Evaluation of endo-crowns retention before and after radiotherapy

Abstract Objectives This study aimed to evaluate endo-crowns retention before and after radiotherapy. Materials and Methods Thirty endodontically treated human molars were divided into three groups according to exposure to radiotherapy: group I (control group), group II (cemented before radiotherapy) and group III (cemented after radiotherapy). Specimens were prepared to receive endo-crowns using computerized numerical control milling machine with the following criteria: occlusal reduction parallel to the occlusal plane (butt joint) 1 mm above cemento–enamel junction, axial preparation with 8° total occlusal convergence, 3 mm pulpal floor depth and trapezoid shape pulp-chamber cavity. The pulpal orifices and undercuts in mesial and distal canals were protected with flowable composite. After cementation with Theracem cement, evaluation of retention of endo-crowns was performed using pull-out test on universal testing machine along the long axis of teeth at constant loading rate of 0.5 mm/min and the forces will be recorded at the point of dislodgment of endo-crown in newton. Result Irradiated groups recorded lower bond strength values than nonirradiated group. There is a highly significant difference between group I (control group) and group II (before radio group) with P value 0.000, also there is a highly significant difference between group I (control group) and group III (after radio group) with P value 0.000, since there is a significant difference between group II and group III. Conclusion Radiotherapy had a negative effect on retention of endo-crowns cemented before and after radiotherapy.