Preload Evaluation of Different Screws in External Hexagon Joint

Purpose: This study compared the maintenance of tightening torque in different retention screw types of implant-supported crowns.Materials and Methods: Twelve metallic crowns in UCLA abutments cast with cobalt-chromium alloy were attached to external hexagon osseointegrated implants with different retention screws: group A: titanium alloy retention screw; group B: gold alloy retention screw with gold coating; group C: titanium alloy retention screw with diamond-like carbon film coating; and group D: titanium alloy retention screw with aluminum titanium nitride coating. Three detorque measurements were obtained after torque insertion in each replica. Data were evaluated by analysis of variance (ANOVA), Tukey's test (P < 0.05), and t test (P < 0.05).Results: Detorque value reduced in all groups (P < 0.05). Group A retained the highest percentage of torque in comparison with the other groups (P < 0.05). Groups B and D retained the lowest percentage of torque without statistically significant difference between them (P < 0.05).Conclusions: All screw types exhibited reduction in the detorque value. The titanium screw maintained the highest percentage of torque whereas the gold-coated screw and the titanium screw with aluminum titanium nitride coating retained the lowest percentage. (Implant Dent 2012;21:46-50)

THE EFFECT of DENTIN PRETREATMENT on THE MICROTENSILE BOND STRENGTH of SELF-ADHESIVE RESIN CEMENTS

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effect of implant connection and restoration design (screwed vs. cemented) in reliability and failure modes of anterior crowns

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

The Effect of Mechanical Cycling and Different Misfit Levels on Vicker's Microhardness of Retention Screws for Single Implant-Supported Prostheses

Purpose: The aim of this study was to evaluate the effect of mechanical cycling and different misfit levels on Vicker's microhardness of retention screws for single implant-supported prostheses.Materials and Methods: Premachined UCLA abutments were cast with cobalt-chromium alloy to obtain 48 crowns divided into four groups (n = 12). The crowns presented no misfit in group A (control group) and unilateral misfits of 50 mu m, 100 mu m, and 200 mu m in groups B, C, and D, respectively. The crowns were screwed to external hexagon implants with titanium retention screws (torque of 30 N/cm), and the sets were submitted to three different periods of mechanical cycling: 2 x 10(4), 5 x 10(4), and 1 x 10(6) cycles. Screw microhardness values were measured before and after each cycling period. Data were evaluated by two-way ANOVA and Tukey's test (p < 0.05).Results: Mechanical cycling statistically reduced microhardness values of retention screws regardless of cycling periods and groups. In groups A, B, and C, initial microhardness values were statistically different from final microhardness values (p < 0.05). There was no statistically significant difference for initial screw microhardness values (p > 0.05) among the groups; however, when the groups were compared after mechanical cycling, a statistically significant difference was observed between groups B and D (p < 0.05).Conclusions: Mechanical cycling reduced the Vicker's microhardness values of the retention screws of all groups. The crowns with the highest misfit level presented the highest Vicker's microhardness values.

Effect of Vertical Misfit on Screw Joint Stability of Implant-Supported Crowns

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Art in the inclusion of children with special needs in dentistry

A proposta deste estudo é relatar a utilização da arte e seus segmentos, como recurso para inclusão da criança portadora de necessidades especiais ao ambiente odontológico. Foi utilizado como método a aplicação da arte em atividades de socioterapia e oficinas, divididas em módulos: sessão de socialização, oficinas de arte e atividades complementares, visando à elaboração de uma anamnese cultural por meio de questionários e a obtenção das preferências artísticas dos 313 participantes, previamente às suas assistências odontológicas no CAOE (Centro de Assistência Odontológica a Portadores de Necessidades Especiais) FOA/Unesp. de acordo com os questionários respondidos, a música e a pintura, segundo a preferência dos participantes, são os segmentos artísticos que mais auxiliam nas atividades de inclusão e adaptação. Concluímos que a utilização da arte na adaptação e inclusão ambiental do paciente, previamente à assistência odontológica, é favorável e eficaz.

Sexual harassment in Dentistry: prevalence in dental school

Objective: Sexual harassment is unlawful in all work and educational environments in most nations of the world. The goals of this study were to describe the sexual harassment prevalence and to evaluate the experiences and attitudes of undergraduate students in one dental school in Brazil. Material and Methods: An 18-item questionnaire was administered to 254 dental students with a completion rate of 82% (208). Students were requested to respond to questions about their background and academic level in dental school, their personal experiences with sexual harassment and their observation of someone else being sexually harassed. Bivariate statistical analyses were performed. Results: Fifteen percent of the students reported being sexually harassed by a patient, by a relative of a patient or by a professor. Male students had 3 times higher probability of being sexually harassed than female student [OR = 2.910 (1.113-7.611)]. Additionally, 25.4% of the students reported witnessing sexual harassment at the school environment. The majority of students did not feel professionally prepared to respond to unwanted sexual behaviors. Conclusion: These findings demonstrate that sexual harassment can occur in a dental school setting. There is a need for ongoing sexual harassment education programs for students and university staff. Increased knowledge of sexual harassment during graduation can better prepare dental professionals to respond to sexual harassment during their practice.

