Method to compare [mu]-tensile bond strength of a self-etching adhesive and [mu]-cohesive strength of adjacent dentin

Abstract

Laboratory results from tensile or micro-tensile testing of adhesive/restorative systems need a gold standard to make their interpretation possible. This can be done by comparing the [mu]-tensile bond strength ([mu]TBS) of the tested adhesive(s) with the [mu]-tensile cohesive strength ([mu]TCS) of the adjancent dentin, which in meant to be replaced by the restoration.

Objectives: to test immediate [mu]TBS of and adhesive/restorative system versus [mu]TCS of the dentin adjacent to the bonded interface, in perfused specimens.

Methods: enamel and roots of five-third sound molars were removed and teeth were perfused (30 cm distelled water) until after the bonding procedure was completed. Parallel grooves (1.5-mm wide X 1.5-mm deep, separeted by 1.5 mm), were drilled in the exposed dentin, under water refrigaration. Teeth were restored (AdheSE/Filtek Z250). Specimens were sawn from grooves to test [mu]TBS (n=32) of dentin, adjacent to adhesive interfaces, both areas to be tested at the same relative depth. Areas to be studied were rounded (mean bonded surface area for both groups, BA=0.68 mm2), and [mu]TBS and [mu]TCS were found. As not all BAs were identical, residuals of [mu]TBS and [mu]TCS values to the regression line relating BA and tensile test result (representing the null hypothesis, i.e. [mu]TBS=[mu]TCS) were compared using a non-parametric test.

Results: difference in the means of residuals was not stadistically significant (two tails p=0.067).

Significance: mean [mu]TBS of the tested adhesive was nor different to mean [mu]TCS of adjacent dentine. The null hypothesis was not rejected.