Objective To evaluate the relationship between dental arch width and the vertical facial pattern determined in skeletal classⅢuntreated patients.Methods A sample of 90 patients with untreated skeletal classⅢin permanent dentition were divided into three groups according to the values of the angle SN-MP and FH/MP(low,medium and high).Individual patients'dental casts and pre-treatment lateral cephalograms were collected.For each subject,dental arch width SN/MP angle and FH/MP angle were measured.Vari-ance and t-test were used for statistical analysis.Results The value of significance is set at P<0.05 among the three groups in the up-per and mandibular intercanine and interpremolares width:low angle >mediu angle>high angle.No statistically significant difference in upper and mandibular intermolar width among the three groups was found.Conclusions The results shows the association between the maxillary and mandibular intercanine and interpremolares width and the vertical facial pattern.As SN-MP angle and FH/MP angle in-crease,the arch form tends to be narrower.%目的 评估未经治疗的骨性Ⅲ类错(牙合)患者垂直骨面型与牙弓宽度的关系.方法 选择90例未经正畸治疗的骨性Ⅲ类错(牙合)畸形患者,恒牙期.根据SN/MP和FH/MP的角度分为三组(高角组、均角组、低角组).收集每位患者的石膏模型,头颅侧位片.测量每副模型上下牙弓的宽度,测量每张头颅侧位片的SN/MP和FH/MP值.采用方差分析和t检验进行统计学分析.结果 上下颌尖牙间宽度、第一前磨牙间宽度各组间的差异有统计学意义,为低角组>均角组>高角组;上下颌牙弓磨牙间的宽度各组间差异无统计学意义.结论 骨性Ⅲ类错(牙合)上下颌尖牙间宽度、第一前磨牙间宽度与垂直骨面型有关,随着下颌平面角的增大,牙弓趋于狭窄.
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