Letteratura scientifica selezionata sul tema "Dental resins Testing"
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Articoli di riviste sul tema "Dental resins Testing"
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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.
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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.
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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.
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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.
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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.
Tesi sul tema "Dental resins Testing"
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Dhanpal, Prashanth Kumar. "Water sorption and resin hydrophilicity of dentin bonding agents". Thesis, Click to view the E-thesis via HKUTO, 2007. http://sunzi.lib.hku.hk/hkuto/record/B39839503.
Testo completo
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Berekally, Thomas L. "Some aspects of Maryland Bridge treatments : an 'in-vivo' and 'in-vitro' study". Title page, contents and summary only, 1989. http://web4.library.adelaide.edu.au/theses/09DM/09dmb487.pdf.
Testo completo
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黃翠 e Cui Huang. "Physical and mechanical properties of some resin-based restorative materials after immersion in two different media". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2001. http://hub.hku.hk/bib/B38628090.
Testo completo
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Raposo, Luís Henrique Araújo 1985. "Critical assessment of mechanical tests parameters for dental materials testing = laboratory and finite element analysis = Avaliação crítica dos parâmetros de ensaios mecânicos envolvendo materiais odontológicos: análise laboratorial e por elementos finitos". [s.n.], 2013. http://repositorio.unicamp.br/jspui/handle/REPOSIP/289562.
Testo completoAbstract (sommario):
Orientador: Lourenço Correr SobrinhoTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba
Made available in DSpace on 2018-08-22T13:42:04Z (GMT). No. of bitstreams: 1 Raposo_LuisHenriqueAraujo_D.pdf: 2958780 bytes, checksum: ecb4c3af4c9972ae8898f1429fd0e8b5 (MD5) Previous issue date: 2013
Resumo: Ensaios mecânicos laboratoriais são essenciais no estudo e desenvolvimento dos materiais odontológicos restauradores, como forma de predizer o comportamento clínico dos mesmos frente às variadas condições existentes no meio oral. Apesar das condições encontradas in vivo dificilmente serem inteiramente representadas in vitro, o completo entendimento dos fatores que impactam o protocolo dos testes é determinante na análise dos resultados. Entretanto, muitos dos testes utilizados para caracterização dos materiais restauradores não são realizados nos padrões necessários, levando a resultados ambíguos para materiais similares, além de dificultar a comparação implementação dos mesmos. O objetivo deste estudo foi avaliar o efeito de diferentes parâmetros empregados em ensaios mecânicos utilizados no teste de materiais odontológicos restauradores para obtenção de propriedades mecânicas ou verificação da resistência de união. Assim, variadas configurações do ensaio de flexão de três pontos e do teste de microcisalhamento foram analisadas de maneira crítica. Pode-se concluir que as modalidades de ensaios mecânicos testadas necessitam de melhor padronização para que os resultados obtidos apresentem menor discrepância e consequentemente maiores representatividade clínicos. A maior padronização dos ensaios mecânicos utilizados na caracterização dos materiais odontológicos permite melhor compreensão do comportamento mecânico dos mesmos, levando a um desenvolvimento mais controlado destes produtos, o que por sua vez, resultará em maior qualidade dos procedimentos reabilitadores
Abstract: Mechanical tests are essential for the study and development of restorative materials and to predict their clinical behavior facing the numerous conditions existing at the oral environment. Despite the situations found in vivo are hardly represented completely in vitro, the full comprehension of the factors that can affect the testing protocols is important for the analysis of laboratory assays. However, most of the tests used for characterizing restorative materials are not performed in the adequate manner, leading to ambiguous results for similar materials and challenging comparisons between materials, besides impairing their improvement. On this way, the present study aimed to evaluate the influence of different testing parameters employed in mechanical tests for obtaining the mechanical properties of dental materials or to check their bond strength. Thus, different three-point bending and microshear designs were evaluated. It was concluded that the mechanical testing modalities studied need better standardization in order to produce results with minimized discrepancies and consequently increased clinical importance. Well standardized mechanical tests for dental materials testing provide better understanding of their mechanical behavior, allowing more controlled development of these products and resulting in an increased quality for rehabilitative procedures
Doutorado
Materiais Dentarios
Doutor em Materiais Dentários
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Allen, James Henry. "A comparison of the enamel demineralization inhibition and shear bond strength of two orthodontic resins". Thesis, Birmingham, Ala. : University of Alabama at Birmingham, 2009. https://www.mhsl.uab.edu/dt/2009m/allen.pdf.
