前磨牙拔除模式对不同错(牙合)畸形Bolton指数全牙比的影响

摘要

目的 探讨前磨牙拔除模式对不同错(牙合)畸形Bolton指数全牙比的影响.方法 选取180副牙性与骨性错(牙合)类型一致的患者模型,Ⅰ、Ⅱ、Ⅲ类每组60例,计算各组拔牙前和采用4种前磨牙拔除模式(4/4 4/4)、(5/5 5/5)、(4/5 4/5)、(5/4 5/4)拔牙后的Bolton指数全牙比,以87％～89％为拔牙后Bolton指数全牙比参考值,对各组4种拔牙模式下Bolton指数全牙比的异常率进行卡方检验.结果 3组完整牙列Bolton指数全牙比差异有统计学意义(P=0.000)；Ⅰ、Ⅱ类组不同模式拔牙后Bolton指数全牙比异常率差异无统计学意义(P＞0.05),Ⅲ类组不同模式拔牙后异常率差异有统计学意义,拔除(5/4 5/4)的异常率小于拔除(4/5 4/5) (P=0.002).结论 从牙量协调的角度考虑,Ⅰ、Ⅱ类错(牙合)畸形采用4种拔牙模式均可,Ⅲ类错(牙合)畸形拔除(5/4 5/4)的模式优于(4/5 4/5).%Objective To investigate the effect of different premolar extraction models on postextraction Bolton overall ratio among different classes of malocclusion. Methods 180 patients with equivalent skeletal and dental classifications were chosen (Group I ,Ⅱ and Ⅲ, with 60 per group). According to dental casts, the Bolton overall ratios of each group were measured and compared before and after hypothetical premolar extraction (the four premolar extraction models were all first premolars, all second premolars, upper first and lower second premolars, and upper second and lower first premolars). Chi-square Test analysis was taken within each group in order to compare the abnormal rates of postextraction Bolton overall ratios. Results The differences of pretreatment Bolton overall ratios among three types of malocclusions were found statistically significant (P=0.000). For Class I and Class Ⅱ group, the four extraction models made no statistically significant differences in the abnormal rates of postextraction Bolton overall ratio (P>0.05). For Class Ⅲ group, the four extraction models made statistically different results that was the upper second and lower first premolar extraction model creating lower abnormal rates than the upper first and lower second premolar extraction model (P=0.002). Conclusion As far as the postextraction Bolton overall ratios are concerned, Class I and Ⅱ malocclusions can choose any of four premolar extraction models, while to Class HI malocclusions, the upper second and lower first premolar extraction model fits better than the upper first and lower second premolar extraction model.