Microshear Bond Strength of Composite Resin to Enamel Treated With Titanium Tetrafluoride and the Carbon Dioxide Laser (۱۰.۶ μm): An In Vitro Study

Abstract Introduction: The present study aims to assess the microshear bond strength (μSBS) of composite to enamel treated with titanium tetrafluoride (TiF۴) and CO۲ laser irradiation.Methods: Fifteen human molars were sectioned and their enamel surfaces were abraded. The sections were randomly assigned to ۵ groups (n = ۱۵): (CO); control group, (AP); treated with ۱.۲۳% acidulated phosphate fluoride (APF) for ۴ minutes, (Ti); ۴% TiF۴ for ۱ minute, (L+AP); CO۲ laser irradiation (۱۰.۶ μm wavelength, ۱ W peak power, ۱۰ ms pulse duration, ۵۰۰ ms repetition time, ۰.۲ mm beam spot size at the tissue level, ۲ cm distance of handpiece tip to tissue surface (DSE, South Cores) followed by ۱.۲۳% APF, and (L+ Ti); ۱۰.۶μm CO۲ laser irradiation followed by ۴% TiF۴ for one minute. Using Tygon tubes, Z۲۵۰ (۳M/ESPE) composite was bonded to the surface of the samples. The μSBS of the composite to enamel was measured using a microtensile testing machine after ۵۰۰ thermal cycles. The data were analyzed by one-way ANOVA and the Tukey HSD test (P < ۰.۰۵).Results: The mean μSBS was ۲۰.۶۶, ۲۰.۲۱, ۱۳.۴۴, ۲۳.۰۱, and ۱۰.۱۶ MPa in CO, AP, Ti, L+AP, and L+Ti groups respectively. Significant differences were observed between CO and Ti (P = ۰.۰۲۶) and also CO and L+ Ti (P < ۰.۰۰۰۱).Conclusion: The application of TiF۴ per se and after CO۲ laser irradiation on enamel decreased the μSBS of the composite to enamel; on the other hand, APF alone and after laser irradiation did not have any adverse effect on the μSBS of the composite to the enamel. Keywords: Acidulated phosphate fluoride; CO۲ lasers; Composite resins; Strength; Titanium tetrafluoride