Impact of Digital Manufacturing Techniques on the Accuracy of Single Unit Fixed Prostheses: A Clinical and Laboratory Study

Abstract

This clinical and laboratory study evaluated the impact of computer aided design and computer aided manufacturing (CAD/CAM) technologies on the accuracy of single unit fixed prostheses, specifically full crowns, in terms of marginal fit, proximal contact integrity, and occlusal accuracy, compared with the conventional lost wax casting technique. A randomized controlled trial was conducted involving 80 patients requiring single unit crowns. Participants were allocated equally into CAD/CAM (n=40) and conventional (n=40) groups. Marginal gap measurements were obtained from 1,280 measurement points using digital microscopy at 50× magnification. The CAD/CAM system demonstrated statistically significant superiority across multiple parameters. Marginal gaps were substantially reduced in the CAD/CAM group (54.3 ± 5.8 µm) compared with conventional techniques (78.6 ± 9.2 µm; p < 0.001). Digitally fabricated restorations exhibited higher consistency and predictability, with a 68% reduction in the need for clinical adjustments compared with conventional methods. Overall fit was rated as excellent in 60% of CAD/CAM crowns versus 40% of conventional crowns. Marginal adaptation was judged superior in 70% of CAD/CAM restorations, and occlusal accuracy was rated ideal in 80% of CAD/CAM crowns compared with 50% in the conventional group. CAD/CAM technology significantly enhances marginal adaptation and occlusal accuracy while reducing chairside time and clinical adjustments. However, conventional methods demonstrated superior proximal contact accuracy, suggesting that hybrid approaches or further technological refinement may optimize outcomes across all parameters.