Individuals exhibiting negative affectivity and social inhibition, qualities of type D personality, may have increased susceptibility to gum disease and related infections affecting soft tissue and bones of the mouth.


Type D personality describes individuals who have high levels of emotions such as anger, distress, hostility, and depression (negative affectivity) and face difficulties in social interactions because they hide their emotions out of fear of rejection or disapproval (social inhibition). Research has shown that individuals with this personality type may be at increased risk for a number of unfavourable health outcomes, including heart disease, type II diabetes, and irritable bowel syndrome. In addition, they are more likely to suffer from sleep disturbances, and to engage in unhealthy behaviours like smoking, poor eating habits, and lack of physical activity.

A recent study published in the Journal of Health Psychology has examined whether, in addition to the above ailments, individuals with type D personality may also be at increased risk of periodontal disease. In particular, the study looked at university students, amongst whom progression of periodontal disease was observed to be common.  In its most benign form, periodontal disease causes inflammation of the gums, but if left untreated, can progress to a more serious infection of the soft tissues and bones of the mouth, and in worst cases, may cause loss of teeth.

The study, conducted at Okayama University in Japan, involved 600 students who underwent oral health examinations at the start of first year (baseline) and a follow-up examination three years later. All participants had clean oral exams (i.e., no periodontal disease) at the start of the study.  Oral hygiene habits were surveyed at baseline and again three years later via questionnaire. Students were also assessed to determine whether they exhibited type D personality traits based on a 14-item type D personality scale which evaluated for characteristics of negative affectivity or social inhibition.

Researchers found that over the course of the study, 186 of the 600 students developed signs indicating onset of periodontal disease. In comparing type D to non-type D students, there was no significant difference between the two groups in terms of oral hygiene habits (i.e., flossing, regular brushing), either at baseline or on three-year follow-up. However, there was a statistically significant higher incidence of periodontal disease among type D individuals compared with non-type D at the three-year follow-up.

Although the study did not attempt to identify the reasons why type D personality might be associated with a higher risk of periodontal disease, the researchers posited that it could be related to higher levels of cortisol and other stress-related hormones that may exist in individuals who experience frequent or severe negative emotional states.  The release of such hormones is known to have a destructive effect on periodontal tissues, and is thus associated with periodontal disease.

Authors of the study suggest that future research that tracks stress and hormone levels among type D personalities may be helpful to further understanding the apparent association indicated by this study. In the meantime, they also suggest that type D personality could be included as a risk factor for periodontal disease, along with other known factors such as type II diabetes, smoking, and stress.


Written By: Linda Jensen

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