An In Vitro Evaluation of Effect of Ionizing Radiotherapy on Push-out Strength of Fiber Posts under Cyclic Loading

Ionizing radiotherapy has a deleterious effect on all vital cells and thus might affect the collagen fibril network of dentin and formation of hybrid layer of composite resins. The present study evaluated the effect of ionizing x-ray radiotherapy on push-out bond strength of fiber posts. Sixty mandibular premolar roots were divided into 4 groups: group I, control group with no irradiation, restored with a quartz fiber post system with cyclic loading; group II, samples were exposed to 60 Gy radiation dosage and than restored; group III, samples were restored and then irradiated; and group IV, samples were restored during irradiation. A push-out bond strength test was done. Radiotherapy significantly reduced the push-out bond strength of fiber posts. Patients undergoing ionizing radiotherapy might have a less than ideal prognosis of fiber posts luted with dual cure resin cement with total etch bonding system, if restorations are done after radiotherapy.