Shear Bond Strength of Composite Resin and Conventional Flowable Composite in Primary Molars Prepared by Bond prep mode and Cutting mode Er, Cr:YSGG Laser (an in vitro study)

Introduction: Recently laser usage became popular in pediatric dentistry due to its efficiently in cutting enamel and dentin without pain, and with lesser vibration and noise, which leads to roughness in the structure of dental tissue like the etching process, which is the first indication for composite restorations cavity preparation. Due to the morphological differences and heterogeneous composition, of primary teeth compared to permanent teeth, the parameters of laser should be differently set. Materials and methods: This study was conducted to evaluate and compare the effect of bond prep mode and cutting mode of Er, Cr: YSGG laser in primary molars on shear bond strength of composite resin and conventional flowable composite using applied on flattened buccal and lingual surface on forty-eight freshly extracted sound natural deciduous molars divided into 2 groups and each group is subdivided into 2 subgroups each according to the mode of preparation: into: group 1: bond prep mode Er,Cr:YSGG laser which were further divided into: subgroup A: composite resin and subgroup B: conventional flowable composite, and group 2: cutting mode Er,Cr:YSGG which were further divided into: subgroup A: composite resin and subgroup B: conventional flowable composite. The samples were subjected to universal testing machine. Results: The mean (SD) values for shear bond strength of Bond prep and cutting modes regardless of restorative material were 22.8 (2.7) and 19.4 (2.7), respectively. Bond prep mode showed statistically significantly higher mean shear bond strength than cutting mode (P-value <0.001, Effect size = 0.296). The mean (SD) values for shear bond strength of composite resin and conventional flowable composite regardless of preparation mode were 20.7 (3.1) and 21.4 (3.3), respectively. There was no statistically significant difference between the two restorations (P-value = 0.394, Effect size = 0.017). Conclusion: The bond prep mode is better than cutting mode, Er,Cr:YSGG Laser irradiation improves shear bond stress and no significant difference between composite resin and conventional flowable composite clinically.