This study evaluated the effect of different adhesive protocols on the shear bond strength (SBS) of bulk-fill resin composite repaired with bulk-fill or conventional composite. Cylindrical bulk-fill resin composite specimens were prepared and allocated into groups according to the bonding strategy: no treatment, Silane+Scotch Bond Multipurpose (S+SBMP), Tetric N Bond Universal, and Single Bond Universal. Following bonding strategy, bulk-fill or conventional composite buildups were performed. After 24 h of storage in distilled water at 37°C, shear force was applied to the interface using a universal testing machine. The data were analyzed by twoway ANOVA and Tukey test (α=0.05). SBS was influenced by the bonding strategy and the composite used (p<0.001). Irrespective of the composite used, the group S+SBMP yielded the highest SBS values (p<0.001). Repair bond strength of bulk-fill composites can be improved by using a silane coupling agent followed by a hydrophobic resin.

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The sealing and bonding characteristics of luting cements may be affected by the application of desensitizers containing ingredients that induce chemical interaction with dentin organic matrix. This study evaluated the effect of different desensitizers on the immediate and long-term shear bond strength (SBS) of a self-adhesive resin cement (SARC) to dentin. Healthy bovine dentin specimens were used for the study. Gluma® Desensitizer, Desensibilize Nano P®, and Soothe® desensitizer were used in study groups, while the control group did not receive any treatment. Next, SARC (RelyXTM U200) in cylindrical mold was applied to the sample surface. All specimens were stored at 37 °C for 24 h or six months and tested for SBS. Additionally, water contact angle was measured using an optical tensiometer. Results were analyzed by analysis of variance and Student-t tests (p ˂ 0.05). Application of the different types of desensitizers had no significant influence on immediate or long-term SBS of SARC to dentin (p > 0.05). Differences for water contact angle were not statistically significant among the tested groups (p = 0.450). Within the limitations of the present study, it can be concluded that the application of the different types of desensitizers had no significant influence on the SBS of a SARC to dentin.

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This study evaluated the three-year lifespan of the bond to dentin of experimental self-etch adhesives containing benzodioxole derivatives-1,3-benzodioxole (BDO) and piperonyl alcohol (PA)-as co-initiator alternative to amines. Adhesive resins were formulated using Bis-GMA, TEGDMA, HEMA, camphorquinone and different co-initiators: BDO, PA or ethyl 4-dimethylamino benzoate (EDAB-amine). An experimental selfetch primer was used to complete the two-step, self-etch adhesive system. Clearfil SE Bond (CSE) was used as commercial reference. Bond strength to human dentin was assessed by microtensile bond strength (µTBS) test, and failure mode was classified. Morphology of the dentin bonding interface was assessed via scanning electron microscopy (SEM). Irrespective of the dental adhesives evaluated, µTBS was higher after 24 hours compared with that after 1.5 and 3 years (p ≤ 0.001). However, adhesives with BDO and PA as co-initiators showed significantly higher bond strength than the bonding resin with EDAB (p ≤ 0.002), independent of the time evaluated. The commercial adhesive CSE showed similar bond strength compared with the other groups (p ≥ 0.05). Mixed failures were mainly observed after 24 hours, while adhesive failures were more frequently observed after 1.5 and 3 years. No notable differences in homogeneity and continuity along the bonded interfaces were detected among the materials in the SEM analysis. In conclusion, benzodioxole derivatives are feasible alternative coinitiators to tertiary amine in camphorquinone-based self-etching dental adhesive formulations.

Objetivo: Avaliar o efeito do envelhecimento térmico por termociclagem na estabilidade de cor e rugosidade superficial de duas resinas compostas, avaliar grau de conversão (GC), sorção (SO), solubilidade (SL) e microdureza. Material e método: Foram confeccionados 10 espécimes (6 mm x 1 mm) para cada resina: Filtek Z350 XT (Z350XT) e Estelite Sigma Quick (ES). Foram avaliados: GC, utilizando um espectrofotômetro no infravermelho, SO e SL. A avaliação da microdureza Vickers (MV) e densidade de ligações cruzadas foram realizadas antes e após a imersão em etanol por 24h. A rugosidade superficial e a estabilidade de cor (CIEDE2000) foram avaliadas antes e após envelhecimento térmico por 2 mil ciclos, alternando 30 s a 5º, 37º e 55ºC. A estabilidade de cor e translucidez foram avaliadas com um espectrofotômetro. Os dados foram submetidos ao teste t (α=0,05). Resultados: ES apresentou resultados de GC maiores (62,5% ± 3,7) que Z350XT (48,7% ± 6,9) (p=0,004). Ambas resinas apresentaram resultados de SO e SL similares. A MV final da ES diminuiu 13% com relação a inicial (p= 0,115). Z350XT apresentou diminuição de 17% (p=0,004). ES apresentou aumento de 115% na rugosidade superficial após a termociclagem (p= 0,001), enquanto a Z350XT apresentou diminuição de 35% (p= 0,299). ES apresentou menor alteração de cor (0,280 ± 0,093), quando comparado a Z350XT (0,549 ± 0,183). A translucidez foi similar para ambos materiais (ES=30,80; Z350XT=30,35). Conclusão: A termociclagem influenciou na alteração de cor e rugosidade superficial das resinas compostas, demonstrando que podem ser alteradas pela degradação na matriz polimérica.

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