Korean J Orthod.  1992 Mar;22(1):205-227.

A roentgenocephalometric study of craniofacial characteristics of the skeletal Class III malocclusions classified by mandibular plane (SN-MP) angle

• Lee HK
• Chung KR
• Park YG

Abstract

This study was aimed to investigate the characteristics & the causative areas of the adult skeletal class III malocclusions with different facial divergency. The lateral cephalograms of 80 subjects with skeletal class III malocclusion from 17 to 29 years of age were classified into 3 groups according to SN-MP angle; hypodivergent group (21.65 +/- 3.52degrees), neutrodivergent group (30.50 +/- 2.29degrees) and hyperdivergent group (40.02 +/- 3.98degrees). The data were gathered by digitizing of the traced cephalograms and were statistically analyzed. The results were as follows: 1. The anterior cranial base of the hyperdivergent group was shortest & tipped upwardly to the FH plane. 2. The maxilla of hyperdivergent group was shortest anteroposterioriy and positioned posteriorly to the anterior cranial base. 3. The degree of the mandibular prognathism in hyperdivergent group was less than the hypodivergent group. The hyperdivergent group showed the down ward & backward rotated mandible. 4. The mandibular ramus & body was short & slender in the hyperdivergent group and the gonial angle was greatest in the hyperdivergent group. 5. The temporomandibular joint was positioned more superioriy to the anterior cranial base in the hyperdivergent group. 6. The cranial base, palatal plane, occlusal plane and mandibular plane were diverged in the hyperdivergent group. And this group had a great anterior total facial height, especially anterior lower facial height. 7. The craniofacial characteristics of skeletal class III malocclusion were critical in the vertical structure than the horizontal.

MeSH Terms

Adult
Dental Occlusion
Humans
Malocclusion*
Mandible
Maxilla
Prognathism
Skull Base
Temporomandibular Joint