(TC19) The Significance of an Appropriate Root-End Filling for Long-Term Outcome

Abstract: A case report of persistent post-treatment apical periodontitis after endodontic nonsurgical retreatment and recurrent lesion after endodontic microsurgery is discussed. A 61-year-old male patient presented with a previously treated mandibular right first molar with persistent lesions on mesial and distal roots. Nonsurgical retreatment was performed; however, at 6 and 12 months, resolution of pathology was not observed. CBCT evaluation revealed an untreated disto-buccal canal. The patient opted for endodontic microsurgery. At eight months on periapical film follow-up, radiographic healing was observed. The patient presented four years later, complaining of tenderness to palpation. A sinus tract with an isolated periodontal pocket on the mesial root and furcation breakdown was noted. CBCT evaluation revealed an area of low density at the apex of the distal root with an intact cortical plate. The patient consented to exploratory surgery to confirm fracture of the mesial root and block biopsy of the distal. Histologic specimens were prepared and stained. Histologic evaluation of the distal root end revealed cementum and bone formation over the cut root surface. Sagittal slices revealed that the ultrasonic preparation was not aligned with the long axis of the untreated disto-buccal canal, indicative of a poor seal. Bacteria were found in the untreated disto-buccal canal and embedded in the retrofilling material. The histological evaluation of the root apex associated with recurrent lesions despite initial healing highlights the importance of root-end management principles during microsurgery.