Three-dimensional evaluation of the relationship between dental and basal arch forms in skeletal class Ⅱ malocclusions with different vertical facial types
ZHAO Shuang;MO Shui-xue;NAN Lan;ZHENG Yi;Department of Ortho-dontics,Affiliated Stomatological Hospital of Guangxi Medical University;
Objective: To investigate the differences and correlations between dental and basal arch forms in skeletal class Ⅱ malocclusions with different vertical facial types.Methods: Totally 51 cases of untreated skeletal class Ⅱ were selected and divided into 17 low angle,17 average angle and 17 high angle patients according to frankfort-mandibular plane( FMA) angle.Three dimensional reconstruction was performed by CBCT.The length and width of arch and base arch were measured respectively,and the differences and correlations between them were analyzed.Results: The molar segments width of the dental arch and base arch in the low angle group was greater than that of the other two groups( P0. 05),and the length of anterior and whole basal arch segment lengths of the high angle group was greater than that of the other two groups( P0. 05).The correlation coefficient of the canine segment were 0. 624,0. 613,and 0. 466( P0. 01) in the high angle,the mean angle and the low angle group,and the molar segments were 0. 742,0. 780,and 0. 858( P0. 01),respectively.The length of the anterior segment were 0. 751,0. 433,0. 598( P0. 01),and the length of the whole segment were 0. 839,0. 703,0. 680( P0. 01).Conclusion: Mandibular arches in the low angle group are more flat,while the high angle group is more narrow.