Exuberant Biofilm Infection in a Lateral Canal as the Cause of Short-term Endodontic Treatment Failure: Report of a Case

Introduction: This article describes a case in which signs and symptoms persisted in spite of the endodontic treatment following high standards to characterize a short-term failure. Methods: After several appointments of root canal treatment in an attempt to resolve persistent symptoms, including 106 days of calcium hydroxide intracanal medication, periradicular surgery was performed, and the root apex and the lesion were subjected to histologic and histobacteriologic analyses. Results: The lesion was diagnosed as a cyst, and the main root canal was free of bacteria and debris. Conclusions: The cause of the short-term failure was an exuberant bacterial biofilm colonizing a lateral canal in the apical root segment. This case report highlights one of the major problems of modern endodontic therapy; bacteria located in areas distant from the main root canal can remain unaffected by treatment procedures and maintain disease. The challenge for researchers and clinicians that arises from this problem is to develop strategies, instruments, or substances that can reach those areas and achieve sufficient reduction in the infectious bioburden to permit predictable periradicular healing.