental resins has been a cause for public concern. The assessment of patient exposure and potential health risks of dental monomers require a reliable experimental and analytical setup. However, the heterogeneous study design applied in current research hinders biocompatibility testing by impeding comparative analysis of different studies and transfer to the clinical situation. Therefore, this review aims to provide information on each step of a robust experimental and analytical in vitro setup that allows the collection of clinically relevant data and future meta-analytical evaluations.
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Kostic, Milena, Nebojsa Krunic, Ljubisa Nikolic, Vesna Nikolic, Stevo Najman, Ivan Kostic, Jelena Rajkovic, Miodrag Manic e Dusan Petkovic. "Testing of residual monomer content reduction possibility on acrilic resins quality". Chemical Industry 65, n. 2 (2011): 171–77. http://dx.doi.org/10.2298/hemind101103008k.
Testo completoAbstract (sommario):
Poly (methyl methacrylate) (PMMA) is material widely used in dentistry. Despite the various methods used to initiate the polymerization of acrylic resins, the conversion of monomer to polymer is not complete thus leaving some unreacted methyl methacrylate (MMA), known as residual monomer (RM), in denture structure. RM in dental acrylic resins has deleterious effects on their mechanical properties and their biocompatibility. The objective of the work was to test the residual monomer reduction possibility by applying the appropriate postpolymerization treatment as well as to determine the effects of this reduction on pressure yields stress and surface structure characteristics of the acrylic resins. Postpolymerization treatments and water storage induced reduction of RM amount in cold-polymerized acrylic resins improved their mechanical properties and the homogenized surface structure. After the polymerization of heat-polymerized acrylic resins the post-polymerization treatments for improving the quality of this material type are not necessary.
6
Widyasrini, Dyah Anindya, e Siti Sunarintyas. "Effects of alkalisation and volume fraction reinforcement of Bombyx mori silk fibre on the flexural strength of dental composite resins". Dental Journal (Majalah Kedokteran Gigi) 53, n. 2 (15 giugno 2020): 57. http://dx.doi.org/10.20473/j.djmkg.v53.i2.p57-61.
Testo completoAbstract (sommario):
Background: Composite resins are widely used in dentistry to restore dental caries. Recently, short fibre-reinforced composite (FRC) resins have been widely used for high-stress areas, especially in posterior teeth. Bombyx mori silk fibre is under research to reinforce dental composite resin as it has good mechanical properties. Purpose: This study aims to obtain the effects of alkalisation and silk fibre volume fraction on the flexural strength of FRC. Methods: Bombyx mori silk fibres were obtained from Perhutani, Pati, Indonesia. Samples were divided into two alkalisation groups (4% and 8%). Alkalisation of the silk fibres was conducted through the scouring process in NaOH, hydrolysis (30% H2SO4) and drying. Silk fibres were then reinforced in a resin matrix. The samples were subdivided based on the fibre volume fraction reinforcements, which were 0%, 5%, 10% and 15%. Each group of samples consisted of three specimens (n = 3). Flexural strength was measured using a universal testing machine. Data were analysed by two-way ANOVA (p < 0.05) and post-hoc least significant difference test (p < 0.05). Results: The results showed the flexural strength (MPa) means of the 4% alkalisation group were 169.31 ± 54.28 (0%), 76.08 ± 43.69 (5%), 107.86 ± 40.61 (10%) and 101.99 ± 10.61 (15%). The flexural strength (MPa) means of the 8% alkalisation group were 169.31 ± 54.28 (0%), 82.62 ± 22.41 (5%), 111.07 ± 32.89 (10%) and 153.23 ± 23.80 (15%). Statistical analysis by ANOVA indicated that the fibre volume fraction affected the flexural strength of composite resins. Conclusion: It can be concluded that the volume fraction of silk fibre increases the flexural strength of composite resins, although the strength is not as high as a composite resin without fibres. However, the alkalisation percentage did not affect the flexural strength of composite resins, and there was no interaction between alkalisation percentage and fibre volume fraction with the flexural strength of composite resins.
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Blazic, Larisa, Slavoljub Zivkovic, Dejan Pantelic e Vladimir Pipic. "Polymerization quality testing of composite resins cured by led light source". Serbian Dental Journal 50, n. 1 (2003): 7–12. http://dx.doi.org/10.2298/sgs0301007b.
Testo completoAbstract (sommario):
The quality of interface between composite resin materials and hard dental tissues is highly dependent on the polymerization light source. Newly developed blue light- emitting diode units for light polymerization of dental restorative materials are the most innovative light source technology in dentistry nowadays. The aim of this work was to estimate the depth of cure of five different light-activating composite resins exposed to different irradiation times (5s, 10s, 20s and 40s) when the experimental LED light source was used. The tested materials were: Tetric Ceram (Vivadent), Point 4 (Kerr), Admira (VOCO), Filtek Z250 (3M) and Diamond Lite (DRM Lab., Inc). The depth of cure testing was determined using a penetrometer. Results after 40s curing time were as following: the deepest depth of cure was achieved after application of Filtek Z 250, Diamond Lite Point 4 and Tetric Ceram. For the restorative material Admira was found the lowest depth of cure for the light exposure of 40s. An experimental LED light source achieved a sufficient depth of cure (over 2 mm) for all tested materials after curing time of 10s. The polymerization light source spectral distribution should be considered in addition to irradiance as a depth of cure indicator.
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Watanabe, Satoru, Yoshiki Ishida, Daisuke Miura, Taira Miyasaka e Akikazu Shinya. "Development of a Weight-Drop Impact Testing Method for Dental Applications". Polymers 12, n. 12 (26 novembre 2020): 2803. http://dx.doi.org/10.3390/polym12122803.
Testo completoAbstract (sommario):
For evaluating the impact strength of dental materials, the Izod test or Charpy test has been used, but specimen preparation for these tests is difficult due to the adjustment of a notch on them. By contrast, a weight-drop impact test does not require notched specimens. Therefore, it might be possible to measure the impact strength more accurately than conventional methods. This study aimed to establish appropriate conditions for applying the weight-drop impact test on small specimens of acrylic resin. To determine the most reliable impact fracture energy of acrylic resins, different diameters and thicknesses of PMMA resin specimens, diameters and weights of the striker, and diameters of the supporting jig were compared. For all specimen thicknesses, when the striker diameter was 6–10 mm, the impact fracture energy was constant when the inner diameter of the specimen-supporting jig was 8–10 mm. In addition, the measured E50% value was mostly equal to the median value of the impact fracture energy. Thus, for the weight-drop impact test, this method was effective for material testing of small specimens, by clearly specifying the test conditions, such as the thickness of disc-shaped specimens, the diameter of the striker, and the inner diameter of the specimen-supporting jig.
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Visco, Anna Maria, L. Calabrese, Nino Campo, A. Bonavita e Lorenzo Torrisi. "Pull-Out Strength Analysis of Quartz Fibre Posts in Dental Implants". Advances in Science and Technology 49 (ottobre 2006): 130–35. http://dx.doi.org/10.4028/www.scientific.net/ast.49.130.
Testo completoAbstract (sommario):
In order to rebuild the decayed teeth it’s necessary to re-establish the elastic properties of lost dental tissues, replacing them with restorative materials. A not corrected reconstructive method in the dental implant could reduce the mechanical performance causing its progressive premature failure. In this work composite materials, based on quartz fibers posts and adhesive resins, were employed with the aim to restore damaged teeth. Two groups of extracted teeth were rebuilt with two different techniques. In the first group of samples (A) the fiber quartz post and the adhesive resins were simply located into the dental implant and then cured by a light source. In the second group (B) the post and the resin were in situ preformed and then photo-cured; the pre-formed post was then cemented to the tooth with the same procedure of the group A. The two different types of dental restorations were mechanically characterized with a pull-out test with an universal testing machine (Lloyd LR10K). The experimental results showed that the B group samples have an higher mechanical strength than the A group samples, evidencing a better interface adhesion between post– adhesive–tooth. The difference of means of pull out stress data was statistically confirmed by the ANOVA method.
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Szczesio-Wlodarczyk, Agata, Jerzy Sokolowski, Joanna Kleczewska e Kinga Bociong. "Ageing of Dental Composites Based on Methacrylate Resins—A Critical Review of the Causes and Method of Assessment". Polymers 12, n. 4 (10 aprile 2020): 882. http://dx.doi.org/10.3390/polym12040882.
Testo completoAbstract (sommario):
The paper reviews the environmental factors affecting ageing processes, and the degradation of resins, filler, and the filler-matrix interface. It discusses the current methods of testing materials in vitro. A review of literature was conducted with the main sources being PubMed. ScienceDirect, Mendeley, and Google Scholar were used as other resources. Studies were selected based on relevance, with a preference given to recent research. The ageing process is an inherent element of the use of resin composites in the oral environment, which is very complex and changes dynamically. The hydrolysis of dental resins is accelerated by some substances (enzymes, acids). Bonds formed between coupling agent and inorganic filler are prone to hydrolysis. Methods for prediction of long-term behaviour are not included in composite standards. Given the very complex chemical composition of the oral environment, ageing tests based on water can only provide a limited view of the clinical performance of biomaterial. Systems that can reproduce dynamic changes in stress (thermal cycling, fatigue tests) are better able to mimic clinical conditions and could be extremely valuable in predicting dental composite clinical performance. It is essential to identify procedure to determine the ageing process of dental materials.
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Pantea, Mihaela, Robert Cătălin Ciocoiu, Maria Greabu, Alexandra Ripszky Totan, Marina Imre, Ana Maria Cristina Țâncu, Ruxandra Sfeatcu, Tudor Claudiu Spînu, Radu Ilinca e Alexandru Eugen Petre. "Compressive and Flexural Strength of 3D-Printed and Conventional Resins Designated for Interim Fixed Dental Prostheses: An In Vitro Comparison". Materials 15, n. 9 (23 aprile 2022): 3075. http://dx.doi.org/10.3390/ma15093075.
Testo completoAbstract (sommario):
A provisionalization sequence is essential for obtaining a predictable final prosthetic outcome. An assessment of the mechanical behavior of interim prosthetic materials could orient clinicians towards selecting an appropriate material for each clinical case. The aim of this study was to comparatively evaluate the mechanical behavior—with compressive and three-point flexural tests—of certain 3D-printed and conventional resins used to obtain interim fixed dental prostheses. Four interim resin materials were investigated: two 3D-printed resins and two conventional resins (an auto-polymerized resin and a pressure/heat-cured acrylic resin). Cylindrically shaped samples (25 × 25 mm/diameter × height) were obtained for the compression tests and bar-shaped samples (80 × 20 × 5 mm/length × width × thickness) were produced for the flexural tests, observing the producers’ recommendations. The resulting 40 resin samples were subjected to mechanical tests using a universal testing machine. Additionally, a fractographic analysis of failed samples in bending was performed. The results showed that the additive manufactured samples exhibited higher elastic moduli (2.4 ± 0.02 GPa and 2.6 ± 0.18 GPa) than the conventional samples (1.3 ± 0.19 GPa and 1.3 ± 0.38 GPa), as well as a higher average bending strength (141 ± 17 MPa and 143 ± 15 MPa) when compared to the conventional samples (88 ± 10 MPa and 76 ± 7 MPa); the results also suggested that the materials were more homogenous when produced via additive manufacturing.
