Evaluation of Thermal and Mechanical Cycling in Adhesive Interface Effectiveness

Objectives: The aim of this study was to evaluate in vitro the adhesive effectiveness in class V cavities using different adhesive systems, being submitted to thermal and load cycling. Methods: Cavities class V were made on amelo-cement junction on buccal and lingual of 40 premolars (n=80). The used adhesive systems were Adper^TM Single Bond 2/3M-ESPE(G1), AdheSE®/Ivoclar-Vivadent(G2), AdperTM Prompt^TM, L-Pop^TM/3M-ESPE(G3) and One Coat 7.0/Coltčne-Whaledent®(G4). Restorations were made conventionally with composite resin. According to used adhesive system were formed 4 groups (n=10). Each group was divided in 2 subgroups (n=10): submitted to thermocycling and occlusal load cycling, and control group. The thermocycling was made using 500 cycles of 5-55°C. The occlusal load cycling was made applying a force of 40-70N during 50000 cycles. The teeth were immersed in 50% silver nitrate solution by 2 hours. Finally, the specimens were evaluated through optic microscopy 40X (marginal microleakage occurrence) and scanning electronic microscopy 1000X (gaps formation). The tracer agent microleakage was measured qualitative (score) and quantitatively (µm). The Kruskal-Wallis and post-hoc de Dunn, and ANOVA two-way and post-hoc Bonferroni tests were used on statistic analysis. Results: Qualitatively on enamel, was not found significative differences among submitted groups: median=0 (p>0.05). Quantitatively on enamel, the microleakage average (µm) was: G1=285.95±452.71, G2=218.37±305.38, G3=192.09±362.58 and G4=191.77±405.68 (p>0.05). Qualitatively on dentin, the microleakage median was: 0.5(G1), 0.5(G2), 1(G3), 0(G4) (p>0.05). Quantitatively on dentin, the microleakage average (µm) was: G1=284.31±436.45, G2=235.23±282.94, G3=145.58± 263.62 and G4=0.00 (p>0.05). On gap formation was not found significative differences: 6.95±9.43(G1), 1.64±2.15(G2), 5.92±6.99(G3) and 5.96±4.66(G4) (p>0.05). Was not found significative differences among control and submitted groups on microleakage and gap formation (p>0.05). Conclusion: Despite of few differences found in used adhesive system performance, this presented similar adhesive effectiveness when were submitted to thermal and mechanical cycling.