Effect of operator variability on dentin bond strength of two-step bonding systems

To examine the influence of operator variability on adhesion to dentin of recently developed two-step bonding systems.

A self-etching primer system, Fluoro Bond/Lite-Fil II A (FB) and a one-bottle adhesive system, Single Bond/Z100 (SB) were employed. Three groups, each consisting of 15 operators, were selected from the dentists at the university (Group 1), undergraduate students (Group 2), and general practitioners (Group 3). Labial surfaces of extracted bovine teeth were ground on wet 600-grit SiC paper and then washed and dried with oil-free compressed air. These surfaces were treated according to each adhesive system's instructions and the restorative resins were condensed into a Teflon mold (2 mm height, 4 mm internal diameter) and then light-cured. The finished specimens were stored in 37 degrees C distilled water for 1 hr. These specimens were tested in a shear mode at a cross-head speed of 1.0 mm/min. The mean and standard deviation were subjected to two-way ANOVA (P < 0.05).

Significant differences in bond strength of the two adhesives were found within each operator group. A wider variation in bond strength was seen for SB compared to FB for the three different groups. Mean bond strengths for the faculty group were statistically greater than those of the other two groups, which did not differ significantly. Even though the specimen preparation was done under in vitro conditions, the large coefficients of variation indicate it may be difficult to create suitable surface conditions for optimal bonding.