替牙期上颌埋伏中切牙正畸疗效的锥形束CT观察

Root and alveolar bone status of maxillary labial inverted impacted incisor in mixed dentition after orthodontic treatment

目的研究替牙期上颌唇侧倒置埋伏中切牙矫治后的牙根长度及牙槽骨状况，以期为上颌中切牙埋伏阻生的治疗和后继维护提供参考。方法对14例替牙期上颌唇侧倒置埋伏中切牙采用改良Nance弓联合固定正畸治疗。随访6～12个月时拍摄锥形束CT，用Simplantl3．0系统三维重建和多平面重建（muhi—planerreconstruction，MPR）方法定点，观察唇舌侧牙槽嵴顶形态，测量治疗后埋伏牙和对侧同名牙牙根长度、牙槽嵴顶至釉质牙骨质界（cemento—enameljunction，CEJ）的长度和牙根被牙槽骨包绕长度占总根长的比例，对埋伏牙和对侧同名牙各测量项目进行成组t检验比较。结果14例患牙唇、舌牙槽嵴顶骨质呈现近远中大致对称的U形。患牙唇、舌侧牙槽嵴顶至CEJ长度[分别为（2．47±1．35）和（1．47±0．84）mm]均较对侧同名牙[分别为（1．03±0．35）和（0．90±0．37）mm]长，差异有统计学意义（P〈0．05）；患牙和对侧同名牙牙根长度[分别为（9．82±2．82）和（10．28±1．38）mm]差异无统计学意义（P=0．59）；患牙牙根唇、舌侧被牙槽骨包绕长度占总根长的比例[分别为（72．83±17．16）％和（85．32±5．98）％]均比对侧同名牙[分别为（89．66±3．98）％和（90．84±4．61）％]小，差异有统计学意义（P〈0．05）。结论替牙期上颌唇侧倒置埋伏中切牙矫治后牙根有足够的长度。患牙唇、舌侧牙槽嵴骨质适应性增生不足，唇侧更明显，需后期植骨。

Objective To study the alveolar bone surrounding situation and the length of the root of the maxillary labial inverted impacted incisor in mixed dentition after orthodontic treatment. Methods Fourteen cases with maxillary labial inverted impacted incisor in mixed dentition were collected. Modified Nance arch and conventional appliance were used. Cone-bean CT（CBCT） was taken after the treatment. Simplantl3.0 three-dimensional reconstruction and multi-planer reconstruction （MPR） method were used to observe the labial and lingual alveolar bone crest morphology, besides, the labial and lingual length from the alveolar bone crest to cemento-enamel junction （CEJ） of the impacted incisor and the homonym tooth after treatment, along with their root length and their labial and lingual length ratio of the root surrounded by the alveolar bone to the total root length were measured. The idependent samples t-test were used to analyze the variable differences. Results The labial and lingual alveolar bone of fourteen cases crest of the diseased tooth after treatment presented general symmetry U shape from qualitative observation through the three- dimensional reconstruction. The labial and the lingual length of the diseased incisor from alveolar bone crest to CEJ[ （2. 47 ± 1.35） and （1.47 ±0. 84） mm] was significant increased than those of the homonym incisor[ （ 1.03 ± 0. 35 ） and （ 0. 90 ± 0. 37 ） mm ] （ P 〈 0. 05 ） ; the length of the diseased incisor＇s post- treatment root [ （ 9. 82 _± 2. 82 ） mm ] was no statistically significant decreased than that of the homonym incisor root[ （ 10. 28 ± 1.38） mm, P =0. 59] ; the labial and the lingual length ratio of the impacted tooth＇s root surrounded bv the alveolar bone to lhe total root length[ （72.83 ± 17. 16）% and （ 85.32 ±5.98 ）%] was statistically significant decrease Ihan those of Ilomonynl teeth [ （ 89. 66 ± 3.98 ） % and （ 90. 84 ± 4. 61 ）% ] （P 〈 0.05 ）. Conclusions The diseased tooth＇s root had gotlell enough lt.ngth after the treatment. The labial and lingual alveolar bone of Ihe maxillary labial inverted impacted incisor in mixed dentition can＇t offer sufficient adaptive hyperplasia after treatment, of whi,＇h labial alveolar bone is more apparent, prompting careful prolettion when they were used.