Effect of segmental Le FortⅠosteotomy and bilateral sagittal split ramus osteotomy on the condyle position in skeletal classⅢmalocclusion patients / 北京大学学报(医学版)

ABSTRACT

Objective:To investigate the effect of segmental Le FortⅠosteotomy and bilateral sagittal split ramus osteotomy ( BSSRO ) on the condyle position in skeletal class Ⅲ malocclusion patients . Methods:In this retrospective study , 19 patients with skeletal class Ⅲmalocclusion who met the inclu-sion criteria were enrolled .All the patients underwent the segmental Le FortⅠ osteotomy and BSSRO . Cone beam computed tomography ( CBCT) scans were performed in the following phases:T1:within one week before the surgeries;T2:within one week post-surgery;T3:three months post-surgery;T4:6 to 14 months post-surgery .The posterior spaces , anterior spaces and the superior spaces of the bilateral tem-poromandibular joints were measured according to the Kamelchuk method respectively .The fossa ratios of the condyle and the distribution of the condyle positions related to the glenoid fossa ( anterior , concentric and posterior position ) were calculated .The results were analyzed statistically .Results:The posterior space , the anterior space and the superior space of bilateral temporomandibular joints in T 2 phase [ right:(2.78 ±1.23) mm, (2.47 ±0.89) mm, (3.07 ±0.85) mm; left: (2.93 ±0.83) mm, (2.69 ± 1.14) mm, (3.44 ±1.16) mm] showed significantly larger spaces than those in T 1 phase [right:(1.81 ±0.95) mm, (1.65 ±0.55) mm, (2.13 ±0.52) mm;left:(2.12 ±1.05) mm, (1.79 ±0.59) mm, (2.15 ±0.93) mm],in T3 phase [right:(2.08 ±1.25) mm, (1.79 ±0.68) mm, (1.80 ±0.76) mm;left: (2.05 ±0.75) mm, (1.99 ±0.94) mm, (2.14 ±0.71) mm] and in T4 phase [right:(1.94 ±0.77) mm, (1.81 ±0.69) mm, (2.05 ±0.69) mm;left:(1.89 ±0.69) mm, (1.80 ±0.61) mm, (2.19 ±0.75) mm], P0.05).The fossa ratio and the condyle position related to the glenoid fossa had no significant difference in all the four phases (P>0.05).The results suggested that the condyle moved downward in T 2 phase and changed to the original pre-surgery position in T3 phase, then keot stable in T4 phase.Conclusion:Segmental Le FortⅠ osteotomy and BSSRO caused significant and transient changes of the condyle position in skeletal class Ⅲmalocclusion patients . However , the condyle tended to move back to the original pre-surgery position and might keep stable .