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Cameli, Norma, Maria Mariano, Flavia Pigliacelli, Martina Silvestri e Antonio Cristaudo. "Occupational Methacrylate Allergy in Dental Personnel". Allergies 1, n. 2 (7 giugno 2021): 123–27. http://dx.doi.org/10.3390/allergies1020010.
Testo completoAbstract (sommario):
Purpose of the article: Acrylate and methacrylate (MA) use in the dental industry is widespread, being utilized in dental prostheses and composite resins, dentin bonding materials, and glass ionomers. However, occupational methacrylate allergy in dental personnel is a growing phenomenon. The aims of this retrospective observational study are to evaluate the risk of occupational contact dermatitis following exposure to methacrylates in dental personnel and to identify possible preventive measures. Materials and Methods: A total of 126 subjects exposed to acrylic and methacrylic resins in their professional context and who reported clinical manifestations were included from our outpatient department database. These were subdivided into two groups: 81 dental technicians and 45 dental hygienists. All the subjects had undergone patch testing with a “methacrylate series” (FIRMA) and readings were taken after 2 days (D2), 4 days (D4), and 7 days (D7). Results: A significantly higher incidence of methacrylate allergy was found in the dental technician group compared to the dental hygienists. Among the dental technicians, 40.7% of the subjects presented skin manifestations. The hands were the most frequently affected sites. Conclusion: Our results confirm the high sensitizing potential of MA in the workplace for dental personnel and in particular an increased professional risk in work where the hands are directly involved (dental technicians). Patch testing as an integrated part of a screening tray is needed for a complete evaluation of occupational skin allergy due to MA in dental personnel. The adoption of proper primary preventive measures, including gloves, protective eyewear, face shields, and disposable gowns, can be useful in preventing new cases of contact dermatitis, which may lead to a change of occupation in dental personnel.
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Silva, Gisele Rodrigues da, Isabela Sousa Araújo, Rodrigo Dantas Pereira, Bruno de Castro Ferreira Barreto, Célio Jesus do Prado, Carlos José Soares e Luís Roberto Marcondes Martins. "Microtensile Bond Strength of Methacrylate and Silorane Resins to Enamel and Dentin". Brazilian Dental Journal 25, n. 4 (2014): 327–31. http://dx.doi.org/10.1590/0103-6440201300009.
Testo completoAbstract (sommario):
The aim of this study was to evaluate the microtensile bond strength (µTBS) of two substrates (enamel and dentin) considering two study factors: type of composite resin [methacrylate-based (Filtek Supreme) or silorane-based (Filtek LS)] and aging time (24 h or 3 months). Twenty human molars were selected and divided into 2 groups (n=10) considering two dental substrates, enamel or dentin. The enamel and dentin of each tooth was divided into two halves separated by a glass plate. Each tooth was restored using both tested composite resins following the manufacturer's instructions. The samples were sectioned, producing 4 sticks for each composite resin. Half of them were tested after 24 h and half after 3 months. µTBS testing was carried out at 0.05 mm/s. Data were analyzed by three-way ANOVA and Tukey's HSD tests at α=0.05. Significant differences between composite resins and substrates were found (p<0.05), but no statistically significant difference was found for aging time and interactions among study factors. The methacrylate-based resin showed higher µTBS than the silorane-based resin. The µTBS for enamel was significantly higher than for dentin, irrespective of the composite resin and storage time. Three months of storage was not sufficient time to cause degradation of the bonding interaction of either of the composite resins to enamel and dentin.
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Song, Hyo-Kyung, Kyung-Hyeon Yoo, Seog-Young Yoon, Hee Sam Na, Jin Chung, Woo-Sung Son, Seung-Min Lee e Yong-Il Kim. "In Vitro Effect of Gallium-Doped Bioactive Glass on Enamel Anti-Demineralization and Bond Strength of Orthodontic Resins". Applied Sciences 9, n. 22 (15 novembre 2019): 4918. http://dx.doi.org/10.3390/app9224918.
Testo completoAbstract (sommario):
White spot lesions (WSL) that occur on teeth after orthodontic appliances have been attached are caused by bacterial demineralization of the enamel surface. This study investigated the anti-demineralization effect of orthodontic resins containing mesoporous bioactive glass nanoparticles (MBN) doped with gallium, which has antibacterial activity, as well as MBN with increased calcium and phosphate contents as these ions can remineralize enamel. Resins (CF, CharmFill Flow, Dentkist, Seoul, South Korea) containing 1%, 3%, and 5% Ga-doped MBN (GaMBN) were characterized using scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and isothermal tests, and their physical properties were measured in terms of Vickers microhardness, bracket retention force, and adhesive remnant index (ARI). Cell viability in the resins was confirmed by testing human dental pulp stem cells (hDPSCs), and ion release tests were performed after 1, 7, and 14 days to determine whether the resins released Ga3+, Ca2+, and PO43–. After 14 days, antibacterial activity was determined using Streptococcus mutans (S. mutans)—the bacteria that causes tooth decay—and the chemical remineralization effect was investigated using a cycle of acid–base solutions. The microhardness of the resins increased with GaMBN concentration whereas their bracket retention force, ARI, and cell viability remained unchanged. The bacterial activity of the 5%-GaMBN resin decreased after 24 and 48 h; however, the change in activity was not statistically significant. Anti-demineralization testing demonstrated that the degree of enamel demineralization decreased as the GaMBN concentration increased, which indicates that resins containing 5%-GaMBN may be viable orthodontic adhesives for preventing WSLs.
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Liber-Kneć, Aneta, e Sylwia Łagan. "Surface Testing of Dental Biomaterials—Determination of Contact Angle and Surface Free Energy". Materials 14, n. 11 (21 maggio 2021): 2716. http://dx.doi.org/10.3390/ma14112716.
Testo completoAbstract (sommario):
The key goal of this study was to characterize surface properties of chosen dental materials on the base on the contact angle measurements and surface free energy calculations. Tested materials were incubated in the simulated oral environment and drinks to estimate an influence of conditions similar to those in the oral cavity on wetting and energetic state of the surface. Types of materials were as follows: denture acrylic resins, composite and PET-G dental retainer to compare basic materials used in a prosthetics, restorative dentistry and orthodontics. The sessile drop method was used to measure the contact angle with the use of several liquids. Values of the surface free energies were estimated based on the Owens–Wendt, van Oss–Chaudhury–Good and Zisman’s methods. The research showed that surface wetting depends on the material composition and storage conditions. The most significance changes of CA were observed for acrylic resins (84.7° ± 3.8° to 65.5° ± 3.5°) and composites (58.8° ± 4.1° to 49.1° ± 5.7°) stored in orange juice, and for retainers (81.9° ± 1.8° to 99.6° ± 4.5°) incubated in the saline solution. An analysis of the critical surface energy showed that acrylic materials are in the zone of good adhesion (values above 40 mJ/m2), while BIS-GMA composites are in the zone of poor adhesion (values below 30 mJ/m2). Study of the surface energy of different dental materials may contribute to the development of the thermodynamic model of bacterial adhesion, based on the surface free energies, and accelerate the investigation of biomaterial interaction in the biological environment.
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Bienek, Diane R., Anthony A. Giuseppetti, Stanislav A. Frukhtbeyn, Rochelle D. Hiers, Fernando L. Esteban Florez, Sharukh S. Khajotia e Drago Skrtic. "Physicochemical, Mechanical, and Antimicrobial Properties of Novel Dental Polymers Containing Quaternary Ammonium and Trimethoxysilyl Functionalities". Journal of Functional Biomaterials 11, n. 1 (18 dicembre 2019): 1. http://dx.doi.org/10.3390/jfb11010001.
Testo completoAbstract (sommario):
The aims of this study were to evaluate the physicochemical and mechanical properties, antimicrobial (AM) functionality, and cytotoxic potential of novel dental polymers containing quaternary ammonium and trimethoxysilyl functionalities (e.g., N-(2-(methacryloyloxy)ethyl)-N,N-dimethyl-3-(trimethoxysilyl)propan-1-aminium iodide (AMsil1) and N-(2-(methacryloyloxy)ethyl)-N,N-dimethyl-11-(trimethoxysilyl)undecan-1-aminium bromide (AMsil2)). AMsil1 or AMsil2 were incorporated into light-cured (camphorquinone + ethyl-4-N,N-dimethylamino benzoate) urethane dimethacrylate (UDMA)/polyethylene glycol-extended UDMA/ethyl 2-(hydroxymethyl)acrylate (EHMA) resins (hereafter, UPE resin) at 10 or 20 mass %. Cytotoxic potential was assessed by measuring viability and metabolic activity of immortalized mouse connective tissue and human gingival fibroblasts in direct contact with monomers. AMsil–UPE resins were evaluated for wettability by contact angle measurements and degree of vinyl conversion (DVC) by near infra-red spectroscopy analyses. Mechanical property evaluations entailed flexural strength (FS) and elastic modulus (E) testing of copolymer specimens. The AM properties were assessed using Streptococcus mutans (planktonic and biofilm forms) and Porphyromonas gingivalis biofilm. Neither AMsil exhibited significant toxicity in direct contact with cells at biologically relevant concentrations. Addition of AMsils made the UPE resin more hydrophilic. DVC values for the AMsil–UPE copolymers were 2–31% lower than that attained in the UPE resin control. The mechanical properties (FS and E) of AMsil–UPE specimens were reduced (11–57%) compared to the control. Compared to UPE resin, AMsil1–UPE and AMsil2–UPE (10% mass) copolymers reduced S. mutans biofilm 4.7- and 1.7-fold, respectively (p ≤ 0.005). Although not statistically different, P. gingivalis biofilm biomass on AMsil1–UPE and AM AMsil2–UPE copolymer disks were lower (71% and 85%, respectively) than that observed with a commercial AM dental material. In conclusion, the AM function of new monomers is not inundated by their toxicity towards cells. Despite the reduction in mechanical properties of the AMsil–UPE copolymers, AMsil2 is a good candidate for incorporation into multifunctional composites due to the favorable overall hydrophilicity of the resins and the satisfactory DVC values attained upon light polymerization of AMsil-containing UDMA/PEG-U/EHMA copolymers.
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Kumar, Gautam VS, Anupama Nigam, Ahmad Naeem, Abhishek Gaur, Kaushik Kumar Pandey e Abhimanyu Deora. "Reinforcing Heat-cured Poly-methyl-methacrylate Resins using Fibers of Glass, Polyaramid, and Nylon: An in vitro Study". Journal of Contemporary Dental Practice 17, n. 11 (2016): 948–52. http://dx.doi.org/10.5005/jp-journals-10024-1960.
