microshear bond strength of scotchbond universal adhesive to primary and permanent dentin: a six-month in vitro study

Objectives: this study aimed to assess the microshear bond strength (msbs) of scotchbond universal adhesive, used in self-etch and etch-and-rinse modes, to primary and permanent dentin at 24 hours and six months. materials and methods: a total of 88 composite micro-cylinders were divided into eight groups (n=11) as follows: (a) etch-and-rinse, 24 hours, primary dentin; (b) self-etch, 24 hours, primary dentin; (c) etch-and-rinse, six months, primary dentin; (d) self-etch, six months, primary dentin; (e) etch-and-rinse, 24 hours, permanent dentin; (f) self-etch, 24 hours, permanent dentin; (g) etch-and-rinse, six months, permanent dentin; (h) self-etch, six months, permanent dentin. the msbs was measured by a testing machine at a crosshead speed of 0.5 mm/minute. data were analyzed using three-way analysis of variance (anova). results: the mean msbs was 12.3±2.3 mpa in a, 18.8±4.1 mpa in b, 11.9±3.7 mpa in c, 16±2.9 mpa in d, 19.1±2.7 mpa in e, 22.8±4.1 mpa in f, 16.2±2.6 mpa in g, and 17.2±4.4 mpa in h. in the self-etch mode, the msbs was significantly higher than that in the etch-and-rinse mode (p<0.001). the msbs in permanent teeth was significantly higher than primary teeth (p<0.001). at six months, the msbs significantly decreased in all groups (p<0.001). conclusion: the micro-shear bond strength of scotchbond universal adhesive decreases over time and depends on the type of tooth and the mode of application of the adhesive.