[Prediction of the mesiodistal size of unerupted canines and premolars in an Iranian population in Shiraz in comparison to Moyers' table]

ABSTRACT

The determination of the tooth size-arch size relationship [space analysis] is an important factor for diagnosis and treatment planning in the mixed dentition. It is essential to use this analysis before eruption of the canines, first and second premolars. This study produced linear regression equations for an Iranian population. Study models of 276 subjects [138 males and 138 females] were selected from pretreatment patients' records of Orthodontic Department of Dental School and private offices in Shiraz. The greatest mesiodistal diameters of all teeth on each model were obtained except the second and third molar by digital caliper with 0.01mm accuracy. Finally, regression equations [Y=a+bx] were formulated to be used clinically for the estimation of mesiodistal width of permanent unerupted canines and premolars. SPSS software and Wilcoxon Signed Ranks test were used to analyze the date. The coefficients of determination [r[2]] of the regressions ranged between 0.17 and 0.47 and were higher for females than males, and also mandible than maxilla. It found significant difference between the prediction of this study and Moyers' prediction. The equations derived in this study were Y=11.71+0.43x and Y=8.22+0.57x for maxilla and mandible respectively. At the other hand, the 85% level was a more accurate determination than the commonly used 75% confidence level likewise. Moyers' prediction tables were found to under-estimate tooth size summation compared with the present investigation