Effect of Laser Conditioning and Different Adhesive Strategies on Bond Strength of a Bulk Fill and a Microhybrid Resin Composite

Abstract

Purpose: To evaluate the effect of laser conditioning and adhesive strategies on bond strength of a bulk fill and a microhybrid resin composite. Methods: 96 human posterior teeth's buccal and lingual surfaces were ground flat to expose dentin surfaces with standard smear layer (N=192). The specimens were divided into 16 experimental groups according to (1) Laser-conditioning (Laser-etched group/control group); (2) Adhesive strategies (etch&rinse, Adper Single Bond2(SB2), two step self-etch ClearfilSE Bond(CSE), multi-mode adhesive All-Bond Universal with self-etching technique(ABU-SE), or etch&rinse technique(ABU-ER); (3) Restorative materials (Z250/SDR). All the restorative applications were applied according to the manufacturer's directions. The specimens were stored in 100% humidity for 24 hours. The specimens were placed on a shear bond test machine at a crosshead speed of 1 mm/min. The values were recorded at the time of failure of composite resins. The bond strength values for shear forces were reported in MPa and derived by dividing the imposed force at the time of fracture by the bonded area. The failed samples were examined under a streomicroscope at X20 magnification to determine the mode of failure. The data were statistically analyzed with three-way ANOVA and multiple comparisons were made by Bon Ferroni test at 5% significance level (p<0.05). Results: SDR and Z250 yielded statistically significant difference when bonded with ABU-ER without laser conditioning (p=0.008). The predominant mode of failure was mixed type. Conclusion: Laser conditioning did not affect shear bond strength values of a bulk fill and a microhybrid resin composites regardless of adhesive system.