Long-term Evaluation of Bonding Performance of Universal Adhesives based on Different Dentinal Moisture Levels.

PURPOSE: To evaluate the microtensile bond strength (µTBS) and silver nitrate uptake (SNU) of three universal adhesives used in etch-and-rinse (ER) and self-etch (SE) modes on dry, wet, and oversaturated dentin surfaces after 24 h and 1 year of water storage. The morphology of the hybrid layer (MHL) and the degree of conversion (DC) were also evaluated. MATERIALS AND METHODS: Human molars were divided into 36 groups according to combinations of the following variables: (i) universal adhesives (Ambar Universal APS [AMB], Prime&Bond Active [PBA], Scotchbond Universal Adhesive [SBU]), (ii) adhesive strategies (ER or SE), (iii) moisture level (dry, wet, or oversaturated dentin surface), and (iv) storage time (24 h or 1 year). After restoration, the specimens were sectioned into resin-dentin sticks and tested for µTBS and SNU according to storage time. For MHL, the specimens were sectioned and evaluated after 24 h using SEM. DC was evaluated using FTIR. ANOVA and Tukey's test were used for statistical analyses (5%). RESULTS: When 24-h vs 1-year data were compared, there was a significant decrease in µTBS and an increase in SNU values for the majority of experimental groups (p < 0.0001). On dry (ER) and oversaturated (ER and SE) dentin, AMB showed higher µTBS than did PBA (p < 0.00001). No significant decrease in µTBS was observed when universal adhesives were applied in the SE mode to dry dentin (p > 0.05). Regarding SNU, at all moisture levels, AMB showed lower SNU values than SBU (p < 0.001). Regarding MHL, SBU showed several imperfections when applied to oversaturated dentin in comparison with AMB and PBA. Regarding DC, when dentin was kept dry or was oversaturated, AMB showed a higher DC than PBA (p < 0.0001). CONCLUSION: The behavior of the different universal adhesives evaluated did not vary when applied to wet or dry dentin. However, the results with oversaturated dentin were dependent on the universal adhesive. Independent of the moisture level and the universal adhesive evaluated, significant degradation of the bonding properties occurred after 1 year of water storage, with the exception of universal adhesives applied to dry dentin in the SE strategy.

Efeito da clorexidina a 2% no mecanismo de adesão do cimento de ionômero de vidro: resistência ao cisalhamento / Chlorhexidine's effect at 2% in the mechanism of adhesion of glass ionomer: shear bond strength

Objetivo: O objetivo deste estudo foi verificar a influência da clorexidina gel a 2% na resistência de união ao cisalhamento do cimento de ionômero de vidro (CIV). Material e Métodos: Foram confeccionados 45 blocos de 10x10mm de dentes bovinos, incluídos em resina acrílica, lixados até obter uma superfície plana em dentina e divididos em 3 grupos (n=15): I - Controle: superfície limpa com spray, seca e restaurada com CIV-Vitro Molar; II - superfície limpa com spray, seca, seguida de aplicação de clorexidina gel a 2%, deixada em repouso por 2 minutos, limpa com "bola" de algodão e restaurada; III - lavagem, aplicação de clorexidina gel a 2%, deixada em repouso por 2 minutos, limpeza com spray, seca e restaurada. Os corpos de prova foram submetidos ao teste de cisalhamento em uma máquina TIRATest 2420. Resultados: Os resultados foram avaliados pelo teste Kruskal-Wallis (p<0,05). Verificou-se diferença significante em função do tratamento aplicado p=0,049. Conclusão: A aplicação da clorexidina por 2 minutos e lavagem posterior comportou-se semelhante ao grupo-controle.

Objective: The goal of this study was to investigate the interference of chlorhexidine gel at 2% by shear tests the adhesion of Glass Ionomer Cement. Material and Methods: The 45 bovine teeth were used and made of blocks of 10x10 mm, including acrylic resin and polished until a flat dentin surface. Then randomly divided into 3 groups (n = 15): I - Control: the surface was cleaned with spray (water/air), dried and restored with glass ionomer Vitro Molar (DFL) II - the surface washed with spray (water/air), dried, followed by the application of chlorhexidine gel at 2%, left to stand for 2 minutes, cleaned with a "ball" of cotton and restored; III - the washing was done with an application of chlorhexidine gel at 2%, left rest to for 2 minutes, then cleaned with spray (water/air), dried and restored. The specimens were subjected to shear stress by the machine TIRATest 2420. Results: The results were analyzed by Kruskal-Wallis (p < 0,05). From the graphical analysis, we found the shear stresses with p = 0,049. It showed a significant difference between the tensions according the treatment applied. Conclusion: The application of chlorhexidine for 2 minutes and posterior rinsing behaved similar to the control group.