正畸前磨牙拔牙模式对前磨牙区比率的影响

摘要

目的:比较正畸不拔牙和拔(44+44)、(55+55)、(45+44)、(54+54)不同模拟拔牙模式后上下颌前磨牙近远中宽度比率,探讨较为 合适的拔牙模式.方法:选取93例Bolton指数前牙比和全牙比都正常的12～16岁患者模型.将4种模拟拔牙模式分为4组,不拔牙模式作为对照组,分别计算不拔牙和4种模拟拔牙模式后上下前磨牙近远中宽度比率,进行方差分析并两两比较.结果:不拔牙与前磨牙不同模拟拔牙模式相比较,上下前磨牙比率差异有显著性(P＜0.01).经两两比较,拔(54+54)和(45+45)模式与不拔牙组的前磨牙比率差异无显著性(P＞0.05),而拔(44+44)和(55+55)模式与不拔牙组前磨牙比率差异有显著性(P＜0.01).结论:前牙比和全牙比正常的安氏不同错(牙)畸形进行拔牙矫治时,前磨牙的拔牙模式会对前磨牙近远中宽度的比率产生影响.(45+45)和(54+54)拔牙模式较为合适,更接近不拔牙的上下前磨牙比率.%Objective; To investigate the effects of different models of premolar extraction on the premolar ratio between low and upper jaws. Methods; 93 pretreatment dental casts of the patients aged 12 ～ 16 years with normal Bolton anterior ratio and overall ratiowere selected. No-extraction and extraction of 4/4/4/4,5/5/5/5,4/4/5/5 and 5/5/4/4 were designed for each cast respectively. Premolar ratiosbetween low and upper jaws of the cases were measured and compared between each pair of extraction models by F-test. Results;Compared with non-extraction, premolar ratio was found statistically different for the first premolar extraction and second premolar extraction ( P < 0.01). The removal of the four first premolars or second premolar extraction created the most severe tooth- size discrepancy , whereas the extraction of all four second premolars created less discrepancies and the smallest range in the tooth size discrepancies. The removal of upper first and lower second premolars, and upper second and lower first premolars created less discrepancies and the smallest range in the tooth size discrepancies. Conclusion; Different premolar extraction models may affect the premolar ratios in the teenagers with normal Bolton anterior ratio and overall ratios.