Effects of Water Flow Rate on Shear Bond Strength of Orthodontic Bracket Bonded to Enamel Surface After Er:YAG Laser Ablation

Abstract

Objective: The aim of present study was to evaluate the effect of water flow rate on enamel surface roughness and shear bond strength (SBS) of orthodontic brackets after Er:YAG laser ablation. Background data: It is well known that external water supply is a fundamental requirement for Er:YAG laser efficiency on dental hard tissues. However, there is no consensus considering the water flow rate used during Er:YAG laser ablation. Methods: Eighty sound human upper premolar teeth were used in the present study. Seventy-six teeth were assigned into four groups according to surface treatments. The 37% phosphoric acid-etched group served as the control. Er:YAG laser irradiation was performed in three subgroups with water flow rates of 25, 36, and 48mL/min, respectively. All specimens were subjected to a SBS test. One specimen from each different surface treatment modality was examined by scanning electron microscopy. Kruskal-Wallis test was used to compare the SBS value of each group. Results: Although the control group had the highest SBS value, statistically no significant differences were found among groups. Conclusions: Er:YAG laser application with a water flow rate of 48mL/min produced better enamel surface alterations without any thermal damage to yield higher SBS values.