正畸拔牙后Bolton指数不调的多因素分析

目的　探讨安氏分类、术前前牙比、全牙比及不同拔牙模式对前磨牙拔除后Bolton指数的影响。方法　随机选择166副安氏错患者的模型,测量术前Bolton指数的前牙比、全牙比及拔牙后的Bolton指数值,以错安氏分类、术前前牙比、全牙比及拔牙模式建立Logistic回归模型,对拔牙后Bolton指数不调的发生进行多因素分析。结果　当术前前牙比、全牙比较小时,前磨牙拔除后Bolton指数趋于协调;而当术前前牙比、全牙比较大时, 前磨牙拔除后Bolton指数更趋于不调。不同的拔牙模式对Bolton指数的影响并不一致,当术前Bolton指数的前牙比、全牙比正常时,上下颌均拔除第一前磨牙,或上颌拔除第一前磨牙,下颌拔除第二前磨牙后,其Bolton指数值则明显高于正常。结论　矫治设计时,不仅要计算完整牙列Bolton指数的全牙比、前牙比,还要对所选择的拔牙模式后的Bolton指数进行分析,并多因素综合考虑,选择合适的拔牙模式。

Logistic Regression Model Analysis on Bolton Ratio of Orthodontic Extraction Model

OBJECTIVE: The purpose of this study was to evaluate the role of Angle's class, overall ratio and anterior ratio in the creation of tooth size discrepancies, and to determine whether any tooth extraction combinations create more severe discrepancies. METHODS: 166 dental casts of orthodontic patients were selected randomly. These models were classified according to angle's criterion. Mesio-distal dimensions of mandibular and maxillary teeth were measured before treatment, and subjected to Bolton's analysis. Hypothetical tooth extraction by the following combinations: all the first premolars, all the second premolars, upper first and lower second premolars, and upper second and lower first premolars, was performed on each patient. The measurement results were again subjected to Bolton's analysis to see whether any tooth-size discrepancy had been created. The results were evaluated statistically by means of Logistic regression model. RESULTS: Overall ratio, anterior ratio and extraction models affected mesio-distal tooth size ratio of both maxillary and mandibular teeth in the final stage of orthodontic treatment, Whereas, the results showed no significant difference among these groups of malocclusion. CONCLUSION: The results suggested that dentists should always keep in mind that each patient should be treated individually and should be aware of that other factors also played important roles in determining what teeth, if any, should be removed and the Bolton analyses of all kinds of extraction models should be carried out, as well as the general Bolton analysis.