Proposed regression equations for prediction of the size of unerupted permanent canines and premolars in Yemeni sample

OBJECTIVE: The aim was to formulate a prediction regression equation for Yemeni and to compare it with Moyer's method for the prediction of the size of the un-erupted permanent canines and premolars. SUBJECTS AND METHODS: Measurements of mesio-distal width of four permanent mandibular incisors, as well as canines and premolars in both arches were obtained from a sample of 400 school children aged 12-14 years old (13.80 ± 0.42 standard deviation) using electronic digital calliper. The data were subjected to statistical and linear regression analysis and then compared with Moyer's prediction tables. RESULTS: The result showed that the mean mesio-distal tooth widths of the canines and premolars in the maxillary arch were significantly larger in boys than girls (P < 0.001), while, in the mandibular arch, only lateral incisors and canines were also significantly larger in boys than in girls (P < 0.001). Regression equations for the maxillary arch (boys, Y = 13.55 + 0.29X; girls, Y = 14.04 + 0.25X) and the mandibular arch (boys, Y = 9.97 + 0.40X; girls, Y = 9.56 + 0.41X) were formulated and used to develop new probability tables following the Moyer's method. Significant differences (P < 0.05) were found between the present study predicted widths and the Moyer's tables in almost all percentile levels, including the recommended 50% and 75% levels. CONCLUSIONS: The Moyer's probability tables significantly overestimate the mesio-distal widths of the un-erupted permanent canine and premolars of Yemeni in almost all percentile levels, including the commonly used 50% and 75% levels. Therefore, it was suggested with caution that the proposed prediction regression equations and tables developed in the present study could be considered as an alternative and more precise method for mixed dentition space analysis in Yemeni.