OBJECTIVETo investigate the morphology change of stomatognathic muscles after zygomatic plasty combined with mandibular angel plasty.

METHODS3D-CT facial soft tissue measurement was performed pre-operative and at 10 days,3 months post-operatively in 59 cases with prominent malar-complex and mandibular angle. The q test (Newman-Keuls method) was used to analyze the variance.

RESULTSThe cross sectional area of masseter muscle and medial pterygoid muscle were both increased at 10 days, reduced at 3 months post-operatively (P < 0.05). The masseter muscle and medial pterygoid muscle cross sectional areas were (4.73 +/- 0.21) cm2 and (3.24 +/- 0.21) cm2 at anterior nasal spine plane, respectively; the pterygoid muscle cross-sectional area was (1.37 +/- 0.35 ) cm2 at the root of coronoid process plane, showing significant difference, when comparing with those before operation (P < 0.05). Lateral pterygoid muscle and temporal muscle had no statistical difference between the pre-and 10 days post-operatively(P > 0.05), however, the temporal muscle was reduced while the lateral pterygoid muscle was increased at 3 months post-operatively. The temporal muscle cross-sectional area was(2.35 + 0.25) cm2 at coronoid process plane; the temporal muscle and lateral pterygoid muscle cross-sectional areas were (1.00 +/- 0.16) cm2 and (3.54 +/- 0.61) cm2 at the root of coronoid process plane, which were significantly different from those before operation (P < 0.05 ).

CONCLUSIONSBecause of osteotomy, muscles attached position are changed in the short term after zygomatic plasty combined with mandibular angel plasty. Masseter muscle and medial pterygoid muscle are inevitably injuried during the operation. With the postoperative recovery, muscles have adaptive changes which reduced compared with those before operation after their reattachment. Zygomatic plasty can cause temporal muscle atrophy;while the lateral pterygoid muscle is rarely involved, the cross sectional area had no statistical difference between the pre- and 10 days post-operative, and the cross sectional area increase at 3 months post-operatively may be due to a compensational enlargement.