Immune checkpoint inhibitors (ICIs), including anti-programmed cell death 1 ligand 1 (PD-L1) antibodies, are significantly changing treatment strategies for human malignant diseases, including oral cancer. Cancer cells usually escape from the immune system and acquire proliferative capacity and invasive/metastatic potential. We have focused on the two immune checkpoints, PD-1/PD-L1 and CD47/SIRPα, in the tumor microenvironment of oral squamous cell carcinoma (OSCC), performed a retrospective analysis of the expression of seven immune-related factors (PD-L1, PD-1, CD4, CD8, CD47, CD56 and CD11c), and examined their correlation with clinicopathological status. As a result, there were no significant findings relating to seven immune-related factors and several clinicopathological statuses. However, the immune checkpoint-related factors (PD-1, PD-L1, CD47) were highly expressed in non-keratinized epithelium-originated tumors when compared to those in keratinized epithelium-originated tumors. It is of interest that immunoediting via immune checkpoint-related factors was facilitated in non-keratinized sites. Several researchers reported that the keratinization of oral mucosal epithelia affected the immune response, but our present finding is the first study to show a difference in tumor immunity in the originating epithelium of OSCC, keratinized or non-keratinized. Tumor immunity, an immune escape status of OSCC, might be different in the originating epithelium, keratinized or non-keratinized.

Background: Dental professionals were thought to have the most significant risk of coronavirus infection at pandemic period. Since the first Corona-Virus Disease-2019 (COVID-19) patient was detected in Japan in January 2020, Japan has faced several waves of Severe Acute Respiratory Syndrome Corona Virus 2 (SARS-CoV-2) infections. However, no cluster of SARS-CoV-2 infections associated with dental practice had been reported in Japan. In this study, we aimed to investigate the actual status of SARS-CoV-2 infection at pandemic period through antibody testing for dental professionals. We further investigated the saliva and oral management-related aerosol to estimate the risk of virus transmission during dental practice. Methods: SARS-CoV-2 antibody titer in the blood of dental professionals and their families was determined during the pre-vaccinated period of the SARS-CoV-2 wave to see the history of infection in Japan. Viral loads in saliva and in the aerosol generated during oral management of COVID-19 patients were detected by RT-qPCR. Results: The antibody testing of dental health care providers during the early phases of the pandemic period in Japan revealed low antibody positivity, which supported the low incidence of infection clusters among dental clinics. The aerosol generated during dental practice may contain trace levels of SARS-CoV-2, indicating the risk of transmission through dental practice is limited. Therefore, SARS-CoV-2 did not spread through dental clinics. Conclusions: Very few SARS-CoV-2 infections were observed in dental professionals who took appropriate infection control measures at the early period of the pandemic. Dental practice using standard precautions seems to be sufficient to prevent SARS-CoV-2 infections.

Takotsubo cardiomyopathy (TCM) is characterized by contractile impairment of the left ventricular apex and excessive contraction of the base of the heart, resulting in transient cardiac dysfunction. Here, we report a case of an implantable cardioverter defibrillator (ICD) that was activated for ventricular fibrillation (VF) caused by TCM one day after removal of maxillomandibular exostoses. The patient was a 53-year-old female who underwent removal of maxillomandibular exostoses in the mid-palate area, bilateral molars of the maxilla, and bilateral mandibular premolars under general anesthesia. Because the patient had a history of VF, an ICD was implanted. Removal was performed without any problems, but VF occurred on the following day, and the ICD was frequently required. Ultrasound examination suggested contractile impairment of the ventricular apex and excessive contraction of the base. Examinations led to a diagnosis of TCM using the Mayo Clinic diagnostic criteria. VF was resolved by administration of amiodarone hydrochloride. The wound in the oral cavity healed favorably, and the patient was discharged from hospital on day 33 without further occurrence of VF. This case highlights important perioperative risk assessment and anesthesia considerations for oral and maxillofacial surgeons managing medically compromised patients undergoing oral surgery.

