Shokri Abbas, Mahmoudzadeh Majid, Baharvand Maryam, Mortazavi Hamed, Faradmal Javad, Khajeh Samira, Yousefi Faezeh, Noruzi-Gangachin Maruf
Department of Oral and Maxillofacial Radiology, Dental School, Hamadan University of Medical Sciences, Hamadan, Iran.
Department of Orthodontics, Dental School, Hamadan University of Medical Sciences, Hamadan, Iran.
Imaging Sci Dent. 2014 Mar;44(1):61-5. doi: 10.5624/isd.2014.44.1.61. Epub 2014 Mar 19.
This study was performed to evaluate the position of impacted mandibular third molars in different skeletal facial types among a group of Iranian patients.
A total of 400 mandibular third molars in 200 subjects with different types of facial growth were radiographically investigated for their positions according to their types of facial growth on the basis of the β angle. The subjects were divided into three groups (class I, II, and III) according to ANB angle, representing the anteroposterior relationship of the maxilla to the mandible. Meanwhile, the subjects were also divided into three groups (long, normal, and short face) according to the angle between the stella-nasion and mandibular plane (SNGoGn angle). ANOVA was used for statistical analysis.
The mean β angle showed no significant difference among class I, II, and III malocclusions (df=2, F=0.669, p=0.513). The same results were also found in short, normal, and long faces (df=1.842, F=2, p=0.160). The mesioangular position was the most frequent one in almost all of the facial growth patterns. Distoangular and horizontal positions of impaction were not found in the subjects with class III and normal faces. In the long facial growth pattern, the frequency of vertical and distoangular positions were not different.
In almost all of the skeletal facial types, the mesioangular impaction of the mandibular third molar was the most prevalent position, followed by the horizontal position. In addition, β angle showed no significant difference in different types of facial growth.
本研究旨在评估一组伊朗患者中不同骨骼面型下下颌阻生第三磨牙的位置。
根据β角，对200例具有不同面部生长类型的受试者的400颗下颌第三磨牙进行影像学检查，以确定其根据面部生长类型的位置。根据代表上颌与下颌前后关系的ANB角，将受试者分为三组（I类、II类和III类）。同时，根据蝶鞍点-鼻根点与下颌平面之间的角度（SNGoGn角），将受试者也分为三组（长面、正常面和短面）。采用方差分析进行统计学分析。
I类、II类和III类错牙合之间的平均β角无显著差异（自由度=2，F=0.669，p=0.513）。在短面、正常面和长面中也得到了相同的结果（自由度=1.842，F=2，p=0.160）。近中阻生位置在几乎所有面部生长模式中最为常见。III类和正常面的受试者未发现远中阻生和水平阻生位置。在长面部生长模式中，垂直阻生和远中阻生位置的频率无差异。
在几乎所有骨骼面型中，下颌第三磨牙近中阻生是最常见的位置，其次是水平阻生。此外，β角在不同类型的面部生长中无显著差异。
