Comparison of Microtensile Bond Strengths of Giomers Using HEMA-Based and HEMA-Free Silane Adhesive with Laser-Cut and Bur-Cut Dentin.

Objectives:Bonding to laser-cut dentin is challenging to different types of adhesive systems. This study design aimed to compare the microtensile bond strength (µTBS) of surface prereacted glass (S-PRG)/giomer restoration to both laser-cut dentin and bur-cut dentin bonded with either bioactive hydroxyethyle methacrylate (HEMA)-based adhesive (with S-PRG filler) or HEMA-free silane-based adhesive (without S-PRG filler) in a laboratory simulation of clinical conditions. Materials and Methods:Forty molar teeth were divided equally into four groups (n = 10 per group): bur-cut dentin bonded with FL-Bond II adhesive, laser-cut dentin bonded with FL-Bond II, bur-cut dentin bonded with BeautiBond Xtream universal adhesive, and laser-cut dentin bonded with BeautiBond Xtream. The dentin was prepared using a bur or laser, depending on the assigned group, after occlusal enamel was removed. After restoration using the respective adhesives, the specimens were thermocycled, their µTBSs were tested using a universal testing machine with a load cell of 100 N and a crosshead speed of 1 mm/min until they failed, and the failure modes were determined using a digital microscope with a 25x magnification. Two-way ANOVA models were used to statically analyze the collected data. The significance level was set at p < 0.05 for all tests. Statistical analysis was performed with R statistical analysis software Version 4.4.2 for Windows. Results:Two-way ANOVA showed that the type of bonding agent had a significant effect on bond strength, with the FL-Bond II samples (16.31 MPa ± 4.10) having significantly higher bond strengths than the BeautiBond Xtream samples (8.58 MPa ± 1.98). The effect of dentin preparation (bur or laser) was not statistically significant (p = 0.766). By far the most common failure mode was mixed failure (90%). The bioactive adhesives showed good bond performance regardless of the dentin preparation method; however, the HEMA-free silane containing universal adhesive was stronger with bur-cut dentin than laser-cut dentin, and the HEMA-based adhesive was stronger than the HEMA-free adhesive with both types of dentin preparation protocol. Conclusions:Laser irradiation did not affect the dentin bond strength of resin composites, while the adhesive's chemical composition played a decisive role in bond performance. The bond performance of FL-Bond II was superior to BeautiBond Xtream across dentin preparations.