Microtensile bond strength evaluation of three adhesive systems in cervical dentin cavities.

To evaluate the influence of the orientation of dentinal tubules on the bonding performance, microtensile bond strengths (MTBS) to dentin in cervical dentin cavities were measured for three current bonding systems.Wedge-shaped cervical cavities (5 x 5 x 3 mm) prepared in extracted human premolars were treated with one of the three adhesive systems, Gluma One Bond, UniFil Bond and Mega Bond in combination with a hybrid-type resin composite. After storage in water for 24 h, the teeth were sectioned longitudinally through the restoration for determination of MTBS, either at the coronal or at the apical wall of the lesion. In an additional group, either the coronal or the apical walls were coated with vaseline prior to adhesive bonding and insertion of the resin composite, and then MTBS was measured.MTBSs (mean +/- SD, MPa) to coronal and apical dentin were 35.1 +/- 19.1 and 16.4 +/- 7.9 for Gluma One Bond, 37.7 +/- 11.5 and 18.6 +/- 8.6 for UniFil Bond, and 27.0 +/- 15.2 and 30.3 +/- 17.0 for Mega Bond, respectively. MTBS to the coronal wall was higher than to the apical wall (p < 0.05) with Gluma One Bond and UniFil Bond, whereas no difference was found with Mega Bond. With all three systems, vaseline coating had no effect on the bond strength (p > 0.05), indicating that the wall-to-wall contraction stresses exerted in the noncoated group had no influence on the bond strength generated.In cervical dentin cavities, apart from the individual adhesive's bonding capacity, the dentinal tubular orientation may have an influence on the bond strength.