On the application of photogrammetry to the fitting of jawbone-anchored bridges.
Misfit between a jawbone-anchored bridge and the abutments in the patient's jaw may result in, for example, fixture fracture. To achieve improved alignment, the bridge base could be prepared in a numerically-controlled tooling machine using measured abutment coordinates as primary data. For each abutment, the measured values must comprise the coordinates of a reference surface as well as the spatial orientation of the fixture/abutment longitudinal axis. Stereophotogrammetry was assumed to be the measuring method of choice. To assess its potentials, a lower-jaw model with accurately positioned signals was stereophotographed and the films were measured in a stereocomparator. Model-space coordinates, computed from the image coordinates, were compared to the known signal coordinates. The root-mean-square error in position was determined to 0.03-0.08 mm, the maximum individual error amounting to 0.12 mm, whereas the r. m. s. error in axis direction was found to be 0.5-1.5 degrees with a maximum individual error of 1.8 degrees. These errors are of the same order as can be achieved by careful impression techniques. The method could be useful, but because of its complexity, stereophotogrammetry is not recommended as a standard procedure.
D003201:Computers; D000044:Dental Abutments; D003758:Dental Implantation, Endosseous; D003779:Denture Design / Q000295:instrumentation; D006801:Humans; D008334:Mandible / Q000033:anatomy & histology; D008953:Models, Anatomic; D010780:Photogrammetry / Q000295:instrumentation; D010781:Photography / Q000295:instrumentation; D013499:Surface Properties