鼠牙正畸移动中牙周膜功能状态与牙根吸收的关系

Relation of root resorption to various periodontal state in experimental tooth movement

目的:探讨鼠牙正畸移动中牙周膜功能状态与牙根吸收的关系.方法:选择33 只6～8 周龄体质量(250±20) g的SD大鼠,随机分为正常对照组(C组,11 只)和实验组(22 只).通过拔除实验组大鼠右下颌所有磨牙,使上颌左、右第一磨牙咬合力改变,3 周后分别形成牙周膜代偿性机能亢进模型和牙周膜废用性萎缩模型,据此实验组又分为萎缩组与亢进组(A、B组,各11 只).在各组大鼠上颌切牙和第一磨牙间放置5 mm镍钛螺簧,初始力值0.59 N(60 g),近中移动磨牙.14 d后处死动物,拍摄X线片测定各组牙齿移动距离,并通过抗酒石酸酸性磷酸酶染色测定牙根吸收情况.结果:牙周膜废用性萎缩组牙根吸收程度[(44.064±13.531) μm]明显大于B、C 2 组[(20.648±2.491 μm),(28.045±5.683) μm,P<0.01],且牙移动距离B组与A、C 2 组也有显著性差异(P<0.01).结论:正畸牙移动中,牙周膜废用性萎缩的无咬合接触牙较咬合力代偿性增强或正常咬合接触牙更易发生牙根吸收.

Objective： To determine the effect of hyper-or hypnfunctional periodontium on tooth movement and on the incidence and extent of root resorption induced hy orthodontic treatment in rats. Methods：33 six-week-old rats （250 ± 20 ）g were divided into normal group（ n = 11 ） and experimental group（ n = 22 ）. A rat model of different periodontal state was established by extracting the right mandibular molars in experimental group, so that after 3 weeks the right maxillary first molars were induced into occlusal hypofunction, and the left maxillary first molars into occlusal hyperfunction as the biting force changed. Accordingly, the experimental group was redivided into hypofunctional group （ n = 11 ） and hyperfunctional group（ n = 11 ）. Orthodontic tooth movement was performed in the three groups by means of a 0.59 N-force closed -coil spring ligated to the upper first molars and incisors for 14 flays, after which the animals were sacrificed. Orthodontic tooth movement （ OTM ） was determined by measnring the space created between the maxillary first and second molars on tracings of the roentgenograms. The active root-resorption lacunae from histological sections, identified by tartrate-resistant acid phosphatase （TRAP） , were measured in terms of depth. Results： The amount（μLm） of root resorption was significantly greater in the tceth with hypofunctional periodontium （44. 064 ± 13.531 ） than that in those with normal （ 28. 045 ± 5. 683 ） or hyperfunctional periodontium （ 20. 648 ± 2.491 ）（P 〈 0. 01 ）. OTM （mm） of the teeth with hypofunctional, hyperfunctional and normal periodontium was 0.6313 ± 0. 141 6,0. 2650 ± 0. 106 6 and 0.6788 ± 0.0901 respectively （ P 〈 0.05 ）. Conclusions ： Non-occluding teeth with hypofunctional periodontium have a higher risk of orthodontically induced root resorption than normally oceluding or over-occluding teeth.