Tesi sul tema "Dentistery"

The above factors emphasize the scope of this thesis for further investigations on zirconia, the improvement of all-ceramic zirconia restorations, and especially the interaction of zirconia and veneering and its influence on the performance of the whole restoration. The introduction, chapter 1, gave a literature overview on zirconia ceramics. In chapter 2, the objective of the study was to evaluate the effect of abrading before and after sintering using alumina-based abrasives on the surface of yttria-tetragonal zirconia polycrystals. Particular attention was paid to the amount of surface stress–assisted phase transformation (tetragonal→monoclinic) and the presence of microcracks. Chapter 3 is based on the idea that the conventional sintering techniques for zirconia based materials, which are commonly used in dental reconstruction, may not provide a uniform heating, with consequent generation of microstructural flaws in the final component. As a consequence of the sintering system, using microwave heating, may represent a viable alternative. The purpose of the study was to compare the dimensional variations and physical and microstructural characteristics of commercial zirconia (Y-TZP), used as a dental restoration material, sintered in conventional and microwave furnaces. Chapter 4 described the effect of sandblasting before and after sintering on the surface roughness of zirconia and the microtensile bond strength of a pressable veneering ceramic to zirconia.

The above factors emphasize the scope of this thesis for further investigations on zirconia, the improvement of all-ceramic zirconia restorations, and especially the interaction of zirconia and veneering and its influence on the performance of the whole restoration. The introduction, chapter 1, gave a literature overview on zirconia ceramics. In chapter 2, the objective of the study was to evaluate the effect of abrading before and after sintering using alumina-based abrasives on the surface of yttria-tetragonal zirconia polycrystals. Particular attention was paid to the amount of surface stress–assisted phase transformation (tetragonal→monoclinic) and the presence of microcracks. Chapter 3 is based on the idea that the conventional sintering techniques for zirconia based materials, which are commonly used in dental reconstruction, may not provide a uniform heating, with consequent generation of microstructural flaws in the final component. As a consequence of the sintering system, using microwave heating, may represent a viable alternative. The purpose of the study was to compare the dimensional variations and physical and microstructural characteristics of commercial zirconia (Y-TZP), used as a dental restoration material, sintered in conventional and microwave furnaces. Chapter 4 described the effect of sandblasting before and after sintering on the surface roughness of zirconia and the microtensile bond strength of a pressable veneering ceramic to zirconia.

Background: Clinical reasoning is the core competency of healthcare. It involves cognition and interaction with the environment to understand clinical situations, make diagnostic and therapeutic decisions, and address clinical problems. Defining competency in clinical reasoning is a difficult objective for dental educators because of our limited understanding of this phenomenon which compromises the validity of any curricular model and assessment method that have been used to date. Objectives: To describe the process and strategies of clinical reasoning used by dental clinicians across different levels of expertise to develop a conceptual framework for curricular design and assessment of competency. Methods: Using “think-aloud” method, I interviewed 18 dental students about biopsychosocial issues influencing oral health identified in 6 vignettes; and 8 orthodontic residents plus 11 orthodontists about problems of craniofacial growth and malocclusion presented in 2 vignettes. The interview transcripts were analyzed to explore the process and strategies of clinical reasoning used by the participants. Results: The reasoning process in both groups included: 1) a ritualistic approach to collect information for a treatment plan; 2) forward and backward reasoning to make and test hypotheses from clinical information; 3) pattern recognition and an integrated script of knowledge and experience triggered by related attributes of the script leading to a clinical diagnosis and plan; and 4) decision trees to evaluate treatment options and maximize the probability and utility of outcomes. Seven reasoning strategies (scientific, conditional, collaborative, narrative, ethical, pragmatic and “part-whole”) were used by both groups. However, experienced clinicians were more confident in their appraisal of uncertain situations and dilemmas as they integrated several reasoning strategies in the process; used refined scripts of knowledge and experience in familiar situations; and were able to reflect on the impact on their reasoning of the larger social, cultural and political context. Conclusions: Clinical reasoning in dentistry is a contextual and interactive phenomenon that requires integration of specific reasoning strategies to address the biopsychosocial factors influencing oral health. Expertise in clinical reasoning develops through continuous framing and solving problems to refine networks of knowledge and experience and develop adaptive strategies to address the contextual determinants of oral health.

Dentists began to use lasers in 1989 in different spheres of their work. Today they use lasers in order to treat periodontal disease, tooth decay, lesion removal. Besides, lasers can be used for teeth whitening.

Oral infectious diseases are probably the most common infectious pathologies affecting humankind. They have a significant impact on both people quality of life and costs for the healthcare system. Thus, their prevention should be high priority for governaments and research institutes. There are hundres of bacterial species in the oral environment, however, only a few of them are pathogenic. In fact, the disease begins when there is an imbalance in the oral biofilm with a prevalence of pathogenic species. In order to prevent oral infectious diseases we can eliminate most of the oral biofilm with mechanical and chemical means. However, in this way also many saprophytic species are eradicated. A smart solution could be to induce a selective pressure for “good” oral bacteria thus hampering pathogenic ones. How can we achive this? Modifying our diet is a possible solution, we demonstrated how cariogenic biofilm development was lowered by using levorotatory carbohydrates instead of dextrorotatory ones. If we already have a carious lesion, it should be removed and the tooth restored with proper materials. However, most of them are methacrylate based and favour biofilm development, moreover, they also seem to select cariogenic species due to the lack of buffering ability. In our study we demonstrated how the use of different materials, the siloranes, could lead to a decrease in the biofilm development, thus theoretically lowering the incidence of secondary caries. If a tooth cannot be recovered and should be extracted, dental implants are probably the best solution for their replacement. However, peri-implantitis is a serious issue affecting up to 50% of the implant and can lead to their loss. The prevention of this oral disease is hence very important. In our study we compared different materials and showed that biofilm formation was similar in all of them. In future studies we will investigate if the biofilm on these materials is similar or not and if they are prevalently pathogenic or saprophytic ones. In conclusion, oral infectious disease are still very common and for decades dentists tried to achieve oral health by eliminating all the biofilm. However, the most innovative strategy is not to eradicate it but to induce selective pressures by using different means thus leading to a beneficial biofilm which does not cause illness but instead promote our health.

The research problem addressed in this thesis is the lack of understanding of dentistry in practice, and the limited amount of work from a HCI-perspective in dental informatics. The aim of this thesis is to gain a deeper understanding of the area as a socio-technical domain from a Distributed cognition-perspective using workplace studies. Dentistry is a complex socio-technical domain where humans, technology, tools and artifacts together form a system. The ubiquitous presence of computers has made a mark on the dental profession with e.g. record systems and digital x-ray, and the integration of IT-system in the dental field may inform how dentists make decisions for their patients and how they perform their work. The problem is that not much work has been done in the dental informatics field from a HCI-perspective. This thesis applies workplace studies and Distributed cognition as an approach to HCI to gain an understanding of dentistry in practice and also draw conclusions how Distributed cognition could be applied as a method in HCI. This thesis presents a detailed account of work in dentistry regarding the propagation of information through representational stages and the roles, tasks and artifacts that are present in the complex socio-technical domain of dentistry. The thesis also provide implications for Distributed cognition regarding how it could be developed to fit into today’s complex socio-technical domains both as a method in HCI and as a theoretical framework. Key words: Dental informatics, Human-computer interaction, Distributed cognition, Workplace studies.

