Comparison of Bond Strength and Mode of Fracture for Brackets Bonded to Porcelain Prepared with Hydrofloric Acid or Laser

Background and aim: Laser ablation as an alternative method for etching porcelain has been proposed. However,previous studies have reported contrasting results. This study is designed to investigate techniques that could obtain maximum bond strength and also modes of their fracture.Materials and method: Fifty samples of porcelain fused to metal according to surface preparation were divided into five groups: ۱.HF acid(۹.۶%) ۲. HF acid+ silane ۳. Co۲ laser (۲w, ۳۰ s) ۴. Co۲ laser+silane ۵.removing the glazed layer with diamond bur (controls). After bonding orthodontic brackets and thermocycling process, the shear bond strength (SBS) measured with Instron. Results analyzed by one way ANOVA and Least Significant Difference (p < ۰.۰۰۱). pattern of debonding was investigated with light microscope and results were analyzed by Kruskall wallis and Mann-whitney (p < ۰.۰۰۱).Results: results showed bond strength of Co۲ laser (۲ w) was clinically high although it was lower than HF acid samples, with better mode of fracture.Conclusion: HF acid in combination with silane showed the highest shear bond strength value while irradiation of grouped pulse Co۲ laser for ۳۰ s in combination with silane could be an alternative for HF acid etching.

Keywords:

Co۲ Laser , HF acid , Porcelain , Shear Bond Strength