Identifying Optimal Composite Resin Depth to Maximize Fracture Resistance when Restoring Immature Endodontically Treated Teeth
Date of Award
Master of Science (MS)
Introduction: This study compared stress distribution of an immature central incisor restored with intracanal composite resin placed at different depths. Methods: Five pre-accessed models were prepared, to simulate immature central incisors, and endodontically treated using a mineral trioxide aggregate plug and different amounts of composite resin with gutta-percha in between the composite resin and mineral trioxide aggregate. (Group 1) Composite resin restored from the cemento-enamel junction, (group 2) composite resin restored from 2 mm apical to the cemento-enamel junction, (group 3) composite resin restored from 4 mm apical to the cemento-enamel junction, (group 4) composite resin restored from the mineral trioxide aggregate, (group 5) no material placed in the canal or access. Teeth were scanned and surface meshes were made for finite element analysis. Each model underwent a 240 Newton load at a 120-degree angle on the palatal fossa to provide evaluations for Von Mises stress distribution. Results: The results showed that placement of composite resin 2 mm apical to the cemento-enamel junction produced the least amount of stress deformation, followed by, in order, composite resin placed 4 mm apical to the cemento-enamel junction, composite resin placed to the mineral trioxide aggregate, and composite resin placed to the cemento-enamel junction. Conclusions: Placement of composite resin 2 mm apical to the cemento-enamel junction increased the fracture resistance of an immature endodontically treated tooth. Placement of composite resin at the cemento-enamel junction or more apical than 2 mm was determined to be unnecessary, as it decreased the fracture resistance.