Objective: The objective of this study was to measure and assess the implant education received by graduates from the University of Iowa College of Dentistry and Dental Clinics. This study measured the self-reported competency levels of dental practitioners with regards to providing and maintaining dental implants as treatment modalities to their patients. The study assessed dental graduates’ willingness to practice and perform dental implant procedures, including both surgical and prosthetic treatments. Additionally, the study identifies challenges that face practicing dentists treating patients with dental implants and identifies the preferred way practitioners seek future training after completing dental school. Methods: A 36-item electronic survey was created and distributed to 737 dentists who graduated from the University of Iowa College of Dentistry and Dental Clinics. Dentists’ demographics, practice characteristics, and detailed self-reported competency in implant dentistry were collected. Statistical analysis of the responses consisted of descriptive statistics and bivariate analysis, and nonparametric Wilcoxon rank-sum test and Spearman’s rank correlation test along with a chi-square test were used for detecting the differences, correlations and associations under different conditions. Results: 154 dentists completed the survey (21% response rate), while only 143 subjects who fulfilled the inclusion criteria were included for the statistical analysis. The survey consisted mostly of males (56.6%). The mean age of respondents was 34.2 years old with a mean practice time of 6.2 years. Of the responding dentists, 21.7% completed a postgraduate training program and 51% of the respondents were in group practice. 66% of the respondents practice in the Midwest region of the US and 71.3% of the respondents took continuing educational courses in implant dentistry and the mean cumulative hours of CE courses in implant dentistry was 33.8 hours. The mean average of implant restorations provided per year was 11.7 and the mean average of implant placements per year was 19.6. There was a significant correlation between cumulative hours of Continuing Education courses and number of implant units on average placed or restored. 64.3% of the dentists are not satisfied with the implant education given at the dental student level. 95.8% of the dentists reported that dental school training is not adequate to surgically place dental implants in their practice. Only 32.4% reported that dental school training was not adequate to restore dental implants in their practice. The preferred way to receive additional training about dental implants is short-term CE courses and workshop courses conducted by implant companies. 23.6% of the dentists reported they are competent at surgically placing dental implants in their practice. 79.1% reported they are competent at restoring dental implants in the dental office. Only 28.4% reported that they feel dental implants are more difficult than other dental treatments. Conclusions: Graduate dentists from the University of Iowa are not expected to be competent in all components of implant dentistry without further postgraduate training. Respondents stated that their dental school training in surgical placement of implants was inadequate. To build upon their dental school training, the two main preferred education pathways as reported by respondents were short-term continuing education courses and workshops courses conducted by implant companies. Within the parameters of this study, we can conclude the following: 1.Age, GPA, number of CE hours in dental implant therapy, specialty status, and time since graduation did not influence undergraduate education satisfaction in dental implant therapy. 2.There is a positive correlation between the number of CE course hours and the number of implant units restored or placed by general dentists. 3.Male dentists, those who practice in group practice settings, and those who have graduated six or more years ago reported a greater number of CE course hours in dental implant therapy. 4.Those who graduated with GPAs less than or equal to 3.4, general dentists, and those who enrolled in a high number of CE courses were more confident in restoring dental implants. 5.Those who graduated with a GPA greater than or equal to 3.5, specialist dentists, and those who enrolled in a high number of CE courses were more confident in surgically placing dental implants. 6.Males, general dentists, those who practice in a group practice setting, and those who graduated six years or more ago restored more implants on average per year. 7.Males, specialist dentists, those who practice outside the Midwest US, and those who graduated six years or more ago surgically place more implants on average per year.

Background: Clinical guidelines have an important role to play in helping to close the gap between research evidence and clinical practice. In order to fulfill this role, guidelines need to be valid, relevant and comprehensive. Despite advances in chemotherapy and radiotherapy, cancer treatment still remains associated with clinically important oral complications that can impact severely on a patient's quality of life. No clear guidelines exist outlining the optimal oral care strategy for children, teenagers and young adults treated for cancer. Aims: (i) To assess the quality of current clinical guidelines for those working within dentistry; (ii) To develop evidence-based guidelines on mouth care for children, teenagers and young adults being treated for cancer; (iii) To compare the quality of published guidelines and their recommendations in light of supporting research evidence. Methods: (i) Dental guidelines, published in English between 1997-2004, were appraised using the Appraisal of Guidelines Research and Evaluation (AGREE) instrument; (ii) A telephone survey of UK cancer centres was undertaken to establish current practice with regard to mouth care for children treated for cancer. National, evidence-based guidelines were developed following, where appropriate, the established methodology of the Scottish Intercollegiate Guidelines Network (SIGN); (iii) A qualitative assessment of previously published guidelines on mouth care for cancer patients was undertaken. Results: (i) The AGREE instrument identified few examples of good quality dental guidelines; (ii) There is diversity in the mouth care provided to children being treated for cancer in the UK, particularly with regard to the use of routine, preventative oral care therapies. The guideline development process required a combination of an evaluation of research evidence and a formal opinion gathering process. A variety of interventions have been used for the management of oral mucositis, candidiasis, xerostomia and herpes simplex virus; few are supported by the research evidence; (iii) Variation exists in the methods used to produce previously published guidelines on mouth care for cancer patients. Recommendations vary irrespective of the supporting evidence-base. Conclusion: Guidelines need to be assessed for quality before being applied in practice. The guideline development process needs to be transparent, with clear links between recommendations and supporting evidence. There is currently variation in the mouth care provided to children, teenagers and young adults being treated for cancer in the UK. National, evidence-based guidelines may help to reduce this variation. Further research is required into the most effective methods of dissemination and implementation, exploring the role of psychological models of behavioural change.

In dentistry, repair and restoration of tooth structure to regain its mechanical properties is the ultimate aim of caries management. Currently, preventive therapies are preferred to operative interference. New preventive approaches are necessary to treat dental caries. Dentine is composed of an organic matrix, consisting of type 1. Degradation of collagen matrix is the main reason for breakdown of resin-dentine bonds and development of secondary caries over time. Hence, preservation of collagen fibrils is essential for preventive and reparative procedures in minimum intervention dentistry. Proanthocyanidin (PA) is a natural collagen cross-linker, which can be obtained from grape seeds, pine bark or elm tree. It has a high affinity to proline-rich proteins, like collagen. Cross-linking of the collagen fibrils increases their mechanical properties and their resistance to breakdown by proteolytic enzymes. Thus, in the first part of the study, with the aim of discovering other possible natural dentine collagen cross-linkers, the effect of two smaller molecular size flavonoids, naringin and quercetin, on the mechanical properties of demineralized dentine was compared to PA. Demineralized dentine treated with PA showed the greatest increase in mechanical properties, followed by quercetin and naringin. The protease inhibitory effect of PA was evaluated by examining its actions on soluble and collagen-bound matrix metalloproteinases and cysteine cathepsins. Proanthocyanidin, even at low concentration of 1%, exhibited excellent inhibitory effects on soluble and matrix-bound proteases. Secondly, PA was incorporated in a dental adhesive to facilitate its application in clinical situations. The effect of PA incorporation on durability of resin-dentine bond was evaluated. Up to 2% of PA could be added to dental adhesive with no adverse effects on immediate resin-dentine bond strength. However, the bond strengths of PA-incorporated adhesives dropped significantly following ageing. This could be attributed to the free radical scavenging effect of PA, which might also have interfered with polymerization of dental adhesive. The mechanical properties of PA-incorporated adhesive were evaluated and it was shown that up to 1% PA could be incorporated into an adhesive resin. With the addition of higher concentration of PA, the mechanical properties of the adhesive resin were reduced with increased solubility. Proanthocyanidin release from the cured resin showed an initial burst for 48 hours and was stabilized after five days. Finally, the remineralization potential of PA on artificial root caries was also compared with quercetin and naringin. All three flavonoids showed remineralization potential; however, their effects were inferior to fluoride. Proanthocyanidin formed a precipitate band on the superficial layer of carious lesion, preventing further mineral deposition. Subsequently, PA was incorporated in a CPP-ACFP (casein phosphoproteins amorphous calcium fluorophosphates) containing-paste to increase the mineral uptake in subsurface layer of caries lesion. Simultaneous application of PA and CPP-ACFP was shown to have a favourable outcome on mineral deposition in root caries lesion.
published_or_final_version
Dentistry
Doctoral
Doctor of Philosophy

Aims: Professionalism is an essential competence for dental professionals and must therefore be assessed in dental education. This research aimed to develop an instrument to assess professionalism within dentistry. Materials and Methods: The work was conducted in three stages: 1. a qualitative in-depth interview study, using framework analysis 2. an assessment strategy was devised and panel tested using focus groups; 3. an assessment tool was evaluated in a test validation study conducted in dental outreach placements. Results: Professionalism was conceptualised as the manner in which one reflects on and reconciles different aspects of professional practice and which demonstrates acceptance of professional responsibility. It is manifest in the manner in which work is carried out. It contains both tacit (self-awareness, awareness of others, trustworthiness, and ability to relate to context) and overt (vocational, altruistic, responsibility and accountability) aspects. Panel testing supported the face and content validity of the system. In a cohort of 81 dental students, staff and student ratings were correlated, all item total correlations exceeded 0.66 and all alphas exceeded 0.95. The intraclass correlations of all domains exceeded 0.96. All hypothesised relationships between domains were significant but domain scores were unrelated to student age or gender. Domain scores correlated with teachers’ global ratings of students’ professionalism. Conclusions: The assessment system is valid and reliable and should be implemented in undergraduate dental education.

