[A cone-beam CT investigation on the effect of two-phase treatment and fixed appliance treatment only on temporomandibular joint].

To assess the effects of two phase treatment(Herbst and fixed appliance) and fixed appliance treatment only(edgewise appliance) on temporomandibular joint in Cass Ⅱ patients with mandibular retrusion using cone-beam CT(CBCT) analysis.Thirty Class Ⅱ patients with mandibular retrusion in the permanent dentition were divided into two groups. Group A consisted of 15 patients with two phase treatment. Group B consisted of 15 patients with fixed appliance treatment only. CBCT was taken before(T1) and after(T2) treatment. The Invivo Dental software was used to calculate the relevant parameters of temporomandibular joint. Wilcoxon analysis was carried out.In group A, the condylar anterior-posterior diameters(7.41[2.55]) and the condylar head height(3.58[0.86]) increased significantly after treatment(P 0.05) after treatment. The changes of condylar head height in group A(0.60[0.48]) showed greater than in group B(0.02[0.21]) (P 0.05).Compared with fixed appliance treatment only, except for condylar growth changes, no significant changes of other skeletal morphology of the temporomandibular joint and the condyle position within the glenoid fossa were found between patients with two phase treatment and with fixed appliance treatment only.