Fox N A, Fletcher G A, Horner K
Department of Oral Health and Development, University Dental Hospital, Manchester.
Br Dent J. 1995;179(11-12):416-20. doi: 10.1038/sj.bdj.4808945.
Impacted maxillary canine teeth occur in about 2% of the population. Late detection of palatal canines may have treatment implications for the patient and medicolegal implications for the dental practitioner. Dental panoramic tomograms (DPT) are widely taken in practice. Image formation in dental panoramic tomography results in relative magnification of objects placed palatal to the image layer and relative diminution of objects buccal to it. This provides a possible means of bucco-palatal localisation of teeth. The aim of this study was assess the validity of DPTs in locating ectopic canines using the vertex occlusal view (VO) as the gold standard. One hundred pairs of radiographs showing 139 ectopic canines were examined. Using the DPT, it was possible to accurately predict the position of a palatally displaced crown in about 80% of cases. The DPT alone is not sufficient for canine localisation, but clinical evidence and suggestion of ectopic positioning on a DPT should warrant further radiographic investigation. Careful interpretation of a radiograph widely used in practice may lead to earlier detection of palatal canines.
上颌阻生尖牙在约2%的人群中出现。腭侧尖牙的延迟发现可能对患者的治疗产生影响，对牙科医生也有法医学方面的影响。牙科全景体层摄影（DPT）在临床实践中广泛应用。牙科全景体层摄影中的图像形成会导致位于图像层腭侧的物体相对放大，而位于其颊侧的物体相对缩小。这为牙齿的颊腭定位提供了一种可能的方法。本研究的目的是以顶点咬合视图（VO）作为金标准，评估DPT在定位异位尖牙方面的有效性。检查了100对显示139颗异位尖牙的X线片。使用DPT，在约80%的病例中能够准确预测腭侧移位牙冠的位置。仅靠DPT不足以进行尖牙定位，但临床证据以及DPT上异位定位的提示应促使进行进一步的影像学检查。对临床实践中广泛使用的X线片进行仔细解读可能会更早发现腭侧尖牙。
