Accuracy of Bracket Position with Two Indirect Bonding Materials. A Randomized Split-Mouth Clinical Trial

Abstract

The aim of this randomized split-mouth clinical trial study was to compare accuracy of self-ligating brackets position using two indirect bonding tray materials: polyvinyl siloxane (PVS) and hot melt adhesive (HM).  Randomized, single-center trial in adults who started orthodontic treatment from an orthodontic graduate program. Patients with permanent dentition and mild crowding (1.1-3.0 mm) in the upper arch were included. Indirect bonding tray materials were randomly assigned to the upper hemiarch using virtual software. Patients, measurements operators, and statisticians were blinded. Twenty-six transfer trays were fabricated (PVS n=13) and (HM n=13). An experienced operator performed the indirect cementation. The primary outcome was the accuracy of bracket position determined by the displacement along the horizontal (mm), vertical (mm), and angular axes (°). Measurements were compared in T0, before and T1, after transfer, on computer images obtained by intraoral scanning. Bracket positioning accuracy was analyzed using linear mixed-effects models accounting for the split-mouth design. Adjusted mean differences with 95% confidence intervals (95% CIs) were estimated. Intra- and interoperator reproducibility measurements revealed high concordance (Min: 0.13, Max:0.25). Thirteen patients (mean age 25.53±9.45 years; Little's Irregularity Index: 1.07±0.78mm) and 128 teeth were analyzed. No statistically significant differences were found between the PVS and HM transfer trays for any of the evaluated outcomes. All adjusted mean differences were small, with 95% confidence intervals including zero and p-values >0.05.  The results suggest that both PVS and HM used for indirect bonding provide accurate bracket placement. HM may represent a clinically viable alternative for indirect bonding due to its satisfactory accuracy and potential accessibility for a broader range of patients and practitioners.