Evaluation of a new radiographic technique: diagnostic accuracy for mandibular third molars

To compare the accuracy of Scanora with that of traditional panoramic and intra-oral radiography for the assessment of impacted mandibular third molars.

Two hundred and fifty-four patients referred for removal of impacted or partly erupted third molars were randomly allocated to one of two groups; 133 were examined by the Scanora system and 121 by a panoramic plus a series of three intra-oral radiographs. The radiographs were read by a trained oral radiologist and her diagnoses validated against the surgeons' findings at operation.

There was agreement about the state of tooth eruption in 71.4% of Scanora and 74.4% of conventional examinations and about tooth position in 77.2 and 69.7% respectively (P < 0.05). The number of roots was assessed more accurately by Scanora (82.7% agreement) than by conventional (71% agreement) examination (P < 0.05). There was agreement about the root morphology in 70.4% of Scanora and 62.4% of conventional examinations. In 12% of the patients, the roots were in very close contact with the canal determined by the surgeon. In approximately 50% of these cases, the close contact to the canal was found by radiography with no significant differences between the methods.

The Scanora method was more accurate when validated against the surgeons' findings for the position and number of roots of ectopic mandibular third molars while both methods were equally accurate in demonstrating the relation between the roots and the inferior alveolar nerve.