Is it possible to improve the accuracy of implants inserted with a stereolithographic surgical guide by reducing the tolerance between mechanical components?

When using a stereolithographic surgical guide, a potentially clinically relevant error may be the mechanical error caused by the bur guide cylinder gap due to the presence of a rotational allowance of drills in the tubes. The aim of the present study was to determine if it is possible to reduce the total error by limiting the tolerance among the mechanical components and to evaluate its clinical incidence. Sixty implants were inserted in eight totally edentate subjects using the External Hex Safe((R)) system with mechanical components modified to minimize the tolerance. Pre- and postoperative computed tomography images were compared, and the angular deviation was calculated between the planned and the placed implants. The mean angular deviation was 2.02 degrees (range 0.81-3.48 degrees; standard deviation 0.87). The results of the present study show that by limiting the error that originates from mechanical components, the total error could be significantly reduced.