Dentistry in Brazil: Its History and Current Trends

The objectives of this article are to provide a short history of dentistry and dental education in Brazil and to analyze the nature of its development to date. The databases consulted are those provided by the Brazilian Federal Council of Dentistry, Brazilian Ministry of Health, Brazilian Ministry of Education, National Institute of Studies and Educational Research Anisio Teixeira, and Brazilian Institute of Geography and Statistics. Formal dental education in Brazil started in the late nineteenth century with the creation of courses annexed to existing schools of medicine in Rio de Janeiro and Bahia. Today, there are 191 institutions of higher education nationwide granting degrees in dentistry (137 private [71.7 percent] and fifty-four public [28.3 percent]), with a total of 17,157 student positions offered annually. These schools graduate around 10,000 professionals per year-one of the highest rates in the world. Both the distribution of schools of dentistry and of dentists varies among the regions of the country, with the greatest concentrations in major metropolitan centers with high population density, resulting in limited coverage in the more deprived regions. A review of epidemiological data for oral health and distribution of dentists in Brazil indicates that there is a lack of systematic planning for the allocation of the dental workforce and a lack of consideration of regional needs in the development of dental training programs in Brazil today.

Shortening of primary dentin etching time and its implication on bond strength

Objective. The aim of this study was to investigate the influence of shortening the etching time on the bond strength of a conventional and a self-etching primer adhesive system used in primary tooth dentin.Methods. Flat dentin surfaces were obtained from 24 primary molars, randomly assigned to 4 experimental groups. The adhesive systems Single Bond and Clearfil SE Bond were applied in two groups according to the manufacturers' recommendations. In the other two groups, the adhesives were applied after half-time of acid etching, 7 s for Single Bond and 10 s for Clearfil SE Primer. Resin crowns were built up and after 24 h storage in water at 37 &DEG; C, the teeth were sectioned to produce beams with cross-sectional area of approximately 0.49 mm(2). Specimens were tested in tension at 0.5 mm/min until failure. Fractured specimens were analyzed to determine the failure mode.Results. Tensile bond strengths for Single Bond in primary dentin were higher than for Clearfil SE Bond. Shortening of acid etching time improved bond strength only for Single Bond, while no statistically significant difference was observed for Clearfil SE Bond when both etching times were compared.Significance. No detrimental effect on bond strength was observed when the time of acid etching was shortened in 50%. Shortening the time for a procedure in a small child without compromising the quality of the work is a very important finding for the practicing pediatric dentist. © 2004 Elsevier Ltd. All rights reserved.

Effect of acid etching time on the degradation of resin-dentin bonds in primary teeth

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Single crowns versus conventional fillings for the restoration of root filled teeth

BackgroundEndodontic treatment, involves removal of the dental pulp and its replacement by a root canal filling. Restoration of root filled teeth can be challenging due to structural differences between vital and non-vital root filled teeth. Direct restoration involves placement of a restorative material e.g. amalgam or composite directly into the tooth. Indirect restorations consist of cast metal or ceramic (porcelain) crowns. The choice of restoration depends on the amount of remaining tooth which may influence long term survival and cost. The comparative in service clinical performance of crowns or conventional fillings used to restore root filled teeth is unclear.ObjectivesTo assess the effects of restoration of endodontically treated teeth (with or without post and core) by crowns versus conventional filling materials.Search methodsWe searched the following databases: the Cochrane Oral Health Group's Trials Register, CENTRAL, MEDLINE via OVID, EMBASE via OVID, CINAHL via EBSCO, LILACS via BIREME and the reference lists of articles as well as ongoing trials registries. There were no restrictions regarding language or date of publication. Date of last search was 13 February 2012.Selection criteriaRandomised controlled trials (RCTs) or quasi-randomised controlled trials in participants with permanent teeth which have undergone endodontic treatment. Single full coverage crowns compared with any type of filling materials for direct restoration, as well as indirect partial restorations (e.g. inlays and onlays). Comparisons considered the type of post and core used (cast or prefabricated post), if any.Data collection and analysisTwo review authors independently assessed trial quality and extracted data.Main resultsOne trial judged to be at high risk of bias due to missing outcome data, was included. 117 participants with a root filled premolar tooth restored with a carbon fibre post, were randomised to either a full coverage metal-ceramic crown or direct adhesive composite restoration. At 3 years there was no reported difference between the non-catastrophic failure rates in both groups. Decementation of the post and marginal gap formation occurred in a small number of teeth.Authors' conclusionsThere is insufficient evidence to support or refute the effectiveness of conventional fillings over crowns for the restoration of root filled teeth. Until more evidence becomes available clinicians should continue to base decisions on how to restore root filled teeth on their own clinical experience, whilst taking into consideration the individual circumstances and preferences of their patients.

Fracture strength of incisor crowns after intracoronal bleaching with sodium percarbonate

Objectives: To compare the fracture resistance of bovine teeth after intracoronal bleaching with sodium percarbonate (SPC) or sodium perborate (SP) mixed with water or 20% hydrogen peroxide (HP). Materials and methods: Fifty extracted bovine teeth were divided into four experimental groups (G1G4) and one control (n = 10) after endodontic treatment. Following root canal obturation, a glass ionomer barrier was placed at the cementoenamel junction. After that, the pulp chambers were filled with: G1 SP with water; G2 SP with 20% HP; G3 SPC with water; and G4 SPC with 20% HP. No bleaching agent was used in the control group. Coronal access cavities were sealed with glass ionomer and specimens were immersed in artificial saliva. The bleaching agents were replaced after 7 days, and teeth were kept in artificial saliva for an additional 7 days, after which the pastes were removed and the coronal access cavities were restored with glass ionomer. Crowns were subjected to compressive load at a cross head speed of 0.5 mm min-1 applied at 135 degrees to the long axis of the root by an EMIC DL2000 testing machine, until coronal fracture. Data were statistically analysed by anova and Tukey test. Results: No differences in fracture resistance were observed between the experimental groups (P > 0.05). However, all experimental groups presented lower fracture resistance than the control group (P < 0.05). Conclusion: SPC and SP led to equal reduction on fracture resistance of dental crowns, regardless of being mixed with water or 20% HP.