A ROENTGENOCEPHALOMETRIC STUDY ON MORPHOLOGIC FACTORS OF NORMAL OCCLUSION AND CLASS III MALOCCLUSION

정상교합 및 III급부정교합의 두개악안면 골격요소에 관한 두부방사선계측학적 연구

There are variations in regional cranial and facial balance as a normal developmental process and regional imbalances often tend to compensate each other to provide functional equilibrium. This study was designed to analyse the patterns of morphologic harmony and inharmony inherent in normal occlusion and malocclusion. The subjects consisted of 92 individuals with normal occlusion and 60 Class III malocclusion patients. Their lateral cephalograms were traced and analysed using the counterpart analysis described by Enlow. The normal occlusion group was divided into Normal Types A and B according to the relative positions of Points A and B. The following conclusions were reached: 1 The normal occlusion consisted of $28.3\%$ of Normal Type A and $69.6\%$ of Normal Type B. 2. The Normal Type A and B differed from each other in the morphology of the cranial base, the mandibular ramus and corpus, and the functional occlusal plane. The Normal Type B showed considerable mandibular protrusion effect in the effective dimension and alignment of the above factors. 3. Most normal individuals showed some degree of disharmony among morphologic factors but the deviations were relatively small. 4. The Normal Type B was less balanced than the Normal Type A. 5. More regional imbalances were involved in Class III malocclusion and the imbalances were more severe.