Al giorno d'oggi, i progressi delle nanotecnologie hanno rivoluzionato drasticamente tutti i campi dell'odontoiatria, dalle malattie orali alla diagnosi, prevenzione e trattamento. Lo scopo di questa tesi di dottorato è stato quello di indagare e valutare l'applicazione delle nanotecnologie nella pratica clinica, con particolare attenzione all'Odontoiatria Preventiva, Estetica e Restaurativa. La prevenzione della carie e il trattamento precoce delle lesioni sono sfide prioritarie per il clinico. Il design basato su nanomateriali, che include idrossiapatite sintetica o suoi derivati, è in grado di imitare alcune delle proprietà meccaniche e strutturali dei tessuti calcificati nativi e quindi può promuovere la remineralizzazione della struttura dello smalto e prevenire l'ipersensibilità della dentina. Inoltre, l'impiego di nanotecnologie nell'arricchimento di gel sbiancanti mediante nanoforme di idrossiapatite è ampiamente utilizzato per evitare i disagi e i danni associati ai trattamenti sbiancanti. Uno dei principali usi delle nanoparticelle nell'Odontoiatria Restaurativa è la loro applicazione come riempitivi nei nanocompositi, fornendo elevata duttilità senza perdita di forza e resistenza ai graffi, con proprietà ottiche, meccaniche e termiche migliorate. Inoltre, i nanocompositi mostrano proprietà estetiche migliorate, come un'elevata ritenzione della brillantezza e un'eccellente lucidabilità e adattabilità. Tra queste caratteristiche migliorate, degne di nota sono quelle mostrate dai nuovi compositi bulk-fill. Infatti, grazie al loro nuovo contenuto di monomero e alle migliorate proprietà di polimerizzazione, i compositi bulk-fill consentono di ottenere rapidamente un adattamento soddisfacente del materiale nella cavità, diminuendo il tempo di seduta necessario, garantendo anche adeguate caratteristiche fisiche della superficie. Pertanto, l'applicazione delle nanotecnologie supporta e facilita le esigenze del clinico, che richiedono protocolli clinici rapidi, sicuri e ripetibili, per ottenere il miglior risultato in un unico appuntamento.
Nowadays, developments in the nanotechnology arena have dramatically revolutionized all fields of dentistry from oral diseases to diagnosis, prevention and treatment. The aim of this PhD thesis was to investigate and evaluate the application of nanotechnologies in clinical practice, with particular attention to Preventive, Aesthetic and Restorative dentistry. Caries prevention and early treatment of lesions are priority challenges for clinicians. Nanomaterial-based design, which includes synthetic hydroxyapatite or its derivatives, is able to mimic some of the mechanical and structural properties of native calcified tissues and can definitely promote the remineralization of the enamel structure and prevent dentin hypersensitivity. Moreover, the employment of nanotechnologies in the enrichment of whitening gels by means of nano-forms of hydroxyapatite are widely used to avoid the discomfort and damages associated with bleaching treatments. One of the principal uses of nanoparticles in restorative dentistry is their application as fillers in nanocomposites, providing high ductility without strength loss, scratch resistance, enhanced optical, mechanical and thermal properties. In addition, dental nanocomposites exhibit increased aesthetic properties, such as high gloss retention and excellent polishability and adaptability. Among these ameliorated characteristics, noteworthy are those showed by the new bulk-fill composites. Indeed, due to their novel monomer content and enhanced curing properties, bulk-fill composites let to rapidly obtain a satisfactory adaptation of the material into the cavity, decreasing the chair-time needed, while also ensuring adequate physical characteristics of the surface. Therefore, the application of nanotechnology supports and facilitates the clinician’s needs, which require rapid, safe and repeatable clinical protocols, to obtain the best result in a single appointment.

Thesis (M.A.)--University of North Carolina at Chapel Hill, 2006.
Title from electronic title page (viewed Oct. 10, 2007). "... in partial fulfillment of the requirements for the degree of Master of Arts in the Department of Operative Dentistry." Discipline: Operative Dentistry; Department/School: Dentistry.

Most people have experienced toothache and know how much it effects the health. It hurts to eat, it ́s hard to sleep and sometimes a small gesture as a smile is avoided because it pains to much. Of course animals have the same issue and feel pain but they can’t tell us how they feel, instead we have to look for signs from their behavior. The recommendation to regularly check the horse’s teeth does minimize the risk of pain. The knowledge within the field of equine dentistry is on the rise and educations and regulations is developing to give the best dental care possible. This has created a need of the right tools adopted to this specific field and this is where a company like Accesia has a chance to be at the forefront of this development. Accesia is a company that have developed tools and educations about the animal dental profession since 2009. Until now the focus has been on smaller animals like cats, dogs and rodents but now they are widening their customer field and develops for this new market, equine dentistry. To get a understanding of this new customers some field studies has been performed and needs that are separate from the previous customer needs has been identified. It ́s not only the size that differs from the dentist working with cats and dogs, it ́s also the working environment and the anatomic conditions that looks completely different. For this thesis the main goal has been to identify how a unit for the tools used by equine dentists should be structured and what parts that should be included to endure the transportation and environment where it will be used. To gain this information, several interviews were conducted with the main users and the experts working on Accesia. The gathered information where later analyzed, concretized and explored in a product concept. This report will go through the different stages in the design process that led to a final design concept which were presented with a prototype and posters at a thesis fair organized by Jönköping University.

A população de cavalos geriátricos é cada vez maior na Europa, sendo as doenças odontológicas uma das áreas com maior importância na vida destes animais. Este trabalho tem como objectivo principal o levantamento sobre a prevalência das principais doenças dentárias em cavalos geriátricos, na região do Alentejo. Em paralelo pretendeu-se também estudar a relação entre o sobrecrescimento dentário e a existência de cáries infundibulares no dente opositor. A amostra foi definida com base na idade, tendo surgido 30 cavalos, com mais de 15 anos, durante um período de quatro meses. Cada equino foi sujeito ao mesmo procedimento de avaliação, sendo todas as alterações dentárias anotadas em formulário pré-concebido. Concluiu-se que as alterações dentárias mais prevalentes foram a boca macia, o sobrecrescimento total e o sobrecrescimento focal, apresentando, cada uma delas, uma prevalência de 56,7%. No que diz respeito ao estudo da relação entre o sobrecrescimento dentário e a existência de cáries infundibulares no dente opositor, comprovou-se a existência de uma relação significativa;Reporting study of the leading dental pathologies in geratric horses, in the Alentejo region. Abstract: The population of geriatric horses is escalating quickly in Europe and odontologic diseases are one of the areas of great concern in these horses. The main aim of this present study is to gather the main dental diseases and their prevalence in geriatric horses in the Alentejo region. Concurrently, it was intended to study as well the relation between dental overgrowth and the existence of infundibular cavities in the opposing tooth. The sample was defined based on age and 30 horses over 15 years old were evalu-ated for a period of 4 months. Every horse was submitted to the same evaluation proce-dure, with all the dental alterations being written down on a pre-developed formulary. In conclusion, the most prevalent dental alterations were smooth mouth, total over-growth and the focal overgrowth, each one exhibiting a prevalence of 56,7%. And it was proven that there's a significant correlation between tooth overgrowth and the presence of infundibular cavities in the opposing tooth.

Simulation in the shape of the “phantom head” is an essential part of every dental training programme. It is used to provide the student with practice before he/she is allowed to carry out restorative dental procedures on patients. In theory, this practice promotes patient safety. However, the learning process lacks clarity, and we do not understand fully how well learned skills transfer to clinical activity. This study asks whether in fact the pre-clinical course is a reliable guarantor of patient safety. It does so by examining four facets of the simulation process: purpose, learning, fidelity and transition, using a mixture of research methods, including comparison of pre-clinical and clinical assessment grades, focus groups with students, one-to-one interviews with their teachers and a questionnaire. The results of these investigations indicate a complex inter-relationship between purpose, learning, fidelity and transition. They also suggest that success in simulated restorative dentistry is a poor predictor of clinical ability, a limitation that needs careful consideration in the light of patient safety. The study recommends changes to increase the complexity and authenticity of the pre-clinical course, and suggests that the student transition needs detailed management, perhaps through a blend of pre-clinical and clinical activity.

Introduction: Ultrasonic scalers are an accepted alternative to hand instruments for the removal of plaque, calculus and stains from teeth. Although the use of these instruments is widespread, the vibrational motion of scalers is not fully understood. Their high frequency, low displacement amplitude oscillations have previously been difficult to analyse. Laser vibrometry is a non-invasive technique for measuring the vibration characteristics of oscillating objects. Aim: The aim of this research thesis was to utilise scanning laser vibrometry to assess a range of dental ultrasonic systems under various operating conditions similar to those employed clinically. … Conclusions: The use of scanning laser vibrometry revealed differences in the operation characteristics of different ultrasonic scalers. Clinicians and researchers should be aware of the variability in the performance of ultrasonic scalers since this may affect both clinical procedures and future research. Further research into the design and operation of ultrasonic scaler tips is needed.

