Lione Roberta, Kiliaridis Stavros, Noviello Andrea, Franchi Lorenzo, Antonarakis Gregory S, Cozza Paola
Department of Clinical Sciences and Translational Medicine, University of Rome "Tor Vergata", Rome, Italy; Department of Dentistry, Università Nostra Signora del Buon Consiglio, Tirana, Albania.
Department of Orthodontics, University of Geneva, Geneva, Switzerland.
Am J Orthod Dentofacial Orthop. 2017 Jun;151(6):1058-1064. doi: 10.1016/j.ajodo.2016.10.035.
The aim of this prospective study was to evaluate the effects of posterior bite-blocks on masseter muscles and on facial growth in prepubertal dolichofacial subjects.
The treatment group comprised 21 consecutive prepubertal dolichofacial patients treated with rapid maxillary expansion followed by mandibular removable bite-blocks. Lateral cephalograms and ultrasonographic scans of the masseter muscles were made before (T1) and after (T2) treatment with bite-blocks. The treatment group was compared with a control group of 21 subjects matched for sex, age, and skeletal vertical pattern. An independent samples t test was used to compare the T1 to T2 changes in ultrasonographic scan measurements between the treatment group and the control group, and the T1 to T2 cephalometric changes in the treatment group. Regression analysis was performed to investigate associations between masseter muscle thickness and cephalometric treatment outcomes.
Masseter muscle thickness showed a statistically significant decrease (-0.7 mm) in the treatment group compared with an increase (+0.6 mm) in the control group. A significant anterior rotation of the mandibular plane was observed in the treatment group as well as significant increases in overbite (1.8 mm) and total posterior facial height (1.5 mm). No significant associations were found between masseter muscle thickness and treatment outcomes apart from a tendency for overbite to increase more in subjects with thicker muscles.
Treatment with removable bite-blocks produced a decrease in masseter muscle thickness and a reduction in vertical facial dimensions due to upward and forward rotation of the mandible. No significant correlation was found between the pretreatment masseter muscle thickness and the T1 to T2 cephalometric changes in the treatment group.
本前瞻性研究的目的是评估后牙合垫对青春期前长面型受试者咬肌及面部生长的影响。
治疗组由21例连续的青春期前长面型患者组成，先行快速上颌扩弓，随后佩戴下颌可摘式牙合垫。在佩戴牙合垫治疗前（T1）和治疗后（T2）拍摄头颅侧位片并对咬肌进行超声扫描。将治疗组与21例性别、年龄和骨骼垂直型相匹配的对照组进行比较。采用独立样本t检验比较治疗组和对照组超声扫描测量值从T1到T2的变化，以及治疗组头颅测量值从T1到T2的变化。进行回归分析以研究咬肌厚度与头颅测量治疗结果之间的关联。
与对照组咬肌厚度增加（+0.6mm）相比，治疗组咬肌厚度有统计学意义的下降（-0.7mm）。治疗组观察到下颌平面显著向前旋转，同时覆盖（1.8mm）和面部后份总高度（1.5mm）显著增加。除了肌肉较厚的受试者覆盖增加趋势更大外，未发现咬肌厚度与治疗结果之间有显著关联。
佩戴可摘式牙合垫治疗导致咬肌厚度降低，以及由于下颌向上和向前旋转导致面部垂直维度减小。治疗组治疗前咬肌厚度与从T1到T2的头颅测量变化之间未发现显著相关性。