Immune checkpoint inhibitors (ICIs), including anti-programmed cell death 1 ligand 1 (PD-L1) antibodies, are significantly changing treatment strategies for human malignant diseases including oral cancer. Cancer cells usually escape from immune system and acquire proliferative capacity and invasive/metastatic potential. We have focused on the two immune checkpoints, PD-1/PD-L1 and CD47/SIRPα in the tumor microenvironment of oral squamous cell carcinoma (OSCC), and performed a retrospective analysis of the expression of seven immune-related factors (PD-L1, PD-1, CD4, CD8, CD47, CD56 and CD11c), and examined their correlation with clinicopathological status. As a result, there were no significant findings relating seven immune-related factors and several clinicopathological statuses. However, the immune-checkpoint related factors (PD-1, PD-L1, CD47) were highly expressed in non-keratinized epithelium-originated tumors when compared to those in keratinized epithelium-originated tumors. It is of interest that immunoediting via immune checkpoint-related factors was facilitated in non-keratinized sites. Several researchers reported that keratinization of oral mucosal epithelia affected the immune response, but our present finding is the first study to show a difference of the tumor immunity in the originating-epithelium of OSCC, keratinized or non-keratinized. Tumor immunity, an immune escape status of OSCC might be different in the originating-epithelium, keratinized or non-keratinized.

Background: Dental professionals were thought to have the most significant risk of coronavirus infection during the pandemic. Since the first Coronavirus Disease 2019 (COVID-19) patient was detected in Japan in January 2020, Japan has faced several waves of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infections. However, no cluster of SARS-CoV-2 infections associated with dental procedures has been reported in Japan. In this study, we aimed to investigate the actual status of SARS-CoV-2 infection during the pandemic through antibody testing for dental professionals. We further investigated saliva and oral management-related aerosol to estimate the risk of virus transmission during dental procedures. Methods: SARS-CoV-2 antibody titer in the blood of dental professionals and their families was determined during the pre-vaccinated period of the SARS-CoV-2 wave to see the history of infection in Japan. Viral loads in saliva and in the aerosol generated during the oral management of COVID-19 patients were detected by RT-qPCR. Results: The antibody testing of dental healthcare providers during the early phases of the pandemic in Japan revealed low antibody positivity, which supported the low incidence of infection clusters among dental clinics. The aerosol generated during dental procedures may contain trace levels of SARS-CoV-2, indicating the risk of transmission through dental procedures is limited. Therefore, SARS-CoV-2 did not spread through dental clinics. Conclusions: Very few SARS-CoV-2 infections were observed in dental professionals who took appropriate infection control measures in the early period of the pandemic. Performing dental procedures using standard precautions seems to be sufficient to prevent SARS-CoV-2 infections.

In this study, we examined the current situation of the dental implant treatments in patients with extensive jaw defects after treatment for various oral and maxillofacial diseases. Additionally, we extracted factors related to the loss of dental implants and assessed the recovery of the masticatory function of the patients. Forty-three patients with extensive jaw defects who underwent dental implant treatments covered by Jap-anese public health insurance at Dokkyo Medical University Hospital were included in this study. The primary diseases of the patients were malignant tumor (n=24), benign tumor (n=12), cleft lip and palate (n=3), trauma (n=2), and osteonecrosis (n=2). One hundred fourteen dental implants were placed in 43 patients, and 9 dental implants were lost during early period of the treatment. The masticatory function in 7 patients with a removable denture on dental implants increased significantly from before to af-ter denture placement (p=0.008). The masticatory function in 3 patients with fixed prosthesis was similar to that in 3 healthy individuals with natural dentition. In uni-variate analysis, loss of dental implants was higher in patients with maxillary dental implants (p=0.025), maxillary cantilever denture retained with implants on existing maxillary bone (p=0.032), and patients who received radiotherapy (p=0.034). In multi-variate analysis, p value of these 3 risk factors did not reach significant level. Despite the complicated surgical conditions and limited option of prosthesis in the patients with extensive jaw defects, good outcomes were achieved and the dental implant treatments improved their masticatory function.