Aging Methods-An Evaluation of Their Influence on Bond Strength.

OBJECTIVES: To evaluate the effect of different artificial aging methods on the bond strength of a resin composite associated with a universal adhesive (Scotchbond Universal) used under two etching approaches (self-etch [SE] or etch-and-rinse [ER]) to enamel and dentin substrates. MATERIALS AND METHODS: A total of 96 noncarious human third molars were prepared and randomly divided according to three factors (n = 6): substrate (enamel and dentin), adhesive approach (SE and ER), and aging method (water storage for 24 hours, 6 months, or 1 year; subjected to 10,000, 20,000, or 30,000 thermal cycles; and sodium hypochlorite [NaOCl] storage for 1 or 5 hours). STATISTICAL ANALYSIS: Microshear bond strength tests were conducted, and the collected data (MPa) were subjected to three-way analysis of variance (ANOVA) with post hoc Bonferroni tests (p < 0.05) and Weibull analysis. The failure pattern was also evaluated. RESULTS: Three-way ANOVA revealed that the factors "substrate" (p = 0.00) and "aging method" (p = 0.00) had a significant effect on the bond strength, but the factor "adhesive approach" did not (p = 0.84). The bond strength in the enamel group for the SE approach was negatively affected under 20,000 and 30,000 thermal cycles. Weibull presented the highest m in the NaOCl storage for the 5 hours group to enamel using the SE and to dentin using ER approaches. Adhesive/mixed failures were predominant for all groups. CONCLUSION: Thermocycling aging (20,000 and 30,000 cycles) significantly reduced the bond strength to enamel using the SE approach. On the contrary, storage with the NaOCl method proved to increase bond strength under the evaluated conditions.

Marginal staining of ultra-thin ceramic veneers

The pigmentation of the resin cement at the tooth/ceramic interface compromises the esthetic and longevity of ultra-thin ceramic veneers. Aim: The aim of this study was to evaluate marginal staining of ultra-thin ceramic veneers cemented to intact enamel (non-prepared) and prepared enamel. Methods:Thirty-two (32) permanent central incisors were selected and randomly divided into two groups: intact enamel (IE) and prepared enamel (PE). The ceramic veneers of PE group were bonded to the prepared enamel and the ceramic veneers of IE group were cemented directly onto the intact enamel, with no preparation. Both preparation and cementation were standardized and performed by a single operator. Each group was subdivided into two subgroups (n = 8) with different immersion media - coffee and water. After an immersion period of 10 days, stereomicroscope images were made at 20X magnification of the mesial, distal, cervical and incisal surface of each specimen. Three blinded, trained and calibrated examiners evaluated the images of the resin cement interface of each surface. The data were subjected to KruskalWallis and MannWhitney statistical analysis. Immersion media and enamel preparation influenced the marginal staining of the tooth/ceramic interface. Results: When immersed in coffee, prepared interfaces presented greater marginal staining than unprepared interfaces. When immersed in water, there was no statistically significant difference between the groups. Conclusion: The cementation of ultra-thin ceramic veneers onto intact enamel is associated with less marginal staining and, consequently, improved esthetics

Glass fiber post treatment - does it influence resin cement bond strength? / Pinos de fibra de vidro pós tratamento - influencia a resistência de união do cimento resinoso?

Abstract Introduction Glass-fiber posts are used in order to improve the retention of restorations in endodontically treated teeth. Objective To evaluate the bond strength of glass-fiber posts submitted to different surface treatments and cemented to the root canal dentin with self-adhesive resin cement. Material and method Thirty roots of human canines were prepared and divided according to two factors: surface treatments (silane, 35% hydrogen peroxide, or sodium bicarbonate) and root thirds (cervical and middle thirds). The glass-fiber posts were cemented with self-adhesive resin cement (RelyX U200). After 24 h, the specimens were prepared for microtensile bond strength test (hourglass format), fracture pattern and micromorphological assessment by scanning electronic microscopy, in order to measure the cement line. Result The data (MPa and µm) were submitted to two-way ANOVA and Tukey's test (α = 5%). The surface treatments influenced the bond strength of the posts cemented with self-adhesive resin cement (p<0.00). The mean bond strength (standard deviations) differed according to the region of root dentin (p<0.00): the cervical region (Control: 19.16MPa (3.71); Silane: 25.65MPa (4.04); Hydrogen peroxide: 24.43MPa (3.16); Sodium bicarbonate: 37.42MPa (8.27)) showed higher bond strength values than the middle third of the root (Control: 14.66MPa (4.65); Silane: 12.52MPa (5.03); Hydrogen peroxide: 10.64MPa (3.33); Sodium bicarbonate: 10.87MPa (2.49)). Conclusion Treatment of the glass-fiber post surface with chemical and physical agents increased the bond strength of the cement-post-dentin interface in the cervical third and the treatment with Sodium bicarbonate showed better results in bond strength.

