Effects of handpiece lubrication on resin-based composite bond strength to enamel

To evaluate the effects of handpiece lubrication on the bond strengths of resin-based composite (RBC) to enamel using two different bonding systems.

Sixty extracted noncarious human maxillary incisors were imbedded in acrylic resin tray material with the facial surfaces exposed. 320 grit sandpaper was used to create a flat surface of enamel. The embedded teeth were randomly divided into two bonding systems groups: half used All-Bond 2 and half used OpiBond FL. Within these two groups the teeth were again randomly divided into three subgroups: Dry: 10 teeth prepared with a sterilized unlubricated handpiece; Lube & Run: 10 teeth prepared with a handpiece that was lubricated and run for 30 seconds prior to use; Lube: 10 teeth prepared with a handpiece that was lubricated and not run prior to its use. The enamel was prepared by lightly roughening with a medium grit diamond in the respective handpieces. The preparations were etched for 15 s with 32% phosphoric acid, rinsed with water for 5 s, and dried with compressed air for 5 s. Either bond system was applied and light-cured. A hybrid RBC was placed and light-cured for 60 s. The teeth were stored in water at 37 degrees C 1 week. Shear bond strengths were measured and the collected data subjected to an ANOVA followed by a Tukey's and Bonferroni t-test were performed.

The Dry group and the Lube & Run group had stronger mean shear strengths than did the Lube group. The difference between the mean shear strengths for the Dry group and the Lube & Run group was not statistically significant (P < 0.05). A significant difference was found between the Dry group and the Lube group and between the Lube & Run group and the Lube group (P < 0.05). The mean shear strength for All-Bond 2 was higher than for OptiBond FL (P = 0.0054).