Дисертації з теми "Restorative and prosthodontics margins"

Prosthodontic and periodontal correlation on teeth In the daily dental practice 3 fundamental/empiric/clinical parameters have a role to establish the clinical success of prosthodontic treatment: function, aesthetic and longevity of the restorations. But, from a scientific point of view, how do we rate the success of the restorations? When analyzing the existing literature, it can be noted that many authors focus their attention on the precision of the margin, to pursuit a small gap between the abutment and the crown, and to achieve the clinical success. Christensen et al.1 and Mc Lean & Von Fraunhofer2 investigated the margins’ clinical acceptability by dentists and asked to measure the gap between the abutment and the crown to a number of practitioners: it was shown that a clinician can clinically appreciate a gap not lower than 120 microns using a sharp explorer. This result may end in a not sure and sufficient seal between the crown and abutment, and consequently leakage at the margins. This finding is not in agreement with the existing data coming from an in vitro study in which the acceptable marginal gap is lower than 50 microns3 Sorensen3 reported that small defects less or equal then 0,050 mm were associated with significantly less fluid flow and bone loss than defects exceeding this value. Martignoni4-5 reported that there are variable definitions regarding what constitutes a margin that cab ne clinically acceptable, and there is no definite threshold for the maximum marginal discrepancy that is clinically acceptable. Many authors accept the criteria established by McLean and Von Fraunhofer2, they completed a 5-year examination of 1000 restorations and concluded that 120 microns should be considered the maximum marginal gap. The adaptation, the precision and the quality of the restoration margin can be of greater significance in terms of gingival health, than the position of the margin6. According to Lang et al. 7 following the placement of restorations with overhanging margins, a subgingival flora was detected which closely resembled that of chronic periodontitis. Following the placement of the restorations with clinically perfect margins, a microflora characteristic for gingival health or initial gingivitis was observed. In patients with suitable oral hygiene, tooth-supported and implant-supported crowns with intra-sulcular margins were not predisposed to unfavorable gingival and microbial responses8. Even among patients receiving regular preventive dental care, subgingival margins are associated with unfavorable periodontal reactions9. Ercoli and Caton10, in a systematic review, describe how placement of restoration margins within the junctional epithelium and supracrestal connective tissue attachment can be associated with gingival inflammation and, potentially, recession or periodontal pocket. The presence of fixed prostheses finish line within the gingival sulcus or wearing of partial, removable dental prostheses does not cause gingivitis if the patients are complaint with self-performed plaque control and periodic maintenance. Procedures adopted for the fabrication of dental restorations and fixed prostheses have the potential to cause traumatic loss of the periodontal supporting tissue. They concluded that restoration margins located within the gingival sulcus do not cause gingivitis if the patients are complaint with self-performed plaque control and periodic maintenance. Tooth-supported and/or tooth-retained restorations and their design, fabrication, delivery, and materials, have often been associated with plaque retention and loss of attachment. Restoration margins placed within the junctional epithelium and supracrestal connective tissue attachment can be associated with inflammation and, potentially, recession. Factors related to the presence, design, fabrication, delivery and materials of tooth-supported prostheses seem to influence the periodontium, generally related to localized increase in plaque accumulation and, less often, to traumatic and allergic reactions to dental materials10. Jansson showd that the influence of a marginal overhang on pocket depth and radiographic attachment decrease with increasing loss of periodontal attachment in periodontitis-prone patients, and the effect on pocket depth of a marginal overhang may act synergistically, potentiating the effect of poor oral hygiene11. Subgingival restorations with their apical borders still located subgingivally after periodontal treatment should be regarded as a risk factor in the progression of periodontitis12. Consequently, placement of the restoration margin supragingivally is recommended, especially in periodontitis-prone patients with an insufficient plaque control12. Dental restorations may be suggested as a risk indicator for periodontal disease and tooth loss. Routine SPT (Supportive Periodontal Therapy) was found to be associated with decrease in the prevalence of deep PPD over time, and it is of the utmost importance in maintaining periodontal health, especially adjacent to teeth