Microleakage of Recent Self-etch Adhesive Systems under Thermocycled Repeated-load Stress

Objective:The purpose of this study was to examine the sealing property of recent self-etch adhesive systems under a combination stress load simulating an oral environment.

Methods:Two types of self-etch adhesive systems, three one-bottled all-in-one systems; Tokuyama Bond Force (BF,Tokuyama Dental), Adper Easy Bond (EB, 3M ESPE) and Clearfil Tri-S Bond (TS, Kuraray medical), and two two-bottled two-step self-etching primer systems; Adper Scotchbond SE (SS, 3M ESPE) and Clearfil SE Bond (SE, control, Kuraray medical) were used. Standardized V-shaped cavity with occlusal margin on enamel and gingival margin on dentin was prepared in the cervical region of 50 extracted human lower premolars. The cavities were pretreated with the adhesive systems (n=10) according to the manufacturer's instructions. The pretreated cavities were filled with composite restorative in a bulk, and were light cured. The restored specimens were subjected to the dye penetration test under a combination stress load condition; thermal cycling (4°C/60°C x 1,250 sets) and simultaneous repeated load (12kgf x 10⁵ times) performed by a custom made multi-function apparatus. Microleakage in occlusal and gingival walls of sectioned and polished specimens were evaluated by a graded criterion. The data of microleakage were statistically analyzed using Kruskal-Wallis rank test and Wilcoxon's signed rank sum test.

Results:Both occlusal and gingival microleakage of BF, EB and TS were statistically similar to those of SE, but the both microleakage of SS were significantly greater than those of SE at p<0.01. Gingival microleakage of EB and TS were statistically smaller than occlusal microleakage at p<0.05. No difference in BF, SS and SE between occlusal and gingival microleakage was recognized.

Conclusion: The sealing property of recent three one-bottled all-in-one adhesive systems were similar to that of SE. Those four systems had better sealing performance than SS as a latest two-bottled self-etching primer system.