Objectives . The purpose of this study was to compare the bond strengths of enamel/composite adhesive interface measured by cantilever bending and micro-tensile test methods.

Materials and methods . Buccal surfaces of bovine incisors were flattened and subsequently composite was placed (Z250, 3M) incrementally after the application of either Adper™ Scotchbond™ SE Self-Etch Adhesive (SE) or Adper™ Single Bond Plus (SB) adhesive (Both from 3M). The samples were then cut with a low-speed cutter to obtain matchstick-shape specimens which were divided into four groups ( n = 30 each) according to the adhesive and test method used: SE-T, SE-B, SB-T and SB-B, where T denotes micro-tensile test and B denotes cantilever bending. The failure mode of each specimen was examined under a microscope, with those having their fracture surfaces lying entirely or partially within the adhesive layer being considered as successful measurements. The results from the two test methods were compared.

Results . Cantilever bending had a higher success rate of bond strength measurement in this study, compared with the micro-tensile method. Bond strengths of SE (53.6 MPa) and SB (46.7 MPa) from the cantilever bend test were 45% and 58%, respectively, higher than those (33.9 and 32.3 MPa) measured with the micro-tensile method. At the same time, the cantilever bend test produced lower standard deviations in the results than the micro-tensile test. Adhesive SE exhibited similar bond strength as SB irrespective of the test method.

Conclusions . Cantilever bending is an efficient method for bond strength measurement. The ratio of bending to tensile bond strength for enamel-composite was around 1.5.