Abstract:

Abstract:Objective To establish an equation between canine and other permanent teeth,and probe a new method to predict the sum of the mesiodistal diameters of unerupted permanent canines.Methods Samples consisted of 118 dental casts　were obtained from Chinese patients (50 males,68 females,respectively).Mesiodistal tooth diameters were measured by a vernier caliper.GAS was used to establish the equation between canine and other permanent teeth，and compared with stepwise regression analysis.Those were modelling samples that optimized equations coefficient(112 samples).Others were inspection samples(6 samples).Results The equation between canine and other permanent teeth was established.    MU=0.0511U1+0.2164U2+0.2780U4+0.0407U5+0.2853U6+0.8321①；ML=0.2998U1+0.1294U2+0.3912U4+0.0088U5+0.0791U6+0.9839②；FU=0.1419U1+0.1741U2+0.3258U4+0.0412U5+0.093U6+1.7355③； FL=0.2796U1+0.3750U2+0.2968U4+0.0268U5+0.0043U6+0.6030④  .Compared with stepwise regression analysis,the mean error of precision  by  GAS was less（P<0.05）.Comparing the practical predictional diameters between two methods,the absolute mean error of male was less by GAS.Conclusion The equation by GAS,which could predict diameters of unerupted canines,shows more accuracy than stepwise regression analysis.It is easy to use and valuable for orthodontic design proposal.

Key words: canine crown diameter;orthodontic;genetic algorithms;stepwise regression analysis