Ho C T, Freer T J
Faculty of Dentistry, University of Queensland, Brisbane, Australia.
Aust Orthod J. 1994 Mar;13(2):64-70.
The standard tooth width ratio tables currently do not provide an overall indication of the final interdigitation of teeth. To provide a comprehensive analysis of inter-arch tooth width discrepancy, this study has developed a combination of cumulative percentage tooth width ratios and a method to visually determine the harmony between maxillary and mandibular tooth widths. Mesiodistal tooth widths from the first permanent molar to the corresponding first permanent molar were measured from 60 sets of pretreatment study models which were selected consecutively. Cumulative percentage ratios relating mandibular teeth to maxillary teeth were calculated utilising the mesiodistal tooth width measurements. The 13 mean cumulative percentage ratios developed in this study were plotted on graph paper showing plus and minus two standard deviations from the mean. These ratios provide a standard from which cumulative percentage ratios obtained from any new case may be compared graphically. Deviations from the mean cumulative percentage ratios are immediately recognised. No simple graphical method of assessment on the final interdigitation of anterior and posterior teeth has previously been devised. The graphical analysis of tooth width discrepancy is invaluable as an aid in localising any tooth width discrepancy and ensuring that incompatible maxillary-to-mandibular tooth widths are recognised prior to orthodontic treatment.
目前的标准牙宽比表并未全面显示牙齿最终的相互交错情况。为了全面分析牙弓间牙宽差异，本研究开发了累积百分比牙宽比以及一种直观确定上颌和下颌牙宽协调性的方法。从连续选取的60套治疗前研究模型中，测量从第一恒磨牙到相应第一恒磨牙的近远中牙宽。利用近远中牙宽测量值计算下颌牙与上颌牙的累积百分比比值。本研究得出的13个平均累积百分比比值绘制在坐标纸上，显示出相对于平均值的正负两个标准差。这些比值提供了一个标准，据此可以将从任何新病例中获得的累积百分比比值进行图形比较。与平均累积百分比比值的偏差能够立即被识别出来。此前尚未设计出用于评估前后牙最终相互交错情况的简单图形方法。牙宽差异的图形分析对于定位任何牙宽差异并确保在正畸治疗前识别出不相容的上颌与下颌牙宽非常有价值。
