Evaluation of the effect of radiation application on bond strength and microleakage of composite resins

Aim: To examine the effect of direct radiation to the teeth on the bond strength and microleakage of aesthetic restorative materials used in the clinic. Materials and Methods: In our study, 120 20-year-old teeth, which were decided to be extracted for periodontal or orthodontic reasons, were used. In teeth divided into two groups; Microleakage in 60 teeth in the first group and bond strength in 60 teeth in the second group were examined. The experimental group samples (n=60) to be irradiated were given a total of 60 Gray radiation, 2Gy/d per day, 5 days a week. Class II (mesio-occlusal) cavities were opened for all teeth to be evaluated for microleakage values. The opened cavities were restored with three different composite resin materials. Sections taken from the obtained samples were examined with the aid of a stereomicroscope and the microleakage values were compared. The tubercles of the teeth to be tested for bond strength were cut and their fissures were reset. A different composite resin was placed in each of the Teflon molds placed on the occlusal surface and polymerized. The bond strength of three different composite resins to the irradiated and non-radiated tooth tissues was evaluated with the help of shear bond tester. Results: Significant differences were observed in both microleakage and bond strength values after irradiation to the samples. Although microleakage values increase after radiation application in all restorative materials; Among the irradiated experimental group samples, it was determined that the material with the highest microleakage score in the occlusal region was the microhybrid-based Filtek Z250 composite resin, and the hybrid-based Charisma Classic composite resin in the cervical region. The lowest bond strength values were observed in hybrid based Charisma Classic composite resin. However, the most common type of rupture was found to be adhesive rupture. Conclusion: Radiation application causes the microleakage of aesthetic restorative materials to increase and their bond strength to decrease. Filtek Z250 composite resin material, which has the highest bonding value, exhibited the highest microleakage value in the occlusal region. Keywords: Radiotherapy, composite resin, microleakage, bond strength