Testo completoAbstract (sommario):
ABSTRACT Introduction As civilization has progressed, there has been continued refinement of materials available for dental practice. The applications of resins have been extended to increased practical uses in numerous areas of prosthetic and restorative dentistry. Certain significant alterations in the technique of manipulation and nature of the dental product have influenced the range of application in dentistry. The present study was done to measure and compare the fracture strength of heat polymerized poly-methyl-methacrylate (PMMA) resin reinforced with fibers of glass, polyaramid, and nylon. Materials and methods The present study was conducted in vitro on 40 PMMA denture base resin specimens. Specimens were divided into four subgroups with ten specimens each and tested for transverse strength using universal testing machine. Results In group I, the transverse strength mean value was 67.82 MPa. In group II, the transverse strength mean value was 59.47 MPa. In group III, the transverse strength mean value was 66.87 MPa, while in group IV, the transverse strength mean value was 66.47 MPa. Conclusion Incorporation of 4% weight glass fibers in loose form significantly increased the transverse strength of denture base PMMA, while 4% of polyaramid fiber in random distribution significantly increased the transverse strength of denture base PMMA. How to cite this article Kumar VSG, Nigam A, Naeem A, Gaur A, Pandey KK, Deora A. Reinforcing Heat-cured Polymethyl- methacrylate Resins using Fibers of Glass, Polyaramid, and Nylon: An in vitro Study. J Contemp Dent Pract 2016; 17(11):948-952.
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Park, Sang E., Maggie Chao e P. A. Raj. "Mechanical Properties of Surface-Charged Poly(Methyl Methacrylate) as Denture Resins". International Journal of Dentistry 2009 (2009): 1–6. http://dx.doi.org/10.1155/2009/841431.
Testo completoAbstract (sommario):
The aim of this study was to examine the mechanical properties of a new surface-modified denture resin for its suitability as denture base material. This experimental resin is made by copolymerization of methacrylic acid (MA) to poly(methyl methacrylate) (PMMA) to produce a negative charge. Four experimental groups consisted of Orthodontic Dental Resin (DENTSPLY Caulk) as a control and three groups of modified PMMA (mPMMA) produced at differing ratios of methacrylic acid (5 : 95, 10 : 90, and 20 : 80 MA : MMA). A 3-point flexural test using the Instron Universal Testing Machine (Instron Corp.) measured force-deflection curves and a complete stress versus strain history to calculate the transverse strength, transverse deflection, flexural strength, and modulus of elasticity. Analysis of Variance and Scheffe Post-test were performed on the data. Resins with increased methacrylic acid content exhibited lower strength values for the measured physical properties. The most significant decrease occurred as the methacrylic acid content was increased to 20%mPMMA. No significant differences atP<.05were found in all parameters tested between the Control and 5%mPMMA.
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Hiers, Rochelle Denise, Pedro Huebner, Sharukh Soli Khajotia e Luis Esteban Florez. "Characterization of Experimental Nanoparticulated Dental Adhesive Resins with Long-Term Antibacterial Properties". Nanomaterials 12, n. 21 (24 ottobre 2022): 3732. http://dx.doi.org/10.3390/nano12213732.
Testo completoAbstract (sommario):
Experimental adhesives with functional nitrogen-doped titanium dioxide nanoparticles (N_TiO2) have been shown to display improved properties. However, these materials have not been characterized regarding their degree of conversion (DC), biaxial flexure strength (BFS), surface roughness (SR), elastic modulus (EM), and long-term antibacterial functionalities. Experimental adhesives were synthesized by dispersing N_TiO2 (10%, 20%, or 30%, v/v%) into OptiBond Solo Plus (OPTB, Kerr Corp., USA). Unpolymerized adhesives (volume = 50 μL/drop, n = 3/group) were individually placed onto a heated (37 °C) attenuated total reflectance (ATR) monolithic diamond crystal (Golden Gate, Specac). The spectra of composites were obtained with a Fourier-transform infrared (FTIR) spectrometer (Nicolet IS50; 500–4500 cm−1; resolution = 4 cm−1, 10 internal scans/spectrum) before and after polymerization. Disk-shaped specimens (diameter = 6.0 mm, thickness = 0.5 mm) for BFS (n = 12/group), SR and EM (n = 3/group), and for antibacterial testing (n = 18/group/time-point) were fabricated and photopolymerized (1 min each; 385–515 nm, 1000 mW/cm2; VALO). DC values (%) were calculated from pre- and post-polymerization spectra using the two-frequency method and tangent-baseline technique. BFS was assessed using a universal testing machine (Instron 68TM-5, crosshead speed = 1.27 mm/min, 25 °C). SR and EM were investigated using an atomic force microscope (Multimode 8) with aluminum-coated silicon probes (8 nm pyramidal tip, spring constant 40 N/m, Bruker). Antibacterial testing was performed by growing Streptococcus mutans biofilms (UA159-ldh, 37 °C, microaerophilic) on the surfaces of specimens for 24 h and then measuring the relative luminescence units (RLU) with a Biotek Synergy HT multi-well plate reader. Results demonstrate that experimental materials containing 10%, 20%, and 30% of N_TiO2 displayed higher levels of DC, had better mechanical properties, and were able to exert strong and durable antibacterial properties without visible light irradiation and after extended periods of simulated shelf-life and aging in PBS. The reported experimental materials are expected to increase the service lives of polymer-based bonded restorations by decreasing the incidence of secondary caries.
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Stanford, J. W. "Future of Materials and Materials Research". Advances in Dental Research 2, n. 1 (agosto 1988): 187–92. http://dx.doi.org/10.1177/08959374880020011301.
Testo completoAbstract (sommario):
The purpose of this paper was to summarize the presentations on porcelain materials, endodontic materials, casting metals, impression materials, armamentarium, amalgam, resins, composites, cements, bonding agents, adhesives, and calcium phosphate materials. Eight series of recommendations for future research are presented and include areas of basic research, animal models, biocompatibility, correlated laboratory and clinical testing procedures, epidemiological studies, workshops and conferences, materials research criteria, and a Dental Research Information Center. These recommendations were subsequently presented to the Programs Advisory Committee for Extramural Research of the National Institute of Dental Research.
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Szalewski, Leszek, Dorota Wójcik, Marcin Bogucki, Jacek Szkutnik e Ingrid Różyło-Kalinowska. "The Influence of Popular Beverages on Mechanical Properties of Composite Resins". Materials 14, n. 11 (5 giugno 2021): 3097. http://dx.doi.org/10.3390/ma14113097.
Testo completoAbstract (sommario):
Currently, composite resins are used in many restorative procedures. Previous studies showed that drinking beverages may affect the mechanical properties such as microhardness or flexural strength of dental composite resins. The aim of the present study was to investigate the influence of common beverages on the mechanical properties of composite resins. Samples of the materials were prepared according to the ISO 4049:2010 standard and producer’s recommendations. The samples were next conditioned in tested fluids: distilled water, sparkling water, Coca-Cola, Red Bull and orange juice for 7 days. Vickers microhardness and flexural strength testing was performed after 7 days. Performed statistic tests confirmed the significance of microhardness changes of the tested materials in terms of both different conditioning of the samples and different composite materials. The mean flexural strength of composites was highest in distilled water and it was reduced after one week in different beverages. We conclude that all tested beverages influenced on Vickers microhardness of tested composite resins. Flexural strength only in one material was statistically significantly influenced by tested beverages. The results of this study should be taken into consideration by a dentist preparing recommendations for the patients after dental treatment with usage of composite material or after cementing composite based fixed dentures.
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Popescu, Florin Dan, Sanda Mihaela Popescu, Răzvan Mercuţ e Horia Octavian Manolea. "Proposal for a Short Patch Test Series of Dental Materials for Patients with Suspected Oral Contact Allergy". Key Engineering Materials 695 (maggio 2016): 65–76. http://dx.doi.org/10.4028/www.scientific.net/kem.695.65.
Testo completoAbstract (sommario):
The selection of patch test haptens contained in oral rehabilitation materials is not an easy task, therefore baseline series and additional dental series are used for screening and to increase the chance for the detection of patient's contact sensitizations. Moreover, the clinical relevance of positive patch tests must be evaluated. We conducted a biomedical literature search, covering a period of thirty years, using the keywords: contact, allergy, dental, allergens, patch, patients, screening, in order to evaluate many studies including large numbers of patients, tested to various hapten series, in different departments, for the detection of the most common contact allergens involved in dental contact hypersensitivity. We propose a short patch test series of oral rehabilitation materials for patients including six metal haptens present in dental alloys for inlays, crowns, bridges and dentures, one monofunctional methacrylate and one epoxy prepolymer present in dental composite resins, dentin bonding agents and prosthetic materials, one epoxy resin type present in root canal sealants, three odorant constituents contained in provisional restorative and root canal filling materials, periodontal dressings and dental impression materials. Contact allergy to dental haptens is a constant studied subject, but the cost of patch testing with screening and additional or extensive series is relevant, therefore the proposal of a shorter dental material series for patients is aimed to promote sustainability of oral rehabilitation and contact hypersensitivity care and to reduce costs in some real-world settings.
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Yang, Song-Yi, e Min-Kyung Kang. "Surface Characterization, Antimicrobial Activity, and Biocompatibility of Autopolymerizing Acrylic Resins Coated with Reynoutria elliptica Extract". Plants 9, n. 10 (29 settembre 2020): 1292. http://dx.doi.org/10.3390/plants9101292.
Testo completoAbstract (sommario):
We conducted surface characterization to assess the biocompatibility and investigate the antimicrobial activity against oral pathogens in autopolymerizing acrylic resins, coated with light-curable coating resin, containing various concentrations of Reynoutria elliptica extract (0, 200, 400, and 600 µg/mL). The R. elliptica extract powder was prepared using a freeze-drying technique. Further, a goniometer and microhardness tester were used to determine the water contact angle, and Vickers hardness, respectively; color measurements were performed on the uncoated and coated acrylic resin disks. The polyphenol content of the extracts from the coated acrylic resin disk was analyzed using UV-VIS spectroscopy. The antimicrobial activity of the coated acrylic resin disk against Streptococcus mutans and Candida albicans was observed for 24 and 48 h by measuring the optical density using spectrophotometry. In addition, biocompatibility was confirmed by testing the cell viability according to ISO 10993-5. The water contact angle, Vickers hardness, and color change values of the coated acrylic resin disks were not significantly different from the control. Polyphenol was detected in all experimental groups, with no significant differences between the experimental groups. The experimental groups exhibited significant antimicrobial activity against S. mutans and C. albicans compared to the control group, after 48 h of incubation. The cell viability between the control and experimental groups was not significantly different. The proposed coating resin containing R. elliptica extract is applicable on dental acrylic resins, due to their antimicrobial properties and excellent biocompatibility, with no deterioration of surface characteristics.