Testo completo
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Francisconi, dos Rios Luciana Fávaro, Marcela Pagani Calabria, Leslie Casas-Apayco, Heitor Marques Honório, Marcela Rocha De Oliveira Carrilho, José Carlos Pereira e Linda Wang. "Chlorhexidine does not improve but preserves bond strength to eroded dentin". American Journal of Dentistry, 2015. http://hdl.handle.net/10757/607304.
Testo completoAbstract (sommario):
El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado.PURPOSE: To evaluate the effect of aqueous solutions of chlorhexidine digluconate (CHX) in different concentrations on bond strength to eroded dentin up to 6 months, using normal dentin as a control. METHODS: Exposed flat dentin of extracted third molars was only ground with 600-grit SiC paper/1 minute (normal dentin - N), or subsequently eroded by a regular-cola soft-drink (eroded dentin - E). N and E were acid-etched, washed, dried and rehydrated with 1.5 μL, respectively, of distillated water (control - NC / EC); of 0.004% CHX (N0.004% / E0.004%); or of 2% CHX (N2% / E2%). Adper Single Bond 2 was applied in all specimens and resin composite buildups were constructed with Filtek Z350. Specimens were sectioned in beams, which were tested (μTBS) immediately or after 6 months of aging. RESULTS: Microtensile bond strength to eroded dentin was always significantly lower than that to normal dentin. Application of tested CHX solutions did not exert a significant effect immediately; however, after aging, the 2% CHX prevented abrupt bond strength loss both to eroded and normal dentin.
Revisión por pares
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Nguyen, San Boi. "Development and use of a miniature ultrasonic pulser receiver". Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=112581.
Testo completoAbstract (sommario):
The field of restorative dentistry and the problem of ultrasonic airframe corrosion in aerospace are introduced as motivation for the construction of a miniature ultrasonic pulser/receiver.A broadly applicable ultrasonic pulser and receiver system is developed. Two pulsers, a 5V square and a 100V spike, and a 52dB amplifier with a 57MHz 6dB bandwidth were constructed as a result. These battery powered devices are tailored for compatibility with a custom built wireless data transmission system, also driven by the same voltage. It is demonstrated that the new pulser/receiver is comparable to the commercial system in performance in certain areas.
The new pulsers/receiver and a commercial one are used in this work. The data is acquired and analyzed using LabView and Matlab. It is shown that the ultrasonic technique can be used to follow the reaction in time as well as to gauge the cure of dental composites. The current work in ultrasonic airframe corrosion detection is furthered and the wireless system's functionality is affirmed.
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Kumar, Naresh. "Exploring the variability in mechanical property testing of dental resin composites". Thesis, University of Birmingham, 2011. http://etheses.bham.ac.uk//id/eprint/1494/.