Background: Virtual reality haptic simulators represent a new paradigm in dental education that may potentially impact the rate and efficiency of basic skill acquisition, as well as pedagogically influence the various aspects of students’ preclinical experience. However, the evidence to support their efficiency and inform their implementation is still limited. Objectives: This thesis set out to empirically examine how haptic VR simulator (Simodont®) can enhance the preclinical dental education experience particularly in the context of operative dentistry. We specify 4 distinct research themes to explore, namely: simulator validity (face, content and predictive), human factors in 3D stereoscopic display, motor skill acquisition, and curriculum integration. Methods: Chapter 3 explores the face and content validity of Simodont® haptic dental simulator among a group of postgraduate dental students. Chapter 4 examines the predictive utility of Simodont® in predicting subsequent preclinical and clinical performance. The results indicate the potential utility of the simulator in predicting future clinical dental performance among undergraduate students. Chapter 5 investigates the role of stereopsis in dentistry from two different perspectives via two studies. Chapter 6 explores the effect of qualitatively different types of pedagogical feedback on the training, transfer and retention of basic manual dexterity dental skills. The results indicate that the acquisition and retention of basic dental motor skills in novice trainees is best optimised through a combination of instructor and visualdisplay VR-driven feedback. A pedagogical model for integration of haptic dental simulator into the dental curriculum has been proposed in Chapter 7. Conclusion: The findings from this thesis provide new insights into the utility of the haptic virtual reality simulator in undergraduate preclinical dental education. Haptic simulators have promising potential as a pedagogical tool in undergraduate dentistry that complements the existing simulation methods. Integration of haptic VR simulators into the dental curriculum has to be informed by sound pedagogical principles and mapped into specific learning objectives.

Occupational stress can impact adversely on individuals’ physical, mental, and emotional wellbeing, and have occupational consequences. Dentistry professionals can experience significantly higher levels of occupational stress, and poorer wellbeing, than other health professionals. Previous research on occupational stress among dentistry professionals has demonstrated differences by individual-level personal and professional characteristics, identified work content and work context sources of occupational stress, and indicated that dentists may not be able to relieve their stress properly. Previous research has, however, focused on dentistry clinicians and students, and less is known about dentistry academics who are likely to have different correlates and sources of occupational stress given differences in their occupational role. Therefore, this research program aimed to investigate occupational stress and wellbeing among dentistry academics including individual-level personal and professional characteristics associated with poor wellbeing, common sources of occupational stress and associations with poor wellbeing, and self-care activities and associations with wellbeing. This research program used a cross-sectional design with a convenience sample of academics in dentistry departments across nine universities in Australia and New Zealand. The thesis comprises three quantitative studies and examined data from an online survey to assess wellbeing, personal and professional characteristics, perfectionism, work content and context sources of occupational stress, and self-care activities. Data were analysed using multiple regression. A total of 119 people consented to the online survey, with 94 (78.9%) providing complete data. The average age of respondents was 50 (±11.7) years, 56.8% were men, and 67% had more than 10 years’ experience as an academic. Results demonstrated poor wellbeing among this group of dentistry academics, with an average score on the iii Psychological General Wellbeing Index (PGWBI) of 67.0±14.1. Lower scores were obtained on PGWBI dimensions of vitality (58.3±19.4), anxiety (62.0±16.9) and positive wellbeing (62.2±17.2) than other dimensions. Study one found a significant association between hours of undergraduate teaching and psychological wellbeing, after adjustment for age, gender, income, and overall health (F(6,79)=19.651, p<.001, adj.R2=.56). Dentistry academics doing more than six hours of undergraduate teaching per week had poorer wellbeing than their counterparts (rpb(92)=- .288, p=.005, age r(84)=.315, p<.005). There were no significant bivariate associations between perfectionism, or other personal and professional characteristics, and wellbeing. Study two found that the leading sources of “substantial” occupational stress were work overload (61% agreement), administration demands (55% agreement), multiple role demands (54% agreement), and time pressure at work (49% agreement). A multiple linear regression model comprising job future, workload and responsibility, job satisfaction, social support, time pressure at work, age, income management, and overall health significantly predicted psychological wellbeing, F(8,77)=13.141, p<.0001, adj.R2=.53, with no significant associations for any of the specific sources of stress with wellbeing. Study three found that the most common types of self-care done “frequently” were lifestyle (57.8%), exercise (44.4%), and recreational (44.4%) activities. The least frequent were intrapersonal activities (13.3%). The multiple linear regression model comprising self-care domains of intrapersonal, interpersonal, exercise, recreational, and professional activities, with adjustment for age, gender, income management, and overall health significantly predicted psychological wellbeing, F(9,76)=9.705, p<.0001, adj.R2=.53, with no statistically significant associations between any of the individual self-care activity domains and wellbeing. The findings of this research program contribute to evidence on occupational stress and wellbeing in dentistry academics and can inform workplace interventions. Results suggest that interventions to improve wellbeing in dentistry academics could prioritise those who are younger, with lower income, in poorer health, and/or teaching more than six hours of undergraduate teaching per week. These interventions could include individual-level and organisational-level strategies to help manage time pressure, work overload, administration demands, and multiple role demands; and increase social support and positive perceptions of job future and job satisfaction. Interventions could promote intrapersonal (e.g., gratitude, mindfulness), interpersonal (e.g., social support), and professional self-care activities (e.g., networking skills) given potentially low rates of these. Future research is warranted to extrapolate and confirm these findings with a larger sample, define the study sample homogeneously, and explore the impact of COVID-19 on sources of stress. Future research is also needed to provide a deeper exploration of ‘lived in’ experiences of dentistry academics related to aspects of undergraduate teaching that contribute to poor wellbeing, or specific aspects of the work role that contribute to work overload; and to explore other aspects of intervention delivery such as preferences for duration, frequency, and type of interventions. If successful, such workplace interventions could reduce the adverse physical, psychological, behavioural, and organisational consequences commonly associated with poor wellbeing and occupational stress among dentistry academics, as well as the financial burden of related compensations claims. In turn these interventions could promote mental and physical wellbeing, and quality of life, as well as organisational indicators such as staff morale and overall work performance and productivity. This work has not previously been submitted for a degree or diploma in any university. To the best of my knowledge and belief, the thesis contains no material previously published or written by another person except where due reference is made in the thesis itself.
Thesis (Masters)
Master of Philosophy (MPhil)
School of Applied Psychology
Griffith Health
Full Text

CAD / CAM techniques applied to solving dental problems demonstrate that there are many solutions available on the market to help the dentist individually perform the rehabilitation of a dental element to meet the specific needs of each patient. These manufacturing technologies close a digital workflow, potentially managed entirely by the dentist, which involves taking the impression of the oral cavity and the dental elements present through an intraoral scanner with the generation of a file on which to create the CAD project and to start extrapolating the file of the final work to be produced by subtractive or additive CAM. The 3D printing techniques allow to work easily with polymeric and ceramic materials, in order to create dental crowns that can satisfy practically all the needs encountered in the dental field. Leaving aside the techniques applied to polymers, this PhD project focuses on the applications of ceramic materials. This PhD thesis focuses on the design, study and implementation of 3D printing of ceramic supports specifically dedicated to the stabilization of dental implants. Through the development of a prototype of a 3D printer, it was possible to obtain the printing of ceramic products useful for the intended purpose.

