Objective To investigate the clinical value of cone -beam computed tomography（CBCT） and nine partition method on alveolar bone for locating the relative orientation of the unerupted teeth. Methods 125 bone unerupted teeth of 99 cases were collected. The bone unerupted teeth zones were scaned by CBCT. The dental corona and root apex of these bone unerupted teeth were classified by the new nine partition method. Results In 125 bone unerupted teeth, 107 teeth located in maxilla, 18 teeth located in mandible. More frequent appearances（35.6%） in the alveolar bone were inner-middle and outer-superior. The representation of 125 bone unerupted teeth seen in surgery was the same with that of the CBCT before exodontia. The accurate rate of diagnosis was 100%. Conclusion CBCT is the most accurate and effective methods to determine the authentic orientation of the bone unerupted teeth. The nine partition method of alveolar bone has clinical value of accurate authentic orientation of the bone unerupted teeth in oral and maxillofacial surgery and orthodontics.