Testo completoAbstract (sommario):
The invention of dental resin based-composites (RBCs) has provided a broad range of materials for the restoration of load-bearing posterior teeth with excellent clinical results and adequate longevity. Currently, a lack of consensus exists among researchers regarding classification of RBCs as a result of slight variations in filler size and associated interchangeable mechanical properties of “microhybrid”, “nanohybrid” and “nanofilled” RBCs. Also, the inconsistency in mechanical property testing of RBCs is evident amongst researchers. This research explored the variability in experimental and statistical testing methodologies of RBCs. The current study identified a wide variation in the bi-axial flexure strength (BFS) of commercial and experimental RBCs with respect to deformation rate with a complex relationship between resin constituents and filler morphology. Experimental unfilled resins revealed deformation rate dependence in BFS following 1 week dry, 1 and 13 weeks wet storage regimes, whereas the addition of fillers modified the deformation rate dependence following 13 weeks wet storage and resulted in the BFS of filled resin composites being independent of testing speed. These findings suggested the need for the development of RBCs with appropriate formulations for clinical situations where variable strain rates may occur, for example, patients with parafunctional habits. To date, the alignment of specimens during storage regimes prior to mechanical property testing has rarely been reported. The effect of specimen alignment on the BFS and surface hardness of RBCs was evaluated and a greater decrease in the both properties were found following wet upright compared with stacked and upper surface exposed alignments. These observations were attributed to a variation in diffusion of water as the result of difference in exposed surface areas of specimens, which may lead to different findings and associated interpretation between investigators. Weibull statistics are used for the analysis of strength data of RBCs, however their applicability to RBCs might be questioned due to some viscous deformation prior to brittle failure. The findings of current study supported the applicability of Weibull statistics for the microhybrid and nanofilled RBCs but not a flowable RBC, which suggested that Weibull statistics may not necessarily be applicable for all RBC types. It was demonstrated that variability and irrelevance in testing methods may cause incorrect interpretation of data among researchers and consequently affect the future research and development of RBCs. Therefore, further standardisation of testing methods is required.
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Najib, Farrah Huthail. "Endodontic sealers their properties and effects on fiber post retention /". Thesis, Birmingham, Ala. : University of Alabama at Birmingham, 2008. https://www.mhsl.uab.edu/dt/2008m/najib.pdf.
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Jelena, Vuletić Rakić. "Испитивање биокомпатибилности објеката од полимера произведених адитивном технологијом за примену у области стоматологије". Phd thesis, Univerzitet u Novom Sadu, Medicinski fakultet u Novom Sadu, 2016. http://www.cris.uns.ac.rs/record.jsf?recordId=101372&source=NDLTD&language=en.
Testo completoAbstract (sommario):
Uobičajeni pristup i testiranju biološkog ponašanja materijala je da se počne sa jednostavnim in vitro testovima baziranim na ćelijskim kulturama. In vitro testovi citotoksičnosti su danas jedan od osnovnih načina za procenu biološkog odgovora na materijal jer su brži, lakši za ponavljanje, ocenjivanje i jeftiniji u odnosu na eksperimente koji se izvode na životinjama i ljudima. Koriste se kao neka vrsta skrining testova za procenu biološke sigurnosti materijala. Za razliku od ćelijskih kultura, istraživanja koja uključuju eksperimentalne životinje pružaju bolji uvid u biokompatibilnost materijala, zbog mogućnosti praćenja kompleksnog imunološkog odgovora živog organizma. Smatraju se neophodnim za ocenu biloških odgovora na novi materijal, pre nego što se on upotrebi na ljudima. Mnogi aspekti biološkog odgovora ne mogu biti reprodukovani in vitro testovima uključujući krvne interakcije, zarastanje rana, reakcije preosetljivosti, karcinogenezu, hroničnu inflamaciju. Eksperimenti na životinjama pružaju informacije o ovim tipovima efekata bez izlaganja ljudi riziku. Cilj ovog istraživanja bio je da se oceni biokompatibilnost objekata od polimera na bazi epoksi smole Accura® ClearVue™ (hemijski sastav: 4,4’- izopropilidendicikloheksanol, produkti oligomerne reakcije sa 1-hlor-2,3- epoksipropanom(40-65%), smešа triaril-sulfonijum soli (50% propilen-karbonata i 50% triaril-sulfonijum heksafluoroantimonatnih soli) (1-10%) i 3-etil-3hidroksimetil-oksetan(10-20%). U oceni citotoksičnosti materijala Accura® ClearVue™ korišćeni su agar diguzioni i MTT test. Oba