Effectiveness of Diode Laser in Debonding Orthodontic Metallic Brackets from Prosthetic Crowns: An In-Vitro Study

Abstract

With the increasing number of adult patients seeking orthodontic treatment, clinicians are required to bond orthodontic attachments to teeth restored with prosthetic crowns, such as zirconia and porcelain fused to metal (PFM), presenting new clinical challenges. Conventional mechanical removal of metallic brackets from these surfaces carries the risk of restoration damage. Therefore, the use of diode laser has been proposed as an adjunctive technique to facilitate safer and more efficient bracket removal. This study aimed to evaluate the effectiveness of diode laser irradiation in debonding metallic orthodontic brackets bonded to zirconia and pfm crowns. A total of 120 samples were allocated into three main groups according to the debonding method: diode laser at 2W/cm², diode laser at 3W/cm², and debonding pliers only. Each group was further subdivided based on the material type: zirconia and pfm. Temperature changes were recorded using a thermocouple sensor, while adhesive remnant index (ARI) scores were assessed under a surgical dental microscope. Statistical analysis was performed using the Mann-Whitney test for temperature changes and the Mann-Whitney and Kruskal Wallis tests for ARI comparisons, with significance set at p < 0.05. The findings demonstrated that laser-assisted debonding facilitated bracket removal compared to conventional plier method, particularly in the pfm irradiated at 3 W. Temperature rise in all laser groups remained within clinically acceptable limits, except for the zirconia group irradiatedat3 W/cm², which occasionally exceeded the 5.5 °C safe threshold (mean= 6.82 °C). ARI scores varied according to the material type and laser power. In conclusion, diode laser use for debonding proved to be an effective and conservative technique, particularly at 3W/cm², for safely removing metallic brackets from pfm crowns with minimal risk of thermal damage and surface alteration. However, diode laser showed to be ineffective for debonding metallic brackets from zirconia crowns at both power settings (2W/cm² and 3W/cm²).