Application of High-Frequency Conduction for Persistent Apical Periodontitis: A Case Report

Abstract

We report the case of a 39-year-old male with Persistent Apical Periodontitis (PAP) caused by infection in an uninstrumented area, wherein conventional chemical root canal treatment is not possible, which was sterilized via highfrequency conduction. He underwent root canal filling after multiple endodontic treatments for tooth #4. As symptoms recurred, he was referred to our department with the chief complaint of dull pain during mastication. Present symptoms were percussion pain of the tooth, buccal mucosa swelling at the apical portion, and grade 1 mobility. Radiography revealed inadequate root canal filling. A radiolucent image 5×6 mm in diameter and with an unclear boundary was observed around the apex. External root resorption was mainly observed in the apical foramen, with a crown root ratio of approximately 1:1. Using 6% sodium hypochlorite under dental microscopy, chemomechanical root canal preparation was performed. Passive ultrasonic irrigation and calcium hydroxide application were conducted three times; however, periapical tissue inflammation did not subside. Therefore, the patient was diagnosed with PAP, and the uninstrumented area was sterilized via high-frequency conduction. High-frequency currents were applied to the apex, root surface, and periapical lesion at 500 kHz and 90 V; periapical tissue inflammation resolved after 2 weeks. Subsequently, the root canal was filled. Follow-up radiography revealed a bone regeneration-like image at 2 months. Bone defects healed at 11 months. Although surgical endodontic therapy is conventionally performed in PAP patients, high-frequency conduction could be a minimally invasive nonsurgical endodontic treatment option for uninstrumented areas in PAP patients.