Abstract: Objective　To evaluate the value of three-dimensional surface reconstruction of spiral CT-shaded surface display (SSD) to examine the impacted teeth before orthodontic treatment.Methods　Three-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.Results　Three-dimensional surface reconstruction of spiral CT and SSD could clearly demonstrate the dental surface image including crown, root neck and root bifurcation in three-dimensionalway, labial or palatal location, erup- tion orientation and relationwith dentition.Conclusion　It is concluded that the three-dimensional surface reconstruction is an ac- curate and effective method to examine impacted teeth before orthodontic treatment.

Key words: three-dimensional reconstruction of spiral CT, shaded surface display, impacted teeth