Traditionnellement, l’approche de soins et de services de santé prédominate chez les dentistes était curative et moins orientée vers la prévention et la promotion de la santé. Et pourtant, il est bien reconnu que plusieurs pathologies de santé sont multifactorielles. Dans cette dynamique, l’intégration d’une approche centrée sur le patient, systémique, et basée sur des facteurs de risque communs est une avenue intéressante pour améliorer la qualité des services. De même, les dentistes sont encouragés à adopter davantage des pratiques de promotion de la santé générale incluant la santé dentaire informées par des données probantes. Ce faisant, des interventions ciblées sur les leviers de changement de comportement des dentistes et visant à réduire les obstacles perçus et réels, sont considérées optimales pour favoriser une pratique clinique basée sur les données probantes afin d’améliorer la qualité des services aux patients. C’est dans ce contexte que se situe cette thèse dont l’objectif est d’explorer les multiples facteurs qui influencent l’adoption des meilleures pratiques par les dentistes au sein des cliniques dentaires privées. Pour illustrer notre travail, le choix porte sur les pratiques de soutien au renoncement tabagique. S’appuyant sur un devis de recherche mixte séquentiel, exploratoire (quali-quanti) et sur des assises théoriques, cette recherche s’intéresse aux déterminants individuels et environnementaux (organisationnels, contextuels et structurels) de l’intention des dentistes du Québec d’utiliser les lignes directrices cliniques canadiennes (LDCC) de renoncement au tabac (demander-conseiller-évaluer-aider et organiser) auprès des adultes qui visitent leurs cliniques dentaires. Basé sur un modèle intégrateur regroupant des concepts de la théorie des structures organisationnelles de Mintzberg, de la théorie des professions de Freidson et de la théorie institutionnelle de Meyer et Rowan, Dimaggio et Powell, le premier article vise à comprendre les facteurs organisationnels, contextuels, économiques, éducationnels, politiques qui entravent ou favorisent les pratiques en soutien au renoncement au tabac en bureau privé au Québec. Un échantillon de 20 dentistes, exerçant dans plusieurs régions du Québec, ont participé aux entrevues individuelles semi-dirigées, d’une durée approximative de 35 à 45 minutes. Il ressort de l’analyse de contenu des données recueillies que le patient est au coeur des interventions cliniques des dentistes. Leurs pratiques en soutien au renoncement tabagique sont tributaires des caractéristiques des LDCC de renoncement au tabac et de la culture en médecine dentaire. Outre ces facteurs, les pratiques en soutien au renoncement tabagique des dentistes sont influencées par la disponibilité des ressources matérielles, informatiques, et humaines qualifiées, le remboursement des services offerts et finalement le leadership du dentiste. Le second article présente le processus du développement et de l’analyse des qualités métrologiques de l’instrument de mesure des facteurs psychosociaux. Vingt-sept autres dentistes à travers la province de Québec ont participé à la démarche de test-retest selon une approche mixte de recherche, de type quali-quantitative. Ainsi, la version finale du questionnaire compte 40 items. L’approche analytique confirme la théorie sous-jacente à cette démarche qui était une version modifiée de la théorie du comportement interpersonnel de Triandis avec des construits de la théorie du comportement planifié d’Ajzen. Par ailleurs, l’analyse de la fiabilité indique des résultats intéressants avec des coefficients alpha de Cronbach variant de 0.74 à 0.94 et une bonne stabilité temporelle avec des coefficients allant de 0.69 à 0.94. Prenant appui sur une version modifiée de la théorie du comportement interpersonnel de Triandis, le dernier article porte sur l’identification des facteurs individuels qui affectent l’intention des dentistes d’utiliser les LDCC de renoncement au tabac. Cinquante-neuf dentistes ont participé à une enquête par questionnaire entre les mois de janvier et septembre 2016. Les dentistes participants présentent une intention favorable d’utiliser les LDCC de renoncement au tabac. De plus, quatre énoncés des LDCC sont plus courants à des proportions variables chez les dentistes, à savoir demander, conseiller, aider et dans une certaine mesure organiser/reférer les patients fumeurs. Les normes professionnelles (β=0.84 ; p≤ 0.0001) et les croyances de contrôle (β=0.30 ; p= 0.01) expliquent 63 % de la variance de leur intention. L’intégration des données qualitatives et quantitatives colligées montre le rôle fondamental des universités et des associations professionnelles de dentistes dans la construction d’une identité professionnelle solide. Pour les participants à cette recherche, c’est une avenue prometteuse pour favoriser la promotion du renoncement au tabac auprès des adultes en clinique dentaire privée, et d’encourager davantage une pratique clinique basée sur les données probantes en médecine dentaire.
Traditionnaly, the predominant approach to healthcare services for dentists was strongly curative and less focused on preventive and promotion of health. Many conditions and diseases are caused by multiple factors. Thus, patient-centred, systemic, and common risk factor approaches are a promising avenue to address these health conditions and improve the quality of care. Dentists are encouraged to engage in general health promotion practices, including the oral health and in the knowledge translation activities. In this manner, targeted interventions are optimal strategies to overcome real and perceived barriers to change by dentists and to favour evidence-based dental practice. Grounded in these principles, this research is related to the science and practice of knowledge translation. Using an exploratory, sequential, mixed methods approach with theory-based underpinnings, this study aims to explore individual and environmental determinants influencing the implementation of Canadian smoking cessation guidelines (5As: Ask, Advise, Assess, Assist and Arrange) by dentists in private practice in Quebec. The first article used a qualitative design and an integrative conceptual framework composed of three theoretical perspectives, including Mintzberg’s Organizational Configuration Theory, Friedson’s Theory of Professions, and Meyer, Rowan, Dimaggio and Powell’ s Institutional Theory to understand organizational, contextual, economic, educational and political factors influencing the adoption of the 5As in private dental clinics in Quebec. Individual semi-directed interviews of 35 to 45 minutes were conducted with 20 private practice dentists. The audio-recorded data were transcribed verbatim, followed by a directed content analysis. Findings indicated that the patient is at the heart of smoking cessation counselling in dental practice in Quebec. Dentists’ attitude and behaviour are affected by different factors including dentist’s leadership style; and the availability of community, human and material resources. Also, other variables include the culture of dental medicine, the compatibility of Canadian smoking cessation guidelines with the practice of dentistry, time constraints, and the lack of reimbursement of counseling practices. The second article was a study carried out to develop and test the psychometric properties of a questionnaire based on a modified version of Triandis’ theory of Interpersonal Behavior (TIB) for exploring the psychosocial determinants of Quebec dentists’ intention to use the Canadian clinical practice guidelines on smoking cessation. Using a mixed-methods exploratory sequential design, a quantitative questionnaire was developed from the results of a qualitative study. Twenty-seven dentists who had not been involved in other aspects of the research project participated in this test-retest. Confirmatory factor analysis was carried out to assess if items supported the predefined basis of TIB-constructs. The final version of the questionnaire has 40 items measuring psychosocial constructs. Confirmatory factor analysis corroborates the theory. Reliability analyses indicate good results with standardized Cronbach alpha ranging from 0.74 to 0.94 and temporal stability coefficients from 0.69 to 0.94. The final article is a cross-sectional study that was carried out on a sample of 59 dentists who had not been involved in other aspects of the research project who were working in private practice between January and September 2016. The study was conducted using a validated and anonymous questionnaire based on a modified version of the Triandis’ Theory of Interpersonal Behaviour. The purpose of this study was to identify the underlying individual mechanisms supporting dentists’ intention to adopt the Canadian smoking cessation clinical guidelines in Quebec. Dentists had a positive intention to use the Canadian guidelines on smoking cessation. Four statements of smoking cessation guidelines like ask-advice-assist and arrange/referwere current in dental practice at the variables proportions. The main predictors of dentists’ intention were professional norm (β=0.85; p≤ 0.0001) and control beliefs (β=0.30; p=0.01), explaining 63 % of variance in dentists’ intention to adopt these guidelines in their practices. Mixed data analysis has shown the major fundamental factors included in the construction of dentists’ professional identity. The results strongly suggest the role of universities and professional dental associations in order to encourage dentists to take a more active role to counsel adult smokers and to have an evidence-based practice.

