Influence of intraoral temperature and relative humidity on the dentin bond strength: an in situ study.

STATEMENT OF THE PROBLEM: The effect of the intraoral environment during adhesive restorative procedures remains a concern, especially in the absence of rubber dam isolation. OBJECTIVE: To evaluate the temperature and relative humidity (RH) at anterior and posterior intraoral sites and their effects on the dentin bond strength of two-step etch-and-rinse adhesive systems. METHODS: Sixty human molars were assigned to six groups according to the adhesive systems (Adper Single Bond Plus and One Step Plus) and intraoral sites (incisor and molar sites). The room condition was used as a control group. Dentin fragments were individually placed in custom-made acetate trays and direct composite restorations were performed. The intraoral temperature and RH were recorded during adhesive procedures. Then, specimens were removed from the acetate trays and sectioned to obtain multiple beams for the microtensile bond strength test. In addition, the adhesive interface morphology was evaluated through scanning electron microscopy. Intraoral conditions were statistically analyzed by paired Students' t-tests and the bond strength data by two-way analysis of variance and Tukey test (α = 0.05). RESULTS: The posterior intraoral site showed a significant increase in the temperature and RH when compared with the anterior site. However, both intraoral sites revealed higher temperatures and RH than the room condition. In regards to the adhesive systems, the intraoral environment did not affect the bond strength, and the One Step Plus system showed the highest bond strength means. CONCLUSION: Despite the fact that remarkable changes in the intraoral conditions were observed for both anterior and posterior sites, the intraoral environment was not able to compromise the immediate dentin bond strength. CLINICAL SIGNIFICANCE: Some conditions of intraoral temperature and relative humidity may not impair the dentin bond strength of two-step etch-and-rinse adhesive systems. Thus, an adequate relative isolation seems to be a good alternative under the specific clinical conditions in which rubber dam isolation is either impossible or very difficult to perform.

Effect of different adhesion strategies on fiber post cementation: Push-out test and scanning electron microscopy analysis.

AIM: The aim of this study was to investigate the effect of phosphoric acid etching and the dentin pre-treatment with sodium hypochlorite (NaOCl) on the push-out bond strength between fiber post and root canal dentin. MATERIALS AND METHODS: Root canals of 48 human incisors were selected, post spaces were prepared and assigned to four groups: G1-37% phosphoric acid (15 s); G2-5.25% NaOCl (2 min) +37% phosphoric acid (15 s); G3-37% phosphoric acid (60 s); and G4-5.25% NaOCl (2 min) +37% phosphoric acid (60 s). Fiber post cementation was performed with two-step etch-and-rinse adhesive system/dual-cured resin cement according to the manufacturer's recommendation. After 24 h, each root was sectioned transversally into three slices (cervical, middle and apical) and the bond strength of each section was determined using a push-out bond strength test. Morphology analysis of the bonded interface was evaluated using a scanning electron microscopy. Push-out strength data (MPa) were analyzed by Analysis of Variance and Tukey-Kramer (α = 0.05). RESULTS: Considering the NaOCl pre-treatment, no statistically significant differences were observed among groups; however, when the phosphoric acid was applied during 60 s in the apical portion without NaOCl pre-treatment, the bond strength was statistically significant increased. CONCLUSION: The NaOCl pre-treatment did not improve the bond strength of adhesive luting cement to root canal dentin. The findings suggest that the use of 37% phosphoric acid for 60 s may have a beneficial effect on bond strength in the apical root third.

Changes on the color parameters of air-abraded resin composite exposed to different colored beverages.

AIM: To evaluate the effect of prophylaxis using sodium bicarbonate and colored beverages on the color parameters of a resin composite. METHODS: Eighty specimens (Z350-3M ESPE) were randomly allocated into eight groups (n = 10), according to the combination of staining solution (artificial saliva, cola, red wine, or coffee) and air-powder abrasion with sodium bicarbonate (either performed or not performed). Specimens were immersed in the staining solution for 48 h (two 24-h cycles). Color evaluation was based on the CIELab system. Two measurements were carried out using a spectrophotometer (Commission Internationale de L'Eclairage L* a* b* system) before and after the immersion period. Final measurement data were analyzed by two-way anova/Tukey's test, and comparisons were made between initial and final measurements by anova/Dunnett's test, with a 5% significance level. RESULTS: Most comparisons between initial and final measurements were statistically significant. Red wine and coffee significantly affected the color parameters (L*, b*, and ΔE). However, only coffee significantly increased a* values. When compared with untreated surfaces, air-powder abrasion resulted in alterations of b* and a* parameters, but did not affect L* and ΔE. CONCLUSIONS: Both colored beverage solutions and air-powder abrasion can affect the color of composite resin restorations.

