Skeletal class 1 and 2 malocclusion evaluation in JMDC orthodontic patients

ABSTRACT

The study was carried out to investigate the etiological skeletal factors differentiating class 2 malocclusions from class one malocclusion patients at Jinnah Medical and Dental College, Orthodontics department. A total of34 [MF ratio 13 21] skeletal class 1 malocclusion patients [group A] and 39 [MF ratio 2316] severe class 2 division one malocclusion [group B] patients were selected at the department of orthodontics, Jinnah Medical and Dental College, Karachi. The age ranged between 18-22 years [mean age 19.8 years]. All group A cases selected had ANB angle range of2-4 0 [mean value 2.70] indicating skeletal class one antero-posterior relationship, while the group B had ANB angle greater than 4 0 [mean value 8.3 0] indicating skeletal class two malocclusion with severe antero-posterior discrepancy. Lateral cephalogram radiographs were traced for both Group A and B, and composite cephalometric analysis comprising skeletal, dental and soft tissue parameters were noted and the mean value obtained by SPSS 10.0 statistical evaluation program. Group Apatients had less cranial base length [S-N], less cranial base angle [S-N-Ar] and greater SNB angle values as compared to the Group B class 2 patients. Furthermore, group B demonstrated backward mandibular rotation tendency [mean Y-axis angle value 65.8 0], high angle tendency and sagittal mandibular deficiency. Cranial base morphology has a significant effect on the underlying skeletal relationship of the jaws. Class two malocclusions have obtuse cranial base angle and longer cranial base lengths. Clockwise mandibular growth rotation pattern may contribute to the mandibular skeletal deficiency in class two patients