Sealing Abilites of Latest All-in-one Adhesives under Thermo-mechanical Cyclic Stress

Objective: The purpose of this study was to examine the sealing ability of a latest experimental all-in-one adhesive; EXL759 (EXL, 3M ESPE), as compared with an all-in-one system; Adper Easy Bond (EB, 3M ESPE), and a popular self-etch system; Clearfil SE Bond (SE, Kuraray), under thermo-mechanical cyclic stress simulating intra-oral environment.

Method:  60 standardized wedge-shaped cavities with occlusal margin on enamel and gingival margin on dentin were prepared in the buccocervical region of extracted human lower premolars. Three systems were applied to the cavities according to manufacturer’s instruction, and resin composites; Supreme Ultra (3M ESPE) for EXL and EB specimens and Clearfil AP-X (Kuraray) for SE specimens, were placed and light-cured. All specimens were stored in a moisture box at 37 ºC for 24hrs, then polished, and divided into two groups (n=10, each system); a group with stress (S+) and a group without stress (S-). For S+ group, restored specimens were thermocyclyed (5ºC/55ºC, 2,000cycles) and cyclic loaded (12kgf×10⁵) simultaneously. For S- group, no stress was applied. Dyeing for an hour, microleakage of S+ and S- specimens were evaluated by a graded criterion, and analyzed using Kruskal-Wallis and Wilcoxen tests.

Result: There were significant differences in occlusal microleakage between S+ and S- groups in EXL(p<0.05), EB(p<0.01) and SE(p<0.05), while the differences in gingival leakage was not recognized regardless of the systems. There were no differences in both occlusal and gingival microleakage among the systems regardless of stress mode. The difference in the microleakage of each system between occlusal and gingival walls was not recognized, regardless of stress mode.

Conclusion: Gingival microleakage of all systems was not influenced by the stress, but occlusal leakage increased by the stress. However the sealing ability of EXL was statistically equivalent to those of EB and SE regardless of stress mode and walls.