with restorations. Finally, these findings may support the treatment of caries lesions and faulty restorations as part of a comprehensive cause-related therapy and should be followed by a regular maintenance program13. The relationship between dental restorations and periodontal status has been examined for some time. Research has shown that overhanging dental restorations and subgingival margin placement play an important role providing an ecologic niche for periodontal pathogens14. An overhanging dental restoration is primarily found in the class II restoration, since access for interdental finishing and polishing of the restoration, and cleansing is often difficult in these areas, even for patients with good oral hygiene. Many studies have shown that there is more periodontal attachment loss and inflammation associated with teeth with overhangs than those without. Presences of overhangs may cause an increase in plaque formation15-21 and a shift in the microbial composition from healthy flora to one characteristic of periodontal disease14. The location of the gingival margin of a restoration is directly related to the health status of the adjacent periodontium8. Numerous studies8-12-25 have shown that subgingival margins are associated with more plaque, more severe gingival inflammation and deeper periodontal pockets than supragingival ones. In a 26-year prospective cohort study, Schatzle et al. 25 followed middle class Scandinavian men for a period of 26 years. Gingival index, and attachment level were compared between those who did and those who did not have restorative margins greater than 1mm from the gingival margin. After 10 years, the cumulative mean loss of attachment was 0.5 mm more for the group with subgingival margins. This was statistically significant. At each examination during 26 years of the study, the degree of inflammation in the gingival tissue adjacent to subgingival restorations was much greater than in the gingiva adjacent to supragingival margins. This is the first study to document a time sequence between the placement of subgingival margins and periodontal attachment loss, confirming that the subgingival placement of margins is detrimental to gingival and periodontal health. Plaque at apical margin of a subgingival restoration will cause periodontal inflammation that may in turn destroy connective tissue and bone approximately, 1-2 mm away from inflamed area14. Determination of the distance between the restorative margin and the alveolar crest is often done with bitewing radiographs; however, it is important to remember that a radiograph is a 2-dimensional representation of 3-dimensional anatomy and structure. Thus, clinical assessment and judgment are important adjuncts in determining if, and how much, bone should be removed to maintain adequate room for the dento-gingival supra crestal connective tissue height attachment14. Although surface textures of restorative materials differ in their capacity to retain plaque26, all of them can be adequately maintained if they are correctly polished and accessible to patient care27. This includes underside of pontics. Composite resins are difficult to finish interproximally and may be more likely to show marginal defects than other materials28. As a result, they are more likely to harbor bacterial plaque29. Intra-subject comparisons of unilateral direct compositive “veneers” showed a statistically significant increase in plaque and gingival indices adjacent to the composites, 5-6 years after placement28. In addition, when a diastema is closed with composite, the restorations are often overcontoured in the cervical-interproximal area, leading to increased plaque retention28. As more plaque is retained, this could pose a significant problem for a patient with moderate to poor oral hygiene14. For that, in absence of more specific prosthodontic parameters to evaluate the integration of crowns in to the periodontal environment, another way to determine the success and health of the restoration is to use the periodontal parameters such as: PPD (Periodontal Probing Depth) that is the measurement of the periodontal sulcus/pocket between the gingival margin and the bottom of the sulcus/pocket; REC (Recession) is the apical migration of the gingival margin measured with the distance between the gingival margin and the CEJ (Cement-Enamel Junction); PI (Plaque Index) the index records the presence of supragingival plaque; BOP (Bleeding On Probing) the presence or not of bleeding on surfaces of the teeth during the probing. The aim of this study/thesis was to propose a clinical procedure to evaluate single unit restorations and their relations with periodontal tissues by a new clinical score: the FIT ( Functional Index for Teeth). FIT, that is a novel index for the assessment of the prosthetic results of lithium disilicate crowns, based on seven restorative-periodontal parameters, that evaluate crowns placed on natural abutments, and want to be a reliable and objective instrument in assessing single partial crown success and periodontal outcome as perceived by patients and dentists.