Resumo Introdução Pinos de fibra de vidro são utilizados para melhorar a retenção das restaurações em dentes tratados endodonticamente. Objetivo Avaliar a resistência de união de pinos de fibra de vidro submetidos a diferentes tratamentos superficiais e cimentados à dentina radicular com cimento resinoso autoadesivo. Material e método trinta raízes de caninos humanos foram preparadas e divididas de acordo com dois fatores: tratamentos de superfície (silano, peróxido de hidrogênio a 35% ou bicarbonato de sódio) e o terço radicular (cervical e médio). Os pinos de fibra de vidro foram cimentados com cimento resinoso autoadesivo (RelyX U200) e foram divididos de acordo com duas regiões: cervical e terço médio. Após 24 horas, foram preparados para microtração (formato de ampulheta), padrão de fratura e avaliação micromorfológica por microscopia eletrônica de varredura, para medir a linha de cimento. Resultado Os dados (MPa e µm) foram submetidos à ANOVA two-way e teste de Tukey (α = 5%). Os tratamentos de superfície influenciaram a resistência de união dos pinos. A média da resistência de união (desvio padrão) diferiu de acordo com a região da dentina radicular (p <0,00): a região cervical (Controle: 19,16Mpa (3.71); Silano: 25,65MPa (4.04); Peróxido de hidrogênio: 24,43MPa (3.16); Bicarbonato de sódio: 37,42MPa (8.27)) apresentou valores de resistência a raiz (Controle: 14,66MPa (4.65); Silano: 12,52MPa (5.03); peróxido de hidrogênio: 10,64MPa (3.33); bicarbonato de sódio: 10,87MPa (2.49)). Conclusão O tratamento com agentes químicos e físicos aumentou a resistência de união da interface cimento-pino-dentina no terço cervical e o tratamento com bicarbonato de sódio apresentou melhores resultados na resistência de união.

Effect of caries-affected dentin on one-step universal and multi-step etch-and-rinse adhesives' bond strength / Efeito da dentina cariada na resistência adesiva de um sistema adesivo universal e um de condicionamento ácido total

Objective: To evaluate the influence of caries-affected dentin on bond strength of a universal one-step and a multi-step etch-and-rinse adhesive system. Material and method: Enamel of 60 third human molars with and without caries was removed to expose dentin. The teeth were randomly assigned to six groups: Single Bond Universal (3M ESPE, St. Paul, MN, USA) in etch-and-rinse and in self-etch mode and Prime & Bond NT (Dentsply Co, Konstanz, Germany), all on sound and caries-affected dentin. Smear layer of the 30 sound dentin specimens was standardized by polishing with 600-grit SiC paper under water cooling. Residual infected dentin of the 30 caries-affected specimens was removed with a number 4 CA carbide bur until no caries smooth tissue was detectable by tactile-visual inspection. Cylinders of a light cured composite resin (Filtek Z350 XT, 3M ESPE) were built up using starch tubes and microshear test was performed until failure. The data was analyzed by one-way ANOVA and Tukey's post hoc test. Result: Significant differences in microshear bond strength (μSBS) were observed for the caries-affected groups, but not for sound dentin. The μSBS of Single Bond Universal were not influenced by the application protocol on sound dentin, however they were lower in the caries-affected group with both application protocols. The μSBS for Prime & Bond NT was not influenced by the dentin conditions. Conclusion: Caries-affected dentin decrease in bond strength of Single Bond Universal in comparison to sound dentin. The bond strength of Prime & Bond NT was not altered by substrate conditions.

Objetivo: Avaliar a influência da dentina afetada na resistência de união de um sistema adesivo universal e de um adesivo de condicionamento ácido total acetonado. Material e método: As faces oclusais de 60 terceiros molares humanos, hígidos e cariados, foram removidas a fim de expor o substrato dentinário. Os dentes foram divididos aleatoriamente em 6 grupos: Single Bond Universal (3M Dental Products, Seefeld, Germany), nos protocolos de condicionamento total e autocondicionante, e Prime&BondNT (DentsplyDeTrey, Konstanz, Germany), em dentina hígida e afetada. A smearlayer de 30 espécimes de dentina hígida foi padronizada com lixas de granulação 600. A dentina residual infectada de 30 espécimes foi removida com uma broca carbide número 4 até que nada fosse detectável por uma inspeção clínica. Pinos de resina composta (Filtek Z350 XT, 3M ESPE, St. Paul, MN) foram construídos usando tubos de amido como matriz. O teste de microcisalhamento foi realizado em uma máquina universal de testes até que houvesse a fratura. Resultado: Diferenças significantes foram observadas na resistência de união apenas para os espécimes de dentina afetada. A resistência de união do Single Bond Universal não foi influenciada pelo protocolo de aplicação nos espécimes de dentina hígida, mas diminuiu para os espécimes de dentina afetada, enquanto que o desempenho da adesão do Prime&BondNT não foi influenciada pela condição dentinária. Conclusão: A dentina afetada reduziu a resistência de união do Single Bond Universal, em comparação à dentina hígida. A resistência de união do Prime & Bond NT não foi alterada pela condição dos substratos.

Perception and Knowledge of Dentists in Southern Brazil Related to use of Atraumatic Restorative Treatment in the Public Health Service

Objective: To investigate the perception and knowledge of dentists regarding use of the Atraumatic Restorative Treatment (ART) in public health services of cities in the central region of Rio Grande do Sul (RS), Brazil. Material and Methods: A crosssectional study was conducted using a self-administered questionnaire with 60 dentists who work with public dentistry services. To evaluate possible associations between the use of ART and the independent variables we used the chi-square test and logistic regression models (α = 0.05). Results: Forty-four questionnaires were completed, resulting in a response rate of 73%. Of the respondents, 70.4% supported the use of ART and 81.8% reported having some training in the technique. However, 72.7% consider ART to be a temporary or urgent treatment. Professionals who do not advocate the use of ART were 76% less likely to use the technique when compared to their colleagues who defend the use of the technique (OR = 0.24, 95% CI = 0.06 to 0.98). Conclusion: While most dentists have knowledge and positive attitude towards ART, greater dissemination is required for this technique can be used effectively on the public service.