Long-term successful retreatment of a tooth with apical periodontitis following resorcinol-formalin endodontic treatment and apical root resection: a 25-year follow-up clinical case report

Abstract

The resorcinol-formalin method, widely used approximately two decades ago due to its simplicity and low cost, has significant disadvantages, including cytotoxicity, incomplete root canal filling, increased tooth brittleness, discoloration, and ankylosis. It remains one of the common causes of exacerbation of apical periodontitis. Current trends in endodontic treatment are focused on tooth preservation. Therefore, tooth-preserving surgical procedures, such as root-end resection and hemisection, are recommended in selected cases. The key principle is a combination of a therapeutic phase aimed at eliminating intracanal biofilm and a surgical phase involving removal of periapical inflammatory lesions. This clinical case describes the treatment of a 54-year-old female patient with mandibular first molar (tooth 4.6) previously treated using the resorcinol-formalin method approximately 30 years earlier. In 2000, a radicular cyst was diagnosed, and root-end resection with cyst removal was performed. The tooth remained asymptomatic for 25 years. After this period, the patient developed pain on biting; cone-beam computed tomography revealed incomplete root canal filling and widening of the periodontal ligament space. Nonsurgical retreatment was performed using dental microscopy, advanced irrigation protocols, intracanal medication, an MTA apical plug, and vertical compaction of gutta-percha. One year after treatment, cone-beam computed tomography demonstrated a reduction in the periapical lesion and restoration of bone structure. Thus, even in cases with an unfavorable initial treatment history, such as previous resorcinol-formalin therapy, successful retreatment and long-term tooth preservation may be achieved. The elimination of intracanal infection combined with appropriate management of periapical pathology plays a decisive role in treatment success.