Cracked teeth have long presented a diagnostic challenge. Previous investigators have considered possible predictive factors, many of which revolve around the tooth’s restorative characteristics. Few have investigated the restorative status of teeth with cracks extending into the pulp chamber. The purpose of this investigation was to determine the prevalence of the different types of restorations present in intrapulpally cracked teeth and determine any other restorative factors that may aid in predicting the presence or extent of an intrapulpal crack. Intrapulpally cracked molars requiring endodontic therapy at the VCU Graduate Endodontic Practice were included in this study. For each tooth, the type of restorative material present and surfaces involved were recorded. The Restoration Volume Proportion (RVP) was calculated to accurately quantify the size of the restoration present. Pulpal and periapical diagnoses, and intrapulpal crack classification were also recorded. Chi squared analysis and logistic regression were used to determine any significant associations. This study included 43 teeth. The study population was 65% female and the average age was 56. Of the various restoration types evaluated, 73% of teeth presented with amalgams, 12% with composites. Class I restorations were 61% of the sample. The most frequently occurring restoration size by volume was a “small” restoration. The most commonly involved teeth were the maxillary 1st molar and mandibular 2nd molar. A significant association was found between restoration size and crack classification suggesting that teeth with larger restorations had a higher incidence of coronal cracks while those with smaller restorations had a higher incidence of radicular cracks. Restoration classification and pulpal walls involved were also significantly associated suggesting that Class II restorations were most frequently associated with cracks involving a single pulpal wall while Class I restorations were evenly associated with one and two wall cracks. Other significant associations were found between tooth type and pulpal walls involved and between restoration surfaces and pulpal wall classification. This study found several significant associations between restoration characteristics and intrapulpal cracks. Further research may continue to reveal how a tooth’s restorative status may influence its risk for the presence of an intrapulpal crack.

One of the most critical aspects of successful crown and bridgework is temporary restorations. Failure of temporary restoratins often affects the patient's confidence and mau result in unscheduled appointments for repair. This study compared the the fracture toughness of two materials commonly used to fabricate provisional restorations, namely Coldpac, a polymethyl methacrylate and Protemp 3 Garant, a bis-acryl composite. It also compard the fracture toughness of the two materials when reinforced with stainless steel wire, glass fibers and polythylene fibers.

The study uses a qualitative comparative case study design to study the adoption, implementation and integration of restorative justice in education (RJE) in public high schools as a remedy to the growing school-to-prison pipeline. Such zero-tolerance, exclusionary policies that dominate schools today adopt punitive tactics towards handling matters of conflict and justice within schools. The retributive approach is gaining harsh criticism as it disproportionately impacts minority youth and criminalizes student behavior. RJE along with other Social Emotional Learning (SEL) approaches is gaining traction within schools as a means of humanizing school environments and emphasizing a student centered perspective. Drawing on human service organizational theoretical frameworks, namely institutional entrepreneurship, innovation implementation, ambiguity-conflict model of policy implementation and diffusion of innovation, this study seeks to expand knowledge on RJE by providing a more critical examination of whether RJE has moved from a more marginal status towards becoming mainstream or standardized practices at schools. The study has a particular focus on the partnerships with community-based organizations (CBOs) many high schools form in order to carry out this work.

The study adopts a two-phased purposively sampled approach conducted over a period of a year. The primary mode of data collection comprised of conducting face-to-face semi-structured interviews with program managers of CBOs (n=10), central district personnel (n=3), which constitutes the first phase, and multiple school personnel across four high schools (n=60), which constitutes the second phase. Using the AtlasTi software, verbatim transcripts of audio-recorded interviews were analyzed using an inductive and deductive coding scheme. Additional sources such as school discipline data, observations, contract documents and other media sources were examined for data triangulation purposes.

