Transverse effects on the nasomaxillary complex one year after rapid maxillary expansion as the only intervention: A controlled study

The aim of this study was to assess by means of cone-beam computed tomography (CBCT) scans the transverse effects on the nasomaxillary complex in patients submitted to rapid maxillary expansion (RME) using Haas expander in comparison to untreated individuals. This prospective controlled clinical study assessed 30 subjects (18 boys and 12 girls) with mixed dentition and during pubertal growth. The treated group was submitted to RME with Haas expander, retention for six months and a six-month follow-up after removal. The control group matched the treated group in terms of age and sex distribution. CBCT scans were taken at treatment onset and one year after the expander was activated. Maxillary first molars (U6) width, right and left U6 angulation, maxillary alveolar width, maxillary basal width, palatal alveolar width, palatal base width, right and left alveolar angulation, palatal area, nasal base width, nasal cavity width and inferior nasal cavity area on the posterior, middle and anterior coronal slices were measured with Dolphin Imaging Software(r) 11.5, except for the first two variables which were performed only on the posterior slice. All transverse dimensions increased significantly (P < 0.05) in the treated group in comparison to the control, except for alveolar angulation and inferior nasal cavity area (P > 0.05). Results suggest that increase of molar, maxillary, palatal and nasal transverse dimensions was stable in comparison to the control group one year after treatment with RME.

本研究旨在通过锥形束计算机断层扫描（cone-beam computed tomography, CBCT），对比采用Haas扩弓器行上颌快速扩弓（rapid maxillary expansion, RME）的患者与未接受治疗的个体，评估其对上颌鼻复合体的横向影响。本前瞻性对照临床研究纳入30名处于青春发育期的混合牙列受试者，其中男性18名、女性12名。治疗组接受Haas扩弓器上颌快速扩弓治疗，术后保持6个月，并在扩弓器拆除后开展6个月随访。对照组在年龄与性别分布上与治疗组匹配。分别于治疗起始时及扩弓器激活后1年采集CBCT扫描影像。采用Dolphin Imaging软件11.5版测量下述指标：上颌第一磨牙（U6）宽度、左右侧U6倾斜度、上颌牙槽宽度、上颌基骨宽度、腭部牙槽宽度、腭基宽度、左右侧牙槽倾斜度、腭部面积、鼻底宽度、鼻腔宽度，以及冠状面后、中、前三层的鼻腔下区面积；其中前两项指标仅于后层冠状面完成测量。结果显示，治疗组除牙槽倾斜度与鼻腔下区面积外，其余所有横向测量指标均较对照组显著升高（P<0.05）。研究结果表明，采用RME治疗1年后，磨牙、上颌、腭部及鼻部的横向尺寸增加效果较对照组保持稳定。