La utilización de circona tetragonal policristalina estabilizada con 3 % mol de itria (3Y-TZP) para fabricar coronas e implantes ha sufrido una fuerte expansión recientemente debido a las buenas propiedades mecánicas, estéticas y de biocompatibilidad que posee este material. La microestructura y composición exacta de 3Y-TZP son específicamente diseñadas por los fabricantes para adecuarse a las normativas existentes. Durante su procesamiento, las prótesis cerámicas son tratadas superficialmente por métodos como el arenado para mejorar su adhesión al cemento protésico y a la porcelana que cubre la pieza dental. Ahora bien, no todos los fabricantes dentales recomiendan el arenado de las coronas previamente a su implantación, ya que el arenado puede introducir defectos superficiales que pueden afectar la integridad estructural de la prótesis así como producir cambios cristalográficos en la superficie. A pesar de que el efecto de arenado en circona ya ha sido parcialmente estudiado, no se han considerado exhaustivamente muchos aspectos como la severidad de las condiciones de arenado, el efecto en las propiedades superficiales, el daño subsuperficial y los cambios de fase. Una comprensión detallada de estos aspectos es necesaria para escoger correctamente las condiciones de trabajo del arenado y para mejorar el diseño microestructural de estos materiales. Esto mejoraría la vida a largo plazo de los implantes cerámicos evitando o retrasando posibles fallos de la pieza. En este trabajo, se ha estudiado el efecto del arenado en 3Y-TZP con diferentes tamaños de grano bajo diferentes condiciones de arenado. También se ha estudiado el efecto de la adición de de nanotubos de carbono multicapa (MWCNT, 0.5-2 vol. %) a una matriz de 3Y-TZP. Una parte del trabajo ha consistido en el estudio de las propiedades mecánicas y de resistencia a la degradación hidrotérmica de 3Y-TZP nanométrica y de los nanocompuestos 3YTZPMWCNT con tamaño de grano nanométrico (90-150 nm) producidos por “spark plasma sintering”, los cuales se ha encontrado que poseen una menor tenacidad de fractura por indentación que 3Y-TZP con tamaño de grano de 300 nm. La adición de un 2% en volumen de MWCNT aumenta la tenacidad de fractura por indentación en alrededor de un 15% con respecto a la matriz del mismo tamaño de grano. El módulo de elasticidad apenas cambia mientras que la dureza disminuye ligeramente.
The use of tetragonal zirconia polycrystals (3Y-TZP) in dental restorations such as crowns and implants has recently increased attention due to their very good aesthetic appearance and mechanical properties in addition to biocompatibility. The restorations undergo several surface treatments such as sandblasting for better adhesion to luting cements and veneering porcelain. However, there is some controversy about using sandblasted crowns, as sandblasting introduces surface flaws and defects that can compromise the strength of the crown as well as crystallographic changes at the surface. Though the effect of sandblasting in zirconia has been previously studied to some extent, many issues like severity of the conditions, effect on surface mechanical properties, subsurface damage and phase transformation zone size have not been still fully addressed. Comprehensive understanding of these aspects will help in choosing better sandblasting conditions and also to improve the microstructural design of the materials for long term performance of the restorations so that clinical failures can be avoided or delayed. In this thesis, the effect of sandblasting on 3 mol% yttria stabilized zirconia (3Y-TZP) with different grain sizes has been studied under different sandblasting conditions. Additionally, nanocomposites formed by adding multiwall carbon nanotubes (0.5-2 vol. %) to 3Y-TZP matrix have been also studied. Initially, the study has been focused in the mechanical properties and hydrothermal degradation resistance of nanometric grain size 3Y-TZP and zirconia multiwall carbon nanotubes nanocomposites (3YTZP-MWCNT). Nanometric grain size 3Y-TZP (90-150 nm) produced by spark plasma sintering have slightly lower toughness compared to standard zirconia with grain size 300 nm. Adding multiwall carbon nanotubes improve the indentation fracture toughness nearly 15% compared to monolithic materials. Elastic modulus hardly changes while hardness decreases slightly for 2 vol.% nanotubes. The materials were subjected to sandblasting using two particle sizes, two pressures and two impact angles, After sandblasting the materials were analyzed looking for roughness, phase transformation and damage. In addition the change in mechanical properties and in hydrothermal degradation resistance induced by sandblasting was evaluated. It has been found that increasing particle size and pressure increases surface roughness. The bi-axial strength of zirconia has been studied only in standard 300 nm grain size 3Y-TZP. The main result has been to show that at impact angle of 90º the biaxial strength increases when sandblasted with 110 um particles while it decreases with 250 um particles. On the other hand, the strength slightly increases when sandblasted under an impact angle of 30° irrespective of the particle size. By using nanoindentation it is shown that mild sandblasting conditions (110 um particle size, 2 bars pressure) have no effect on the surface mechanical properties such as, elastic modulus and contact hardness. A model based on the formation of residual compressive stresses is presented in order to explain the indentation the shorter length of the indentation cracks in sandblasted material as well as to rationalize the increase in strength of sandblasted material under mild sandblasted conditions. The microstructural change induced by sandblasting near the surface consists of: i) a thin layer of plastically deformed grains; ii) phase transformation; and iii) occasional microcracking. The fraction of monoclinic volume fraction induced after sandblasting under the studied conditions is of about 10-15%, and with transformation up to a depth of about 10-13 um. Finally it is shown that in sandblasted conventional 3Y-TZP, the kinetics of hydrothermal degradation are slower than in the starting material.

The aim of the present study is to develop an explanation of the information seeking behaviour of dental professionals that relates the three main instances of this behaviour (users, their information needs, use of information sources) in a meaningful way. The research looks into the information-seeking behaviour of one of the less investigated groups of health practitioners and it does so from a qualitative point of view, using data collected by means of semi-structured interviews. 110 dental professionals were interviewed between May 1989 and June 1990. The interviewees were dental professionals in Sheffield District Health Authority (postgraduate students; academic staff; community service dentists; hospital staff and general dental practitioners). A coding paradigm based on grounded theory was applied to analyze their replies. This basic paradigm explains the information-seeking behaviour of dental professionals in terms of 'conditions' that provoke seeking information; 'strategies' implemented to seek information; 'interactions' the ways in which information sources are used. The conditions for their information needs are created by their clinical tasks (diagnosis, treatment and delivery of dentistry) or their academic tasks (teaching and lecturing, research and publications). Dental professionals apply six basic strategies for seeking information: Reading, Talking, Enquiring, Attending/organizing continuing education events, Watching and Using the library. Each of these strategies is associated with the use of certain information sources: Reading with written/printed literature, Talking with colleagues, Enquiring with individuals from other occupations or professions, Attending... with courses and conferences, Watching with audiovisual materials and Using the library with the use of printed literature via a library service. While the strategies are common to every subgroup in the study, the actual patterns of information-seeking vary from subgroup to subgroup because the strategies are implemented in different ways by each of them. The reason for this variation is determined by the particular combination of clinical and academic tasks of each subgroup. The findings - apart from describing how a representative group of dental professionals uses a variety of information sources - have several implications for library and information services, computer applications, dental training and further research in health care user studies.

Background: Recently, there has been renewed interest in the importance of reducing sugar intake to control dental caries both in the UK and internationally. Although diet advice to promote oral as well as general health is recommended for all dental patients, those at high risk of dental caries are particularly in need of additional professional support tailored to their needs. For this reason, diet diaries have been recommended as a dietary assessment tool that enables the tailoring of effective dietary advice for individual patients in dental practice (Watt et al., 2003). However, despite the recognised merits of diet diaries as dietary assessment and self-monitoring tools in the general literature (Thompson and Subar, 2013), an early search of literature revealed that very little empirical work had been devoted to this topic in the dental context. The overall aim of this research is to explore the use of diet diaries in the dental clinical setting. It offers some important insights into the possible barriers and facilitators of their use to support dietary advice. Methods Four studies were undertaken to meet the general aim and the objectives of the thesis. A range of qualitative and quantitative research methods were used. Dentists’ current practices and perceived influences of diet diaries usage in dental practice were investigated using a postal questionnaire survey to general dental practitioners (GDPs) (Study I). A case-vignette based on a diet diary was incorporated into this questionnaire to deepen understanding about how dentists interpret and use diet diaries to formulate dietary advice (Study II). A retrospective study was carried out to estimate the return rate of diet diaries and its associated factors among paediatric dental patients in a teaching dental hospital (Study III) - a different setting where dental remuneration is less of an issue. Finally, a qualitative case study was conducted to investigate factors associated with patients’ adherence to diet diaries issued to paediatric dental patients in a teaching dental hospital setting (Study IV). Findings Study I found that the majority of English GDPs did not use diet diaries to collect diet information (62%), mainly because of constraints related to finance and time. Other barriers identified were poor patient compliance and a perceived lack of necessary skill relating to dietary counselling. Diet diaries were more likely to be used in children than in adults, and for patients with high levels of caries. Study II demonstrated that GDPs rely upon a strategy of intelligent selection to filter complex dietary information in order to generate dietary advice. Challenged with a large field of information, they select what they see as a subset of either the most useful or the easiest information for patients to understand and implement. Study III found that the return rate of diet diaries by children and their families in a dental hospital setting was low (34%). Return rate was associated with patients’ demographic and oral health maintenance habits. Content analysis of returned diet diaries showed that diet diaries did not consistently capture the full range of complexities of dietary aspects relevant to oral health. Information on sugar amount, consumption context, sequence of intake within meals, prolonged contact with teeth and sugars consumed near bedtime – all were partially or completely missing from the returned diaries. Study IV concluded that adherence to diet diaries is a multi-contextual phenomenon associated with interacting factors which are generally related to the patient (parent/child), the dentist and the diet diary itself. Conclusions Diet diaries were not frequently used by dental practitioners, nor were they frequently returned or adequately completed by patients and their families. The use of diet diaries as a dietary assessment and monitoring tool is complicated by many factors related to the dentist, patients and the diet diaries itself. Therefore, multifaceted interventions targeted at patients, providers and the healthcare system are required if the use of diet diaries is to be enhanced. A motivated patient, a time-efficient tool as well as appropriate support from health care system appear to be necessary for the successful use of diet diaries.