The findings highlight the critical role played by CBOs to bring about RJE adoption at both the policy level as well as the local schools. However post RJE reform at the policy level, the role and the agency of the CBOs have diminished as evidenced in my findings. Despite the RJE seed being planted by CBOs at schools, the principals make the ultimate adoption decisions about catalyzing RJE reform within schools. Successful implementation of RJE within schools includes three main factors: leadership, effective communication on RJE programming and invigorating a positive school culture. Schools which diffuse and institutionalize RJE as a part of SEL compared to schools that integrate RJE as a part of discipline are more likely to be contributing to the care ethos and nurturing healthy school cultures. However, such a contribution has not redefined the notion of policing and justice within schools, as the study finds traces of the retributive approach still operational within these schools.

Using the various organizational theoretical frameworks I argue that there are five critical aspects that have come in the way of RJE reform dole out. Firstly, there is a discrepancy in RJE policy vis a vis practice because the CPS Central District Office is using coercive tactics and mandating the use of RJE within schools, which has resulted in resistance to RJE. Secondly, precarity of school-CBO partnerships are playing out largely because of resource dependency issues of CBOs who have lost their ability to effect change beyond adoption. Thirdly, findings highlight the constant state of urban flux in operation at these schools such as drastic leadership changes, staff attrition, neighborhood gentrification amongst others, which has made embedding RJE into the fabric of schools very challenging. Principals have emerged as being very crucial to the RJE change process, since they are contending with both policy level actors as well as CBOs to continue to inspire their own personnel to implement and institutionalize RJE reform. Finally, especially at the local school level personnel appear to be more misinformed about the key components of RJE, thus training efforts need to be reoriented with fidelity and quality control in mind. Thereby, RJE has definitely moved away from the margins but it is still not the mainstream practice at schools. RJE has failed to upkeep its promise and potential especially towards marginalized, communities of color.

Greater district engagement, continued CBO agency as well as sustained programmatic endeavors spearheaded by principals at the local school level are important for RJE to pose as a true alternative to punitive sanctions rather than being coopted by the retributive approach. Therefore, my study pushes the field of human service delivery, in that instead of focusing on the outcomes of RJE, per se, it looks at the process of and challenges in implementing this innovation, providing insight into improving contracting relations between partners and questions the sustainability of reform efforts within urban environments.

Digital technology is advancing rapidly in dentistry. Computers are making what were previously manual tasks easier, faster, cheaper and more predictable. Layered manufacturing processes can produce complex shapes at affordable prices with little or no waste. The challenge for the dental materials research community is to mach the new technology with materials that are suitable for use in dentistry. This can potentially take dental materials research in a totally different direction. The new generation of ceramic materials presents interesting options, both in terms of material selection and in terms of fabrication techniques. A closer understanding of the dynamics of the materials with respect to design of the restoration and the intended use is required to enable these restorations to perform productively.

Uma correta reabilitação protética baseia-se no estudo detalhado de técnicas específicas, através das quais a combinação de materiais restauradores provisórios e protocolos de confeção adequados se mostra fundamental para o sucesso do tratamento. O estudo das propriedades dos materiais provisórios, em conjunto com um protocolo de confeção apropriado, permitiu o desenvolvimento de várias tecnologias e soluções reabilitadoras, nas quais participam uma equipa multiprofissional e o paciente, visando atingir o objetivo terapêutico. Este trabalho visa realizar uma revisão da literatura relativa à evolução e à relevância dos materiais restauradores provisórios na busca da excelência estética e funcional, durante o processo de reabilitação protética, e na manutenção da arquitetura tecidual periodontal, desafio atual de equipas multidisciplinares. Para isso foi elaborada uma pesquisa bibliográfica na PubMed/Medline, B-On, Scielo e na biblioteca da Universidade Fernando Pessoa.
A correct prosthetic rehabilitation is based on the detailed study of specific techniques, through which the combination of temporary restorative materials and suitable confection protocols is fundamental to a successful treatment. The study of the properties of the provisional materials, combined with an appropriate preparation protocol, allowed the development of several rehabilitation technologies and solutions, in which participate a multiprofessional team and the patient, aiming at reaching the therapeutic objective. This work aims to review the literature on the evolution and relevance of temporary restorative materials in the pursuit of aesthetic and functional excellence, during the prosthetic rehabilitation process, and in the maintenance of periodontal tissue architecture, the current challenge of multidisciplinary teams. For this, a bibliographic research was elaborated in PubMed /Medline, B-On, Scielo and in the library of the Fernando Pessoa University.

