A 57 year old man visited the Department of Conservative Dentistry with discomfort around the left lower posterior tooth (tooth #36) that was undergoing root canal treatment. He stated that nonsurgical endodontic treatment was initiated on tooth #36 in a private clinic because of severe spontaneous pain 2 weeks before. He had received a temporary crown on tooth #36 and did not exhibit any symptoms at the time. He felt spontaneous pain on tooth #36 after crown fracture due to mastication of hard food. His medical history was non-contributory. When the patient visited our clinic, he complained of spontaneous throbbing pain in tooth #36. A clinical examination revealed sensitivity to percussion on teeth #34, 35, and 36. Periodontal probing of the mesial gingiva on tooth #36 showed a 5 mm pocket and appearance of slight alveolar bone loss. Increased periodontal space on tooth #36 was observed, and periapical radiography indicated perforation of the pulpal floor of the tooth (Figures 1a and 1d). When the temporary filling material was removed, perforation of the pulpal floor, in which Depulpin had been placed, was confirmed (Figures 1b and 1c). Previously initiated therapy and symptomatic apical periodontitis were diagnosed for tooth #36. After canal negotiation, the perforation site of the pulpal floor was repaired with Mineral trioxide aggregate (MTA, ProRoot MTA, Dentsply Tulsa, Tulsa, OK, USA) under an operating microscope (OPMI, PICO, Carl Zeiss, Gottingen, Germany). Root canal treatment for tooth #36 was scheduled.

After 2 days, the patient presented with severe pain in the same tooth. After the access cavity was opened, unset MTA was found. Although all canals were negotiated and shaped, the tooth was symptomatic. The perforated site remained inflamed, even though it had been repaired with MTA. Based on the perforation size and contact period of Depulpin, the prognosis of the tooth was regarded as hopeless. Therefore, tooth #36 was extracted. After 4 days, the patient complained of pain in the left mandible even after the extraction. Distal septal bone loss around tooth #35 was observed, mobility was increased to degree 2, and sensibility of the tooth to the electric pulp test was absent. Pulp necrosis in tooth #35 was diagnosed and root canal treatment was initiated.

After 4 days, the patient reported persistent pain in the extraction site. Teeth #34 and 35 were sensitive to percussion, and pus discharge from the extraction site was observed. The patient was referred to the Department of Oral and Maxillofacial Surgery for evaluation of the extraction site. A bone scan showed increased inflammation of the left mandible. A biopsy was performed and the final diagnosis was determined as acute and chronic osteomyelitis of the left mandible. Extraction of teeth #33, 34, 35, and 37, and decortication and saucerization of the left mandible were performed (Figures 2a - 2c). After 3 months, the patient did not show any symptoms (Figure 2d).

A 39 year old woman was referred to the Department of Oral and Maxillofacial Surgery with acute pain and swelling in the left mandible. Nonsurgical endodontic treatment on tooth #35 and incision and drainage in the left mandible had been performed at a private clinic 1 week before. She experienced severe pain, left facial swelling, and restricted mouth opening after the treatment. She was admitted and treatment with intravenous antibiotics (Combicin Inj., 3 g, Samsung Pharm., Seoul, Korea) was scheduled. Her medical history was non-contributory.

After 10 days, the patient was referred to the Department of Conservative Dentistry for root canal treatment of teeth #27 and 35. The patient exhibited a decrease in spontaneous pain in tooth #35 after administration of medication. A clinical examination revealed decreased left facial swelling and limited mouth opening. However, tenderness to palpation on gingival tissue around tooth #35 remained. A periapical radiolucent lesion on tooth #35 was observed and initiation of previous root canal treatment on tooth #27 was confirmed in the periapical radiograph (Figure 3). Previously initiated therapy with acute apical abscess on tooth #35, and previously initiated therapy with normal apical tissue on tooth #27 was diagnosed. Root canal treatments were scheduled for teeth #27 and 35. When temporary filling material was removed, it was observed that Depulpin had been used on tooth #27. Since root canal treatment of tooth #35 was initiated around the same time in the same local clinic, the use of Depulpin in tooth #35 was strongly suspected. After 1 month, teeth #33 and 34 demonstrated negative responses to an electric pulp test. Consequently, root canal treatments of teeth #33 and 34 were performed. After completion of root canal treatment of teeth #33 - 35, alveolar bone exposure persisted and the initial incision line of gingival tissue around #33 - 34 did not show signs of healing (Figure 4). The patient was referred to the Department of Oral and Maxillofacial Surgery for further evaluation. Additional radiographic examination was performed and a bone scan showed increased inflammation of the left mandible. Final diagnosis was determined as focal osteomyelitis of the mandible in the region around teeth #33 - 35. Teeth #33 and 34 were extracted, and decortication and saucerization of the left mandible were performed in the Department of Oral and Maxillofacial Surgery (Figures 5a and 5b). After surgery, the patient did not present with any specific symptoms (Figure 5c).