Effect of Gamma Radiation and Lead Shielding on Microleakage and Restoration Adaptation in Teeth Restored with a Total-Etch System

Aim: To evaluate the effect of gamma radiation, with and without lead shielding, on microleakage and restoration adaptation in teeth subjected to radiation before and after the restoration following a total-etch bonding system. Materials and Methods: A total of 125 intact human teeth were selected for this study and divided into five groups. Group I (n=25) received no radiation and served as control. Group II (n=25) was radiated following a standardised protocol of 2 Gy/ day, 5 days/week, for 6 weeks, totalling 60 Gy before restoration without shielding and Group III (n=25) radiated before restoration with shielding using a 0.5 mm thick lead mould shaped into a “C” tube. Group IV (n=25) was radiated after restoration without shielding and Group V (25 samples) after restoration with shielding. All teeth had standardised Class V cavities prepared on their buccal surfaces, which were then restored with a total-etch composite resin system. Microleakage was evaluated using a dye penetration method, and restoration adaptation was assessed using Scanning Electron Microscopy (SEM). Data were analysed using the Kruskal–Wallis ANOVA test. Results: Significant differences were observed in dye penetration and restoration adaptation among the groups. Teeth exposed to unshielded gamma radiation before cavity preparation (Group II) showed the highest microleakage and widest gaps compared to those exposed after preparation (Group IV) or any other group. Conclusion: Unshielded gamma radiation before cavity preparation results in greater microleakage and poorer restoration adaptation compared to post-preparation exposure. Lead shielding significantly mitigates these adverse effects.