Hypermobility and trauma as etiologic factors in patients with disc derangements of the temporomandibular joint

The aim of the study was to investigate patients with temporomandibular joint (TMJ) disc derangement with its two clinical variants reciprocal clicking (RC) and chronic closed lock (CCL) with regard to the etiologic factors, previous jaw trauma and general (GJH) and local joint hypermobility (LJH). 42 patients (21 with RC and 21 with CCL) and 20 control individuals were studied. The patients and controls were asked whether they had sustained any jaw trauma in the past and were then examined for the presence of GJH and LJH, using defined criteria. Patient and control groups were compared. Statistical evaluation included chi(2) test and paired Student's t test. Odds ratio was calculated in order to assess the relative risk of developing RC and CCL when the etiological factor was present. The results showed a significant association between RC and GJH (OR = 9.6, p = 0.0010) as well as LJH (OR = 38, p = 0.0001). CCL was clearly associated with GJH (OR = 7.5, p = 0.0030) while its association with LJH was not significant (OR = 9.5, p = 0.0582). No significant association with previous trauma was found. The results indicate that GJH is an important etiologic factor for the development of RC and CCL of the TMJ.