In the department of dentistry and oral surgery, at medical university hospital, 1) highly specialized medical care, 2) oral management of patients admitted to other departments, 3) training of oral surgery specialists and education for residents and medical students are required. Regarding 1), performing operations was restricted only when the state of emergency was declared in the first pandemic of COVID-19 on April 2020, and for 2), we treated all requested cases, while significantly limiting aerosol-producing procedures such as the use of air scalers. After that, with the background of genetic test for COVID-19 at the time of admission and the fulfillment of personal protection equipment such as N95 mask, it has become possible to perform medical treatment almost as usual. In 3), training of specialists was continued as before, and observation practice was partially restricted in order to avoid the risk of aerosol exposure in medical student education.

Cases of the coronavirus disease 2019 (COVID-19) were first reported in December 2019 in Wuhan, China and it rapidly spread worldwide. As of August 2022, the number of reported COVID-19 cases worldwide has passed 550 million, with more than 6.3 million deaths (according to the World Health Organization (WHO)). The pandemic has affected clinical practice, as well as the daily life. Since oral and maxillofacial surgeons examine and treat the oral cavity and its surrounding structures in daily clinical practice, they are always exposed to the risk of infection through exposure to saliva, droplets, and aerosols which contain severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative virus of COVID-19.

　In this article, we reviewed impact of COVID-19 on oral and maxillofacial surgery with particular focus on several recommendations.

Adenocarcinoma not otherwise specified (NOS) is a malignant salivary gland tumor without the histological characteristics of other salivary gland tumors. It rarely occurs in the small salivary glands and development in the molar glands is extremely rare. We report a case of adenocarcinoma NOS occurring in the retromolar pad. The patient was a 75-year-old woman with a protrusive 10 × 15 mm mass in the retromolar region. The lesion was elastic soft and had an irregular surface. Biopsy resulted in a histopathological diagnosis of adenocarcinoma NOS. No regional or distant metastasis was observed in imaging. The tumor was successfully resected under general anesthesia. The postoperative course was uneventful and there has been no recurrence or metastasis seven years after the surgery.

Oral focal mucinosis (OFM) is a rare disease that forms a mass with the production of mucoid substances under the oral mucosa. The details of OFM etiology and pathophysiology are not clear. We report a case that was histopathologically diagnosed as OFM; however, nine years had passed between the diagnosis and the time of the first treatment. The patient was a 64-year-old male found to have a 13 × 9 mm mass in the left palate. Biopsy revealed growth of collagen fibers and mucoid substances containing hyaluronic acid below the epithelium, and OFM was initially diagnosed. His next planned visit to the hospital was interrupted, and nine years following his initial visit, he requested the treatment and was re-examined. The mass had increased to 17 × 12 mm toward the hard palate and was resected under general anesthesia. The mass was surrounded by fibrous tissue and was easily detached from the surrounding tissue, with no exposed bone observed. There was no histopathological change in the tissue structure. No recurrence after resection has been observed.