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Alagha, Ebaa Ibrahim, e Mustafa Ibrahim Alagha. "Microhardness Assessment of Two Nanohybrid Composite Resins with Two Curing Technologies". Open Access Macedonian Journal of Medical Sciences 9, n. D (17 aprile 2021): 81–86. http://dx.doi.org/10.3889/oamjms.2021.5868.
Testo completoAbstract (sommario):
AIM:This study evaluated the influence of two light sources on the microhardness of two recent composite resins. MATERIALS AND METHODS: A total of 120 specimens were prepared and divided into two groups according to the composite resin restoration used (Tetric EvoCeram Bulk fill) and (Universal Nanohybrid Mosaic). Each group was subdivided into four subgroups according to the curing sources used with different curing duration’s laser curing system (SIROLaser) for 10, 15, and 20 s and conventional blue light system (LED) for 20 s. A microhardness testing machine was used to assess the microhardness of Tetric EvoCeram Bulk fill and Universal Nanohybrid Mosaic. Two-way ANOVA statistical test was used for comparing resin composite and curing energy effect on different variable studied. One-way ANOVA followed by pair-wise Tukey’s post hoc tests was performed to detect significance between each composite subgroups and t-test for subgroups. P ≤ 0.05 is considered statistically significant in all tests. RESULTS: LED cured Tetric EvoCeram Bulk fill composite resin recorded higher bottom to top ratio (B/T ratio) than laser cured one and the difference in B/T ratio between both energies was statistically non-significant. LED cured Mosaic composite resin recorded higher B/T ratio than laser cured one . The difference in bottom to top ratio between both curing devices was statistically significant. CONCLUSION: SIROLaser Blue laser device increases the degree of polymerization and achieves better curing of composite resins than LED. RECOMMENDATION: Different types of curing systems are present in the dental practice. The use of SIROLaser Blue laser to photopolymerize composite resin will offers proper polymerization properties.
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Liu, Fang, Cheng Qian, Li Xu, Rongxiu Zhang, Liang Liu, Zhigang Wu, Kai Zhang, Shengkai Liao e Xiaofei Xie. "Analysis on the Performance of Nano-Composite Resin Dental Restorative Materials". Science of Advanced Materials 13, n. 5 (1 maggio 2021): 927–37. http://dx.doi.org/10.1166/sam.2021.3995.
Testo completoAbstract (sommario):
After long-term use of resin materials for dental repair, plaque is easy to accumulate on the surface to form biofilms, which can cause caries. Although antibacterial agents are applied to oral resins, the antibacterial ability, mechanical performance, and biocompatibility of the material have to be considered. In this study, the cationic polymer NPVP with different lengths of alkyl chain is adopted to modify the carbon–nanodiamond (CND), and hydroxyethyl methacrylate (HEMA) is introduced to reduce the cytotoxicity of the modified particles and improve the compatibility with the resin matrix. Among the multiple composite samples obtained, MND-H10 shows the best de-aggregation effect, with a particle size of 70 nm. In addition, it plays a good antibacterial effect against Gram-negative bacteria (GNB) Escherichia coli (E. coli) and Gram-positive bacteria (GPB) Staphylococcus aureus (S. aureus). On this basis, the polymerizable antibacterial nano-composite particles (modified nano-diamonds, MNDs) are prepared and polymerized with the resin matrix Bisphenol A bis-methyl/glycidyl acrylate (Bis-GMA)/Triglycol dimethacrylate (TEGDMA) to construct an antibacterial dental repair material. After testing, the Vickers hardness, flexural strength, and flexural modulus of the 0.6 wt% modified resin material all increase by more than 45%. Due to the addition of nano-particles, the material shows a certain antibacterial ability, an increased hydrophilicity, and antibacterial adhesion ability. 10 patients with clinically defective or missing dentition during June 2017 to October 2017 are selected from the affiliated hospitals of the college, who are treated with the threaded implants. After a year of clinical observation, the threaded implants have achieved better osseointegration results.
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Kyoizumi, Hideaki, Junji Yamada, Toshimitsu Suzuki, Masafumi Kanehira, Werner J. Finger e Keiichi Sasaki. "Effects of Toothbrush Hardness on in vitro Wear and Roughness of Composite Resins". Journal of Contemporary Dental Practice 14, n. 6 (2013): 1137–44. http://dx.doi.org/10.5005/jp-journals-10024-1464.
Testo completoAbstract (sommario):
ABSTRACT Aim To investigate and compare the effects of toothbrushes with different hardness on abrasion and surface roughness of composite resins. Materials and methods Toothbrushes (DENT. EX Slimhead II 33, Lion Dental Products Co. Ltd., Tokyo, Japan) marked as soft, medium and hard, were used to brush 10 beam-shaped specimens of each of three composites resins (Venus [VEN], Venus Diamond [VED] and Venus Pearl [VEP]; HeraeusKulzer) with standardized calcium carbonate slurry in a multistation testing machine (2N load, 60 Hz). After each of five cycles with 10k brushing strokes the wear depth and surface roughness of the specimens were determined. After completion of 50k strokes representative samples were inspected by SEM. Data were treated with ANOVA and regression analyses (p < 0.05). Results Abrasion of the composite resins increased linearly with increasing number of brushing cycles (r2 > 0.9). Highest wear was recorded for VEN, lowest for VED. Hard brushes produced significantly higher wear on VEN and VEP, whereas no difference in wear by toothbrush type was detected for VED. Significantly highest surface roughness was found on VED specimens (Ra > 1.5 μm), the lowest one on VEN (Ra < 0.3 μm). VEN specimens showed increased numbers of pinhole defects when brushed with hard toothbrushes, surfaces of VEP were uniformly abraded without level differences between the prepolymerized fillers and the glass filler-loaded matrix, VED showed large glass fillers protruding over the main filler-loaded matrix portion under each condition. Conclusion Abrasion and surface roughness of composite resins produced by toothbrushing with dentifrice depend mainly on the type of restorative resin. Hardness grades of toothbrushes have minor effects only on abrasion and surface roughness of composite resins. No relationship was found between abrasion and surface roughness. Clinical significance The grade of the toothbrush used has minor effect on wear, texture and roughness of the composite resin. How to cite this article Kyoizumi H, Yamada J, Suzuki T, Kanehira M, Finger WJ, Sasaki K. Effects of Toothbrush Hardness on in vitro Wear and Roughness of Composite Resins. J Contemp Dent Pract 2013;14(6):1137-1144.
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Ramburrun, Poornima, Nadine A. Pringle, Admire Dube, Razia Z. Adam, Sarah D’Souza e Marique Aucamp. "Recent Advances in the Development of Antimicrobial and Antifouling Biocompatible Materials for Dental Applications". Materials 14, n. 12 (9 giugno 2021): 3167. http://dx.doi.org/10.3390/ma14123167.
Testo completoAbstract (sommario):
The risk of secondary bacterial infections resulting from dental procedures has driven the design of antimicrobial and antifouling dental materials to curb pathogenic microbial growth, biofilm formation and subsequent oral and dental diseases. Studies have investigated approaches based primarily on contact-killing or release-killing materials. These materials are designed for addition into dental resins, adhesives and fillings or as immobilized coatings on tooth surfaces, titanium implants and dental prosthetics. This review discusses the recent developments in the different classes of biomaterials for antimicrobial and antifouling dental applications: polymeric drug-releasing materials, polymeric and metallic nanoparticles, polymeric biocides and antimicrobial peptides. With modifications to improve cytotoxicity and mechanical properties, contact-killing and anti-adhesion materials show potential for incorporation into dental materials for long-term clinical use as opposed to short-lived antimicrobial release-based coatings. However, extended durations of biocompatibility testing, and adjustment of essential biomaterial features to enhance material longevity in the oral cavity require further investigations to confirm suitability and safety of these materials in the clinical setting. The continuous exposure of dental restorative and regenerative materials to pathogenic microbes necessitates the implementation of antimicrobial and antifouling materials to either replace antibiotics or improve its rational use, especially in the day and age of the ever-increasing problem of antimicrobial resistance.
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Siejka-Kulczyk, Joanna, Joanna Mystkowska, Małgorzata Lewandowska, Jan R. Dabrowski e Krzysztof Jan Kurzydlowski. "The Influence of Nano-Silica on the Wear Resistance of Ceramic – Polymer Composites Intended for Dental Fillings". Solid State Phenomena 151 (aprile 2009): 135–38. http://dx.doi.org/10.4028/www.scientific.net/ssp.151.135.
Testo completoAbstract (sommario):
Ceramic – polymer composites based on acrylic (bis–GMA) and urethane – methacrylate (UM) resins with a 60 % total volume fraction of filler consisting of micro particles of glass and nano-particles of silica were fabricated. The nano-silica contents were: 0, 10, 20 vol. %. The composite samples were subjected to wear tests using an occlusion simulator tester which applies reciprocating movement and cyclic loading on the test material. This method of testing provides some similarity to the masticatory pattern occurring in the mouth during eating. The enamel of a human tooth was used as a counter-sample. The coefficient of friction was determined and the wear resistance of the composite samples containing the various nano-silica contents was established. In addition, the relative influence of the composite composition on the rate of wear of the human tooth enamel was estimated. The results of the study indicate that the addition of nano-silica significantly improves the wear resistance of the ceramic – polymer composites and reduces the wear of enamel. It was found that the addition of nano-silica has no influence on the coefficient of friction. It was also established that composites based on UM resin show better wear resistance than those based on a mixture of bis-GMA and TEGDMA resin.
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Mikov, Ivan, Ivan Turkalj e Marina Jovanovic. "Occupational contact allergic dermatitis in dentistry". Vojnosanitetski pregled 68, n. 6 (2011): 523–25. http://dx.doi.org/10.2298/vsp1106523m.
Testo completoAbstract (sommario):
Introduction. Dental professionals may be at increased risk of developing occupational allergic diseases specially to methacrylates that can permeate protective disposable gloves. Case report. We presented a case of occupational allergic contact dermatitis in a 28-year-old dental technician. The patient had complained of itching and cracking of fingers for 6 months. The dermatitis improved over weekends. Skin erythema and scaling were present with primarily involvement of the fingertips. Patch testing with dental series gave positive vesicular reaction to methyl methacrylate. Follow-up after 6 months of allergen avoidance showed a complete regression of dermatitis. Conclusion. Methacrylates serve as bases for acrylic resins which are used in prosthetics. Methyl methacrylate as a small molecular acrylate can permeate thin protective disposable gloves. Using adequate personal protective equipment, like nitrile rubber gloves, is the most important preventive measure in this occupation. Health practitioners should recognize possible occupational hazards in dentistry and implement appropriate preventive measures to protect health of workers.
