A Successful Case of Endodontic Treatment for Infection during Chemotherapy for a Patient with Terminal Stage of Gastric Cancer

Abstract

A 71-year-old man who had been diagnosed with inoperable stage Ⅳ gastric cancer was scheduled to undergo chemotherapy（S1/CDDI）in the Clinic of General Surgery, Fukuoka Dental College Medical and Dental General Hospital in May 2015. He was introduced to our department for oral management during chemotherapy. On the first day he visited our department, we performed dental checks that included dental X-rays, and found a large periapical lesion over 5 mm in diameter at the root apex of the left mandibular first premolar. Previous reports on oral health care during chemotherapy including hematopoietic cell transplantation typically recommend extraction of teeth with chronic periapical cysts over 5-6 mm in diameter before chemotherapy to prevent blast crisis and bloodborne infection. However, he had never felt any subjective symptoms and strongly hoped for tooth preservation. Therefore, we tried endodontic treatment for the infection after obtaining informed consent. On the first day of dental treatment, he took 1 g of prophylactic amoxicillin 1 hour before the endodontic treatment. We used, in order, iodine glycerin, metronidazole, and calcium hydrate paste for medical application in the root canal. The therapeutic course of the root canal treatment was good and the root canal filling was completed 3 months after the initial dental treatment. Since then, we have continuously monitored his oral health, including the periapical lesion, with X-rays and monthly professional oral health care. At 18 months after the root canal filling, bone formation was seen around the periapical lesion. Eight months after starting S1/CDDI chemotherapy, his gastric cancer, including lymph node metastasis, had been greatly reduced, as confirmed by PET-CT. Thereafter, the chemotherapy regimen was changed to XELOX therapy, and oral mucositis developed because of acute reduction of the white blood cell count. We treated the mucositis using CO₂ laser, topical anesthesia for pain relief and oral health care, while keeping his mouth clean daily to prevent secondary microbial infection until the mucositis disappeared. With the aid of dental treatment, the oral mucositis gradually healed within 2 weeks. The left mandibular first premolar did not show any symptoms of recurrent infection throughout the duration of chemotherapy, despite the reduction of the white blood cell count below the reference value. In conclusion, we suggest that it is possible to preserve an infected tooth with a large periapical cyst during chemotherapy if the tooth is asymptomatic and is treated appropriately.