The number of teeth in the oral cavity decreases with age, and a decline in masticatory and swallowing functions, which is not seen in younger generations, is frequently observed in the elderly. In a society with a markedly aged population, it is necessary to provide new oral health services that are tailored to the oral conditions of the aged. Many studies have found that good oral health in the aged contributes to improved general health and quality of life (QOL) [1
]. The World Health Organization (WHO) has indicated that oral health is one of the behavioral determinants of active aging [3
]. Further, some epidemiological studies have reported that declining oral function may be associated with malnutrition in aged individuals [4
]. In Japan, oral health measures for the aged play a major role in national health promotion policies, such as the establishment of goals related to the oral function of the aged in the national health plan [6
]. These changes in oral health due to aging of the population have a significant impact on the work of dental professionals.
Due to the aging of the global population, Federation Dentaire Internationale (FDI) launched The Oral Health for an Ageing Population (OHAP) project in 2015 to strengthen the role of the oral health community in achieving health longevity [7
]. Usui et al. conducted a survey of dental experts on areas of dental need that were expected to increase in the future in Japan. The study reported that a high percentage of respondents cited “home dentistry”, “dentistry for the aged”, “feeding and swallowing”, “regenerative dentistry”, and “preventive dentistry” as the key areas [8
]. Additionally, oral care services provided regularly by dental professionals have a significant effect on reducing aspiration pneumonia [9
]. The provision of oral health services is fundamental to maintaining the health of the elderly.
It has been reported that oral health care provided by dental hygienists is also effective in enhancing swallowing functions [10
]. In a recent epidemiological study, the introduction of an oral function improvement program for the aged reduced the risk of frailty [11
]. Thus, dental hygienists play an essential role in the implementation of oral health care services for the aged. As the number of elderly people increases, dental hygienists need to be adequately deployed in the community to ensure continued oral health care. In addition, it is necessary to supply sufficient professional education to dental hygienists concerning elderly care to provide safe oral health services to the aged with underlying diseases. In Japan, the percentage of elderly aged 65 years and above had already reached 28.4% in 2019. This is an extremely high percentage, even among developed countries [12
] and, consequently, there is a great need to increase the workforce of dental hygienists.
The prevalence of dental caries in children has decreased significantly in Japan. In addition, the proportion of elderly individuals who still have their original teeth is increasing each year. According to the 2016 Survey of Dental Diseases in Japan, 51.2% of people at 80 years of age have 20 or more of their original teeth remaining. However, the prevalence of dental caries and periodontal disease among the aged remains high. Thus, there is a strong need to expand the system for providing lifelong oral health services. Furthermore, oral health services for the aged requiring long-term care are provided by the long-term care insurance system that started in 2000. When a dental hygienist under the direction of a dentist provides oral care to aged people who require nursing care, the nursing care insurance provides additional benefits. If a dentist or dental hygienist provides technical advice and guidance on oral care to nursing staff working in a residential facility, they can also receive additional payment under the nursing care insurance system.
As of 2018, the total number of employed dental hygienists in Japan was 132,635, of which only 73 were men. In Japan, the Dental Hygienist Act granted dental hygienist licenses to mainly women until 2013. As a result, 99.95% of employed dental hygienists were women. There is a significant shortage of dental hygienists who can provide adequate dental health services to all generations [13
]. Thus, there is an urgent need to expand the workforce of dental health hygienists. However, the ratio of employed dental hygienists to the total number of registered dental hygienists was merely 46.0% in 2018 [14
]. To address the shortage of dental hygienists in Japan, it is important to establish work policies that allow registered dental hygienists to continue working. However, few studies have explored the employment status of dental hygienists in Japan.
In addition to basic conditions of employment, such as wages and working hours, related factors such as marriage and childbirth may affect employment since most dental hygienists in Japan are women. Furthermore, acquiring adequate professional education for rendering dental hygiene services is another factor affecting employment status. Therefore, the purpose of this study was to investigate factors related to the working status of dental hygienists in Japan by comparing the multiple factors between employed and unemployed dental hygienists.
2. Subjects and Methods
2.1. Study Setting
This study was a self-administered questionnaire survey for members of three alumni associations of dental hygiene training schools; it was not a national survey. Since all members of the alumni association were women, no gender analysis was conducted in this study. The distinction between unemployed and employed was based on whether the respondents were engaged in dental hygiene work at the time they answered the questionnaire. Those who were engaged in some occupation but not engaged in dental hygiene work were classified as not employed.
2.2. Selection of Subjects and Research Design
The study included three alumni associations representing dental hygienist training schools in three different regions (Kanto, Kyushu, and Hokkaido) of Japan. All three alumni associations have been in existence for more than 40 years. We conducted a survey using a self-administered questionnaire to individuals aged 20–59 between August 2018 and December 2019. Since only 4.5% of employed dental hygienists in Japan are over 60 years old, the target age range for analysis was defined. The questionnaires were sent to 1444 alumni members by mail, and the secretariat of each alumni association executed the stratified random sampling method. The survey organizer received stickers printed with the sampling results, which were used to send the questionnaire to the alumni members. The respondents completed the questionnaires anonymously.
2.3. Survey Items
Based on the national survey items concerning employment [15
], we examined the following: the subjects’ basic characteristics, employment status, working condition preferences, and participation in professional skill development training programs within the past year. We obtained basic demographic information such as the respondents’ age, marital status, and number of children. The respondents were asked about their current and desired employment status (full-time or part-time). The respondents were also asked to indicate whether they assign priority to each of the following five items using a binominal scale: wages, working hours, working location, job description, and human relations at the workplace.
2.4. Analysis Methods
After examining the descriptive statistics of each variable, we explored the associations between employment status and each variable by conducting a bivariate analysis using either a chi-square test or unpaired t-test. Next, we conducted a multiple logistic regression analysis (likelihood ratio, forward–backward stepwise selection method) to include the independent variables that showed a significant association to employment status in the bivariate analysis. We obtained the odds ratios, which were adjusted for the inter-relationship between the independent variables. We also included the alumni association category as an independent variable in the analysis since we incorporated responses from three different alumni associations in this study. Finally, we identified the factors that were closely related to the employment of dental hygienists in Japan after a multiple logistic regression analysis. The significance level was set at p = 0.05. IBM SPSS Statistics for Windows Version 26.0 (IBM Corp., Armonk, NY, USA) was used for statistical processing.
2.5. Ethical Approval
This study was conducted as per the guidelines of the Declaration of Helsinki. The analytical data did not contain any information by which the participants could be identified. The ethics review committee at the Nippon Dental University College at Tokyo approved the study (Approval No.: Tokyo Tanrin-218).