Influence of Psychosocial Factors and Habitual Behavior in Temporomandibular Disorder–Related Symptoms in a Working Population in Japan

Akira Nishiyama1, *, Koji Kino1, Masashi Sugisaki2, Kaori Tsukagoshi1
1 Temporomandibular Joint and Oral Function, Comprehensive Oral Health Care, Comprehensive Patient Care, Graduate School, Tokyo Medical and Dental University, Tokyo, Japan
2 Department of Dentistry, Jikei University School of Medicine, Tokyo, Japan

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© Nishiyama et al.; Licensee Bentham Open.

open-access license: This is an open access article licensed under the terms of the Creative Commons Attribution Non-Commercial License ( which permits unrestricted, non-commercial use, distribution and reproduction in any medium, provided the work is properly cited.

* Address correspondence to this author at the 1-5-45, Yushima, Bunkyo-ku, Tokyo 113-8549, Japan; Tel: +81-3-5803-5713; Fax: +81-3-5803-5713; E-mail address:



The symptoms of temporomandibular disorders (TMD) are directly influenced by numerous factors, and it is thought that additional factors exert indirect influences. However, the relationships between TMD-related symptoms (TRS) and these contributing factors are largely unknown. Thus, the goal of the present study was to investigate influences on TRS in a working population by determining the prevalence of TRS, analyzing contributing factors, and determining their relative influences on TRS.

Materials and Methods:

The study subjects were 2203 adults who worked for a single company. Subjects completed a questionnaire assessing TRS, psychosocial factors (stress, anxiety, depressed mood, and chronic fatigue), tooth-contacting habit, and sleep bruxism-related morning symptoms, using a 5-point numeric rating scale. Our analysis proceeded in 2 phases. First, all variables of the descriptor were divided into parts by using an exploratory factor analysis. Second, this factorial structure was verified by using a confirmatory factor analysis with structural equation modeling.


Of 2203 employees, 362 reported experiencing TRS (16.4%). Structural equation modeling generated a final model with a goodness of fit index of 0.991, an adjusted goodness of fit index of 0.984, and a root mean square error of approximately 0.021. These indices indicate a strong structural model. The standardized path coefficients for “habitual behavioral factors and TRS,” “psychosocial factors and habitual behavioral factors,” “psychosocial factors and TRS,” and “gender and habitual behavior factors” were 0.48, 0.38, 0.14, and 0.18, respectively.


Habitual behavioral factors exert a stronger effect on TRS than do psychosocial factors.

Keywords: Temporomandibular disorders, habitual behavior, psychosocial factors, questionnaire, screening, structural equation modeling, .