APPLICABILITY OF MIXED DENTITION PREDICTION EQUATIONS IN CONTEMPORARY POPULATION OF PASHTUNS

OBJECTIVE: To determine the accuracy of Tanaka and Johnston and Bherwani s prediction equations when applied to a sample of Pashtun population of Pakistan. METHODS: Odontometric data from casts of 180 subjects (90 males and 90 females, ages 13-19 years) of Pashtun origin was collected using digital callipers. Mesiodistal widths of mandibular incisors, mandibular and maxillary canines and premolars were measured. Data was analyzed using SPSS software version 20. RESULTS: Data was analysed for 90 male and 90 female subjects with a mean age of 15.7±1.7years and 15.4±1.5 years, respectively. Statistically significant right and left tooth size difference was found only for upper arch in males (mean 0.08, p=0.027). Statistically significant gender dimorphism was noted with males showing larger tooth sizes. Tanaka and Johnston equations significantly overestimated the sizes of canine and premolars segments for upper (mean difference=0.72±0.96, p=0.000) and lower (mean difference=0.75±0.94, p=0.000) arches when applied to ethnic Pashtun population. Customized regression equations represented by y=a+b(x) were derived for unerupted canine and premolars segments of Pashtun population. The values for coefficient of correlation (r) ranged from 0.59 to 0.73 and the coefficient of 2 determination (r^2) ranged from 0.36-0.52. CONCLUSION: Tanaka and Johnston equations developed for North th American population (at 75 percentile) should be used with caution for mixed dentition analyses in local Pashtun population as it overestimates tooth sizes in males and females. Regression equations developed in this study can be used for diagnostic planning in local Pashtun children.