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Derban, Paula, Romeo Negrea, Mihai Rominu e Liviu Marsavina. "Influence of the Printing Angle and Load Direction on Flexure Strength in 3D Printed Materials for Provisional Dental Restorations". Materials 14, n. 12 (18 giugno 2021): 3376. http://dx.doi.org/10.3390/ma14123376.
Testo completoAbstract (sommario):
The CAD/CAM techniques, especially additive manufacturing such as 3D printing, constitute an ever-growing part of obtaining different dental appliances and restorations. Of these, provisional restorations are of frequent use in daily dental practice and are the object of this study. Masticatory and parafunctional forces determine flexure on these prostheses. This study investigates the influence of the printing angle and loading direction of the applied force on the flexure strength of two commercially available printable resins—Detax Freeprint Temp and Nextdent MFH Vertex dental. Ten rectangular beam specimens printed at the angle of 0, 45 and 90 degrees were fabricated of each of these materials, with an addition of 10 at 0 degrees for the investigation of the load direction. Three-point bending tests were performed in a universal testing machine. Flexure strength, strain at break and Young’s modulus were determined and a statistical analysis was performed on the obtained data. According to the statistical analysis, the flexural strength has a significance dependence with respect to degrees of orientation, for both investigated materials.
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Jassé, Fernanda Ferreira Albuquerque, Cristiane de Melo Alencar, Natália Fernandes Pollo, Cecy Martins Silva e Edson Alves de Campos. "Molars Fracture Resistance with Class II Cavities Restored with Different Resin - Based Materials". Journal of Health Sciences 23, n. 1 (18 marzo 2021): 25–29. http://dx.doi.org/10.17921/2447-8938.2021v23n1p25-29.
Testo completoAbstract (sommario):
AbstractThe teeth weakening due to the preparation of class II mesio-occluso-distal cavities is a challenge for the clinician. The objective of this study was to evaluate the molars fracture resistance with class II mesio-occluso-distal cavities restored with different restorative techniques and materials. Forty extracted molars were divided into 5 groups: Group 1 – intact healthy teeth (positive control); Group 2 – unrestored teeth with mesio-occluso-distal class II cavities (negative control); Groups 3 to 5 – restored teeth with standardized dimensions. In groups 3 to 5, the cavities were restored with flow resin only, flow resin coated with a nano-hybrid resin, and nano-hybrid resin only, respectively. All specimens were tested for resistance to fracture using an axial compressive load, a metallic sphere measuring 8 mm in diameter on a universal testing machine EMIC DL-2000. A 10 kN load cell operated at a speed of 5 mm/min until the tooth fracture. Data were subjected to analysis of variance and Tukey’s tests (α = 0.05). Group 3 showed higher fracture strength (2243.1 ± 473.7N) when compared to groups 2, 4 and 5. This difference was statistically significant (p<0.05). The fracture strength of teeth restored with flow mesio-occluso-distal restorations was similar to that of intact natural teeth.
Keywords: Compressive Strength. Composite Resins. Dental Cavity Preparation.
ResumoO enfraquecimento dos dentes devido às preparações de cavidades mesio-ocluso-distal é um desafio para o clínico. O objetivo deste estudo foi avaliar a resistência à fratura de molares com cavidades mesio-ocluso-distais classe II restauradas com diferentes técnicas e materiais restauradores. Quarenta molares extraídos foram divididos em 5 grupos: Grupo 1 – dentes saudáveis intactos (controle positivo); Grupo 2 – dentes não restaurados com cavidades mesio-occluso-distais classe II (controle negativo); Grupos 3 a 5 – dentes restaurados com dimensões padronizadas. Nos grupos 3 a 5, as cavidades foram restauradas apenas com resina flow, resina flow recoberta com uma resina nano-híbrida e somente resina nano-híbrida, respectivamente. Todas as amostras foram testadas quanto à resistência à fratura usando uma carga compressiva axial, usando uma esfera metálica medindo 8 mm de diâmetro em uma máquina de teste universal EMIC DL-2000. Uma célula de carga de 10 kN operava a uma velocidade de 5 mm/min até a fratura do dente. Os dados foram submetidos à análise de variância e testes de Tukey (α = 0,05). O grupo 3 apresentou maior resistência à fratura (2243,1 ± 473,7N) quando comparado aos grupos 2, 4 e 5. Essa diferença foi estatisticamente significante (p <0,05). A resistência à fratura dos dentes restaurados com resina flow foi semelhante à dos dentes naturais intactos.
Keywords: Força Compressiva. Resinas Compostas. Preparo da Cavidade Dentária.
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Sinniah, SD, SP Jones, G. Georgiou, SJ Cunningham e A. Petrie. "Bond Strengths of Composite Resins used for the Attachment of Bonded Retainers". Compendium of Oral Science 3, n. 1 (1 settembre 2016): 17–24. http://dx.doi.org/10.24191/cos.v3i0.17515.
Testo completoAbstract (sommario):
Objectives: To compare the bond strengths and survival of flowable and non -flowable composite resins used with bonded retainers. Setting: Department of Orthodontics, UCL Eastman Dental Institute, United Kingdom. Methods: Flowable composite resins (TransbondTM Supreme LV, StarFlowTM and Tetric EvoFlow®) and non-flowable control resin (TransbondTM LR) were made into cylinders prior to bonding to hydoxyapatite discs. They were then mounted into jigs and tested in the InstronTM Universal Testing Machine in both shear and tensile modes. Results: The highest mean shear bond strength was seen with StarFlowTM (14.09 MPa), which was significantly higher than both TransbondTM LR (9.48 MPa) and TransbondTM Supreme LV (8.20 MPa). The mean shear bond strength of Tetric EvoFlow® (11.86 MPa) was also significantly higher than TransbondTM Supreme LV. The highest mean tensile bond strength was seen with Tetric EvoFlow® (2.14 MPa), which was significantly higher than TransbondTM LR (1.15 MPa) and TransbondTM Supreme LV (0.61 MPa) but not significantly different to StarFlowTM (1.47 MPa). For shear loading, StarFlowTM had the highest 50th percentile survival estimate at 15.10 MPa, followed by Tetric EvoFlow® (13.00 MPa) and TransbondTM Supreme LV (7.50 MPa). TransbondTM LR had a 50th percentile estimate at 9.00 MPa. For tensile loading, Tetric EvoFlow® had the highest 50th percentile survival estimate at 2.50 MPa, followed by StarFlowTM (1.30 MPa) and TransbondTM Supreme LV (0.50 MPa). TransbondTM LR had a 50th percentile estimate at 1.00 MPa. Conclusions: Mean shear bond strengths for all of the resins were significantly higher than the mean tensile bond strengths. StarFlowTM and Tetric EvoFlow® could potentially be suitable clinical alternatives to TransbondTM LR due to its low viscosity flow characteristics and adequate shear and tensile bond strengths.
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Emami, N., e KJ Söderholm. "Young's Modulus and Degree of Conversion of Different Combination of Light-Cure Dental Resins". Open Dentistry Journal 3, n. 1 (1 ottobre 2009): 202–7. http://dx.doi.org/10.2174/1874210600903010202.
Testo completoAbstract (sommario):
Objectives: To evaluate Young's modulus and degree of conversion of several combinations of bisGMA, UEDMA, TEGDMA light-cure dental resin. Methods: Young's modulus and DC% were studied for 21 different resin combinations of bisGMA, TEGDMA and UEDMA. Small universal testing machine and photo-calorimetry were used for the tests. The results were evaluated using ANOVA and Duncan's multiple range tests and regular t-test. Results: Young's modulus varied between 2.37±0.2 GPa (100% TEGDMA) and 4.15±0.2 GPa (100% bisGMA). By adding TEGDMA to bisGMA or UEDMA, the Young's modulus decreased significantly (p<0.05). Degree of conversion was significantly (p<0.05) higher when the wt% of TEGDMA was high in the mixtures than for highly concentrated bis-GMA (resin mixtures with TEGDMA in comparison to mixture with bisGMA had higher degree of conversion). DC% was significantly higher (p<0.05) for binary mixtures of UEDMA and TEGDMA, and significantly lower for 100 wt% bis-GMA (p<0.05). The DC% values were between 53.1%±0.9% (100% bisGMA) and 85.6%±1% (80% UEDMA-20% TEGDMA). The concentration of bisGMA, in the monomer mixture, affected DC% and Young's modulus oppositely. Conclusions: The differences in the values for DC% were mostly justified by the differences in the molecular structures of the different monomers. It was also revealed that higher DC% does not always result in a higher Young's modulus, because molecular and network structural parameters play major roles in the final physical properties of the mixtures.
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Khalesi, Rayhaneh, Mahdi Abbasi, Zahra Shahidi, Masoumeh Hasani Tabatabaei e Zohreh Moradi. "Interfacial Fracture Toughness Comparison of Three Indirect Resin Composites to Dentin and Polyether Ether Ketone Polymer". European Journal of Dentistry 14, n. 03 (luglio 2020): 456–61. http://dx.doi.org/10.1055/s-0040-1713309.
Testo completoAbstract (sommario):
Abstract Objectives Advances in laboratory composites and their high wear resistance and fracture toughness have resulted in their growing popularity and increasing use for dental restorations. This study sought to assess the fracture toughness of three indirect composites bonded to dental substrate and polyether ether ketone (PEEK) polymer. Materials and Methods This in vitro study was conducted on two groups of dental and polymer substrates. Each substrate was bonded to three indirect composite resins. Sixty blocks (3 × 3 × 12 mm) were made of sound bovine anterior teeth and PEEK polymer. Sixty blocks (3 × 3 × 12 mm) were fabricated of CRIOS (Coltene, Germany), high impact polymer composite (HIPC; Bredent, Germany), and GRADIA (Indirect; GC, Japan) composite resins. Composites were bonded to dentin using Panavia F 2.0 (Kuraray, Japan). For bonding to PEEK, Combo.lign (Bredent) and Visio.Link (Bredent) luting cements were used. In all samples, a single-edge notch was created by a no. 11 surgical blade at the interface. The samples were subjected to 3,500 thermal cycles, and their fracture toughness was measured in a universal testing machine (Zwick/Roell, Germany) by application of four-point flexural load. Statistical Analysis Data were analyzed using one-way analysis of variance, Kruskal–Wallis. Results The fracture toughness of CRIOS–PEEK interface was significantly higher than HIPC–PEEK. The fracture toughness of GRADIA–PEEK was not significantly different from that of HIPC and CRIOS. The fracture toughness of GRADIA–dentin was significantly higher than HIPC–dentin. Conclusion Considering the limitations of this study, GRADIA has the highest bond strength to dentin, while CRIOS shows the highest bond strength to PEEK.
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Sá, Juliana de, Francisca Vieira, Carlos Manuel Aroso, Mónica Cardoso, José Manuel Mendes e António Sérgio Silva. "The Influence of Saliva pH on the Fracture Resistance of Three Complete Denture Base Acrylic Resins". International Journal of Dentistry 2020 (1 novembre 2020): 1–12. http://dx.doi.org/10.1155/2020/8941876.
