A Clinical Anatomy Study On Surgical Correction Of The Prominent Mandibular Angle

Purpose The purpose of this study was to determine the reasons of the prominence of mandibular angle and the relationship between the gonion degree \the height and breadth of the mandibular ramus \ bigonial breadth and the eversion degree of gonion;and provide a morphological and anatomic basis for correcting the prominence of mandibular angle. Methods 1.20 adult fresh skulls was performed. The bigonial breadth \the degree of the gonion angle and the height and breadth of the mandible ramus \thinkness of the gonion\ the dietance between mandibular foramen and the posterior\inferior edge of mandibule and gonion were obtained .The descriptives data were analysised by software SPSS 10.0. 2. In axial computed tomography, it is possible to measure the thickness\breadth of the masseter and the medial ptergoid in the transection and the mandibular angle,the bigonial breadth in the anter-poster X-Ray .The date were initial analysed using a simple correlation and indpendent samples T-test. 3. The observation and measurement of the relationahip between the gonion and the artery \the branches of the facial nerve\the partotid duct;the morphology and artery of the masseter muscle were done oii 12 cadaver heads(24 lateral) Result 1 .The descriptives data of the mandibular angle \the height and breadth of the ramus \ bigonial breadth and the eversion degree of gonion\the thickness of gonion was 119?.830 , 67.71?.20mm, 35.30?.27 mm 104.51 ?.16mm, 18.70?10.57, 5.77?1.23 mm; The bigonial breadth was significantly related with the degree of the gonial eversion angle (r=0.875,P=0.000)and the height of mandibular ramus (r=0.741,P=0.000);The height mandibular ramus was significantly related with both the bigonial breadth and the gonial eversion angle;the ramus breadth was significantly negitive related with the cent of gonion (r=-0.6 1 4,P=0.004). 2.The bigonial breadth and gonial eversion angle was significantly related with the thickness of masseter muscle(P=0.000),otherwise the thickness of the medial ptergoid was on the contary(P=0.65\0.15).There was significant differences between the group of prominent and the normal in the gonial angle (P=0.000)\ the bigonial breadth (P=0.001) and thickness of masseter muscle(P=0.002).But there was no difference in the thickness of the medial pterygoid muscle(P=0.449). 3. On the line between the gonion and the attachment of masserter muscle at the point of anterior-zygomatic arch ,the distence(mm)between the transversa facil artery parotid duct .. facial nerve zygomatic branches\buccal branches and the gonion was 72, 62,2, 54 ?2,16 ?2mm.The masseter muscle was inserted into the deep and superficial fibres.The central nutritious artery laid in the super-fibers.Tlie deeper fibers could be moved during operation to avoid damnify of the main artery and nerve. Conclusion The thickness of the master muscle was a important factor that affected the lower facial morphology.The hyperplasia of masserter muscle caused the mandibular angle enlarged. The operation of correcting enlarged mandibular angle by an ititraoral approach was a security and feasible method. When ostectomy for reducing the withed of the lower face was to do ,the changes above mentioned should be considered respectively.