The Effect Of Hyper-erupted Third Molar On The Structural And Functional Of Temporomandibular Joints

Objective To investigate the effect of unilateral hyper-erupted third molar on the structural and functional of temporomandibular joints.Method 150 individuals, 100 with unilateral hyper-erupted third molars (50 upper and 50 lower) as test groups and 50 without hyper-erupted third molars as control group, were enrolled in present study. All subjects were undertaken all round clinical examination of stomatognathic system and the diagnostic casts were also be getted.Taking transcranial radiogram of bilateral temporomandibular joints at intercnspal position. Linear measurements of TMJ space which were also determined condyle process positions were performed. The results were analyzed by statistical method.Result1.There was statistical differences in the changes of all spaces except 30°and 150°in the first test group(P<0.05) and only 90°and 120°in the second test group(P<0.05).2.There was statistical differences between the first test group and the control group when condyle was in the posterior in 0°and 180°directions(P<0.05).3.There was also statistical differences between the first test group and the control group in the ratios of jaw muscle pain,clicking and opening type changed,and both occlusal interference between the test groups and the control group(P<0.05).. ConclusionUnilateral hyper-erupted third molar may change the jaw movement profile,causing temporomandibular joint space altered and condylar process movement,and consequently produce dysfunctions like jaw pain and clicking.