Dental caries is the main reason for placement and replacement of restorations (Keene, 1981). More than 60 percent of dentists' restorative time is spent replacing existing restorations. The replacement of restorations can result in a cavity preparation larger than its predecessor which leads to weakening of the remaining tooth structure (Mjör, 1993). Considering the traditional surgical dental caries management philosophy, it was based on "extension for prevention" and restorative material needs rather than on preserving the healthy tooth structure (Black, 1908). In the 1970s, the surgical dental paradigm began shifting to a new approach for caries management: Minimally Invasive Dentistry (MID). It was based on the medical model that prioritizes caries risk assessment, early caries detection, remineralization of tooth structure, and especially preservation of tooth structure through minimal intervention in the placement and replacement of restorations (Yamaga et al, 1972). The minimal intervention paradigm emphasizes use of adhesive restorative materials in order to minimize the size of cavity preparation (Murdoch-Kinch & McLean, 2003). Hence, a cross-sectional study using an online survey instrument (30-item) was conducted among National Network for Oral Health Access (NNOHA) and American Association Community Dental Programs (AACDP) members. Besides demographics, the survey addressed the following items using a 5-point Likert scale: knowledge, attitudes and behavior concerning MID among general practitioners. Specific questions focused on practitioner and practice characteristics, previous training and knowledge of MID, knowledge use of restorative, diagnostic and preventive techniques and whether MID was considered to meet the standard of care in the U.S., which was the main outcome of the study. Chi-square, Fisher's exact test, Wilcoxon rank-sum test, and two-Sample t-test were used to identify factors associated with beliefs that MID meets the standard of care. Overall, 86% believed MID met the standard of care for primary teeth, and 77% believed this for permanent teeth. The study found that those with more favorable opinions of fluoride to be more likely to believe MID met the standard of care, but no demographic or practice characteristics were associated MID standard of care beliefs.

2008/2009
Zirconia based materials have been widely used in construction of dental prosthesis because of their mechanical and aesthetical properties and a lot of money have been invested in their development, but no one of the producers considered the aging of zirconia. In this job have been demonstrated, with Raman spectroscopy, the low temperature degradation of zirconia and has been investigated the residual stress in zirconia-alumina composites at room temperature and in open-air after 8 years of aging, then have been investigated the phase trasformation of tetragonal zirconia into monocline form of pure zirconia and alumina-zirconia composites tested in water with a thermal fatigue cycle between 5°C and 55°C. A partial solution of the problem is proposed. Atomic Force Microsopy and Near-field Scanning Optical Microscopy techniques have been tested as method of investigation and validation of the results.
I materiali a base di zirconia trovano vasto impiego nella realizzazione di protesi dentali grazie alle loro proprietà meccaniche ed estetiche e molti soldi sono stati investiti nel loro sviluppo, ma nessuno dei produttori ha considerato il fenomeno di invecchiamento della zirconia. In questo lavoro è stato dimostrato, attraverso l‘impiego della spettroscopia Raman, il degrado a bassa temperatura della zirconia ed è stato analizzato lo stato tensionale interno in compositi allumina-zirconia mantenuti a temperatura ambiente in aria per 8 anni; a seguire è stata analizzata la trasformazione di fase da tetragonale a monoclino della zirconia in campioni sia di zirconia pura che in campioni di composito alumina-zirconia, testati in acqua e sottoposti ad un ciclo di fatica termica tra 5°C e 55°C. Viene anche proposto un metodo corretivo del problema. La microscopia a forza atomica e la microscopia ottica in campo prossimo sono state testate come strumento di verifica e validazione dei dati ottenuti.
XXII Ciclo
1980

2012/2013
The subject of this thesis is the stability of the adhesive interface in dentistry. Success in adhesive dentistry means long lasting restorations. However, there is substantial evidence that this ideal objective is not achieved. Current research in this field aims at increasing the resin-dentin bond durability. This doctoral research examines the fundamental processes responsible for the aging mechanisms involved in the degradation of resin-bonded interfaces, as well as some potential approaches to prevent and counteract this degradation. Resin-dentin bond degradation is a complex process that is not completely understood, involving the hydrolysis of both the resin and the collagen component of the hybrid layer. The hydrophilic and acidic characteristics of current dentin adhesives have made hybrid layers highly prone to water sorption, which causes polymer degradation and results in decreased resin-dentin bond strength over time. These unstable polymers inside the hybrid layer may result in an incomplete encapsulation of collagen fibers, which become vulnerable to mechanical and hydrolytical fatigue, as well as degradation by host-derived proteases with collagenolytic activity. These enzymes, such as matrix metalloproteinases (MMPs) and cysteine cathepsins, have a crucial role in the degradation of type I collagen, the organic component of the hybrid layer. The first part of this thesis aims to review the current knowledge regarding adhesion to the tooth substrate (Chapter 1), focusing on the fundamental processes that are responsible for the degradation of the adhesive interface (Chapter 2). Since the permeability of adhesives to water is particularly evident in simplified adhesive formulations, the research activity was focused on self-etch and universal adhesive systems’ behavior. Thus, the research study reported in Chapter 3 showed that the bond strength and nanoleakage expression of two-step and one-step self-etch tested bonding systems were affected by storage for 6 month and 1 year in artificial saliva. Although it is generally accepted that the permeability of adhesives to water is particularly evident in simplified adhesive formulations, the stability over time was not related to the number of steps of bonding systems, but to their chemical formulations. The performance of a new universal (or multi-mode) adhesive system through storage in artificial saliva was also investigated. The original results presented in Chapter 4 found that improved bonding effectiveness of the tested universal adhesive system on dentin was obtained when the adhesive was applied with the self-etch approach. Indeed, the etch-and-rinse approaches tested (both on wet and dry dentin) resulted in immediate bond strength comparable to the self-etch mode but expedited long-term aging resulted in reduced bond strength and increased nanoleakage expression, irrespective of dentin wetness. Moreover, the results of the zymographic analysis showed evident changes in dentinal MMP-2 and -9 enzyme activities after the application of the tested adhesives, revealing differences in the extent of enzyme activation. These findings exhibit that the activation of endogenous MMPs is not related to the adhesive system or the strategy employed. Thus, regardless of the approach and the material used in bonding procedures, a stable and durable bond is not achieved. Therefore, experimental strategies that aim to enhance the adhesive interface, particularly improving the durability of the resin-dentin bond strength by inhibiting intrinsic collagenolytic activity and increasing the resistance of dentin collagen matrix to enzymatic degradation are needed. The last part of the thesis is focused on both the strategies to inhibit the proteolytic and collagenolytic activity of the endogenous proteases and the methods to increase the mechanical strength of collagen network and its resistance to enzymatic degradation (Chapter 5). Chlorhexidine (CHX) has been used as a non-specific MMP inhibitor to prevent degradation of hybrid layers. However, CHX is water-soluble and may leach out of hybrid layers, compromising its long-term anti-MMP effectiveness. An entirely different approach is to treat the acid-etched dentin containing activated matrix-bound MMPs with cross-linking agents that inactivate the catalytic site of proteases. In particular, the ability of a cross-linker agent, 1-ethyl-3-(3-dimethylamino-propyl) carbodiimide (EDC), to prevent collagen degradation was evaluated under occlusal cycle loading. Previous research successfully utilized EDC to increase the durability of resin-dentin bonds by increasing the mechanical properties of the collagen matrix; however, the 1 to 4 hrs required for that procedure was clinically unacceptable. For this reason, the purpose of the last part of the research, presented in Chapter 6, was to evaluate the ability of 0.5 M EDC short-time (1 min) pre-treatment to improve the stability of demineralized dentin collagen matrices by quantifying the release of telopeptide fragments over time. The results showed that EDC application for 1 min may be a clinically relevant and effective means for stabilizing the collagen network not only by strengthening the fibrils, but also by reducing the enzymatic degradation rate. Thus, dentin collagen reinforcement and strengthening through EDC cross-linking might be of importance to improve the bond strength and structural integrity of the resin-dentin interface over time against the enzymatic and hydrolytic degradation.
La tesi qui presentata riguarda la stabilità dell'interfaccia adesiva in odontoiatria. Il successo delle moderne terapie conservative è rappresentato dalla longevità dei restauri adesivi. Tuttavia, vi è una sostanziale evidenza che questo obiettivo ideale non sia raggiunto. La stabilità dell’interfaccia adesiva dipende dalla formazione di uno strato ibrido, compatto e omogeneo, durante l’impregnazione del substrato dentinale da parte dei monomeri adesivi. Poiché lo strato ibrido rappresenta un’entità complessa, in cui interagiscono componenti biologiche diverse (matrice dentinale collagenica e cristalli d’idrossiapatite residui) e non (monomeri resinosi e solventi), i fenomeni d’invecchiamento interessano in maniera sinergica sia la porzione resinosa che quella dentale. L’articolato processo che porta alla degradazione dell’interfaccia adesiva coinvolge infatti la componente resinosa, attraverso l’idrolisi della resina negli spazi interfibrillari, e quella organica, attraverso la disorganizzazione delle fibre collagene dovuta ad un incompleto incapsulamento delle stesse, nonché alla degradazione da parte di proteasi intrinseche con attività collagenolitica. È stato dimostrato come questi enzimi, le metalloproteinasi della matrice (MMP) e le catepsine, abbiano un ruolo cruciale nella degradazione del collagene di tipo I, la principale componente organica dello strato ibrido. Inoltre le caratteristiche idrofile e acide degli attuali sistemi adesivi dentinali hanno reso lo strato ibrido molto suscettibile all'assorbimento di acqua, comportando, attraverso l’idrolisi, la degradazione dello stesso e andando così a contribuire ad una diminuzione della forza di legame nel tempo. Attualmente l’interesse della comunità scientifica mira ad aumentare la durata del legame adesivo con il substrato dentinale. Dopo un’attenta analisi delle attuali conoscenze riguardanti adesione al substrato dentale (Capitolo 1), la prima parte della tesi si propone di valutare i processi fondamentali che sono responsabili della degradazione dell'interfaccia adesiva (Capitolo 2). Poiché la permeabilità all’acqua degli adesivi è particolarmente evidente nelle formulazioni semplificate, l'attività di ricerca si è concentrata sull’analisi del comportamento dei sistemi adesivi self-etch e dei recenti sistemi adesivi universali. I risultati riportati nel Capitolo 3 ha dimostrato come la forza di legame e l’espressione del nanoleakage dei sistemi adesivi self-etch two-step e one-step testati sia negativamente influenzata dall’invecchiamento in saliva artificiale per 6 mesi e 1 anno. Sebbene sia generalmente accettato che la permeabilità degli adesivi all'acqua è particolarmente evidente in formulazioni di adesivi semplificati, la stabilità nel tempo non è stata correlata al numero di passaggi dei sistemi adesivi, bensì alle loro composizioni chimiche. Sono state in seguito analizzate anche le prestazioni di un nuovo sistema adesivo universale (o multimodale). I risultati presentati nel Capitolo 4 hanno stabilito una migliore efficienza adesiva del sistema universale, testato sul substrato dentinale, quando l'adesivo è stato applicato con l'approccio self-etch. Infatti, la tecnica etch-and-rinse, testata sia su dentina umida che secca, ha comportato una forza di adesione immediata paragonabile alla modalità self-etch, ma a tempi di invecchiamento incrementali si è evidenziata una diminuzione della forza di legame e una maggiore espressione del nanoleakage, a prescindere dalla condizione di umidità dentinale. Inoltre, i risultati dell'analisi zimografica hanno mostrato evidenti variazioni dell’attività enzimatica delle metalloproteinasi MMP-2 e -9 dopo l'applicazione degli adesivi testati. Questi risultati dimostrano come l'attivazione delle MMP endogene non sia correlata al sistema adesivo o alla strategia adottata. Ne evince che, indipendentemente dal metodo e dal materiale utilizzato nelle procedure adesive, non si è in grado di stabilire un legame affidabile e duraturo. Pertanto si avverte l’esigenza di strategie sperimentali che mirino a migliorare la stabilità dell’interfaccia adesiva, in particolare incrementando la durata della forza di legame in dentina inibendo l'attività collagenolitica intrinseca e aumentando la resistenza del collagene alla degradazione enzimatica. L'ultima parte della tesi è focalizzata quindi sulle strategie per inibire l'attività proteolitica e collagenolitica delle proteasi endogene e sui metodi per aumentare la resistenza meccanica del collagene alla degradazione enzimatica (Capitolo 5). Un potente agente antibatterico, la clorexidina (CHX), è stato usato come inibitore non specifico delle MMP al fine di impedire la degradazione dello strato ibrido. Tuttavia la CHX, essendo solubile in acqua, può dissolversi nello strato ibrido, compromettendo la sua efficacia anti-MMP a lungo termine. Un approccio completamente diverso è quello di trattare la dentina mordenzata con agenti cross-linker. In particolare, simulando il carico occlusale, è stata valutata la capacità di un agente cross-linker, l’1-etil-3-(3-dimetilammino-propil) carbodiimmide (EDC), per prevenire la degradazione del collagene. Precedenti ricerche hanno utilizzato con successo l’EDC con lo scopo di aumentare la durata dell’interfaccia adesiva, aumentando le proprietà meccaniche della matrice di collagene; tuttavia, il tempo necessario (da 1 a 4 ore) richiesto per tali procedure è clinicamente inaccettabile. Per questo motivo, lo scopo dell’ultima parte della ricerca, presentata nel Capitolo 6, è stato quello di valutare la capacità di 0,5 M EDC nel breve periodo di pretrattamento (1 min), andando a quantificare il rilascio di frammenti di telopeptidi di collagene nel corso del tempo. I risultati hanno dimostrato che l'applicazione di EDC per 1 min può essere un approccio clinicamente rilevante ed efficace nello stabilizzare il collagene, non solo rafforzando le fibrille, ma anche riducendo la velocità di degradazione enzimatica. Di conseguenza, l’utilizzo di questo cross-linker può garantire una valida strategia per migliorare la forza di legame e l'integrità strutturale dell'interfaccia adesiva nel tempo contro l’attività enzimatica intrinseca del collagene e la degradazione idrolitica.
XXVI Ciclo
1985

