Effect of Cad-Cam Systems and Monolithic Block Type on Marginal Accuracy

Objectives: The marginal fit and accuracy is one of the most important criteria for evaluation of the clinical acceptability of a restoration. Producing CAD-CAM crowns can be affected by different parameters. The aim of this in vitro study was to evaluate the marginal accuracy of 3 different monolithic crowns milled and produced with four different CAD-CAM systems.
Methods: An upper right first molar Frasaco (Frasaco® Germany) tooth was prepared for all-ceramic crown. A chairside CAD/CAM system with the intraoral scanning device GC Aadva Lab Scan was used to scan the tooth to create a master scan. From this scan 120 model analogs from Zirkohnzahn PMMA (Zirkohnzahn,Germany) material were produced as prepared abutment. GC Initial (Group I, GC Dental Products), Gc Cerasmart (Group CS; GC Dental Products), and Prettau (Group P; Zirkonzahn) used as block material. The crowns were produced from every block by four different milling machine; Matsuura Milling Machine (M), Roland DWX-51D Milling Machine (R), Cerec MCXL (C) ve Zirkonzahn Milling Unit M1 (Z) (n=10).The milled restorations were scanned with Solutionix c500 (Solutionix, South Korea) and inner surfaces compared to the originally and calculated with 3D surface using analysis software programme Geomagic Control&Autodesk Powershape (NC, USA).


Results: The smallest marginal gap for the inner surface was achieved in Group M ( 51 ± 12 μm, P<.05). Group R achieved smallest marginal gap through 63 ± 14 μm, P<.05. In Group Z shows the marginal gap as 69 ± 13 μm and Group C exhibited marginal gap as 82 ± 21 μm. The mean values of Group IM were significantly lower than those of other groups (P<.05). However, all values were within the clinical tolerance.
Conclusions: Within the limitation of this in vitro study; crown restorations' marginal fit and accuracy affected by the CAD-CAM milling system and also block type