Variation in mesiodistal root angulation of panoramic images generated from cone-beam computed tomography.

OBJECTIVE To compare the mesiodistal root angulation of panoramic images generated from traditional panoramic tomography or cone-beam computed tomography (CBCT). METHODS CBCT scans and panoramic radiographs of 20 patients were collected. The Invivo- Dental 5.0 was separately applied for maxillary or mandibular panoramic image generation. The generation method was assorted by two head positions, the Frankfort plane horizontal position (P1) and the occlusal plane horizontal position (P2), and three central plane settings (root apical plane, tooth centre plane and crown marginal plane). The amount of mesiodistal root angulation on panoramic images generated from CBCT (GPIs) deviated from that on the traditional panoramic images was calculated by paired sample test. The variation trends were explored with different head rotation and incisors' buccolingual root inclination. RESULTS By selecting the tooth centre plane, the GPIs were suggested to be generated by the Frankfort plane horizontal position for maxilla; while the occlusal plane horizontal position was advised for mandibular GPIs' generation. Moreover, the mesiodistal root angulations were demonstrated to regularly change along with variations of head rotation and the incisors' buccolingual root inclination. CONCLUSION Panoramic images can be generated from CBCT by the standard operating procedures with proper head position and central plane setting. But cautions should be taken during the generation, bearing the variability of mesiodistal root angulation in mind.