Ionizing irradiation affects the microtensile resin dentin bond strength under simulated clinical conditions

OBJECTIVES: This study evaluated the effect of ionizing radiations on resin–dentin interface in terms of marginal adaptation and micro-tensile bond strength under thermocycling and mechanical loading. MATERIALS AND METHODS: Forty extracted human mandibular third molars were divided into four groups. GR I: No Irradiation and Class II MO cavities were prepared that were restored with composite restorations; GR II: Teeth were irradiated and restored; GR III: Teeth were restored and irradiated; GR IV: Teeth were restored during irradiation dosage fractions. All samples were thermal and mechanical loaded with 5000 cycles, 5 ± 2-55 ± 2°C, dwell time 30 s and 150,000 cycles at 60N. Resin–dentin slabs were trimmed into dumbbell-shaped slabs and microtensile bond strength was measured. The bond strength data was analyzed by one-way analysis of variance test. RESULTS AND CONCLUSIONS: Irradiation before tooth preparation deteriorated the microtensile bond strength.