To evaluate the impact of severe acute respiratory syndrome coronavirus 2 (SARS-Cov-2) on clinical dental practice, we report the current infection prevention practices and their outcomes at Kyushu Dental University Hospital. Dental hospitals cannot admit patients infected with SARS-Cov-2 (coronavirus disease 2019 [COVID-19]) ; thus, the most important measure we can take is to minimize the risk of spreading COVID-19 during dental treatment. We have been conducting COVID-19 screenings at the hospital entrance and implementing strict standards and infection control measures, such as the use of personal protective equipment. To date, no COVID-19 clusters have occurred. To evaluate the impact of the COVID-19 pandemic, we examined patient numbers and hospital revenue in 2019, 2020, and 2021. When compared to pre-COVID-19 pandemic levels in 2019, the number of outpatients decreased by 17% in 2020 and by 11% in 2021. The number of inpatients admitted to the oral surgery department decreased sharply by 48% in 2020 and by 21% in 2021. The number of inpatient surgeries under general anesthesia decreased by 41% in 2020 and by 15% in 2021. Although these data indicate recovery, it is not enough, as the decline in the number of inpatients was particularly severe. In contrast, the number of new outpatients in the oral surgery department declined by 7% in 2020 and increased by 12% in 2021. The number of outpatient oral surgeries remained almost unchanged in 2020, and there was a 9% increase in 2021. These findings suggest that, although the demand for the oral surgery department has not decreased, the number of hospitalization cases is decreasing, perhaps due to obstacles such as polymerase chain reaction testing for the coronavirus on hospital admission. Furthermore, the decline in general dentistry visits was addressed by providing more comprehensive treatments in one appointment and increasing the treatment unit price. Thus, the reduction in outpatient revenue stayed at 7% in 2020 and the revenue increased slightly to 101% in 2021. The decline in revenue from hospital admission was 35% in 2020 and 15% in 2021. Under life coexisting with SARS-Cov-2, we believe that instead of increasing the number of patients, increasing the treatment unit price by providing more concentrated treatments is a better way to manage hospitals. This, in turn, will decrease the actual number of patient visits (as treatments will be completed in a shorter period of time), which may be in the best interest of our patients.

　Background: Our hospital confirmed the first COVID-19 positive patient on March 3, 2020. On April 9,2020, SARS-CoV-2 was transmitted to patients with other diseases and multiple medical workers in a ward containing mild COVID-19 patients. All medical care for new patients and emergency patients was stopped, and all operations were stopped.

　Method: Throughout dentistry and oral and maxillofacial surgery, we thoroughly implemented patient care, treatment, aerosol countermeasures associated with inpatient and outpatient surgery, and infection protection. Inpatient general anesthesia surgery was resumed on May 20, 2020, and the results of inpatient and outpatient surgery for 1 year and 5 months until October 15, 2021 were summarized.

　Result: Outpatient surgery for dentistry and oral and maxillofacial surgery was performed in 876 (98%) of 893 cases. Inpatient surgery could be performed in 459 of 469 (97%). Although there was no difference in the achievement rate of surgery, all 4 patients who were positive for SARS-CoV-2 in the preoperative PCR examination were outpatients, and the ratio was equivalent to 0.4% of the patients scheduled for outpatient surgery.

We report a case of a calculus-like calcified body on the buccal region. The patient was a 68-year-old man. He was referred to our hospital for further examination due to opaque images found in front of the left mandibular branch on panoramic radiography. Findings from the first visit confirmed a hard mass with a diameter of 10 mm under the left buccal mucosa. There were no subjective symptoms, and saliva outflow from the parotid papilla was good. CT findings showed a high-density structure (1300 HU) about 11 × 9 mm in size. It was circular and clearly demarcated on the outer side of the mandible, left of the masseter muscle anterior margin. The lesion was located slightly below the parotid duct, and there was no apparent continuity with the parotid duct. Extirpation of the mass was performed through an intraoral approach with the patient under general anesthesia. There was no contact between the lesion and the parotid duct. The excised substance was a calcified body 10 × 10 × 13 mm in size covered with a thin capsule of connective tissue. Histopathologically, the body comprised calcified material with a concentric laminated plate structure, while the surrounding capsule comprised fibrous tissue with plasma exudate and bleeding. No conduit structure was found. The final diagnosis was heterotopic calculus-like calcification. The postoperative course was uneventful.

Sialadenoma papilliferum (SP) was first reported in 1969. The lesion is characterized by extroverted papillary hyperplasia of the mucosal epithelium and introverted hyperplasia of the ductal epithelium. In 2020 a tumor lacking exophytic growth was reported as SP-like intraductal papillary tumor (SP-IPT) by Nakaguro et al. We report a case of SP-IPT of the lower retromolar gingiva. An 84-year-old woman visited our hospital due to a mass on the left lower jaw. A mass of 15 × 11 × 6 mm was found in the alveolar part of the left lower molar, and CT imaging showed no apparent bone destruction. The tumor was removed under general anesthesia. It was partially pedunculated and well-defined, and the surface mucosa was smooth. Histopathologically, the lining epithelium in the inner layer of the tumor duct was papillary protruding toward the lumen, and no exophytic growing tumor tissue was observed. Immunohistochemistry showed positive immuno-reactions for P-63 protein and V600E mutant BRAF protein. Therefore, we diagnosed SP-IPT. There was no evidence of recurrence one year after the excision, however the patient died of heart failure one year and three months after the operation.

Pure red cell aplasia (PRCA) is a hematopoietic disease with severe anemia that reduces only the red blood cell system. It is divided into congenital and acquired, and the annual prevalence of acquired PRCA is about 0.3 people per million, which is considered to be an extremely rar disease. We report a case of idiopathic PRCA diagnosed during treatment of a patient with oral cancer. A 45-year-old man visited our department with a complaint of pain in the right tongue margin. A partial tongue resection was performed according to a diagnosis of right tongue cancer. Two months later, late cervical lymph node metastasis was observed, and a right neck dissection and postoperative chemoradiotherapy were performed. Subsequently severe anemia, which was not due to side effects of postoperative adjuvant therapy, was observed during the course. Detailed examination led to a diagnosis of PRCA. The PRCA was relieved by administration of cyclosporine. Currently, neither PRCA nor tongue cancer recurrence is observed.