COMPARISON OF THE THIXOTROPIC PROPERTIES OF DIFFERENT COMPOSITE MATERIALS FOR BONDING FIXED ORTHODONTIC APPLIANCES DURING EXPERIMENTAL BRACKET PLACEMENT

Abstract

Introduction. The use of fixed orthodontic appliances for the treatment of various malocclusions is a widely applied therapeutic approach in modern dental practice. The application of specialized composite materials for bonding bracket systems to the tooth surface is consequently a routine procedure in clinical dentistry. The phenomenon of uncontrolled flow of orthodontic composites during bracket placement should be considered a key rheological factor that determines the quality of adhesion and the accuracy of orthodontic appliance positioning. The aim of the study was to compare, under experimental conditions, the thixotropic properties of several contemporary orthodontic light-cured composite materials based on the level of bracket “drift effect.” Methodology and methods of the study. Metal brackets (attachments) were temporarily bonded to an organic glass plate using nonpolymerized materials: «JenOrtho», «GC Ortho Connect», «Orthocem», «Biofix», «Enlight», and BracePaste, with six samples per each material. The plates with bonded brackets were positioned vertically and maintained at 37.0 °C for 30 minutes in a thermostat. The thixotropic properties of the materials were assessed based on the degree of secondary bracket displacement (“drift effect”). Summary of the primary study material. The analysis of secondary bracket displacement (“drift effect”) showed that most materials did not exhibit measurable displacement, while only two did. «GC Ortho Connect» demonstrated a statistically significantly higher level of secondary displacement compared to all other composite materials (p < 0.001). «Orthocem» also showed a statistically significant difference compared to the groups without displacement (p < 0.05). For brackets bonded with Biofix, where only minimal displacement was observed, no statistically significant differences were identified. Conclusions. The highest level of displacement was observed for «GC Ortho Connect», whereas «JenOrtho», «Enlight», and «BracePaste» demonstrated complete positional stability. The type of material accounts for the majority of variability in the observed outcomes, highlighting its key role in ensuring the accuracy of bracket fixation.