Mandibular jaw opening was related with general joint mobility in a non-patient adolescent group. The angular rotation of the mandible at maximum jaw opening was slightly larger in females than in males and significantly larger in hypermobile individuals. No significant relationship between linear measuring of maximal mandibular opening capacity and peripheral joint mobility was found either at active (AROM) or at passive range of mandibular opening (PROM). PROM was strongly correlated to the mandibular length. Clinical signs in the great jaw closer muscles could not be associated to decreased AROM. The mean value of the difference between PROM-AROM (DPA) was 1.2 mm. Frequent clenching and/or grinding was correlated to increased DPA only in hypermobile adolescents (r = 0.49***). Those with DPA exceeding 5mm had all reciprocal clicking.

Joint mobility was assessed in each member of an epidemiological sample of 96 girls and 97 boys, 17 years old, and graded by means of the hypermobility score of Beighton et al. Twenty two per cent of the girls and 3% of the boys could perform five or more of the nine manoeuvres. The prevalence of symptoms and signs of internal derangement in the temporomandibular joint was higher in adolescents with hypermobility of joints (score 35/9). In subjects with a high mobility score oral parafunctions (overuse) correlated more strongly with several signs and symptoms of craniomandibular disorder than in those with a low score.

Abstract— Correlations between craniomandibular disorders (CMD) symptoms and an inherited factor (general joint hypermobility) were studied in 193 adolescents (96 girls and 97 boys). They answered a questionnaire concerning CMD symptoms, oral parafunctions, head and jaw trauma and symptoms from other joints. Joint mobility was assessed by determining the Beighton score (0‐9). Twenty‐eight percent of the girls and 21% of the boys could perform four or more of the maneuvres. Twenty‐two percent of the girls and 3% of the boys were extremely hypermobile (score ≥5). Eighty‐nine percent were aware of some oral parafunction and the prevalences of oral habits were about the same in the two groups. Girls reported significantly more dysfunction symptoms than boys. No indication was found that oral parafunctions generally produced CMD but a systemic factor (joint hypermobility) seemed to play an important role when the masticatory system was exposed to local forces as in oral parafunction. This may be one explanation for the predominance of females among CMD patients.

In 193 non-patient adolescents, unilateral contacts in retruded contact position (RCP) were seen more often in girls than in boys (P < 0.001) and were more frequent in subjects with than without general joint instability (P < 0.05). A negative correlation (r = -0.70***) was found between the side of the temporomandibular joint sound and the side of unilateral contact in RCP. Boys with unilateral contacts in RCP had more non-reciprocal clicking than girls. No signs were found indicating that a unilateral contact in RCP is an aetiological factor for development of temporomandibular disorders. Unilateral contacts in RCP may in adolescents be considered a predictive factor for temporomandibular joint disturbance. Contradictory causes may determine the sagittal distance between RCP and ICP.

The purpose of the investigation was to study the relationship between general joint mobility and dysfunction among patients with craniomandibular disorders (CMD). Joint mobility was assessed in 74 female patients and 73 controls, using Beighton's modification of the Carter & Wilkinson hypermobility score. Twenty-five (83%) of 30 patients with score greater than or equal to 3 (lax joints) had temporomandibular joint (TMJ) involvement. Eighteen (41%) of 44 patients with score 0-2 (no laxity) had TMJ involvement. The difference between these groups was statistically significant (p less than 0.001). General joint laxity should therefore be taken into consideration in diagnosis and treatment of CMG.