OBJECTIVETo evaluate the value of three-dimensional surface reconstruction of spiral CT-shaded surface display (SSD) to examine the impacted teeth before orthodontic treatment.

METHODSThree-dimensional surface reconstruction of spiral CT and shaded surface display (SSD) was applied to twenty patients whose impacted teeth couldn't be judged clearly through the panorama and occlusal films.

RESULTSThree-dimensional surface reconstruction of spiral CT and SSD could clearly demonstrate the dental surface image including crown, root neck and root bifurcation in three-dimensional way, labial or palatal location, eruption orientation and relation with dentition.

CONCLUSIONIt is concluded that the three-dimensional surface reconstruction is an accurate and effective method to examine impacted teeth before orthodontic treatment.