Accuracy of a fixed value nasion relator in facebow design.

PURPOSE: This study examined whether a fixed value nasion relator accurately locates the orbitale in a patient population.

MATERIALS AND

METHODS

The mean value for the vertical distance between soft tissue nasion and orbitale was determined through the analysis of cephalometric radiographs of 114 adult patients. This value was then compared to a facebow design, which uses a fixed value of 25.4 mm.

RESULTS

In this study, the mean distance between the orbitale and nasion was found to be 26.8 mm. The values ranged from 15.9 to 39.4 mm with a standard deviation of 3.87 mm.

CONCLUSION

The difference between the calculated mean and the 25.4 mm fixed value was less than 2.0 mm and presumed to be clinically irrelevant; however, an accumulation of design errors combined with the variation within the patient population was asserted to be clinically relevant and makes the use of a fixed value nasion relator impractical.