III급 부정교합의 조기 치료 예후 예측을 위한 두부방사선 계측 변수의 평가

Evaluation of various cephalometric measurements to predict the prognosis of early Class III malocclusion treatment

Ⅲ급 부정교합을 조기에 치료했을 때, 치료 후 retention 기간 중에 교합이 안정적으로 유지되는 경우와, 재발되어 성장 완료 시기에 악교정수술을 해야 하는 경우를 경험하게 된다. 어린 년생부터 장기간에 걸쳐 교정치료를 했음에도 재발되어 악교정수술을 하는 경우에, 환자와 보호자는 소모된 시간과 경비에 대해 많은 실망을 하는 경우를 볼 수 있다. 교정치료 후 보정기간 중에 있는 30증례를 조사했다. 치료 완료된 교합상태를 교합안정 정도에 따라 good, fair, relapse군으로 나누어 치료 전 골격형태를 관찰한 결과, AB-MP항목이 유의성 있는 차이를 보였다. 조기에 Ⅲ급 부정교합을 치료하는 경우에, 치료 후 안정에 관한 예후를 평가하는데 AB-MP를 활용할 수 있다 AB-MP이 65이상인 경우에 조기치료가 권장되고, 60이하인 경우에는 성장이 완료될 때까지 연기할 수 있다.

The aims of this study were to investigate the differences in the early craniofacial morphology of Class Ⅲ malocclusions with good, fair and poor occlusal stability and to elucidate a key determinant for distinguishing the cases. Lateral cephalograms of 30 subjects with Class Ⅲ malocclusion in the mixed dentition were analyzed at the start of treatment (mean age of 8.58 ±1.47). All subjects were reevaluated after a mean period of 7.50±1.94 years comprising active treatment and retention. At this time, the samples were divided into three groups: good (10 subjects), fair (10 subjects) and poor (10 subjects) occlusal stability groups. According to the results of ANOVA, there were significant morphological differences in the early stage among the good, fair and poor occlusal stability groups, especially in variables that represented the vertical skeletal relationships. As well, there were already more dental compensations in the poor occlusal stability group. Stepwise discriminant analysis on the measurements at the time of first observation identified only one predictive variable: AB to mandibular plane angle (AB-MP). With this discriminant function, 83.3% of the original grouped cases were correctly classified and the canonical correlation coefficient was 0.857. In conclusion, AB-MP can be a possible predictor for the eventual prognosis of early Class Ⅲ treatment. If it is below 60, the prognosis of early Class Ⅲ treatment is expected to be poor, while if it is above 65, a good prognosis is expected.