Aim To evaluate the impact of a dual-cured adhesive system on the in situ degree of conversion (DC), bond strength (BS) and failure mode (FM) of adhesive interfaces in dentin cavities restored with a bulk-fill resin composite. Methods 4-mm-deep dentin cavities with a 3.1 C-factor were created in 68 bovine incisors (n = 17 per group). The light-cured (Scotchbond™ Universal) or the dual-cured (Adper™ Scotchbond™ Multi-purpose Plus) adhesive system was applied to the cavities, which were then restored with a bulk-fill resin composite (Filtek™ Bulk Fill). In situ DC analysis was performed by means of micro Raman spectroscopy at the top and bottom interfaces. Push-out BS was measured in a universal testing machine after 24-h or 6-month water storage. FM was determined with a stereomicroscope. Data of in situ DC and BS were analyzed by two-way analysis of variance (ANOVA) and Tukey test (p<0.05), while the FM was analyzed descriptively. Results The groups that received the dual-cured adhesive system showed statistically higher in situ DC and BS than those that received the light-cured adhesive system. Cohesive failure mode was the most frequent in all conditions. Conclusion In situ DC and BS were influenced by the curing strategies of the adhesive systems with better performance of the dual-cured material.

OBJETIVO: Avaliar a eficácia da remoção de lama dentinária por agentes de limpeza cavitária através da análise de microscopia de força atômica (MFA). METODOLOGIA: Cinco terceiros molares humanos hígidos foram seccionados transversalmente na porção coronária, obtendo discos de dentina de 2 mm, que foram desgastados com lixas de granulação 600, por 10 s.Foram feitos cortes seriados longitudinais e perpendiculares entre si, obtendo-se quarto espécimes de cada dente. Os espécimes foram divididos em 4 grupos: GI- clorexidina a 2%; GII- água de hidróxido de cálcio; GIII- solução fluoretada a 1,23%; GIV - ácido fosfórico 37%. As soluções foram aplicadas com pincel por 60 s, com exceção do ácido fosfórico que foi aplicado por 15 s e lavado com água destilada pelo mesmo tempo. Os espécimes foram analisados por MFA. RESULTADOS: Todos os espécimes de GI e GII apresentaram 100 % dos túbulos dentinários obliterados por lama dentinária. Os espécimes de GIII e GIV apresentaram 0 % dos túbulos obliterados por lama dentinária. CONCLUSÃO: A solução de fluoretada a 1,23 % foi eficiente na remoção de lama dentinária, podendo ser empregada na limpeza de cavidades.

PURPOSE: To evaluate the efficacy of smear layer removal by cavity cleaning agents by the use of atomic force microscopy (AFM). METHODS: Five intact human third molars were sectioned in the coronal portion to obtain dentin disks, which were ground with 600-grit abrasive paper for 10 s. Serial longitudinal sections were made perpendicular to each other to create four specimens, from each tooth. The specimens were divided into four treatment groups: GI, 2% chlorhexidine; GII, calcium hydroxide solution; GIII, 1.23% fluoride solution; and GIV, 37% phosphoric acid. The solutions were applied with a brush for 60 s, with the exception of the 37% phosphoric acid, which was applied for 15 s and rinsed with distilled water for 60 s. The specimens were examined by AFM. RESULTS: All of the specimens in GI and GII showed 100% of the dentin tubules obliterated by the smear layer. However, all of the specimens in GIII and GIV showed 0% of the dentin tubules obliterated by the smear layer. CONCLUSION: The 1.23% fluoride solution was effective in removing the smear layer and can be used as a cavity cleanser.

O objetivo deste trabalho foi mostrar os diferentes padrões micromorfológicos da interface adesiva que podem ser encontrados em fragmentos de um mesmo espécime em função da variação de fatores durante o processamento dos mesmos para análise em MEV. Para isso, cilindros de resina foram cimentados na dentina da superfície oclusal de terceiros molares inclusos recém-extraídos e posteriormente seccionados longitudinalmente para observação no MEV. Os resultados obtidos indicaram uma grande variação no direcionamento e comprimento dos "tags". Isso indica a necessidade de uma padronização dos sítios de dentina, angulação de seccionamento dos espécimes e escolha de fragmentos a serem visualizados, a fim de evitar possíveis erros de interpretação ao se analisar a eficiência da penetração dos sistemas adesivos.

The aim of this study was to demonstrate the different micromorphologic aspects of the adhesive interface, which can be observed in fragments of the same specimen in function of variations during the processing for scanning electron microscopy. Resin blocks were cemented on the dentin of the occlusal surfaces of recently extracted third molars and were longitudinally sectioned for observation through SEM. The results showed wide variation in the direction and length of tags. There is need for standardization of the angulation with which the specimens are cut, so as to avoid mistakes in the analysis of the penetration efficacy of adhesive systems.