testa rađena sun a ćelijskim kulturama L929 (mišiji fibroblasti) i MRC-5 (humani fibroblasti). Ocena biokompatibilnosti testiranog materijala vršena je na osnovu urađenog testa iritacije oralne mukoze na modelu bukalne kesice hrčka, što je definisano standardom ISO 10993-10:2010. Biokompatibilnost materijala ispitana je i implantacijom uzoraka u potkožno tkivo dorzuma pacova soja Wistar.Uobičajeni pristup i testiranju biološkog ponašanja materijala je da se počne sa jednostavnim in vitro testovima baziranim na ćelijskim kulturama. In vitro testovi citotoksičnosti su danas jedan od osnovnih načina za procenu biološkog odgovora na materijal jer su brži, lakši za ponavljanje, ocenjivanje i jeftiniji u odnosu na eksperimente koji se izvode na životinjama i ljudima. Koriste se kao neka vrsta skrining testova za procenu biološke sigurnosti materijala. Za razliku od ćelijskih kultura, istraživanja koja uključuju eksperimentalne životinje pružaju bolji uvid u biokompatibilnost materijala, zbog mogućnosti praćenja kompleksnog imunološkog odgovora živog organizma. Smatraju se neophodnim za ocenu biloških odgovora na novi materijal, pre nego što se on upotrebi na ljudima. Mnogi aspekti biološkog odgovora ne mogu biti reprodukovani in vitro testovima uključujući krvne interakcije, zarastanje rana, reakcije preosetljivosti, karcinogenezu, hroničnu inflamaciju. Eksperimenti na životinjama pružaju informacije o ovim tipovima efekata bez izlaganja ljudi riziku. Cilj ovog istraživanja bio je da se oceni biokompatibilnost objekata od polimera na bazi epoksi smole Accura® ClearVue™ (hemijski sastav: 4,4’- izopropilidendicikloheksanol, produkti oligomerne reakcije sa 1-hlor-2,3- epoksipropanom(40-65%), smeša triaril-sulfonijum soli (50% propilen-karbonata i 50% triaril-sulfonijum heksafluoroantimonatnih soli) (1-10%) i 3-etil-3hidroksimetil-oksetan(10-20%). U oceni citotoksičnosti materijala Accura® ClearVue™ korišćeni su agar diguzioni i MTT test. Oba testa rađena sun a ćelijskim kulturama L929 (mišiji fibroblasti) i MRC-5 (humani fibroblasti). Ocena biokompatibilnosti testiranog materijala vršena je na osnovu urađenog testa iritacije oralne mukoze na modelu bukalne kesice hrčka, što je definisano standardom ISO 10993-10:2010. Biokompatibilnost materijala ispitana je i implantacijom uzoraka u potkožno tkivo dorzuma pacova soja Wistar.
The usual approach in testing biological behavior of materials is to start with simple in vitro tests based on cell cultures. In vitro cytotoxicity tests are one of the basic methods of assessing the biological response to material because they are faster, cheaper, easier for repeating and evaluating compared to experiments carried out on animals and humans. They are used as a kind of screening test for evaluating the biosafety of materials. Unlike cell culture, studies involving experimental animals provide better insight into the biocompatibility of materials due to the possibility of monitoring the complex immune response of a living organism. They are considered necessary for assessing the biological response to new material before it is used on humans. Many aspects of a biological response cannot be reproduced with in vitro tests, including blood interaction, wound healing, hypersensitivity reactions, carcinogenesis, chronic inflammation. Animal experiments provide information about these types of effects without exposing humans to risk. The aim of this study was to evaluate the biocompatibility of polymer objects on the basis of epoxy resins Accura® ClearVue ™ (chemical composition: 4.4' Isopropylidenedicyclohexanol, oligomeric reaction products with 1-chloro-2.3-epoxypropane (40-65%), a mixture of triaryl sulfonium salt (50% propylene carbonate and 50% of a triarylsulfonium hexafluoroantimonate salt) (1- 10%) and 3-ethyl-3-hydroxymethyl-oxetane (10-20%). In the assessment of the cytotoxicity of materials Accura® ClearVue ™ agar diffusion and MTT tests were used. Both tests were conducted on cell cultures L929 (mouse fibroblasts) and MRC-5 (human fibroblasts). An assessment of the biocompatibility of the tested material was done on the basis of an oral mucosa irritation test on a hamster cheek pouch as defined by ISO 10993-10: 2010. The biocompatibility of the material was also tested with the implantation of a samples into the dorsal subcutaneous tissue of a Wistar rats. The subcutaneous implantation test, as one of the most reliable methods for assessing the biocompatibility of dental materials, is defined by ISO 10993-6: 2010. The study was conducted on 30 rats which were sacrificed in groups
Atti di convegni sul tema "Dental resins Testing"
1
Raines, Regan, e Roozbeh (Ross) Salary. "Investigation of the Effects of Photopolymer Resin Composition on the Mechanical Properties of Complex Dental Constructs, Fabricated Using Digital Light Processing". In ASME 2022 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/imece2022-95049.
