Histopathological evaluation of bone tissue response to endodontic sealers and gutta-percha using an intraosseous implantation model in Wistar rats

Aim: To comparatively evaluate the biological response of bone tissue to different endodontic sealers and gutta-percha (GP) using an intraosseous implantation model in Wistar rats. Materials and Methods: Bone tissue responses to six endodontic materials, resin-based sealer (Seal Pex), calcium hydroxide-based sealer (Sealapex), silicone-based sealer (GuttaFlow 2), calcium silicate-based sealer (Ceraseal), MTA-based sealer (MTA Fillapex), and GP, were evaluated in 21 Wistar rats. An empty cavity served as the control. Standardized bone cavities were prepared in the femur and filled with the test materials. Histological evaluation was performed at 7, 30, and 90 days ( n = 3) by assessing inflammatory cell infiltration, collagen fiber formation, hard tissue barrier formation, abscess formation, and material polarization. Data were analyzed using Fisher’s exact test ( P < 0.05). Results: All materials induced an acute inflammatory response at 7 days. Resin-based sealer and MTA Fillapex showed significantly higher inflammatory cell infiltration, giant cell presence, and abscess formation. At 30 and 90 days, calcium hydroxide-based, calcium silicate-based, and silicone-based sealers, along with GP, demonstrated reduced inflammation, improved collagen organization, and advanced hard tissue barrier formation. In contrast, resin-based sealer and MTA Fillapex exhibited persistent inflammation and delayed bone healing. Conclusion: Bone tissue response to endodontic obturation materials was material- and time-dependent. Although all tested materials are routinely used in clinical practice, calcium hydroxide-based, calcium silicate-based, and silicone-based sealers, along with GP, exhibited a more favorable biological response over time. The comparatively prolonged inflammation observed with resin-based sealer and MTA Fillapex underscores the need for careful material selection and controlled obturation, particularly in cases with periapical involvement.