Effect of Nd: YAG laser on the micro-tensile bond strength of composite resin to dentin by using different universal adhesives

Abstract

Background and aims: This study aimed to evaluate the effect of Nd: YAG laser on the tensile bond strength of composite resin to dentin using different universal bonding systems. Methods: In this laboratory study, 84 extracted third molar were used to prepare 252 dental samples. The samples were randomly divided into 12 groups based on universal adhesives (Prime and Bond Elect, G-Premio universal bind, ALL BOND) and their application mode (self-etch or total etch) and based on the use or non-use of laser. After preparation of class five cervical cavities on the buccal surface of all teeth, Nd: YAG laser pulses for 100 microseconds at a radiation frequency of 15 Hz with a wavelength of 1.064 nm and at a 90 angle, perpendicular to the specimen surface, and at a distance of 5 mm from it were applied to the cavities of the laser groups. Subsequently, all the cavities were restored with composite resin and after preparing the dental samples, a universal test machine was used to measure the strength of the microtensile bond. The failure mode for each sample was observed under a stereomicroscope. For data analysis, the Bonferroni test to compare two-by-two bondings, the independent t-test to compare the average microtensile bond strength with the type of bonding agent and etching mode between samples with and without laser and the three-way anova test according to the normal distribution of the data was used. Results: The average microtensile bond strength in non-laser samples was higher than the average in laser samples (P<0.001). In comparison with the bonding agent type in both cases with and without laser, the highest average microtensile bond strength was related to ALL-BOND (P<0.001), meanwhile the lowest average tensile strength in samples without laser was related to G-Premio universal adhesive (P<0.001), and the lowest average microtensile strength in samples with laser belonged to Prime and Bond Elect group (P<0.001). Conclusion: Nd: YAG laser irradiation of the dentin surface before applying the adhesive significantly decreased the microtensile bond strength of the composite resin to the dentin surface. Trial registration number: IR.TBZED.REC. 1400.612.