Influence of Different Fabrications on Fitting Accuracy of Metal Copings

Objectives: The purpose of the present study was to evaluate the marginal and internal gaps of cobalt-chromium (Co-Cr) copings fabricated by different techniques, including casting, selective laser melting (SLM) and computer-aided machined (CAM).
Methods: Thirty standardized rock stone-tooth replicas of a maxillary first premolar were produced for coping placement and divided into 3 groups (n=10 each) according to the different fabrications. Scanning of the replicas and coping designing was performed using the exocad^® Dental CAD system. Ten copings were milled from composite resin blocks and casted and fabricated by lost-wax casting. The other 20 copings were produced using the CAM and the SLM methods; 10 samples were made in each group. The marginal and internal gaps were measured by replica techniques.
Results: In all measured areas, the gap of the metal copings produced by the SLM was larger than that of the metal copings produced using the casting and CAM. Statistically significant differences were found among groups.
Conclusions: The marginal and internal gaps of metal copings produced by different fabrication techniques have a significant effect on marginal and internal fits of the resulting restorations.