Prediction Of Anterior Crossbite In Mixed Dentition After The Treatment In Deciduous Dentition For Class Ⅲ Malocclusion

Objective:By studying the morphological characteristics of jaw bones and permanent tooth germ about children in deciduous dentition for class III malocclusion to those of children after the treatment in mixed dentition, Discuss the predictor of anterior crossbite in mixed dentition after the treatment in deciduous dentition for class Ⅲ malocclusion.Materials and Methods:Cephalometric measurements of27children diagnosed with Class Ⅲ malocclusion Before and after treatment. If anterior crossbite in mixed dentition, defined as the crossbite group (8cases); normal occlusion in mixed dentition, is defined as the normal group (19cases). Student’s t-tests were performed to assess differences between the crossbite group and normal group with SPSS16.0. The statistical significance was set at P<0.05.Results:After the treatment in deciduous dentition for class Ⅲ malocclusion,the incidence of anterior crossbite in mixed dentition was8.79%.The results showed that,in T1-T2and T3-T4,statistically significant differences were observed in the Measurement of SN、SAr、NA、CoA、NS-PNS、A’-ANS、 A’-PNS、AA’、CoGn、GoGn、CoGo、Ui/SN、Li/MP、∠SNG、∠SNF(P<0.01); but BMe/MP、∠Id-B-Pog、Ui/Li were significantly decreased (P<0.01).In T1-T2,∠SNA、∠ANB、Y-axis、Wits、Convexity、BC’、C’C" and BMe were significantly increased (P<0.01),∠ANS-A-Pr were significantly decreased (P<0.01); but in T3-T4, these measuring project was no significant difference. In T1-T3, Normal group of AA’ length is significantly greater than the crossbite group (P<0.05); the BC ’and BMe length is significantly smaller than the crossbite group (P<0.05). In T2-T4, Normal group of∠ANB、Wits、Convexity、Ui/SN、∠SNG,significantly greater than crossbite group (P<0.05); Normal group of∠ANS-A-Pr significantly less than crossbite group (P<0.05).Conclusions:After early interceptive treatment in deciduous dentition for class III malocclusion, the incidence of anterior crossbite in mixed dentition is low. The length of AA’、BC’and BMe can serve as the predictor of anterior crossbite in mixed dentition after the treatment in deciduous dentition for class III malocclusion.