Intraoral environment conditions and their influence on marginal leakage in composite resin restorations.

Color matching in the anterior superior incisor region (ASIR) is very difficult when using a rubber dam during restorative procedures. This study measured temperature/relative humidity parameters in the ASIR and evaluated the influence of the inhalation/downtime/exhalation mouth-breathing cycle on microleakage in composite resin restorations performed in the region, using three different adhesive systems. Sixty bovine incisors were randomly assigned to six groups (n=10) according to environmental conditions (laboratory environment or intraoral conditions) and the three adhesive systems being tested (Prime & Bond NT (PB), Single Bond (SB) and Clearfil SE Bond (CL)). The composite resin restored specimens were thermocycled (800 cycles, 5-55 degrees C), immersed in a 2% methylene blue-buffered solution and sectioned longitudinally The dye penetration on the margin of the restoration was evaluated and non-parametric statistical analyses were performed. The temperature and humidity parameters in the ASIR showed significant differences when compared to the laboratory environment. Restorations performed in the ASIR environment showed no increases in microleakage. As it was shown that temperature/humidity in ASIR do not affect marginal sealing in direct composite resin restorations negatively, better color matching can be safely achieved without the use of a rubber dam.

Intraoral environment conditions and their influence on marginal leakage in composite resin restorations

Color matching in the anterior superior incisor region (ASIR) is very difficult when using a rubber dam during restorative procedures. This study measured temperature/relative humidity parameters in the ASIR and evaluated the influence of the inhalation/ downtime/exhalation mouth-breathing cycle on microleakage in composite resin restorations performed in the region, using three different adhesive systems. Sixty bovine incisors were randomly assigned to six groups (n=10) according to environmental conditions (laboratory environment or intraoral conditions) and the three adhesive systems being tested (Prime & Bond NT (PB), Single Bond (SB) and Clearfil SE Bond (CL)). The composite resin restored specimens were thermocycled (800 cycles, 5-55°C), immersed in a 2% methylene blue-buffered solution and sectioned longitudinally. The dye penetration on the margin of the restoration was evaluated and non-parametric statistical analyses were performed. The temperature and humidity parameters in the ASIR showed significant differences when compared to the laboratory environment. Restorations performed in the ASIR environment showed no increases in microleakage. As it was shown that temperature/ humidity in ASIR do not affect marginal sealing in direct composite resin restorations negatively, better color matching can be safely achieved without the use of a rubber dam.

A selecao de cor na regiao dos incisivos superiores (RIS) e muito dificil quando se utiliza isolamento absoluto durante o procedimento restaurador. O objetivo deste trabalho foi mensurar os parametros de temperatura e umidade relativa na RIS e avaliar a influencia do ciclo de inspiracao e expiracao na microinfiltracao de restauracoes em resina composta realizadas na RIS, utilizando tres sistemas adesivos. Sessenta incisivos bovinos higidos foram distribuidos, aleatoriamente, em seis grupos (n=10) de acordo com as condicoes ambientais (laboratorial ou condicao intraoral) e um dos tres sistemas adesivos testados (Prime & Bond NT (PB), Single Bond (SB) and Clearfil SE Bond (CL)). Os especimes restaurados com resina composta foram termociclados (800 ciclos, 5-55°C), imersos em solucao de azul de metileno a 2% e seccionados longitudinalmente. A penetracao de corante ao longo da margem da restauracao foi mensurada e analisada estatisticamente usando testes nao parametricos. Os parametros de temperatura e umidade relativa em RIS foram significativamente diferentes quando comparados aos encontrados em condicoes laboratoriais. As restauracoes realizadas em RIS nao apresentaram aumento na infiltracao marginal, quando comparadas as restauracoes executadas em laboratorio. Como as condicoes de temperatura e umidade intraoral nao apresentaram efeito negativo no selamento marginal de restauracoes em resina composta, a nao utilizacao do uso de isolamento absoluto pode ser considerada quando restauracoes esteticas em dentes anteriores forem realizadas.

Morphologic texture characterization allied to cigarette smoke increase pigmentation in composite resin restorations.

