Effect of radiation therapy on the micro push-out bond strength of tricalcium silicate-based repair cements used for furcation perforation sealing

Background Head and neck radiation therapy induces structural and compositional changes in dentin that may impair its interaction with bioactive dental materials, especially tricalcium silicate-based repair cements. Purpose This in vitro study evaluated the effect of radiation therapy on the micro push-out bond strength of two tricalcium silicate-based repair cements used for sealing furcation perforations. Materials and methods Dentin slices (2 mm) obtained from the cervical region of human maxillary molars were prepared with a central cavity simulating a furcation perforation and assigned to irradiated (70 Gy) or non-irradiated groups. The perforation-like cavities were filled with either MTA HP or Biodentine. After setting, the specimens were subjected to the micro push-out test. Bond strength data were analyzed using two-way ANOVA followed by Bonferroni's post hoc test, and failure mode distribution was assessed using Fisher's exact test (α = 5%). Results Radiation therapy significantly reduced the bond strength of both tricalcium silicate-based repair cements (p = 0.0001). Under non-irradiated conditions, Biodentine showed higher bond strength than MTA HP (p < 0.0001), whereas no difference was observed between the materials after irradiation (p = 1.0). Radiotherapy also influenced the failure pattern, increasing the occurrence of cohesive failure within the cement in irradiated specimens from Biodentine group (p < 0.05). Conclusion Radiation therapy compromised the adhesion of tricalcium silicate-based repair cements to dentin, which may negatively affect their performance in furcation perforation sealing.