The Japanese Dental Hygienists Law states that the mission of dental hygienists is the prevention of oral disease under the instruction of dentists by following treatments, including the mechanical removal of deposits found on the healthy root surface and under healthy free gingiva, drug application on the tooth and oral cavity, assisting in dental treatment, and oral health instructions [1
]. Dental hygienists in Japan play an important role as healthcare professionals and have been asked to perform a wide variety of clinical practice skills in the Japanese super-aging society. There is a demand for visiting home dental care, oral care for hospitalised patients, and oral health management for older people requiring long-term care. Previous studies have revealed that oral health management of dental hygienists for older adults or hospitalised patients is effective in improving not only oral health, but also general health conditions [2
], thus, emphasizing the social role of dental hygienists as professionals in oral health management. However, the employment rate of dental hygienists in Japan is very low compared to other countries [5
]. According to a national survey from 2014, the number of registered dental hygienists in Japan was approximately 250,000, but the number of employed dental hygienists was 116,299 [7
]. An insufficient number of dental hygienists may lead to serious problems that affect the supply of dental health care services. Prevention of leaving jobs and support for re-employment are important in maintaining a stable employment rate. Therefore, the development of a positive working environment for dental hygienists is important [7
Job satisfaction is an important prerequisite for a good work environment [8
]. Previous studies have reported that job satisfaction is a key factor in continuing employment, especially for healthcare professionals, including dental professionals [9
]. Johns et al. reported that perceived job boredom and lack of benefits helped determine whether a dental hygienist would leave clinical practice. However, salary was implicated as a reason for continuing work [12
]. Given these findings, perceived job attractiveness and satisfaction, including employment stability and specialty as a dental hygienist, may lead to motivation and positive attitudes toward work, which in turn may promote individual career formation.
To ensure stability of the dental hygienist workforce, it is necessary to determine which issues affect dental hygienists and analyse their effects on job attractiveness and satisfaction. However, little is known about how dental hygienists perceive their job attractiveness and satisfaction in Japan. The aim of this study was to clarify the issues of Japanese dental hygienists regarding their job satisfaction, job demands, and work environment.
In this large-scale study of dental hygienists in Japan, we investigated the association between job attractiveness and satisfaction, and the current status of the factors dental hygienists feel would improve the work environment. To the best of our knowledge, this is the first report describing the detailed characteristics of occupational awareness among Japanese dental hygienists, which cannot be clarified by the results of simple descriptive statistics. This study has been conducted by the Japan Dental Hygienists Association every five years. Many of the items were dichotomous responses. This survey confirmed the results of the previous survey. Dichotomous responses lack depth of information compared to those rated on a Likert-type scale. However, when applied to item response analysis, results obtained using dichotomous variable are easy to interpret [15
]; this study utilized the merits of such variables. Item response theory analysis is a powerful analytical method, especially for dichotomous variables. It is widely used in educational research and tests, such as the widely-known TOEFL. It is also applicable in medical research. Valuable information, rather than a simple descriptive analysis of frequency, can be presented using IRT. The slope and location of item information curve can provide valuable information on the response pattern in a questionnaire. We have been frequently applying IRT for in our research studies. When interpreting the descriptive analysis of job attractiveness, more than 90% of dental hygienists gave positive responses for all items except ‘Stable income’ and ‘Easy to change work place and gain employment’. Moreover, the item response curve revealed that the curves of all items were shifted backward, that is, many respondents responded that the work of dental hygienists was attractive. This result suggests that most dental hygienists find value in their jobs. Therefore, the strength that the dental hygienists perceive attractiveness of these tasks is an important factor for their work continuity. Most dental hygienists recognised attractiveness in the stability of their status as a worker, that is, having a national qualification made it easy to change where they work.
Notably, direct involvement with people and contributions to life and society tended to be perceived as attractive only if other factors were met. According to the item information curve, income stability and easy to change work place and gain employment had high item information. These two items were more attractive than the other items. The results of IRT and factor analysis indicated that many dental hygienists considered that easy to change work place and stable income were more important than national qualifications (Table S1[A]
). In contrast, for ‘Contribution’ factors, all items were presented as sigmoidal curves. This suggests that dental hygienists find more value regarding aspects related to the contribution of their work as job attractiveness increases (Table S1B
Factors directly linked to daily life, such as employment status and income stability, may be prerequisites for the attractiveness of work as a dental hygienist. With respect to t the factors dental hygienists feel would improve the work environment, item information curves of salary and appraisal of specialty and license were backwards. This indicates that many dental hygienists requested these two items rather than other working conditions. Conversely, item information curves for childcare support and shortened working hours were forward-facing, indicating that a limited number of dental hygienists requested for the improvement of these two conditions. When comparing the item response curve and item information curves of the factors dental hygienists feel would improve the work environment with attractiveness, curves were gentle sloped sigmoid curves and were in a limited area. This indicates that even though the salary and appraisal of specialty were common requests, the need to improve other conditions depended about each dental hygienist. In other words, the perception of the working environment may be influenced by the circumstances and view of each dental hygienist; thus, a subdivided validation of each of these factors is necessary.
A previous study reported that reducing the workload, enhancing welfare, and career developments were associated with job satisfaction among healthcare staff in China [16
]. However, the results of this study showed that the demands about salary and employment stability were more pronounced than the workload. This trend of salary emphasis was like findings from previous studies about dental care providers [17
The results from the SEM showed that factors related to the working environment significantly influenced factors of assured income regarding job attractiveness. Previous studies have also reported that turnover of healthcare professionals is caused by dissatisfaction with their work, but it is inferred that the factors causing dissatisfaction may differ depending on job content and educational background [16
]. In particular, improvement in salary may improve the job satisfaction of dental hygienists in Japan. Detailed verification is necessary for the improvement of working conditions of dental hygienists for the planning of specific measures to prevent turnover. Therefore, further study is necessary to investigate the association between leaving jobs and job satisfaction. The results of the SEM showed that the job satisfaction of dental hygienists presented their characteristics as professionals. Supporting people’s health, such as contributions to people and society, had high loadings. Ayers et al. reported that one of the independent factors associated with career satisfaction among New Zealand dental therapists was whether they felt that they were a valued part of the dental community [19
], so increasing the value of work may increase job satisfaction. The improvement of both the contribution to people and society and assured salary may be issues for ensuring dental hygienists’ satisfaction and improving the quality of dental services in Japan.
There are some limitations to the present study. First, the participants may have a variety of backgrounds. For example, years of education before obtaining a dental hygienist’s license, years of clinical experience, and place of employment may have led to differences in job attractiveness, satisfaction, and the factors dental hygienists feel would improve the work environment. Correspondence analysis also revealed the characteristics of the participants according to their generations, which warrants the need for in-depth examination in the future [21
]. Second, the duties of dental hygienists are stipulated by the legislation and regulations of each country, and the specific content varies widely, so the results have limited generalizability outside of Japan. Job satisfaction is a key factor in the stable career formation of healthcare providers; therefore, studies comparing and examining differences on a global scale are desirable in the future.