Purpose: To establish a recording method for edentulous arch relations and to perform quantitative accuracy evaluation in vitro.
Materials and Methods: Edentulous maxilla and mandible models with complete dentures were mounted on an articulator simulating arch relations in protrusion (A), left and right laterotrusion (B and C, respectively), and small opening (D) positions, aided by a metal foil wax record. In the test group, a tracking system was used to record the 3D trajectories of targets from intercuspation to positions A, B, C, and D, and the average of these trajectories was used for rehabilitation of the digital arch relations of A, B, C, and D. In the control group, the six pairs of positioning cylinders were pasted on the axial model surfaces. The center points of the bottom surfaces of the cylinders in the A, B, C, and D positions were measured for rehabilitation of digital arch relations in the control group. With the maxilla as the common area, the arch relations in the test group were registered with the control group, the 3D deviations of the mandible were calculated, and displacements in the horizontal left/right, horizontal anterior/posterior, and vertical directions were analyzed.
Results: Three-dimensional deviations of the mandible in the A, B, C, and D positions were 131 ± 39 μm, 133 ± 44 μm, 120 ± 51 μm, and 112 ± 52 μm, respectively. The mean absolute values of displacement in the mandible were less than 200 μm.
Conclusion: By using the optical jaw-tracking system, the accuracy of arch-relation records as measured on an articulator was acceptable for clinical demand. Further investigations among patients are required to clinically verify the results of this study.