Testo completoAbstract (sommario):
Abstract The overarching goal of this research work is to fabricate mechanically robust, dimensionally accurate, and porous dental structures, potentially used for the treatment of dental fractures, anomalies, as well as structural deformities with a focus on oral and maxillofacial surgery applications. In pursuit of this goal, the objective of the work is to investigate the mechanical properties of dental constructs, composed of medical-grade photopolymer resins and fabricated using digital light processing (DLP) process. The fabricated dental constructs not only are porous, but also have complex microstructures imparted by triply periodic minimal surface (TPMS) designs. This study tests the following central hypothesis: the mechanical properties of DLP-fabricated dental structures are significantly affected by photopolymer resin composition. In addition, the following research question is answered in this study: which of the chosen medical-grade photopolymer resins has the most significant impact on the mechanical properties of fabricated dental structures. DLP is a vat-photopolymerization additive manufacturing process, which has emerged as a high-resolution, robust method for the fabrication of a broad range of biological tissues and constructs for oral and dental tissue engineering applications. In the DLP process, the printing process takes place on the basis of radiation-curable resins or liquid photopolymers. Upon exposure to UV light, the resin materials become a solid (via chemical transformation) through a process known as photopolymerization. The DLP process consists of several parameters (such as layer thickness, cure depth, and UV lamp intensity) that significantly influence the functional properties of fabricated dental structures. In spite of the advantages and engendered applications, DLP is inherently complex; the complexity of the DLP process, to a great extent, stems from complex physio-chemical phenomena (such as UV light photopolymerization) in addition to resin (photopolymer)-process interactions, which may adversely affect not only the surface morphology, but also the mechanical properties and ultimately the functional characteristics of the fabricated dental scaffolds. As a result, integrated physics-guided process and material characterization would be required for optimal fabrication of porous and complex dental structures. Particularly in this study, the influence of three medical-grade photopolymer resins on the compression properties as well as the dimensional accuracy of TPMS dental constructs is systematically investigated. The compression properties of the DLP-fabricated dental constructs are measured using a compression testing machine. Furthermore, the dimensional accuracy of the dental constructs is measured via physical measurements and with the aid of a laser scanner. Besides, analysis of variance (ANOVA) is utilized to identify statistically significant photopolymer resin(s). The outcomes of this study pave the way for high-resolution fabrication of complex and porous dental structures with tunable medical and functional properties.
2
Bolton, Brock, Vlado Semiga, Sanjay Tiku, Aaron Dinovitzer e Joe Zhou. "Full Scale Cyclic Fatigue Testing of Dented Pipelines and Development of a Validated Dented Pipe Finite Element Model". In 2010 8th International Pipeline Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/ipc2010-31579.
