Effect of Cavity Configuration on Bonding of Self-etch Adhesive Systems

Objective: The purpose of this study was to examine the effect of cavity configuration on the bonding of self-etch adhesive systems to dentin cavity floor.

Methods: Two types of self-etch adhesive system, an one-bottle all-in-one system; Clearfil Tri-S Bond(TS, KURARAY) and a two-bottle self-etching primer system; Clearfil SE Bond(SE, KURARAY), were used. The occlusal enamel of 50 human extracted upper molars was ground horizontally and flat dentin surface was exposed. Those tooth specimens were divided into five groups. Five types of standardized cavity having the same dimensions size(4.0mm long Χ 4.0mm wide Χ 2.0mm deep) but with different C-value, i.e., ClassI(C-value=3.0), MO(1.7), MOD(1.0), MODB(0.7), Flat(0.3), were prepared in tooth specimens(n=10). Cavities were pretreated with either TS or SE according to the manufacturer's instruction and restored clinically with the same volume of a composite restorative. After storage in a moisture box at 37°C for 24hr, the restored specimens were vertically sectioned, and four defined sticks having quadrate cross-sectioned form(1.0mm Χ 1.0mm) were obtained from each restored specimen. The micro-tensile bond strength(μ-TBS) of the sticks to dentin surface on cavity floor were measured. The data of μ-TBS were examined using One-way ANOVA and Weibul analysis.

Results: The mean μ-TBS of TS/SE in MPa were ClassI(3.0); 16.7/24.6, MO(1.7); 16.9/23.3, MOD(1.0); 17.6/24.8, MODB(0.7); 19.5/24.6, Flat(0.3); 20.4/24.4. For TS, the μ-TBS was statistically influenced by the cavity configuration(C-value). But for SE, the value did not vary with the cavity configuration(C-value). Weibul modulus of TS/SE were ClassI(3.0); 4.37/5.60, MO(1.7); 7.13/6.15, MOD(1.0); 6.79/6.47, MODB(0.7); 7.34/6.98, Flat(0.3); 8.03/7.04. For TS, Weibul modulus of ClassI(3.0) was statistically smaller than those of the other cavities. For SE, the value of ClassI(3.0) was statistically smaller than those of MODB(0.7) and Flat(0.3). Regardless of the system, Weibul modulus increased with decreasing C-value.

Conclusions: The effect of cavity configuration(C-value) on the bond strength to dentin cavity floor did vary with the system applied. However the bonding reliability was improved as the C-value decreased, regardless of the system used in this study.