Testo completoAbstract (sommario):
Aim and Background. The absorption of fluids by denture base materials diminishes the mechanical properties such as hardness, strength, and fatigue limit due to the plasticizing effect of water. This study aimed to evaluate the influence of oral pH on the fracture resistance of prosthetic bases made of three different heat-polymerizable acrylic resin brands: RS Vertex®, Triplex Hot®, and Megacryl®. The strength needed to fracture the resins and the resistance to fracture each resin were evaluated. Methods. Ten prosthesis bases prepared with each brand of resin were subjected to neutral and low pH conditions (pH 7 and pH 4) by submerging them in artificial saliva for 30 days. After exposure, the fatigue resistance of the resins was tested using a Dental CS® Testing Machine. Statistical Analysis Test. The data sets were described quantitatively in terms of mean (M) and standard deviation (SD). Shapiro–Wilk tests and unilateral analysis of variance (ANOVA) were performed and complemented by Tukey’s multiple comparison tests. The effect size (η2), whose cohort points followed Cohen’s recommendations: 0.01 (low), 0.06 (medium), and 0.14 (high), was calculated. The results were considered significant if p < 0.05 and marginally significant if p < 0.10 . Results. One-way ANOVA showed that Megacryl® had the highest fracture resistance at pH 7 (52.23 Kgf), compared with Triplex Hot® ( p < 0.001 ) and RS Vertex® ( p = 0.034 ). Two-way ANOVA confirmed the interaction between brand and pH ( p = 0.022 ), also revealing that brands comparison is significant or marginally significant, when pH is not considered (Megacryl® versus Triplex Hot®, p < 0.001 , and RS Vertex®, p = 0.058 ; Triplex Hot® versus RS Vertex®, p = 0.051 ), and pH 7 results were significantly higher ( p = 0.003 ), even when brands are not considered. Hence, Megacryl® at pH 7 was found to have the highest fracture resistance, detached from other brands and pH values. Conclusion. It can be concluded within the limitations of this study that there are differences in the fracture resistance among the three brands of acrylic resin. Megacryl® was found to have the highest fracture resistance, and Triplex Hot® was the lowest. The results also show that exposure to a low pH environment decreases the fracture resistance of the Megacryl® and RS Vertex® resins.
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de Jesus, Ricardo Huver, Pâmela Rodrigues Pires, Raquel Cavallini Silva, Suyanni Chieppe dos Santos Manfioletti, Carlos Frederico Bettcher Silva e Lucas Campagnaro Maciel. "Resistência à compressão de compósitos de preenchimento único". Full Dentistry in Science 12, n. 46 (2021): 118–23. http://dx.doi.org/10.24077/2021;1246-118123.
Testo completoAbstract (sommario):
A new class of composite resins called single fill resins (Bulk-Fill) was proposed to simplify restorative procedures. They allow filling dental cavities in layers of approximately 4mm. This study aims to compare the compression strength of single fill composites with different polymerization times. Four Bulk-Fill composites were used Filtek Bulk-Fill, Filtek Bulk-Fill Flow, Tetric N-Ceram Bulk-Fill, and Tetric N-Flow Bulk-Fill, and also a conventional composite Filtek Z350 XT as a control group. One hundred cylinders were manufactured in a matrix with 4.7mm diameter and 4mm height for Bulk-Fill compounds, and 2mm height for the control group. Half of the specimens of each material was photopolymerized for 10 seconds and the other half for 20 seconds (n = 10). The samples were stored in distilled water for 48 hours at 37°C and subjected to compression testing in a universal test machine. Variance analysis was performed with t-test of multiple comparisons between groups and student t-test for the different polymerization times with significance index p=0.05. The results did not show statistically significant difference in relation to polymerization time. However, there was a statistically significant difference between the control and Filtek Bulk-Fill Flow groups, which presented higher strenght to compression than the Filltek Bulk-Fill, Tetric N-Ceram Bulk-Fill, and Tetric N-Flow Bulk-Fill groups. The type of resin can influence its resistance to fracture. The polymerization time did not have any influence in the materials strength.
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Monteiro, Jaiane Bandoli, Ricardo Toledo Abreu, Lívia Salgado, Thais Cachuté Paradella, Ivone De Oliveira Salgado e Renato Cilli. "Effect of shear bond strength of metallic orthodontic brackets bonded with and without dental adhesive". Brazilian Dental Science 21, n. 4 (24 ottobre 2018): 395. http://dx.doi.org/10.14295/bds.2018.v21i4.1597.
Testo completoAbstract (sommario):
<p><strong>Objective</strong>: The aim of this study was to evaluate the shear bond strength (SBS) of two materials for bonding orthodontic brackets on dental enamel before and after thermocycling. <strong>Material and Methods: </strong>Forty bovine incisors were divided into four groups (n=10). All teeth were etched with 35% phosphoric acid (3M Espe). For bonding of the brackets, G1 and G2 received orthodontic composite resin (Fill Magic Ortodôntico) and G3 and G4, an adhesive (ScotchBond) was used before the orthodontic resin Transbond XT (3M Unitek). G1 and G3 were kept at 37ºC for 24h and G2 and G4 were submitted to thermocycling (5000 cycles, at 5ºC - 55ºC) prior to SBS testing, performed by a universal machine (EMIC) at 1 mm/min, with a 50kgf load cell. Results were analyzed with two-way ANOVA, followed by Tukey's test (p=0.05). Adhesive surfaces were evaluated through stereomicroscopy and classified according to the type of failure presented. <strong>Results</strong>: Surface treatment with dental adhesive presented higher SBS values, regardless thermocycling (G3: 12.01 MPa; G4: 12.36 MPa) and the lowest values occurred in G2 (8.89 MPa). For groups without adhesive and with thermocycling, a higher number of completely adhesive failures between composite and enamel were present. For groups in which dental adhesive was used, regardless thermocycling, the failures were mainly adhesive between composite and the bracket. <strong>Conclusion</strong>: Surface etching of enamel with 35% phosphoric acid with or without adhesive showed a positive effect on SBS. The application of adhesive on enamel surface contributed to the maintenance of SBS values after thermocycling.</p><p> </p><p><strong>Keywords</strong></p><p>Aging; Orthodontic brackets; Composite resins; Shear strength.</p>
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Kati, Firas Abd. "Effects of chemical disinfectants on surface hardness of heat -cured acrylic resins. In vitro study". Journal of Oral Research 10, n. 6 (31 dicembre 2021): 1–6. http://dx.doi.org/10.17126/joralres.2021.074.
Testo completoAbstract (sommario):
Introduction: Acrylic resins (i.e., heat cured acrylic resins) are the most common materials used to manufacture removable dental prostheses involving maxillofacial prostheses such as obturators. Their mechanical and physical properties must be adequate for their use and durability. It is therefore vital to assess how their properties are affected by different disinfectants. Aims: The purpose of this research was to evaluate the effect of chemical disinfectants on surface hardness of the acrylic resins. Material and Methods: Forty specimens (65 mm in length, 10 mm in width and 2.5 mm thick) were manufactured from heat cured acrylic resins for hardness testing according to ISO 1567:1999. The study consisted of four main sets according to the disinfectants applied (control, 1% hypochlorite, 4 % chlorhexidine, and Efferdent®) and each set contained ten specimens. All specimens were placed in saline solution at 37°C and incubated for 60 days. Acrylic specimens were then tested by using a hardness tester three times and the average reading was recorded. All data were analyzed using SPSS version 16. The results were analyzed at a significant level (p≤0.05). The ANOVA (analysis of variance) test was used to assess whether there were any significant differences among all groups. The comparisons between means were obtained by using a Tukey test. Results: There was a slight decrease in the mean values of surface hardness after immersing in chemical disinfectants. The chlorhexidine-assigned specimens had the lowest value of mean surface hardness. On the other hand, the control group had the highest mean value. However, there were no significant differences regarding surface hardness among all groups (p>0.05). Conclusion: The use of chemical disinfectants slightly decreases the surface hardness of heat-cured acrylic resins.
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Valizadeh, Sara, Elham Farhadi, Aida Moradi e Sedighe S. Hashemikamangar. "Evaluation of the Effect of Cold Plasma Treatment on the Microshear Bond Strength of Composite Resin Restorations to Dentin using Different Adhesive Systems and the Effect of Thermocycling". Open Dentistry Journal 15, n. 1 (31 dicembre 2021): 734–41. http://dx.doi.org/10.2174/1874210602115010734.
Testo completoAbstract (sommario):
Introduction: Currently, non-thermal plasma is used to modify the enamel and dentin surfaces to improve the bonding surface to dental composite resins. Non-thermal plasma creates a hydrophilic surface, decreases the contact angle, and improves the bonding quality. The present study aimed to evaluate the microshear bond strength (µSBS) of composite resins to dentin using different adhesive systems. Materials and Methods: Bovine incisor teeth were randomly assigned to three groups of G-Premio, Clearfil SE Bond, and Adper Single Bond adhesive groups after preparation. Each group was divided into two subgroups in terms of argon plasma surface preparation, and each subgroup was divided into two groups in terms of thermocycling (n=12). The microshear bond strength of the samples was determined using a universal testing machine. Three-way ANOVA was used to analyze the effect of the adhesive, plasma preparation, and thermocycling. Post hoc Tukey tests were used for two-by-two comparisons of µSBS. Statistical significance was set at P <0.05. Results: The results of the µSBS test showed that the application of plasma resulted in a significant increase in the mean µSBS in the G-Premio group, with no significant increase in the Clearfil SE bond and Adper Single groups. The effect of thermocycling after plasma application was significant only in the Adper Single group. Conclusion: The application of plasma might increase the bond strength of composite resins to dentin. However, further studies are necessary.
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Sahebalam, Rasoul, Alireza Boruziniat, Fahimeh Mohammadzadeh e Abdolrasoul Rangrazi. "Effect of the Time of Salivary Contamination during Light Curing on Degree of Conversion and Microhardness of a Restorative Composite Resin". Biomimetics 3, n. 3 (22 agosto 2018): 23. http://dx.doi.org/10.3390/biomimetics3030023.
Testo completoAbstract (sommario):
Saliva contamination is a major clinical problem in restorative procedures. The purpose of this study was to evaluate the effect of the time of salivary contamination during light curing on the degree of conversion and the microhardness of a restorative composite resin. Eight groups of 10 samples for measuring the microhardness and eight groups of 5 samples for evaluating the degree of conversion were prepared. The samples of each group were contaminated with human saliva at a certain time. The first group (T0) was contaminated before light curing. The specimens in groups T2–T30 were contaminated at 2, 5, 10, 15, 20 and 30 s after the start of light curing, respectively. The samples of group T40 were contaminated after light curing. The degree of conversion and the microhardness of the specimens were measured by Fourier transform infrared (FTIR) spectroscopy and Vickers hardness testing techniques, respectively. The results of this study revealed that there were no significant differences between the groups in terms of the degree of conversion of the composite resin. Consistent with the findings for the degree of conversion, significant differences in the microhardness between the groups were not found. In conclusion, from a clinical point of view, the results of our study showed that the time of salivary contamination (before, during or after light curing of composite resin) has no significant effect on the polymerization (degree of conversion) and one of the important mechanical properties of dental composite resins (microhardness).
