No heritability of temporomandibular joint signs and symptoms.
The causes of temporomandibular joint (TMJ)-related signs and symptoms are largely unknown. We tested the hypotheses that these signs and symptoms, as well as oral parafunctional habits, are substantially heritable. Questionnaire and clinical data were collected from 494 twins, including pairs of reared-apart and reared-together monozygotic (MZ) and dizygotic (DZ) twins. A history of joint-area pain, joint noises, and clenching and grinding habits was scored as present or absent. Twenty-nine percent of the population experienced at least one sign or symptom. Nearly one-quarter of subjects clenched or ground their teeth, and 8.7% reported a history of joint-area pain. Pain was associated with clenching, grinding, and joint noises. MZ twins were no more similar than DZ twins for any outcome, suggesting that genetic factors do not influence these traits in the population. Reared-together MZ twins were no more similar than reared-apart MZ twins, suggesting a negligible effect of the family environment on these outcomes. Environmental factors unique to each twin appeared to be the major determinants of variation in this population.
Michalowicz
B S
BS
Oral Health Clinical Research Center, University of Minnesota School of Dentistry, Minneapolis 55455, USA. micha002@tc.umn.edu
Pihlstrom
B L
BL
Hodges
J S
JS
Bouchard
T J
TJ
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D001168:Arthritis / Q000150:complications; D002012:Bruxism / Q000150:complications; D016009:Chi-Square Distribution; D004200:Diseases in Twins; D030342:Genetic Diseases, Inborn; D006184:Habits; D006801:Humans; D008875:Middle Aged; D008910:Minnesota / Q000453:epidemiology; D016017:Odds Ratio; D011795:Surveys and Questionnaires; D013705:Temporomandibular Joint Disorders / Q000453:epidemiology / Q000209:etiology* / Q000235:genetics*