替牙期未萌尖牙、前磨牙宽度和预测方程的建立

目的优化选择针对未萌尖牙、前磨牙宽度预测的基牙组合。方法取正畸科初诊患者的研究模型,按一定标准随机选出恒牙列模型180副,利用电子游标卡尺(精度0.01 mm)测量牙冠近远中径,并对测量值进行相关与回归分析。结果得到了与未萌尖牙、前磨牙宽度相关度较高的基牙组合,即,上颌第一磨牙和上、下颌中切牙联合;此组合与上、下颌预测牙的相关度分别为0.753和0.834,具有统计学意义(P≤0.001)。以此为基础进行回归分析,建立了预测上、下颌尖牙、前磨牙宽度之和的回归方程。结论建立了一组适合中国北方地区替牙期儿童未萌尖牙、前磨牙宽度的预测方程:男性Y=0.64X+6.89(上颌),Y=0.79X+2.45(下颌);女性Y=0.64X+6.86(上颌),Y=0.72X+3.90(下颌)(Y代表一侧未萌尖牙、前磨牙近远中宽度和,X代表双侧上颌第一磨牙及上、下颌中切牙的近远中宽度和的一半)。

Prediction equations for widths of unerupted canine and premolars in mixed dentition

Objective To predict unerupted canines and premolars in mixed dentition for Chinese.Methods 180 study casts of initial patients under 20 years old(80 males and 100 females without a history of orthodontic treatment) were selected from the Orthodontic Department of Stomatology of the Fourth Military Medical University.The patients had complete permanent dentition and were free of congenitally missing teeth,extracted teeth,malformed teeth,broken or chipped teeth,or carious lesion that might affect the mesiodistal tooth width.The mesiodistal widths of all permanent teeth were measured to 0.01mm.The data were subjected to regression analysis.Results The combination of permanent upper and lower central incisors and upper first molars was selected as the best predictor for the unerupted canine and premolars in this sample,and the correlation coefficients between the variables were 0.753 for maxillary teeth and 0.809 for the mandibular teeth.The P value was less than 0.001 respectively for male and female.Conclusions Equations predicting summation of mesiodistal crown-widths of upper and lower unerupted canine and premolars in male and female were established respectively.For male: Y=0.64X+6.89(upper),Y=0.79X+2.45(lower);For female: Y=0.64X+6.86(upper),Y=0.72X+3.90(lower)(Y represents the summation of the mesiodistal crown-widths of unerupted canine and premolars on one buccal side,while X represents half of the summation of the mesiodistal crown-widths of upper and lower central incisors and upper first molars:11,21,16,26,31 and 41).