Rapid maxillary expansion in mouth breathers: a short-term skeletal and soft-tissue effect on the nose

Abstract Introduction Rapid maxillary expansion can change the form and function of the nose. The skeletal and soft tissue changes can influence the esthetics and the stability of the results obtained by the procedure. Objective The aim of this retrospective study was to evaluate the short-term effects of rapid maxillary expansion on the skeletal and soft tissue structures of the nose, in mouth-breathing patients, using a reliable and reproducible, but simple methodology, with the aid of computed tomography. Methods A total of 55 mouth-breathing patients with maxillary hypoplasia were assessed and were divided into an experimental group treated with rapid maxillary expansion(39 patients, 23 of which were male and 16 female, with an average age of 9.7 years and a standard deviation of 2.28, ranging from 6.5 to 14.7 years) and a control group (16 patients, 9 of which were male and 7 female, with an average age of 8.8 years, standard deviation of 2.17, ranging from 5.11 to 13.7 years). The patients of the experimental group were submitted to multislice computed tomography examinations at two different points in time: (T1) pre-rapid maxillary expansion and (T2) three months after the procedure. The control group underwent to the same exams at the same intervals of time. Four skeletal and soft tissue variables were assessed, comparing the results of T1 and T2. Results There was in the experimental group a significant increases in all the skeletal and soft tissue variables (p < 0.05) but no significant alteration was found in the control group. When comparing the experimental group and the control group, the most important change occurred in the width of the pyriform aperture (p < 0.001). Conclusion Rapid maxillary expansion is capable of altering the shape and function of the nose, promoting alterations in skeletal and soft tissue structures. This kind of study may, in the future, permit the proper planning of esthetic procedures at the tip and base of the nose and also the performance of objective measurements in early or late surgical outcomes.

## 摘要
快速上颌扩弓（rapid maxillary expansion, RME）可改变鼻部的形态与功能。其引发的骨骼及软组织变化，会影响该术式治疗效果的美观性与稳定性。
本回顾性研究旨在采用可靠、可重复且简便易行的方法，借助计算机断层扫描（computed tomography, CT）技术，评估口呼吸患者接受快速上颌扩弓后，鼻部骨骼与软组织结构的短期变化情况。
### 方法
本研究共纳入55例伴上颌发育不全的口呼吸患者，按分组分为实验组与对照组：实验组共39例，其中男23例、女16例，平均年龄9.7岁，标准差2.28，年龄范围6.5~14.7岁；对照组共16例，其中男9例、女7例，平均年龄8.8岁，标准差2.17，年龄范围5.11~13.7岁。实验组患者分别于快速上颌扩弓前（T1）及术后3个月（T2）两个时间点接受多层CT检查；对照组患者于相同时间间隔接受同等检查。本研究评估了4项骨骼及软组织变量，对比T1与T2的检测结果。
### 结果
实验组所有骨骼及软组织变量均出现显著升高（p<0.05），而对照组未观察到显著变化。对比两组患者数据后发现，变化最为显著的指标为梨状孔宽度（p<0.001）。
### 结论
快速上颌扩弓可改变鼻部形态与功能，诱导骨骼及软组织结构发生改变。此类研究未来可用于规划鼻尖与鼻底的美学手术方案，同时实现对早期或晚期手术效果的客观量化评估。