Bishara S E, Jakobsen J R
Department of Preventive and Community Dentistry, University of Iowa, Iowa City 52242, USA.
Am J Orthod Dentofacial Orthop. 1998 Nov;114(5):573-6. doi: 10.1016/s0889-5406(98)70019-8.
The determination of the tooth size-arch length discrepancy in the mixed dentition requires an accurate prediction of the mesiodistal widths of the unerupted permanent teeth. Three approaches have been used to estimate the mesiodistal crown widths of unerupted canines and premolars: (1) measurements from erupted teeth, (2) measurements from radiographs, and (3) a combination of measurements from erupted teeth and from radiographs of unerupted teeth. The purpose of this study was to compare two mixed dentition prediction methods that do not require the use of periapical radiographs of the unerupted permanent teeth. The two methods compared were the Tanaka/Johnston and the Boston University Prediction approaches. Records on 33 male and 22 female subjects who were participants in the Iowa Longitudinal Growth Study were used in the present study. The findings indicated that on the average the Tanaka/Johnston approach slightly overestimated the tooth size of the unerupted teeth (mean = 1.1 +/- 0.9 mm). On the other hand, the Boston University approach slightly underestimated the tooth size of the unerupted teeth (mean = -0.1 +/- 1.2 mm). The findings further indicated that there were statistically significant correlations between the predicted and actual tooth size. In general the r values were higher for the Tanaka/Johnston method than with the Boston University approach. The error involved in the use of the predicted equations was expressed as the standard error of the estimate. The present findings indicated that the standard error of the estimate for Tanaka/Johnston prediction equations ranged between 0.67 and 0.92 mm and the corresponding values for the Boston University equations ranged between 0.92 and 1.02 mm. Depending on the stage of dental development, i.e., which deciduous and permanent teeth are present, the Tanaka/Johnston approach can be used when the four mandibular incisors have completely erupted, whereas the Boston University approach can be used when all the deciduous canines and first molars are still present.
混合牙列中牙弓长度与牙量不调的测定需要准确预测未萌出恒牙的近远中宽度。有三种方法可用于估计未萌出尖牙和前磨牙的近远中牙冠宽度：（1）测量已萌出牙齿；（2）测量X线片；（3）结合测量已萌出牙齿和未萌出牙齿的X线片。本研究的目的是比较两种不需要使用未萌出恒牙根尖片的混合牙列预测方法。所比较的两种方法是田中/约翰斯顿法和波士顿大学预测法。本研究使用了爱荷华纵向生长研究中33名男性和22名女性受试者的记录。结果表明，平均而言，田中/约翰斯顿法略微高估了未萌出牙齿的牙量（平均值 = 1.1 ± 0.9 mm）。另一方面，波士顿大学法略微低估了未萌出牙齿的牙量（平均值 = -0.1 ± 1.2 mm）。结果还表明，预测牙量与实际牙量之间存在统计学上的显著相关性。一般来说，田中/约翰斯顿法的r值高于波士顿大学法。使用预测方程所涉及的误差用估计标准误表示。目前的结果表明，田中/约翰斯顿预测方程的估计标准误在0.67至0.92 mm之间，波士顿大学方程的相应值在0.92至1.02 mm之间。根据牙齿发育阶段，即存在哪些乳牙和恒牙，当四颗下颌切牙完全萌出时可使用田中/约翰斯顿法，而当所有乳牙尖牙和第一磨牙仍存在时可使用波士顿大学法。
