Adjustment of CAD–CAM crowns with and without a 3D‐printed model: Comparative study of marginal fit

PURPOSE: This study evaluated and compared the marginal fit of CAD-CAM zirconia crown copings with and without a 3D-printed control model. MATERIALS AND METHODS: This prospective in vitro trial involved 30 zirconia crown copings made from the same STL file. These were divided into two groups. Half of them had their own 3D-printed control model made from the same STL file (With-Printed-Model group), whereas the other half lacked any control model (No-Printed-Model group). Both groups underwent manual adjustments in a systematic way. Their marginal gaps were evaluated using a digital optical microscope from eight zones: buccal, mesiobuccal, mesial, mesiopalatal, palatal, distopalatal, distal, and distobuccal. RESULTS: The mean values with standard deviations for the With-Printed-Model and No-Printed-Model groups were 15.18 ± 14.49 and 12.46 ± 14.09 µm, respectively. All crown copings from both groups were below 75 µm. Statistical analysis showed a significant difference between the two groups. CONCLUSION: The No-Printed-Model group demonstrated superior marginal fit compared to the With-Printed-Model group. However, the largest marginal gaps from each group were still within the clinically acceptable range below 75 µm. Although the 3D-printed control model did not improve marginal fit, its primary function is to effectively identify major manufacturing errors.