DETECTION OF Bolton INDEX FOR ANGLE CLASS III MALOCCLUSION PATIENTS

Objective To study the influence of the upper and lower tooth size on the orthodontic diagnosis and therapy through detection of Bolton index in patients with Angle class Ⅲ malocclusion and analyze the differences of mesiodistal tooth size between maxillary and mandibular teeth. Methods The Bolton index was measured and analyzed in 100 pretreatment casts of Angle classⅢ patients(male 50,female 50) and compared with normal Bolton index. Results In Angle classⅢ patients,the mean anterior ratio was(79.70±2.73)% and the mean overall ratio was(92.21±2.3)%,both the ratios were bigger than the normal reference,the differences being significant(u=3.29,3.72;P0.05).Of the 100 patients,the normal anterior ratio and normal overall ratio within normal limits were 55% and 54%,respectively;the sex differences were not significant(P0.05).Conclusion Too big Bolton index is likely to be one of the reasons that cause Angle class Ⅲ malocclusion.Bolton analysis should be regarded as one evidence in the diagnosis and plan-making of orthodontic therapy.