推上颌磨牙向后导致第二磨牙锁的探讨

Probability of buccal crossbite of second molars related to molar distalization

目的探讨上颌第二恒磨牙萌出前推上颌恒磨牙向后导致上颌第二恒磨牙锁的可能性。方法研究组:推磨牙向后的患者16例;对照组:未经正畸治疗的患者130例。两组皆拍摄X线头颅侧位片。研究组分别测量推磨牙向后之前和第二磨牙建时的牙弓后段可用间隙和拥挤度,对照组测量治疗前的牙弓后段可用间隙和拥挤度。比较两组上颌第二磨牙发生锁的构成比、两组上颌第二磨牙发生锁和无锁者其牙弓后段拥挤度的差异、以及牙弓后段拥挤度与锁形成的相关性。结果研究组发生锁胎的比例大于对照组;研究组和对照组上颌第二磨牙发生锁者其牙弓后段拥挤度均大于无锁者;牙弓后段拥挤度与锁形成的相关性有统计学意义(P<0.01)。结论上颌第二恒磨牙萌出前推上颌恒磨牙向后可能导致上颌第二恒磨牙锁。

Objective To assess the probability of buccal cmssbite of maxillary second molar in or after the process of maxillary molar distalization before maxillary second molar eruption. Methods Patients were divided into 2 groups：molar distalization group（ 16 patients） and control groups （130 patients, without orthodontic treatment ）. Cephalometric were taken for two groups. Posterior crowding were measured before molar distalization and after occlusion created for distalization group, and were measured before treatment for control group. The proportion of buccal crossbite of second molar was compared between two groups. The differences of posterior crowding degree between the cases who had buccal crossbite of maxillary second molar and who without buccal crossbite were compared. The correlation between buccal crossbite of maxillary second molar and posterior crowding was analysed. Re.suits The proportion of buccal crossbite of second molar in distalization group was greater than in contrul group. The posterior crowding degree was greater in whom happened buccal crossbite than that without buecal crossbite. There was significant different between buccal crossbite of maxillary second molar and posterior crowding （P 〈0.01 ）. Conclusion Molar distalization before maxillary second molar eruption may cause buccal crossbite of maxillary second molars.