成年女性骨性Ⅱ类错[牙合]畸形患者腭平面倾斜度对上前牙内收正畸治疗效果的影响

Efficacy of palatal plane inclination on orthodontic treatment of anterior teeth retraction in adult female patients with skeletal classⅡmalocclusion

目的观察不同腭平面倾斜度的骨性Ⅱ类错[牙合]畸形成年女性患者切牙管与上颌中切牙牙根的位置、切牙管唇侧骨皮质厚度,探讨腭平面倾斜度对上前牙内收正畸治疗效果的影响。方法60例骨性Ⅱ类错[牙合]畸形成年女性患者均行口腔颌面锥形束CT扫描,测量腭平面倾斜度,计算腭平面与眼耳平面夹角度数,分为顺时针组30例(腭平面与眼耳平面夹角<—2.5°)和平行组30例(腭平面与眼耳平面夹角—2.5°~4.5°)。以腭平面为参考平面,应用软件建立与腭平面平行的鼻腭孔高度水平面(N水平面)、上颌中切牙牙根根尖高度水平面(R水平面)、切牙孔高度水平面(I水平面),测量矢状面影像上切牙管长度、N水平面切牙管唇侧牙槽骨板厚度(the thickness on the N plane,NT)、R水平面切牙管唇侧牙槽骨板厚度(the thickness on the R plane,RT)、I水平面切牙管唇侧牙槽骨板厚度(the thickness on the I plane,IT)及各水平面影像上切牙管宽度、切牙根尖间距、切牙与切牙管距离等参数。比较2组切牙管长度、NT、RT、IT及各水平面影像上切牙管宽度、切牙管与上颌中切牙牙根之间的位置关系。结果顺时针组NT[(10.68±2.12)mm]、RT[(8.55±1.59)mm]、IT[(8.64±1.39)mm]均大于平行组[(8.74±2.42)、(7.22±1.85)、(7.56±1.43)mm](t=3.32,P=0.002;t=3.00,P=0.004;t=2.97,P=0.004),切牙管长度、N水平面切牙管宽度、R水平面中切牙根尖间距、R水平面切牙管宽度、R水平面切牙管与右侧中切牙根尖距离、R水平面切牙管与左侧中切牙根尖最短距离、I水平面切牙管宽度、I水平面切牙管与右侧中切牙间最短距离、I水平面切牙管与左侧中切牙间最短距离与平行组比较差异均无统计学意义(P>0.05)。结论腭平面顺时针方向倾斜的成年女性骨性Ⅱ类错[牙合]畸形患者上切牙唇侧牙槽骨较厚,在正畸治疗中可较大程度内收上前牙;腭平面倾斜度较小者上切牙唇侧牙槽骨较薄,内收上前牙程度受限;测量骨性Ⅱ类错[牙合]畸形患者腭平面与眼耳平面角度,评估腭平面倾斜度可为制订正畸方案提供参考。

Objective To observe the positions of the incisor canal and the maxillary central incisor root,and the thickness of the buccal cortical bone of the incisor at different palatal plane inclinations in adult female patients with skeletal classⅡmalocclusion,and to investigate the influence of the palatal plane inclination on orthodontic treatment of anterior teeth retraction.Methods Sixty adult female patients with skeletal classⅡmalocclusion were included in the study.Cone-beam computed tomography(CBCT)was performed to measure the palatal plane inclination and calculate the angle between the palatal plane and the orbito-meatal plane.The patients were divided into clockwise group(30 patients,palatal plane inclination-2.5°)and parallel group(30 patients,palatal plane inclination-2.5°to 4.5°).Using the palatal plane as the reference plane,software was used to establish the N plane,R plane and I plane,which were the horizontal planes with the same height as the nasopalatine foramen,the root apex of the maxillary central incisor,and the incisive foramen,respectively.In the CBCT images,the length of the incisor canal,the thickness of the buccal cortical bone of the incisor canal on the N(NT),R(RT)and I planes(IT),the width of the incisor canal on each plane,the distance between the root apex of the maxillary central incisor,and the distance between incisor and incisor canal were measured.The length of incisor canal,the NT,the RT,the IT,the incisor canal on different planes,and the positional relationship between the incisor canal and the root of the maxillary central incisor were compared between two groups.Results The NT,RT and IT were greater in clockwise group[(10.68±2.12),(8.55±1.59),(8.64±1.39)mm]than those in parallel group[(8.74±2.42),(7.22±1.85),(7.56±1.43)mm](t=3.32,P=0.002;t=3.00,P=0.004;t=2.97,P=0.004),and there were no significant differences in the length of the incisor canal,the width of the incisor canal on the N and I planes,the distance between the root apex of the maxillary central incisor and the incisor canal on the R plane,the width of the incisor canal on the R plane,the shortest distance between the incisor canal and the root apex of the right and left central incisors on the R plane,and the shortest distance between the incisor canal and the right and left central incisors on the I plane between two groups(P>0.05).Conclusions In adult female patients with skeletal classⅡmalocclusion whose palatal plane inclination is clockwise,the buccal cortical bone of the maxillary central incisor is thicker,which can facilitate the retraction of anterior teeth during orthodontic treatment.In contrast,patients with less palatal plane inclination have thinner buccal cortical bone of the maxillary central incisor,which may limit the degree of anterior teeth retraction.The measurement of the angle between the palatal plane and the orbito-meatal plane in patients with skeletal classⅡmalocclusion can provide a reference for developing orthodontic treatment plans.