A comparison of facebow and dentofacial analyzer mountings

This investigation compared the accuracy and reliability of one arbitrary facebow (4000 FB Pana -Mount) to the recently introduced "Dento-Facial Analyzer" (4300 FB Kois) for locating and trasferring the hinge axis to articulator. A kinematically located transverse horizontal axis provided the reference.

Fourteen subjects, 9 female and 5 male, and 3 types of facebows were utilized in this study. One orientation record was made with each of 3 instruments to mount 1 pindexed maxillary cast 3 times for each subject on the same articulator. In order to measure the distance from articulator's hinge axis to first molar bilaterally; a small nail was inserted in the stone cast in the area of the first molar on both sides. A small indentation on the hinge axis of the articlator served as the second reference point. A 6-inch/150 mm digital caliper was used for measuring the distance between these points with an accuracy of 0.03 mm and resolution of 0.01 mm. Four repeat measurements were done on both sides of each mounted cast and averaged.

The arbitrary earbow recorded the hinge axis closer to the kinematic axis (within 4.18 mm on the right side and 3.57 mm on the left side) with smaller standard deviation compared to the Dento-Facial Analyzer (5.58 mm on the righ side and 5.72 mm on the left side).

The arbitrary facebow was found to be more accurate as compared to the Dento-Facial Analyzer for reliability and accuracy and may serve better when occlusal function is a primary concern.

The simplicity of the use of Dento-Facial Analyzer did not improve the accuracy of mounting the maxillary cast onto the articulator. As a result it should be used in the clinic cautiously.