Testo completoAbstract (sommario):
Dents in buried pipelines can occur due to a number of potential causes; the pipe resting on rock, third party machinery strike, rock strikes during backfilling, amongst others. The long-term integrity of a dented pipeline segment is a complex function of a variety of parameters, including pipe geometry, indenter shape, dent depth, indenter support, pressure history at and following indentation. In order to estimate the safe remaining operational life of a dented pipeline, all of these factors must be accounted for in the analysis. The goal of the full scale experimental program described in this paper is to compile a database of full scale dent test results that encompasses many of the dent types seen in the field, including plain dents, dents interacting with girth and long seam welds, and dents interacting with metal loss features, in both the unrestrained and restrained condition. The dents are pressure cycled until a fatigue failure occurs in the dent. Typical data recorded includes indentation load/displacement curves, applied pressures, pipe wall OD strains along the axial and circumferential centerlines, and axial and circumferential dent profiles. The full scale tests are being performed on behalf of PRCI and US DoT. This paper is intended to show the matrix of dents considered to date and present a representative summary of the data recorded. In addition to presenting the full scale test program and resulting data, this paper summarizes ongoing efforts to develop a validated pipeline dent integrity assessment model. The model under development makes use of the aforementioned full scale experimental data, to validate a finite element model of the denting and re-rounding process for a variety of dent scenarios (i.e. depths, restraints, indenter sizes). The paper discusses the efforts under way to develop and validate the finite element model with the goal being to estimate the fatigue life. The paper is an extension of work discussed in a previously presented IPC paper [1].
3
Tiku, Sanjay, Vlado Semiga, Aaron Dinovitzer e Geoff Vignal. "Full Scale Cyclic Fatigue Testing of Dented Pipelines and Development of a Validated Dented Pipe Finite Element Model". In 2012 9th International Pipeline Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/ipc2012-90427.
Testo completoAbstract (sommario):
Dents in buried pipelines can occur due to a number of potential causes; the pipe resting on rock, third party machinery strike, rock strikes during backfilling, amongst others. The long-term integrity of a dented pipeline segment is a complex function of a variety of parameters, including pipe geometry, indenter shape, dent depth, indenter support, pressure history at and following indentation. In order to estimate the safe remaining operational life of a dented pipeline, all of these factors must be accounted for in the analysis. The paper discusses the full-scale dent testing being completed to support the development of pipeline integrity management criteria and is a continuation of the work discussed in previous IPC papers [1,2]. The material and structural response of the pipe test segments during dent formation and pressure loading has been recorded to support numerical model development. The full scale experimental testing is being completed for pipe test specimens in the unrestrained and restrained condition using different indentation depths and indenter sizes. The dents are pressure cycled until fatigue failure in the dent. This paper presents typical data recorded during trial including indentation load/displacement curves, applied pressures, strain gauges along the axial and circumferential centerlines, as well as dent profiles. The use of the full-scale mechanical damage test data described in this paper in calibrating and validating a finite element model based integrity assessment model is outlined. The details of the integrity assessment model are described along with the level of agreement of the finite element model with the full scale trial results. Current and future applications of the integrity assessment model are described along with recommendations for further development and testing to support pipeline integrity management.
4
Dinovitzer, Aaron, Sanjay Tiku e Mark Piazza. "Dent Assessment and Management: API Recommended Practice 1183". In 2020 13th International Pipeline Conference. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/ipc2020-9724.
Testo completoAbstract (sommario):
Abstract Pipeline dents can be developed from the pipe resting on rock, a third-party machinery strike, rock strikes during backfilling, amongst other causes. The long-term integrity of a dented pipeline segment is a complex function of a variety of parameters including pipe geometry, indenter shape, dent depth, indenter support, secondary features, and pipeline operating pressure history at and following indentation. In order to estimate the safe remaining operating life of a dented pipeline, all of these factors must be considered and guidelines for this assessment are not available. US DOT regulations (49 CFR 192 and 195) include dent repair and remediation criteria broadly based upon dent depth, dent location (top or bottom side), pressure cycling (liquid or gas), and dent interaction with secondary features (weld, corrosion, cracks). The criteria defined above are simple to use, however, they may not direct maintenance to higher risk dent features and be overly conservative or, in some cases, unconservative. PRCI, USDOT, CEPA and other full-scale testing, finite element modelling and engineering model development research has been completed to evaluate the integrity of pipeline dents. These results have demonstrated trends and limits in dent behavior and life that can improve on existing codified and traditional treatment of dents. With these research results a guideline for dent management can be developed to support operators develop and implement their pipeline integrity management programs. This paper provides an overview of the newly developed API recommended practice for assessment and management of dents (RP 1183). The RP considers dent formation strain, failure pressure and fatigue limit states including the effects of coincident features (i.e. welds, corrosion, cracks and gouges). This paper will focus on how pipeline operators can derive value from this step change in integrity management for dents. The paper describes the basis for the dent screening and integrity assessment tools included in the RP. This RP provides well founded techniques for engineering assessment that may be used to determine the significance of dent features, if remedial actions are required and when these actions should be taken.