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Scaminaci Russo, Daniele, Francesca Cinelli, Chiara Sarti e Luca Giachetti. "Adhesion to Zirconia: A Systematic Review of Current Conditioning Methods and Bonding Materials". Dentistry Journal 7, n. 3 (1 agosto 2019): 74. http://dx.doi.org/10.3390/dj7030074.
Testo completoAbstract (sommario):
Background. Reliable bonding between resin composite cements and high strength ceramics is difficult to achieve because of their chemical inertness and lack of silica content that makes etching impossible. The purpose of this review is to classify and analyze the existing methods and materials suggested to improve the adhesion of zirconia to dental substrate by using composite resins, in order to explore current trends in surface conditioning methods with predictable results. Methods. The current literature, examining the bond strength of zirconia ceramics, and including in vitro studies, clinical studies, and a systematic review, was analyzed. The research in the literature was carried out using PubMed and Cochrane Library databases, only papers in English, published online from 2013 to 2018. The following keywords and their combinations were used: Zirconia, 3Y-TZP, Adhesion, Adhesive cementation, Bonding, Resin, Composite resin, Composite material, Dentin, Enamel. Results. Research, in PubMed and Cochrane Library databases, provided 390 titles with abstracts. From these, a total of 93 publications were chosen for analysis. After a full text evaluation, seven articles were discarded. Therefore, the final sample was 86, including in vitro, clinical studies, and one systematic review. Various adhesive techniques with different testing methods were examined. Conclusions. Airborne-particle abrasion and tribo-chemical silica coating are the pre-treatment methods with more evidence in the literature. Increased adhesion could be expected after physico-chemical conditioning of zirconia. Surface contamination has a negative effect on adhesion. There is no evidence to support a universal adhesion protocol.
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Sodagar, Ahmad, Mohamad Sadegh Ahmad Akhoundi, Abbas Bahador, Yasamin Farajzadeh Jalali, Zahra Behzadi, Farideh Elhaminejad e Amir Hossein Mirhashemi. "Effect of TiO2 nanoparticles incorporation on antibacterial properties and shear bond strength of dental composite used in Orthodontics". Dental Press Journal of Orthodontics 22, n. 5 (ottobre 2017): 67–74. http://dx.doi.org/10.1590/2177-6709.22.5.067-074.oar.
Testo completoAbstract (sommario):
ABSTRACT Introduction: Plaque accumulation and bond failure are drawbacks of orthodontic treatment, which requires composite for bonding of brackets. As the antimicrobial properties of TiO2 nanoparticles (NPs) have been proven, the aim of this study was to evaluate the antimicrobial and mechanical properties of composite resins modified by the addition of TiO2 NPs. Methods: Orthodontics composite containing 0%, 1%, 5% and 10% NPs were prepared. 180 composite disks were prepared for elution test, disk agar diffusion test and biofilm inhibition test to collect the counts of microorganisms on three days, measure the inhibition diameter and quantify the viable counts of colonies consequently. For shear bond strength (SBS) test, 48 intact bovine incisors were divided into four groups. Composites containing 0%, 1%, 5% and 10% NPs were used for bonding of bracket. The bracket/tooth SBS was measured by using an universal testing machine. Results: All concentration of TiO2 NPs had a significant effect on creation and extension of inhibition zone. For S. mutans and S. sanguinis, all concentration of TiO2 NPs caused reduction of the colony counts. Composite containing 10% TiO2 NPs had significant effect on reduction of colony counts for S. mutans and S. sanguinis in all three days. The highest mean shear bond strength belonged to the control group, while the lowest value was seen in 10% NPs composite. Conclusions: Incorporating TiO2 nanoparticles into composite resins confer antibacterial properties to adhesives, while the mean shear bond of composite containing 1% and 5% NPs still in an acceptable range.
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Morita, Aryan, H. Dedy Kusuma Yulianto, Susmira Delta Kusdina e Nunuk Purwanti. "Differences of Streptococcus mutans adhesion between artificial mouth systems: a dinamic and static methods". Dental Journal (Majalah Kedokteran Gigi) 49, n. 2 (14 febbraio 2017): 67. http://dx.doi.org/10.20473/j.djmkg.v49.i2.p67-70.
Testo completoAbstract (sommario):
Background: Various materials have been used for treating dental caries. Dental caries is a disease that attacks hard tissues of the teeth. The initial phase of caries is a formation of bacterial biofilm, called as dental plaque. Dental restorative materials are expected for preventing secondary caries formation initiated by dental plaque. Initial bacterial adhesion is assumed to be an important stage of dental plaque formation. Bacteria that recognize the receptor for binding to the pellicle on tooth surface are known as initial bacterial colonies. One of the bacteria that plays a role in the early stage of dental plaque formation is Streptococcus mutans (S. mutans). Artificial mouth system (AMS) used in bacterial biofilm research on the oral cavity provides the real condition of oral cavity and continous and intermittent supply of nutrients for bacteria. Purpose: This study aimed to compare the profile of S. mutans bacterial adhesion as the primary etiologic agent for dental caries between using static method and using artificial mouth system, a dinamic. method (AMS). Method: The study was conducted at Faculty of Dentistry and Integrated Research and testing laboratory (LPPT) in Universitas Gadjah Mada from April to August 2015. Composite resin was used as the subject of this research. Twelve composite resins with a diameter of 5 mm and a width of 2 mm were divided into two groups, namely group using static method and group using dynamic method. Static method was performed by submerging the samples into a 100µl suspension of 1.5 x 108 CFU/ml S. mutans and 200µl BHI broth. Meanwhile AMS method was carried out by placing the samples at the AMS tube drained with 20 drops/minute of bacterial suspension and sterile aquadest. After 72 hours, five samples from each group were calculated for their biofilm mass using 1% crystal violet and read by a spectrofotometer with a wavelength of 570 nm. Meanwhile, one sample from each group was taken for its surface image using Scanning Electron Microscope (SEM). Result: The results showed that S. mutans biofilm mass in the group using static method was 0.34, while in the group using AMS method was 0.09. The results of the statistical analysis then showed that there was a significant difference (p=0.02) in the formation of bacterial biofilm mass between those groups. SEM image in the group using static method also showed that the attachment of S. mutans was more numerous and had a longer chain than in the group using AMS method. Conclusion: There is a difference in the profile of S. mutans bacterial adhesion between using AMS method and static method.
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Mada, Diana Carla, Cristina Gasparik, Alexandra Iulia Irimie, Marius Dan Mada, Diana Dudea e Radu Septimiu Campian. "Evaluation of chromatic changes of a nanocomposite resin using the new whiteness index". Medicine and Pharmacy Reports 91, n. 2 (26 aprile 2018): 222–28. http://dx.doi.org/10.15386/cjmed-893.
Testo completoAbstract (sommario):
Background and aims. To evaluate the staining effects of two brands of coffee and the bleaching efficiency of two in-office bleaching methods, upon different opacities of a commercial nanocomposite.Methods. Twenty four specimens of each opacity, A3 Dentin, A3 Body and A3 Enamel, were fabricated from Filtek Supreme (3MEspe). The specimens were further divided into two groups (n=12) and were immersed in two coffee solutions (Bio Organic Coffee Bellarom, 100% Arabica, and Iulius Meinl Coffee), for 24 hours. Between the staining sessions, the specimens were stored in sterile water, at 37°C. Each group was further divided into three (n=4), in order to be bleached, as follows: Group 1 - Beyond 35% in office, for 4 applications of 15 minutes each, Group 2 – Zoom Day White 6% in office, for 4 applications of 15 minutes each, Group 3 – Control Group, stored in sterile water. Color values were measured with a dental spectrophotometer Vita EasyShade 4.0 and five measurements were recorded for each sample at a time. Lightness L*, color coordinates a* and b* were recorded, at baseline, after staining in coffee and after bleaching. Whiteness index (WID) of the three composite resins (A3D, A3B, A3E) in the three moments were calculated, as well as the color difference Delta E* correspondent to the staining and bleaching process. Data were analyzed using one-way repeated measures ANOVA and the WID index was calculated WID (p<0.05). Univariate analysis of variance was performed for assessing the influence of staining solution upon composite resins, as well as for testing the effect of bleaching agents. The significance level was set at α=0.05 and pairwise comparisons were adjusted by the Least Significant Difference method.Results. The pairwise comparisons showed no significant difference between the effects of the two bleaching agents upon the WID, meaning that they induce almost similar color changes. The results of the univariate ANOVA test indicated a significant effect of the composite resin and the staining solution upon the WID (p<0.05). However, no significant interaction effect was found between the composite resin and the staining solution (p=0.095). There was a significant difference in the staining effect of the two coffee solutions only for A3B and A3E composite resins (p<0.05).Conclusions. The chromatic changes of the nanocomposite resin could be evaluated by the variation of the whiteness index. The staining effect induced by the two types of coffee was similar. The most effective protocol was the in-office bleaching method based on Beyond 35%.
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Bilgrami, Afreen, Afsheen Maqsood, Mohammad Khursheed Alam, Naseer Ahmed, Mohammed Mustafa, Ali Robaian Alqahtani, Abdullah Alshehri, Abdullah Ali Alqahtani e Shahad Alghannam. "Evaluation of Shear Bond Strength between Resin Composites and Conventional Glass Ionomer Cement in Class II Restorative Technique—An In Vitro Study". Materials 15, n. 12 (17 giugno 2022): 4293. http://dx.doi.org/10.3390/ma15124293.