A study was carried in conjunction with the Orthodontic department at Halmstad General Hospital in Sweden to investigate the possibility of reducing cost and manufacture time of dental implant drill guides.

The current system involves sending a digital image in STL format to the Materialise factory in Belgium where information of the position of dental implants is translated onto a moulded mouthpiece. Drill guides are placed in the mouth piece which is then returned to the surgeon. The mouthpiece complete with drill guides is then placed in the patients mouth and used as a guide for the implant drill holes. The cost of 10000 sek and a turnaround time of 2 weeks gave rise to the need for a faster and cheaper solution.

A new mouthpiece was designed comprising of a solid cube which could be clearly seen on the x-ray. Linearisation of the cube faces is used to find a reference point from which to drive a 5 axis drilling platform. The mouthpiece is placed in the drill platform which is driven by stepper motors which in turn are controlled by a microcontroller. Co-ordinates are entered via a PC interface. The PC software then translates these co-ordinates into motor steps which are sent to the microcontroller. The drill platform then positions the mouthpiece in order to drill guide holes for the dental implants.

The study showed that the machine design gave an acceptable degree of accuracy and repeatability. Further enhancements could be made by automating the detection of the cube using image analysis techniques. The study was also limited by the lack of graphical and geometrical data concerning the position of the implant. For the purpose of this study the co-ordinates for the implants guides is entered by hand.

It was concluded that further software and hardware enhancement would be needed before the application could be developed commercially.

Objectives: The UBC Graduate Pediatric Dentistry Program’s oral sedation clinic has evolved since it began in 2011. The study aimed to evaluate the effectiveness and safety of the various sedation regimens used, and to assess how regimens were influenced by the experience and opinions of clinical instructors. Methods: A retrospective chart review of all oral sedation appointments that took place between March 2011 and May 2014 was completed. The outcome variables of interest were effectiveness and safety. Descriptive and comparative statistics were applied to analyze quantitative data. Six UBC Pediatric Dentistry clinical instructors were invited for interviews through a purposive sampling technique to further understand both their views toward sedation regimens and teaching sedation to graduate students. Thematic analysis was applied to code interview transcripts. Results: There were 195 oral sedation appointments during the study period. The three most commonly used regimens were: midazolam and hydroxyzine (MZH) (45%); midazolam (MZ) (24%); and meperidine, chloral hydrate, hydroxyzine, and dimenhydrinate (MCHHD) (17%). With respect to safety, vital signs and level of sedation were examined. Children undergoing MZH sedations were rated to be in “deep” sedation 1.4% of the time, compared to 12.5% in the MCHHD group. MZH sedations were rated “effective/very effective” 90% of the time, compared with 88% for MCHHD sedations. Data for sedation level and effectiveness of the MZ group was limited. Domains that emerged from the interviews were safety, effectiveness, preparation, and preferences; with risk tolerance as the overarching theme. Conclusion: MZH and MCHHD have similar effectiveness however MZH has a better safety profile. Clinicians with higher risk tolerance tended to practice sedation more frequently than those with low risk tolerance. Accordingly, high risk tolerance clinicians felt students should learn sedation more extensively than did those with low risk tolerance. Two main recommendations emerged from the study: (1) complete and inclusive sedation records are critical to fully understanding the effectiveness and safety of sedation regimens; 2) clinicians may desire to have self-awareness regarding their risk tolerances in the context of both practicing and teaching oral sedation in pediatric dentistry.
Dentistry, Faculty of
Graduate