Ezoddini Ardakani F, Zangouie Booshehri M, Behniafar B
Associate Professor, Department of Oral and Maxillofacial Radiology, Faculty of Dentistry, Shahid Sadoughi University of Medical Sciences, Yazd, Iran.
Iran J Radiol. 2011 Mar;8(1):15-21. Epub 2011 Mar 30.
BACKGROUND/OBJECTIVE: Panoramic and periapical radiographs are normally used in impacted third molar teeth surgeries. The aim of the present study was to evaluate and compare the distortion of the erupted third molar teeth on panoramic and periapical radiographs.
A total of 44 radiographs were obtained of 22 patients (age range, 18-24 years) referred to the faculty of dentistry for orthodontic treatment. A plaster cast was prepared and panoramic radiography was taken for all patients to plan the orthodontic treatment and periapical radiography was taken for investigation of tooth structure details. Therefore, a total of 66 views and samples were studied by two methods: 1) Measuring the angle between the longitudinal plane of the third molar and occlusal plane. 2) Measuring the angle between the longitudinal plane of second and third molar. Finally, 132 records were evaluated by one individual.
There was no significant statistical difference between the mean position of the third molar on panoramic, periapical radiographs and the casts. However, measurements of the third molars on periapical radiographs were slightly closer to the measurements of the casts compared to the panoramic radiographs.
Distortion does not have a specific effect on the diagnosis of the position of the third erupted molars by periapical or panoramic radiographs, though various studies have shown that these radiographs have an amount of distortion and periapical radiographical distortion is less than that in panoramic radiography.
背景/目的：全景片和根尖片通常用于阻生第三磨牙手术。本研究的目的是评估和比较全景片和根尖片上已萌出第三磨牙的变形情况。
共获取了22例（年龄范围18 - 24岁）转诊至牙科学院进行正畸治疗患者的44张X线片。制作石膏模型，为所有患者拍摄全景片以规划正畸治疗，并拍摄根尖片以研究牙齿结构细节。因此，通过两种方法对总共66个视图和样本进行了研究：1）测量第三磨牙纵轴与咬合平面之间的角度。2）测量第二磨牙和第三磨牙纵轴之间的角度。最后，由一人对132条记录进行评估。
第三磨牙在全景片、根尖片上的平均位置与石膏模型之间无显著统计学差异。然而，与全景片相比，根尖片上第三磨牙的测量值与石膏模型的测量值略为接近。
尽管各种研究表明这些X线片存在一定程度的变形且根尖片的变形小于全景片，但变形对通过根尖片或全景片诊断已萌出第三磨牙的位置并无特定影响。
