上下颌唇挡对替牙晚期儿童牙合的影响

The effect of maxillary and mandibular lip bumper on teeth and dental arch in late mixed dentition

目的:研究上下颌唇挡同时应用对替牙晚期儿童牙牙合的影响。方法:选择替牙晚期上下牙列轻度或中度拥挤患儿12例,上下颌均采用唇挡治疗8个月,进行治疗前后X线头影测量分析和模型测量分析,并对治疗前后的测量值变化进行配对t检验。结果:唇挡治疗后,SNA、SNB分别增加1.02°和0.97°(P<0.05),上下切牙前移均是牙冠向近中倾斜,而根尖相对固定的控制性倾斜,旋转中心接近根尖。上下磨牙远中倾斜效果不同,上磨牙远中倾斜直立,旋转中心接近牙冠;下磨牙远中倾斜移动,旋转中心接近阻抗中心;上颌磨牙间牙弓宽度、牙弓周径分别增加4.12mm和5.09mm(P<0.01),下颌磨牙间牙弓宽度、牙弓周径分别增加4.07mm和6.86mm(P<0.01)。结论:在儿童生长发育高峰期,唇挡可有效地引起上下颌牙弓横向和纵向变化,减轻或解除上下牙弓拥挤。

PURPOSE： To study the effect of maxillary and mandibular lip bumper on tooth and dental arch in late mixed dentition. METHODS： Twelve subjects with mild or moderate crowding were selected. They were treated with maxillary and mandibular lip bumper for eight months. Analysis of cephalometrics and model measurements were done before and after treatment and paired t test were performed respectively for their changes. RESULTS： After treatment, SNA and SNB increased by 1.02°and 0.97° （P〈0.05）. Upper and lower incisor both had controlled tipping movement. The crown of incisor moved mesially and had root apex were fixed relatively. The center of rotation was close to root apex. The upper and lower molar moved differently. Upper molar was upright distally and the center of rotation was close to the crown. However, the lower molar tipped distally and the center of rotation was close to the center of resistance.The width between the first molars and length of maxillary dental arch increased by 4.12mm and 5.09mm （P〈0.01）. The width between the first molars and length of mandibular dental arch increased by 4.07mm and 6.86mm （P 〈0.01）. CONCLUSION： Clinical application of lip bumper could cause transverse and vertical changes in dental arch ,which help to decrease or remove crowding.