A Medicina Dentária constitui uma área do conhecimento médico incumbida de zelar, não só, pelo seu domínio de atuação clínico específico, mas também pelo bem-estar do paciente a nível sistémico nas suas várias dimensões: física, mental e social. Neste contexto, encontra-se sujeita a um processo de constante transformação, no qual o desenvolvimento técnico prossegue a par da evolução do conhecimento e dos princípios éticos que guiam estes profissionais de Saúde. Este trabalho propõe-se a ilustrar cada uma destas valências, utilizando como base para tal, o trabalho clínico e científico realizado pelo autor na Clínica Dentária Universitária da Universidade Católica Portuguesa, buscando caracterizá-lo segundo parâmetros clínicos e científicos considerados relevantes. Para isso é efectuada uma análise estatística dos atos clínicos realizados pelo autor procedendo-se à caracterização da amostra populacional assistida, bem como à interpretação, tipificação e resolução de algumas situações de âmbito clínico. Procura ainda retratar o Estado da Arte e os respectivos fundamentos decorrentes da evidência científica, fornecendo uma leitura epidemiológica e clínica da população servida, e proporcionando um olhar informado sob as situações clínicas encontradas e os desafios científicos a ter em consideração.
Dentistry, as a medical field, not only is it responsible for the zeal of its own specific area of clinical intervention, but also the patient's well being at the systemic level and at its various dimensions: physical, mental and social. That being, it finds itself suffering constant evolution, requiring a concomitant transformation of its clinical techniques, scientific knowledge and ethical grounds for the professionals who practice it. This paper proposes itself to illustrate each of these competences, using for it, the clinical and scientific work carried out by the author at the University Dental Clinic of the Portuguese Catholic University, seeking to characterize it according to clinical and scientific parameters that assert themselves to be relevant to such endeavor. To attain such goal, a statistical analysis of the clinical acts performed by the author and of certain idiosyncrasies of the served population sample is made. By the same token, an interpretation, illustration and resolution of clinical cases is also performed. It seeks to illustrate the current state-of-the-art and its respective concepts, which derive themselves from scientific evidence, aiming at providing an epidemiological and clinical reading of the assisted population, as well as rendering an informed look of clinical situations encountered and of the scientific challenges to be considered.

Os procedimentos restauradores e a saúde periodontal estão intimamente relacionados. Conhecendo esta realidade é de extrema importância saber o que pode desencadear uma quebra nesta harmonia, quais as suas consequências e o que se pode fazer para reparar esta condição. Torna-se inevitável abordar temas como o espaço biológico, localização das margens do procedimento restaurador e biocompatibilidade dos materiais usados em dentística. O objectivo desta monografia é avaliar a forma como estas duas áreas da Medicina Dentária se conjugam a de fim de melhorar a estética e a saúde oral do paciente. Foi realizada uma pesquisa bibliográfica tendo por base artigos e revistas científicas através do PubMed, Science Direct, Scielo, B-on e Google Académico, e livros cujo limite temporal recaiu entre 1961 e 2017.
The restorative procedures and the periodontal health are intimately related. Knowing this reality, it is of extreme importance to know what can trigger a break in this harmony, which are the consequences and what can be done to repair this condition. It becomes inevitable to approach themes like the biologic width, the margins location in a restorative procedure and the biocompatibility of the materials used. In this monography, it is possible to observe the way that this two areas of the Dentistry conjugate with each other, so that they can improve the aesthetics and the oral health of the patient. A bibliographic search was made based on articles and scientific journals through PubMed, Science Direct, Scielo, B-on and Google Academico, and books whose time limit fell between 1961 and 2017.