STATEMENT OF THE PROBLEM: The staining effect of tobacco smoke on resin color is clinically observed. However, there is no evidence determining whether this staining is increased on texturized surfaces or if the color change is superficial and can be removed by repolishing procedures. OBJECTIVE: To evaluate the effect of tobacco smoke on the color of a composite with smooth or texturized surfaces, before and after repolishing. MATERIALS AND METHODS: Forty composite specimens were allocated into four groups (N = 10): Smooth surface not exposed (G1) and exposed to tobacco smoke (G2), texturized surface not exposed (G3), and exposed to tobacco smoke (G4). During 21 days, G2 and G4 were daily exposed to the smoke from 20 cigarettes. Color measurements were carried out at baseline, after 21 days, and after repolishing. Variables L* (luminosity), b* (blue-yellow), and DeltaE (total color change) were statistically analyzed (repeated measures analysis of variance/Tukey). RESULTS: Texturized and smooth specimens presented similar luminosity at baseline. Tobacco smoke significantly reduced L* in G2 and G4, and increased b* in G4. After repolishing, L* increased and b* reduced in stained groups, but values continued to be different from baseline ones. Repolishing significantly reduced DeltaE, but values from stained groups were still greater than that from unstained groups. CONCLUSION: Tobacco smoke changes the color of composite, and surface texture can increase the staining. Repolishing reduces superficial staining, but this procedure may not return the composite to baseline color. CLINICAL RELEVANCE: Smokers that will receive anterior composite restorations should be warned about the negative cosmetic effect of the smoking habit on the color of restorations.

Effect of surface sealant and repolishing procedures on the color of composite resin exposed to cigarette smoke.

This study evaluated the effect of cigarette smoke on the color of composite resins, with and without the application of a surface sealant and before and after the restorative material was repolished. Twenty composite resin specimens were divided into two groups (n = 10); one of which received a surface sealant. Both groups were exposed daily to the smoke of 20 cigarettes. Color analyses were performed using a spectrophotometer at different intervals: prior to cigarette smoke exposure (baseline), 21 days after cigarette smoke exposure, and after the specimens were repolished using aluminum oxide discs. Cigarette smoke caused a decrease in lightness (L*), especially in samples that received the sealant (p = 0.014). At 21 days, there was an increase in yellow pigment for both groups, with higher values (p = 0.00001) and predominant red pigmentation in the samples that received sealant. An increase in lightness and a decrease in yellow pigments (p < 0.05) were reported in both groups after repolishing. Cigarette smoke significantly altered the color of the composite resin (DeltaE > or = 10.34), especially in the specimens that received the sealant. In this study, the sealant tested intensified cigarette staining, and although repolishing decreased surface pigmentation, it was unable to restore the original color of the composite resin.

Influência de irrigantes intra-canais na microinfiltração de restaurações em resina composta / The influence of root canal irrigants on microleakage of composite resin restorations

Objetivo: Este estudo avaliou a influência de irrigantes endodônticos na microinfiltração de restaurações em resina composta. Materiais e métodos: Sessenta incisivos bovinos foram separados em quatro grupos (n=15). Cavidades classe V padronizadas foram preparadas 1mm abaixo a JCE sendo expostas por 10 min às substâncias químicas: G1 - água destilada (controle); G2 - NaOCI 0.5 por cento G3 - EDTA 17 Por cento ; G4 - NaOCI 5.25 Por cento. Os dentes foram restaurados com resina composta (Z250 - 3M/ESPE), e após 800 ciclos térmicos (5+2°C e 55+2°C), os foram imersos em solução tamponada de azul de metilebo a 2 por cento (pH 7.0). Os dentes foram seccionados em duas metades e avaliados através de lupa estereoscópica (40X) por três examinadores independentes, de acordo com um escore padronizado (0-4). Os dados foram submetidos à análise estatística usando Kruskal Wallis e testes de comparações múltiplas. Resultados: Diferenças significativas foram identificadas entre o grupo de controle (G1)e o grupo que utilizou o NaOCI 5.25 por cento (G4) (p=0,018) Conclusão: Assim, pode-se concluir que a utilização do NaOCI a 5,25 por cento resultou em um aumento da infiltração marginal quando comparado ao grupo controle, que, por sua vez, não diferiu dos demais grupos experimentais

Sistemas matrizes para restauraçöes de cavidades classe II: vantagens e limitaçöes / Matrix systems for restorations in class II cavities: advantages and limitations

Os sistemas matrizes säo dispositivos que substituem uma ou mais paredes ausentes em uma cavidade, possibilitando a reconstruçäo correta da anatomia dental, através de uma restauraçäo. Säo inúmeros os tipos existentes, cada um com suas características específicas, vantagens, limitaçöes e indicaçöes de uso. Conhecendo os diferentes tipos de sistemas matrizes e suas aplicaçöes, o profissional de Odontologia tem seu trabalho facilitado. Assim o objetivo deste trabalho é apresentar uma revisäo de literatura sobre os diferentes sistemas matrizes que podem ser utilizados em restauraçöes de cavidade classe II em dentes posteriores, ficando sua escolha e aplicaçäo na dependência do operador