The occlusal plane in the facial context: inter-operator repeatability of a new three-dimensional method

The repeatability of a non-invasive digital protocol proposed to evaluate the three-dimensional (3D) position of the occlusal plane in the face is assessed. Dental virtual models and soft tissue facial morphology of 20 adult subjects were digitally integrated using a 3D stereophotogrammetric imaging system. The digital 3D coordinates of facial and dental landmarks were obtained by two different operators. Camper's (facial) and occlusal (dental) planes were individuated, and their 3D relationships were measured. The repeatability of the protocol was investigated and showed no significant differences in repeated digitizations. The angle between occlusal and Camper's planes was smaller than 2° in the frontal and horizontal projections. In the sagittal projection, the angle was observed to be, on average, 4.9°. The determined occlusal plane pitch, roll and yaw values show good agreement with previously published data obtained by different protocols. The current non-invasive method was repeatable, without inter-operator differences and can facilitate assessment of healthy subjects. A method for imaging facial structures in 3D, without harmful X-rays, has been successfully demonstrated by researchers in Italy. By merging data from stereophotographic images of individual faces with laser scanning information from dental casts, Chiarella Sforza and colleagues at the Universita` degli Studi di Milano accurately determined the orientation of the occlusal plane—where the upper and lower teeth make contact. Two different operators repeated the process in 20 adult volunteers with errors generally less than 1 millimeter. This non-invasive type of imaging, although still technical and expensive, avoids the potential dangers of radiographic techniques such as X-rays and CT scanning. The technique could eventually prove useful for basic dental diagnoses and treatments, monitoring growth in children or even researching healthy volunteers to assess biological variability among populations.