5
Raines, Regan, James B. Day e Roozbeh (Ross) Salary. "Experimental Characterization of the Mechanical Properties of Medical-Grade Dental Implants, Fabricated Using Vat-Photopolymerization Additive Manufacturing Process". In ASME 2022 17th International Manufacturing Science and Engineering Conference. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/msec2022-85436.
Testo completoAbstract (sommario):
Abstract The overarching goal of this research work is to fabricate mechanically-robust and dimensionally-accurate dental implants for the treatment of dental fractures, anomalies, and structural deformities with a focus on oral and maxillofacial surgery applications. In pursuit of this goal, the objective of the work is to investigate the mechanical properties of several triply periodic minimal surface (TPMS) scaffolds, composed of a medical-grade photopolymer resin, fabricated using digital light processing (DLP) process. DLP is a vat-photopolymerization additive manufacturing process; it has emerged as a high-resolution method for the fabrication of a broad spectrum of biological tissues and constructs for tissue engineering applications. However, the DLP process is intrinsically complex; the complexity of the process stems from complex physiochemical phenomena (such as UV light photopolymerization) as well as resin (photopolymer)-process interactions, which may adversely influence the mechanical properties, the surface morphology, and ultimately the functional characteristics of fabricated dental scaffolds. Consequently, physics-based process and material characterization would be an inevitable need. In this study, several TPMS scaffolds (having complex internal geometries) were fabricated, based on a medical-grade photopolymer resin. The compression properties of the fabricated dental scaffolds were measured using a compression testing machine. In addition, the bioactivity of the scaffolds was assessed in a simulated body fluid (SBF). The outcomes of this study pave the way for the fabrication of complex dental implants with tunable medical and functional properties.
6
Tiku, Sanjay, Amin Eshraghi, Vlad Semiga, Luis Torres e Mark Piazza. "Improved Pipeline Dent Integrity Management". In 2016 11th International Pipeline Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/ipc2016-64530.
Testo completoAbstract (sommario):
Pipeline dents can be developed from the pipe resting on rock, a third party machinery strike, rock strikes during backfilling, amongst other causes. The long-term integrity of a dented pipeline segment depends upon parameters including pipe geometry, indenter shape, dent depth, indenter support, secondary features, and pipeline operating pressure history at and following indentation. US DoT and other standards include dent repair and remediation criteria broadly based upon dent depth, dent location (top or bottom side), pressure cycling (liquid or gas), and dent interaction with secondary features (weld, corrosion, cracks). These criteria are simple and easily applied, however, they may not direct maintenance appropriately and be overly conservative or, in some cases, unconservative. Previous IPC papers have discussed the full-scale dent fatigue testing and dent modelling efforts to support integrity management criteria development by collecting material and structural response during dent formation and pressure loading. The present paper will present the results of this extensive dent structural and fatigue life numerical simulation program using a validated finite element (FE) analysis process. The paper describes the numerical simulation technique, as well as, the development of the novel engineering tool for integrity management, eliminating the need for numerical simulation of individual dent features to assess the relative integrity threat they pose. The development of the engineering tool presented in this paper considers the dent formation, re-rounding and through life response to pressure fluctuations to evaluate the fatigue life of dent features. The results of these analyses are used to develop fatigue life trends based on dent shape, restraint condition and operating pressure. These trends were used to develop models to predict dent relative severity and life based upon ILI inspection dent shape data for single peak dents. Dent shape has also been used to determine the restraint condition of a dent and its influence on the dent feature fatigue life. The tools were developed to address many of the uncertainties inherent in existing regulatory repair and remediation criteria. Current and future applications of the integrity assessment model are described along with recommendations for further development and testing to support pipeline integrity management, industry guidelines and standards. The results of this research will be of use in improving integrity management decisions and support further development of industry guides and standards. As such the information presented in this paper will be of interest to pipeline operators, integrity management specialists, in-line inspection (ILI) organizations and regulators. The recommendations presented in this paper may be used to influence the direction of pipeline standards in their direction in the disposition of dent features.
