Association between hypoplastic condyles and temporomandibular joint disc displacements: a cone beam computed tomography and magnetic resonance imaging metrical analysis.

This study investigated the association between hypoplastic condyles and disc displacements without reduction (DDw/oR). Consecutive patients with non-syndromic unilateral condylar hypoplasia were recruited and clinical, cone beam computed tomography (CBCT) and magnetic resonance imaging (MRI) data were acquired. Linear measurements including condylar head width, depth, height and condyle length were determined with CBCT while MRI was used to assess disc position, morphology and displacement. A total of 43 patients were enrolled of which 93.02% had a history of temporomandibular disorders (TMDs) and 83.72% presented with TMD signs and symptoms. Depth and height of the condylar head along with condyle length of hypoplastic joints (6.68±1.67mm, 4.97±1.25mm and 14.49±3.02mm, respectively) were significantly lesser than normal joints (7.77±1.26mm, 6.35±1.45mm and 18.20±3.18mm) (P<0.001). The prevalence of DDw/oR was significantly higher in hypoplastic joints (79.07% versus 13.95%) (P<0.001). Joints with hypoplastic condyles had shorter disc lengths (6.99 ± 2.16 mm vs, 8.45 ± 2.26 mm) (P=0.007). Furthermore, disc displacements were significantly more advanced (8.52 ± 2.84 mm) and severe (76.74% with severe translations) when compared to the contralateral side (4.77 ± 2.97 mm and 32.56%) (P<0.05). A significant association was observed between condylar hypoplasia and temporomandibular joint DDw/oR with hypoplastic joints exhibiting more severely displaced and deformed discs. DDw/oR coupled with repaired degenerative joint disease may mimic condylar hypoplasia radiographically.