TMJ and TMD
The temporomandibular joint (TMJ) is a joint formed by the glenoid fossa of the temporal bone and the mandibular condyle. An articular disc separates the joint into two cavities which allows gliding and rotary joint movements (Maini & Dua, 2023).
Temporomandibular disorder (TMD) refers to a group of conditions affecting the chewing muscles and the TMJ. Common symptoms are pain, restricted movement, and odd sounds issuing from the joint. Symptoms can appear at any age but the highest incidence is in adults between 20 to 40 years of age. Women are much more likely to be affected than men, but the reason is as of yet unknown. About 60 to 70 percent of the population will experience TMD, but only 5 to 12 percent seek treatment (Maini & Dua, 2023).
TMD is the third largest dental issue after caries and periodontal diseases with higher emotional upset being present along with bruxism—unconscious teeth clenching and grinding—triggered by life stressors and poor coping skills (Maini & Dua, 2023).
The Big Five Personality Trait Model and TMD
Among many personality theories currently in vogue, the most popular is quite likely the Five Factor Model of Personality based on five central personality factors: Extraversion (vs. Introversion), Openness to Experience, Conscientiousness (the drive to get things done), Agreeableness, and Neuroticism. These are the so-called “Big Five.”
Past research shows that certain personality traits increase the risk of developing physical diseases. The original research began with the discovery of the “Type A” personality and cardiovascular disorders, but the field has expanded since then. The most dysfunctional traits are:
- suppressing negative emotions especially anger
- obsessively driven to achieve especially at high level of results
- taking on more responsibilities than what is reasonable or manageable
- exhibiting obsessive-compulsive behaviors especially perfectionism
- being very vulnerable to depression (Bornstein, 2003).
Within the last 20 years a new personality type has arisen—the Type D—which is marked by the suppression of negative emotions; it a type marked by extreme emotional distress, but this distress is hidden. This type is based on two key personality factors: neuroticism and introversion. And, recently, the field of dentistry has come to believe that TMD and Type D personality are related.
TMD and Personality Factors
A recent study examined 75 adults between the ages of 19 to 52 who were diagnosed with TMD along with a control group of 75 subjects without TMD. The research method consisted of a questionnaire and clinical examination. Those subjects who clenched their teeth scored higher in conscientiousness. Participants with more headaches scored higher in neuroticism. People with more cracked enamel were more introverted while those with worn dental surfaces were more neurotic. Sound-related symptoms during joint movements were more neurotic, more introverted, and less conscientious. Those people with joint pain were more conscientious (Mitrowska-Guźmińska et al., 2022).
Closing Thoughts
I’ve always been interested in psychosomatic[1] phenomena because I suffered from somatic symptoms starting in early grade school with almost daily stomach aches before leaving for school. Later, the pains moved to my head, the day I declared myself as a Journalism major as an undergraduate. I consulted with an MD at that time and he simply took out his prescription pad and wrote on it: “Stop worrying.”
My bad luck to have consulted a real asshole. This path eventually led me to the discovery of self-hypnosis and the effects of emotions on the body. Which brings me to a second major interest.
I had always been taught, not formally, but informally, as it were, that emotions, like my psychosomatic body symptoms, were “all in my head.” This also cause me to notice that our society has historically dismissed the realities of the effects of the mind on the body. Recent research, and I discuss this more in in my textbook on somatic psychology that emotions are a holistic experience; they are “emotional body experiences” and must be seen and treated that way. This idea has not yet caught on within our society—pretty much a society of dunderheads as I am forced to conclude in my old age. The closest we as a culture have come to appreciating the effects of mental effects on the both is in the concept of stress, yet again, it is a very limited appreciation and only quasi-mental, as it were, as stress comes from the environment and so that makes it somehow more okay than say a somatized experience of pain or paralysis.
Personality traits are based on beliefs. These create attitudes. Which, in turn, fuel actions which become habits and character. The bodymind is a holistic event. It is only our Cartesian prejudices that blind us to our somatic reality.
Paul Shane, Ph.D., LMT
Director, Academic Content
References
Bornstein, R. (2003). Psychodynamic models of personality. In T. Millon & M. Lerner (Eds.), Handbook of Psychology: Personality and Social Psychology, Vol. 5. Hoboken, NJ: John Wiley & Sons, Inc., pp. 117–134.
Fava, G., Cosci, F., & Sonino, N. (2017). Current psychosomatic medicine. Psychotherapy & Psychosomatics 86, p. 13-30.
John, O., Naumann, L., & Soto, C. (2008). Paradigm shift to the integrative Big Five trait taxonomy: History, measurement, and conceptual issues. In O. John, R. Robins, & L. Pervin (Eds.), Handbook of personality: Theory and research, Third Edition. New York, NY: The Guilford Press, pp. 114–158.
Maini, K. & Dua, A. (2023). Temporomandibular Syndrome. National Library of Medicine StatPearls, https://www.ncbi.nlm.nih.gov/books/NBK551612/.
Mitrowska-Guźmińska, M., Gębska, M., Jonko, K., Dalewski, B., Palka, L., Cheć, M., & Sobolewska, E. (2022). Effect of personality type on occurrence of temporomandibular disorders: A cross-sectional study. Environmental Research and Public Health 20, 352, https://doi.org/10.3390/ijerph20010352.
[1] See Fava, Cosci, & Sonino (2017).
Revised on 03-20-25.