Testo completoAbstract (sommario):
The success of dental restorations depends mainly on the ability to bond to other filling materials and tooth substances, in order to resist the multitude of forces acting on the bond within the oral cavity. Although the shortcomings of composite resins have been significantly reduced over the past three decades, microleakage due to shrinkage under masticatory loads is unavoidable. In order to overcome such problems, two materials laminated with matched properties can be used to achieve optimum results. The sandwich technique is an approach in which dentine is replaced by glass ionomer cement (GIC), and enamel is replaced by composite resin. In the past, numerous materials have been proposed with adequate properties to be used in this manner, but the results are conflicting in terms of bonding to the various forms of GIC, and the appearance of microcracks or gap formation during functional loading. This study aimed to evaluate the shear bond strength (SBS) and mode of failure between the following core materials: composite resins (CR) (Methacrylate Z350™, Ceram X™, and Spectrum™) with a base material of glass ionomer cement (GIC, Ketac Molar™). Eight samples were made with the help of polytetrafluoroethylene sheets (TEFLON, Wilmington, DE, USA). Each sheet consisted of holes which were 4 mm in diameter and 2 mm in thickness. The combination of materials was sandwiched. The samples were stored in distilled water and then placed in an incubator for 24 h in order to ensure complete polymerization. The samples were thermocycled for 500 cycles between 5–55 °C/ 30 s. Following thermocycling, SBS testing was performed using a universal testing machine. Additionally, scanning electron microscopy (SEM) was performed on representative samples for the bond failure analysis between GIC and the composite resins. The Ceram-X™ nanocomposite showed significantly higher bond strength than Methacrylate Z350™ or Spectrum™ (p = 0.002). The Methacrylate Z350™ and the Spectrum™ composite specimens demonstrated a similar SBS (p = 0.281). The SBS of the Ceram X™ to GIC was the highest compared to Methacrylate Z350™ and Spectrum™. Therefore Ceram X™ may produce a better bond with GIC, and may protect teeth against recurrent caries and failure of the restoration. Methacrylate Z350™ is comparable to Spectrum™ CR and can be used as an alternative. A combination of adhesive and mixed failure was observed in Methacrylate Z350™ CR and GIC, while adhesive failure was predominantly found in both Ceram X™ and Spectrum™ with GIC restorations.
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Consani, Rafael Leonardo Xediek, Tatiane Marinho, Atais Bacchi, Ricardo Armini Caldas, Victor Pinheiro Feitosa e Carmem Silvia Pfeifer. "Repair Strength in Simulated Restorations of Methacrylate- or Silorane-Based Composite Resins". Brazilian Dental Journal 27, n. 4 (agosto 2016): 463–67. http://dx.doi.org/10.1590/0103-6440201600730.
Testo completoAbstract (sommario):
Abstract The study verified the bond strength in simulated dental restorations of silorane- or methacrylate-based composites repaired with methacrylate-based composite. Methacrylate- (P60) or silorane-based (P90) composites were used associated with adhesive (Adper Single Bond 2). Twenty-four hemi-hourglass-shaped samples were repaired with each composite (n=12). Samples were divided according to groups: G1= P60 + Adper Single Bond 2+ P60; G2= P60 + Adper Single Bond 2 + P60 + thermocycling; G3= P90 + Adper Single Bond 2 + P60; and G4= P90 + Adper Single Bond 2 + P60 + thermocycling. G1 and G3 were submitted to tensile test 24 h after repair procedure, and G2 and G4 after submitted to 5,000 thermocycles at 5 and 55 ?#61616;C for 30 s in each bath. Tensile bond strength test was accomplished in an universal testing machine at crosshead speed of 0.5 mm/min. Data (MPa) were analyzed by two-way ANOVA and Tukey's test (5%). Sample failure pattern (adhesive, cohesive in resin or mixed) was evaluated by stereomicroscope at 30?#61655; and images were obtained in SEM. Bond strength values of methacrylate-based composite samples repaired with methacrylate-based composite (G1 and G2) were greater than for silorane-based samples (G3 and G4). Thermocycling decreased the bond strength values for both composites. All groups showed predominance of adhesive failures and no cohesive failure in composite resin was observed. In conclusion, higher bond strength values were observed in methacrylate-based resin samples and greater percentage of adhesive failures in silorane-based resin samples, both composites repaired with methacrylate-based resin.
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Tanjung, Steven, Rudy Djuanda e Angela Evelyna. "Perbedaan Kekuatan Geser Perlekatan (Shear Bond Strength) Antara Self – Adhering Flowable Composite dan Flowable Composite dengan Sistem Adhesif Self – Etch pada Dentin". SONDE (Sound of Dentistry) 4, n. 1 (4 luglio 2019): 16–25. http://dx.doi.org/10.28932/sod.v4i1.1767.
Testo completoAbstract (sommario):
Restoration is a treatment to restore the structure of missing dental hard tissue due to caries. Flowable composite has good adaptability to the cavity wall so that it is widely used as an intermediate layer. Composite resins require an adhesive system to bond chemically with dental hard tissue. Self - adhering flowable composite combining etching, priming, and adhesive in one flowable package. This study was conducted with the aim to determine the difference in shear bond strength between Self – adhering flowable composite and flowable composite with self – etch adhesive system on dentine. The number of samples used was 38 pieces. After dentin was prepared and fixed, samples was divided into 2 groups, each group consisting of 19 samples. First group was applied with self – adhering flowable composite, second group was applied with flowable composite with self – etch adhesive system. Samples was immersed in pH 6.8 normal saline and stored for 24 hours, then dried and shear bond strength was tested using a universal testing machine. The data obtained were analyzed using independent t – test. The statistical analysis using independent t – test showed that there were significant differences in the shear bond strength between the two groups, p=0,000 (p<0.05). The study concluded that there is difference of shear bond strength between self – adhering flowable composite and flowable composite with self – etch adhesive system on dentine.
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Darzé, Fernanda Medeiros, Flávia Lucisano Botelho do Amaral, Fabiana Mantovani Gomes França, Cecília Pedroso Turssi e Roberta Tarkany Basting. "Effect of 10% sodium bicarbonate on bond strength of enamel and dentin after bleaching with 38% hydrogen peroxide". Revista de Odontologia da UNESP 44, n. 5 (6 ottobre 2015): 257–61. http://dx.doi.org/10.1590/1807-2577.1073.
Testo completoAbstract (sommario):
AbstractIntroductionBy-products of hydrogen peroxide degradation released during dental bleaching influence the polymerization of adhesive systems and composite resins, causing a reduction in shear bond strength to the tooth.Objectivethe aim of this article was to evaluate the effect of 10% sodium bicarbonate (SB), applied for different lengths of time, on the shear bond strength to enamel and dentin after bleaching.Material and methodEnamel and dentin blocks were divided into groups (n=10): (1) control: no bleaching; (2) immediate: bleaching immediately followed by restoration; (3) 14-day: bleaching, restoration 14 days later; (4) SB for 10 minutes: bleaching, SB gel for 10 minutes, immediately followed by restoration; (5) SB for 20 minutes: bleaching, SB gel for 20 minutes, immediately followed by restoration. A 38% hydrogen peroxide gel (Opalescence Boost/Ultradent) was used. After application of the adhesive system, composite resin cylinders were mounted on the surface of the substrates in order to test shear bond strength. Result: ANOVA and Tukey tests showed significantly higher mean enamel bond strength values for the 14-day follow-up group and without significant differences for control group. Mean bond strength values obtained for the other groups were intermediate. When testing dentin, the Tukey test revealed a significantly higher mean bond strength value for the 14-day follow-up group when compared with application of SB for 20 minutes.ConclusionSB gel applied was unable to reverse the low bond strength to enamel and dentin after bleaching treatment.
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Ranganath, LM, Ajay Gaikwad, Saket K. Jain e Kapil S. Pal. "Evaluation of Flexural Strength of Polymethyl Methacrylate modified with Silver Colloidal Nanoparticles subjected to Two Different Curing Cycles: An in vitro Study". Journal of Contemporary Dental Practice 19, n. 3 (2018): 262–68. http://dx.doi.org/10.5005/jp-journals-10024-2249.
Testo completoAbstract (sommario):
ABSTRACT Aim Silver colloidal nanoparticles have been incorporated into acrylic resins to induce antimicrobial properties. However, as additives, they can influence the mechanical properties of the final product. Mechanical properties are also dependent on different curing cycles. The aim of this study was to evaluate flexural strength of a denture base resin incorporated with different concentrations of silver colloidal nanoparticles subjected to two different curing cycles. Materials and methods Lucitone 199 denture base resin was used into which silver colloidal nanoparticles were incorporated at 0.5 and 5% by polymer mass. Specimens devoid of nanoparticles were used as controls. A total of 60 specimens were fabricated and divided into two groups. Each group was divided into three subgroups consisting of 10 specimens each. The specimens were fabricated according to American Dental Association (ADA) specification No. 12 and tested for flexural strength using universal testing machine. Results Silver colloidal nanoparticle incorporation at 0.5% concentration increased the mean flexural strength in both curing cycles by 7.5 and 4.4%, respectively, when compared with the control group. Conclusion The study suggested that the mean flexural strength value of 0.5% silver colloidal nanoparticles in denture base resin was above the value of the control group both in short and long curing cycles, which makes it clinically suitable as a denture base material. However, at 5% concentration, the statistically significant amount of decrease in flexural strength compared with the value of control group both in short and long curing cycles gives it a questionable prognosis. Clinical significance The specimens incorporated with the antimicrobial agent 0.5% silver colloidal nanoparticles and processed by long curing cycles showed significant increase in its flexural strength compared with the control group, which makes it clinically suitable as a denture base material. How to cite this article Munikamaiah RL, Jain SK, Pal KS, Gaikwad A. Evaluation of Flexural Strength of Polymethyl Methacrylate modified with Silver Colloidal Nanoparticles subjected to Two Different Curing Cycles: An in vitro Study. J Contemp Dent Pract 2018;19(3):262-268.
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Malara, P., A. Pasieka, K. Paluch e K. Sobolewska. "Assesment of the binding strength of selected bonding systems used for cementation of implantoprosthetic suprastructures". Journal of Achievements in Materials and Manufacturing Engineering 1, n. 80 (2 gennaio 2017): 18–24. http://dx.doi.org/10.5604/01.3001.0010.1443.
Testo completoAbstract (sommario):
Purpose: of this paper is the assessment of the strength of binding of selected bondingsystems used for fixing prosthetic works. The characteristics of cement materials used forsettling the crowns on the implant abutments were also included. The study has presentedthe evaluation of the binding strength of selected bonding systems used for fixed prostheticworks.Design/methodology/approach: Metal substructures of single-unit cement-retainedcrown were designed and manufactured using CAD/CAM technology. Created wax modelswere changed to metal substructures and settled on the abutments attached to implantreplicas with a group of commonly used dental cements. The binding strength was testedon Zwick Z 100 static tensile testing machine.Findings: It was found that MaxCem is the strongest material among the tested cementswhich can withstand the force of 175 N. Double cured cements containing the resins maywithstand very high tensile strengths which can be a problem when the crown needs to betaken off. The bonding strength of the dental cements can be influenced by the width of thefilm, its thickness, even distribution of the cement between the crown and the abutment andthe setting time. The higher the viscosity of the cement, the lower the retention of the crownon the implant abutment.Research limitations/implications: In order to limit the designing and manufacturingerrors the whole technological process should be carried out with CAD/CAM technology.The cement should be evenly distributed inside the metal cup to prevent from creation ofempty spaces between the crown and the abutment. It may be necessary to design andmanufacture special holders to maintain the samples in the testing machine to minimalizethe risk of creation initial tensile forces.Practical implications: The research gives an insight into the possibilities of choosingthe cement for bonding the crown onto the implant abutment preserving the connectionbetween the bone and the implant in case of necessity of the removal of the crown.Originality/value: The research is focused on the binding strength of the cements mostcommonly used for settling the crowns on the implant abutments. It hel