Reference-based digital concept to restore partially edentulous patients following an immediate loading protocol: a pilot study

PURPOSE:
To describe the use of a computer-aided three-dimensional planning protocol in combination with previously placed reference elements and computer-aided design/computer-assisted manufacture (CAD/CAM) technology to restore the partially edentulous patient.

MATERIALS AND METHODS:
Mini-implants and/or reference brackets were inserted or positioned in specified locations in a test cast and in two patients prior to imaging to act as definitive fiducial markers. This served as a fixed base to better define a setup for the fabrication of a surgical template used during computed tomographic imaging. A simulated partially edentulous maxilla was used for the study, and two partially edentulous patients participated. With the CT images, a CAD/CAM superstructure was created prior to surgery and inserted immediately after surgery. Fit of the prosthesis was assessed using three-dimensional tension measurements with strain gauges.

RESULTS:
Mean misfit for all implants in the x-, y-, and z-axes was 26.6, 24.8, and 10.4 μm, respectively. The total misfit calculated according to the Pythagorean theorem was 42.6 μm.

CONCLUSIONS:
Based upon this pilot study in two patients and an in vitro analysis, it appears that the use of reproducible fiducial markers consisting of mini-implants and reference brackets results in the fabrication of an acceptably accurately fitting definitive prosthesis prior to implant placement.