7
Alexander, Chris, e Franz Worth. "Assessing the Use of Composite Materials in Repairing Mechanical Damage in Transmission Pipelines". In 2006 International Pipeline Conference. ASMEDC, 2006. http://dx.doi.org/10.1115/ipc2006-10482.
Testo completoAbstract (sommario):
Mechanical damage involving dents with gouges is one of the leading causes of transmission pipeline failures in terms of both static and cyclic pressure loading. Because of the severity of this defect type, pipeline companies are required to respond to these anomalies by either removing damaged sections or repair using welded sleeves. For more than 10 years, composite materials have been used to repair corroded pipelines and their use has gained wide acceptance across the pipeline industry. Numerous systems have been tested with results being presented in the open literature. Testing was recently performed to assess the use of a water-activated composite repair system, Aquawrap®, in terms of its ability to repair mechanical damage subjected to cyclic pressure service. The Aquawrap® repair system has been extensively tested on corrosion defects but testing on pipes with dents had not been done. The water activated pre-preg urethane resin system offers excellent long tern (creep-rupture) strength combined with easy low cost field installation. Pipes having diameter to wall thickness ratios ranging from 34 to 68 were fitted with dents and gouges. Repair involved removing the gouged material of the pipe after indentation and repairing using the composite sleeve. The result of this specific test program showed that on-average the fatigue life for mechanically-damaged pipes can be increased on the order of three orders of magnitude when repaired by grinding and installing composite sleeves. This paper provides details on the methodology of the test program, results, and most importantly, information that can be used by operators in repairing their pipeline systems.
8
Blyukher, Boris, Tadeusz Niezgoda, Jerzy Malachowski, Wieslaw Szymczyk, St Ochelski e A. Kiczko. "Laboratory Scale Experimental Simulation of a Pipe Rested on a Saddle Supporting System for Verification of Numerical Modeling". In ASME/JSME 2004 Pressure Vessels and Piping Conference. ASMEDC, 2004. http://dx.doi.org/10.1115/pvp2004-3001.
Testo completoAbstract (sommario):
The paper presents results of preliminary experimental and numerical tests over research and development of the numerical, FEM (Finite Elements Method) based method of pipeline strain/stress condition assessment with the use of data possessed from inline inspection tool. At the beginning, the research is focused on an example of a typical flaw which may be detected in oil or gas transporting pipeline by Geometry Measuring Pipeline Intelligent Gauge (Geo-PIG) during inline inspection. Such a typical flaws are dents and folds in the pipe which rests on a supporting concrete block or other type of saddle supporting system. The research method is based on numerical simulation and analysis. But it must be verified experimentally. For the needs of experimental verification of the numerical method tests were conducted at laboratory scale. Artificial dents, folds, and ovalizations were created with the use of material strength testing machine for samples of weldless thin walled pipe rested on specialized stand, simulating a saddle supporting system. The process of buckling during the three-point bending test took place close to the middle support with visible local buckling in the pipe wall. The experiment was conducted under the strict control, enabling measurements of deformations and strains in selected points located on external surface of the pipe wall. Since the Military University of Technology (MUT in Warsaw) itself is not a provider of inline surveys with the use of Pipeline Intelligent Gauge PIG), the substitutive equipment was used for deformation measurements on tested pipes with so called “digitizing arm” which was the analogue of the real inline inspection tool. The use of 3D digitizing arm was successful. The data collected with the use of this tool are coherent and may be used for verifications of FEM modeling. The preliminary numerical test models for the experiment simulation are also presented. The only disadvantage of laboratory tests was that they do not allow to conduct investigation on pressurized pipe for technical as well as for safety reasons. Experimental research on deformations and strains conducted for bent pipes will allow verifying strains and stress distributions obtained from numerical calculations. This will allow improving methods of numerical simulations.