The present survey suggested that continuous dental intervention is essential not only for oral health, but also to prevent complications such as pneumonia. Although it is important to minimize the spread of COVID-19, we should also consider the prevention of pneumonia and other diseases that can be fatal to older people.
It is surprising that the occurrence rates of pneumonia, hospitalization, and mortality significantly decreased in facilities with no interruption to dental services, and that there was no difference in 2019 and 2020 rates in facilities in which dental services were interrupted in 2020. It may be that these complications did not increase even in facilities with interrupted dental services in 2020 because of the widespread infection countermeasures. In Japan, the first confirmed case of COVID-19 infection was recorded on January 16, 2020, and on February 3, 2020, many of the passengers and crew members of the cruise liner “Diamond Princess” were found to be infected when the ship docked in the Port of Yokohama . Following the declaration of a state of emergency in April 2020 , personal infection control behaviors, such as mask wearing, handwashing, gargling, and social distancing , have been adopted. Hand hygiene is an effective infection control method in long-term care facilities for older people . In addition, following government instructions to avoid unnecessary outings, family visits to such facilities have been limited. These personal infection control behaviors may suppress various infections, including pneumonia and influenza. In fact, the number of patients with influenza in Japan declined sharply from 7,285,000 in 2019 (https://www.mhlw.go.jp/content/000620714.pdf) to 140,000 in 2020 (https://www.mhlw.go.jp/content/000752481.pdf). These personal infection control behaviors should be continued even after the COVID-19 pandemic.
Therefore, we suggest that the suppression of complications was achieved by both the implementation of infectious disease countermeasures and continuation of dental services. These results emphasize the importance of dental intervention and support previous findings [4, 14].
In the present study, 78 facilities (37.7%) stopped receiving dental services. Although we did not obtain detailed information about the interruption of dental visits, it is likely that any routine or non-urgent dental treatments were postponed. Although the interruption did not increase the prevalence of pneumonia, it is possible that the lack of dental treatment or examinations led to an increase in dental plaque, tongue coating, and dental calculus, and a worsening of caries and periodontal disease. We identified a need for continuing dental treatment, sufficient oral care products, and guidelines for oral hygiene during the COVID-19 pandemic from dental personnel and the government. There is a high risk of infection during dental treatment and oral hygiene care through aerosol transmission . Additionally, dental personnel visiting the facilities may transmit COVID-19. There is no current guideline about the suspension of visiting dental services, and it is left to facilities and dentists to make judgments about this. There is a need for the development of a guideline for visiting dental services and oral hygiene care in geriatric facilities during pandemics of infectious diseases.
There were some study limitations. The first limitation is the possibility of sample selection bias. The survey response rate is used as an indicator of survey quality, and the validity of findings from surveys with low response rates can be questioned . Sivo et al. suggest that an average mail survey response rate of 48.8% is moderately high . Although our survey response rate was 45.1%, it is comparable with that of a German nursing home survey (45.5%) . However, the possible of sample selection bias cannot be ruled out. The second limitation is that we did not examine the relationship between the interruption of dental services and the spread of COVID-19 in each region. Because the duration of emergency states and the number of infected people differed across regions , further analysis is needed. Third, the type of dental treatment and the number of patients receiving each treatment were not recorded. Fourth, the reasons for hospitalization, mortality, and the interruption of medical services were not investigated. As this survey focused on dentistry, surveys focusing on medical home visits are needed. Finally, the type of extra oral care measures that facilities adopted were not recorded.
Despite these limitations, the current results clearly demonstrate that continuation of dental services in facilities during the COVID-19 pandemic led to a decline in the rates of pneumonia, hospitalization, and mortality. The maintenance of visiting dental services is important even during an infectious disease pandemic.