[Comparison of two different methods of rapid expansion combined with maxillary protraction in the treatment of skeletal class Ⅲ malocclusion].
To compare the effect of bone-anchored versus tooth-borne rapid palatal expansion (RPE) combined with maxillary protraction in the treatment of skeletal class Ⅲ patients with maxillary hypoplasia. Twenty-six skeletal class Ⅲ patients with maxillary hypoplasia in the late mixed or early permanent dentition were selected. All the patients underwent RPE combined with maxillary protraction in the Department of Orthodontics, Nanjing Stomatological Hospital, Medical School of Nanjing University from August 2020 to June 2022. The patients were divided into 2 groups. Thirteen patients were enrolled in the bone-anchored RPE group [4 males and 9 females, aged (10.2±1.7) years] and the others were in the tooth-borne RPE group [5 males and 8 females, aged (10.1±1.0) years]. Ten sagittal linear indices [Y-Is distance (the distance from the incisor edge of the maxillary incisor to the vertical reference axis), Y-Ms distance (the distance from the mesial contact point of the maxillary first molar to the vertical reference axis), the relative distance between the maxillary and mandibular molars, overjet, etc.], 6 vertical linear indices [PP-Ms distance (the distance changes from Ms to the palatal plane), etc.] and 8 angle indices [SN-MP angle (the upper external angle of the intersection of the sella-nasion plane and the mandibular plane), U1-SN angle (the lower internal angle of the intersection of the long axis of the maxillary central incisor and the sella-nasion plane), etc.] were measured on the cephalometric radiographs before and after the treatment. Six coronal indicators (the inclination of the left and right first maxillary molar, etc.) were measured on cone-beam CT images before and after the treatment. The proportion of skeletal and dental factors in the changes of overjet were calculated. The differences of the index changes between groups were compared. After the treatment, the anterior crossbite were corrected in both groups, and classⅠor classⅡ molar relationship were attained. In bone-anchored group, the changes of Y-Is distance, Y-Ms distance and maxillary and mandibular molar relative distance were (3.23±0.70), (1.25±0.34) and (2.54±0.59) mm, respectively, significantly less than those in the tooth-borned group in which the corresponding changes were (4.96±0.97) mm (-5.92, 0.001), (3.12±0.83) mm (-7.53, 0.001) and (4.92±1.35) mm (-5.85, 0.05), respectively. The change of overjet in the bone-anchored group was (4.45±1.25) mm, significantly less than that in the tooth-borned group (6.14±1.29) mm (-3.38, 0.05). Skeletal and dental factors accounted for 80% and 20% of the overjet changes in the bone-anchored group, respectively. While in the tooth-borned group, skeletal and dental factors accounted for 62% and 38% of the overjet changes, respectively. The PP-Ms distance change in the bone-anchored group [(-1.62±0.25) mm] was significantly less than that in the tooth-borned group [(2.13±0.86) mm] (-15.15, 0.001). The changes of SN-MP and U1-SN in the bone-anchored group were -0.95°±0.55° and 1.28°±1.30°, respectively, significantly less than those corresponding indices in the tooth-borned group (1.92°±0.95°, -9.43, 0.001; 7.78°±1.94°, -10.04, 0.001). In the bone-anchored group, the inclination changes of maxillary bilateral first molars in the left and right sides were 1.50°±0.17° and 1.54°±0.19°, significantly less than the corresponding indices in the tooth-borned group (2.26°±0.37°, 6.47, 0.001; 2.25°±0.35°, 6.81, 0.001). The bone-anchored RPE with maxillary protraction could reduce the adverse tooth compensation effect, including the protrusion of maxillary anterior incisors, the increase of overjet and mandibular plane angle, and the mesial movement, extrusion and buccal inclination of maxillary molars.
比较骨支抗方式和牙支持方式快速扩弓联合前方牵引治疗上颌发育不足的骨性Ⅲ类错(牙合)的疗效差异。 回顾性选取2020年8月至2022年6月于南京大学医学院附属口腔医院·南京市口腔医院正畸科进行快速扩弓联合前方牵引治疗的处于替牙列中晚期或恒牙列早期的骨性Ⅲ类错(牙合)伴上颌发育不足的患者26例。患者分为2组（每组13例）：骨支抗方式组使用骨支抗方式快速扩弓联合前方牵引装置进行矫治，其中男性4例，女性9例，年龄（10.2±1.7）岁；牙支持方式组使用牙支持方式快速扩弓联合前方牵引装置进行矫治，其中男性5例，女性8例，年龄（10.1±1.0）岁。于矫治前后头颅侧位X线片上测量矢状向线性指标［Y-Is距和Y-Ms距（分别为上切牙切缘点、上颌第一恒磨牙近中接触点至垂直参考轴的距离）、上下颌磨牙相对距离、前牙覆盖等］10项、垂直向线性指标［PP-Ms距（上颌第一恒磨牙近中接触点至腭平面的距离）等］6项和角度指标［SN-MP角（前颅底平面与下颌平面相交的上外角）、U1-SN角（上中切牙长轴与前颅底平面相交的下内角）等］8项，于矫治前后锥形束CT上测量冠状向指标（上颌左侧和右侧第一磨牙倾斜度等）6项；计算矫治前后前牙覆盖变化量中骨性效应和牙性效应占比。比较各指标矫治前后变化量的组间差异。 矫治后两组前牙反(牙合)均解除，磨牙建立中性或远中关系。骨支抗方式组Y-Is距、Y-Ms距、上下颌磨牙相对距离的矫治前后变化量［分别为（3.23±0.70）、（1.25±0.34）和（2.54±0.59）mm］均显著小于牙支持方式组［分别为（4.96±0.97）、（3.12±0.83）和（4.92±1.35）mm］（-5.92，0.001；-7.53，0.001；-5.85，0.05）。骨支抗方式组前牙覆盖矫治前后变化量［（4.45±1.25）mm］显著小于牙支持方式组［（6.14±1.29）mm］（-3.38，0.05）；骨支抗方式组前牙覆盖矫治前后变化量中骨性效应占80%，牙性效应占20%；牙支持方式组前牙覆盖矫治前后变化量中骨性效应占62%，牙性效应占38%。骨支抗方式组PP-Ms距矫治前后变化量［（-1.62±0.25）mm］显著小于牙支持方式组［（2.13±0.86）mm］（-15.15，0.001）。骨支抗方式组SN-MP角、U1-SN角矫治前后变化量（分别为-0.95°±0.55°、1.28°±1.30°）显著小于牙支持方式组（1.92°±0.95°、7.78°±1.94°）（-9.43，0.001；-10.04，0.001）。骨支抗方式组上颌左侧和右侧第一磨牙倾斜度矫治前后变化量（分别为1.50°±0.17°、1.54°±0.19°）均显著小于牙支持方式组（分别为2.26°±0.37°、2.25°±0.35°）（6.47，0.001；6.81，0.001）。 骨支抗方式快速扩弓联合前方牵引能减少传统牙支持方式快速扩弓联合前方牵引时发生的上前牙唇倾、前牙覆盖增加、磨牙前移伸长颊倾以及下颌平面角增大等不利的牙齿代偿效应。.