Influence of Therapeutic Radiation and Treatment Timing on Dislodgment Resistance of Four Root Canal Sealers: An In Vitro Push-Out Bond Strength Study.

Abstract

Objectives: This in vitro study investigated whether therapeutic radiation and the timing of radiotherapy in relation to endodontic treatment influence the dislodgment resistance of four commonly used root canal sealers bonded to radicular dentin.

Methods: Seventy-two extracted human single-rooted teeth were standardized and allocated into four experimental groups according to the sealer used: AH Plus, Cerafill RCS, Sealapex, and Tubliseal. Each group was further divided into three subgroups based on the irradiation protocol: nonirradiated control, root canal treatment followed by radiotherapy, and radiotherapy followed by root canal treatment. Irradiated specimens received a cumulative dose of 70 Gy using a medical linear accelerator. Root canals were instrumented with the ProTaper rotary system and obturated using a single-cone technique with the assigned sealer. Following specimen preparation, push-out bond strength (PBS) was measured using a universal testing machine, and the mode of bond failure was evaluated under stereomicroscopy.

Results: AH Plus demonstrated the highest PBS across all experimental conditions, followed by Cerafill RCS, whereas Sealapex and Tubliseal exhibited comparatively lower values. Exposure to therapeutic radiation produced a modest reduction in bond strength; however, neither radiation nor the sequence of radiotherapy and endodontic treatment resulted in statistically significant differences within individual sealer groups. Failure mode analysis showed a predominance of cohesive and mixed failures, with no significant differences among the irradiation protocols.

Conclusions: Within the limitations of this in vitro investigation, therapeutic radiation had only a limited influence on the adhesion of the evaluated root canal sealers to radicular dentin, and the timing of radiotherapy relative to root canal treatment did not significantly affect dislodgment resistance. AH Plus consistently demonstrated superior bonding performance under both irradiated and nonirradiated conditions, indicating its potential suitability for endodontic treatment in patients undergoing head and neck radiotherapy.