Lien L C, Soh G
Dental Clinic, 333 Orchard Road #03-54, Mandarin Hotel Shopping Arcade, Singapore 238867.
Singapore Dent J. 2000 Dec;23(1 Suppl):68-71.
The orthopantomogram (OPG) provides as assessment of root length and characteristics before orthodontic tooth movement. This study determined the accuracy of the OPG in assessing tooth length. Investigators compared the radiographic and actual tooth lengths in permanent first premolars indicated for orthodontic extractions. Results showed that the mean lengths measured from OPG were consistently higher than the actual lengths by 22% (p < 0.001) for maxillary teeth and by 1% for mandibular teeth. This study found that there is elongation of root images in OPG.
全景曲面断层片（OPG）可在正畸牙齿移动前对牙根长度及特征进行评估。本研究确定了OPG在评估牙齿长度方面的准确性。研究人员比较了因正畸需要拔除的恒牙第一前磨牙的X线片测量长度与实际牙齿长度。结果显示，从上颌牙齿的OPG测量的平均长度始终比实际长度高22%（p < 0.001），而下颌牙齿高1%。本研究发现OPG中牙根影像存在伸长现象。
