Morphological Interfacial Observations and Bond Strengths of Self-etch Adhesives

Objective: The purpose of this study was to test the micro tensile bond (MTB) strengths and FE-SEM morphological observations of the resin-dentin interface to human dentin comparing three self-etch adhesives. Methods: Dentin surfaces were prepared with 600-grit SiC paper from freshly extracted human third molars. The self-etch adhesive systems in this study were; BeautiBond (Shofu Inc. Kyoto Japan) a recently developed one-bottle system, FluoroBond Shake-one (Shofu) a two-bottle one-step system, and FL-Bond II (Shofu) a two-step system. Each adhesive system was applied to the prepared dentin surface following manufacturer's instructions. Clearfil AP-X resin composite (Kuraray Medical, Tokyo, Japan) was incrementally built to a height of approx. 10mm and light cured. After 24-hrs storage in distilled water at 37°C, MTB tests (n=15 per system, CHS=1.0mm/min) were performed using an Instron 4443. Data were analyzed by ANOVA & Tukey's test (p<0.05). FE-SEM observations of resin-dentin interface were performed on additional specimens, each was Argon ion (Ar-ion) beam etched for 30, 60 sec with 1 kV acceleration voltage (EIS-200ER, Elionix, Tokyo, Japan), and the etched resin-dentin interface observed by FE-SEM (ERA-8900FE, Elionix). Results: MTB MPa-mean values and (S.D.) were: BeautiBond 33.2 (8.5), FluoroBond Shake-one 22.3 (5.0), and FL-Bond II 27.5 (7.4). Conclusions: BeautiBond showed statistically highest MT bond strengths of the three adhesives studied. The hybrid layer of each Ar-ion etch specimen showed an extremely fine meshwork structure.