In vitro comparison of the maxillary occlusal plane orientation obtained with five facebow systems Presented at the Graduate Student Research Competition (placed first) at the Annual Meeting of the Pacific Coast Society for Prosthodontics, Laguna Beach, Calif, June 2014.

Abstract

Statement of problem The sagittal and coronal orientation of the maxillary occlusal plane plays an important role in the esthetic and functional outcome of dental prostheses. The accuracy of contemporary facebow transfer systems in transferring this orientation to semiadjustable articulators has not been quantified. Purpose The purpose of this in vitro investigation was to analyze the sagittal and coronal orientation of the occlusal plane with 5 different facebow transfer systems. Material and methods A phantom head containing a maxillary typodont (control) was oriented so that the Frankfort horizontal plane was horizontal. The angle between the occlusal plane of the maxillary arch of the phantom head and the Frankfort horizontal plane was measured along the sagittal and coronal planes with a digital protractor. Fifteen facebow records using each of 5 facebow transfer systems (test groups) were made on the phantom head containing the maxillary typodont. Diagnostic casts of the maxillary typodont were mounted on semi-adjustable arcon articulators from the facebow records. The same angles measured on the control were measured on the test groups. These angles were compared with the same angle measured on the maxillary arch of the phantom head (control). All measurements were made by 2 operators. Results Significant differences in the sagittal and coronal orientation of the occlusal plane were noted. Compared with the control, the Denar system had the least significant difference in the coronal orientation of the occlusal plane, while the Pana-Mount system had the least significant difference in the sagittal orientation of the occlusal plane. An intergroup comparison of the test groups showed significant differences among the groups. The Kois system showed the greatest difference in the coronal plane orientation, while the Denar system showed the greatest difference in the sagittal plane orientation. Conclusions None of the tested facebow systems exactly replicated the sagittal and coronal orientation of the maxillary occlusal plane. Significant differences in the sagittal and coronal orientation of the occlusal plane were observed between the test groups and the control. Intergroup comparisons revealed significant differences in the sagittal and coronal orientation of the occlusal plane.