Evaluation of Different Design Modes of a CAD/CAM System

Objectives: The aims of this study were to compare occlusal and interproximal contacts of crowns generated by three different CAD/CAM design modes through the Planmeca PlanCAD Design Center Software (DCS); and compare tooth morphology of these crowns to master unprepared crowns of right mandibular first molars through the Planmeca Compare Software (PCS).
Methods: Impressions of mandibular and maxillary arches from 40 dental students were taken with silicone elastomeric materials and alginate, respectively. Standardized crown preparations were performed on the right mandibular first molar of each cast and scanned using the Planmeca PlanScan. Three different crowns were designed using distinct design modes provided by the DCS: 1) Pre-Op, 2) Library A, and 3) Library C. Contact points on both mesial and distal surfaces were considered for interproximal evaluation. Contact points in the mesial marginal ridge, central fossa, distal marginal ridge, mesiobuccal cusp and midbuccal cusp were considered for occlusal evaluation. Ideal ranges of interproximal and occlusal contacts provided by the software were used as reference and evaluated by a calibrated researcher. 120 IPS Empress CAD LT crowns (Ivoclar Vivadent) were milled to compare tooth morphology to their master crowns through the PCS. Frequency of ideal and no ideal contacts were evaluated through Chi-Square test and tooth morphology through one-way ANOVA and Tukey post-hoc test (α=.05).
Results: The majority of occlusal and interproximal contacts were not ideal for all three CAD/CAM design modes with no significant difference amongst them (p>.05). PreOp presented higher scores (89.93%) of tooth morphology than Library A (45.98%) and Library C (50.28%).
Conclusions: Frequency of ideal occlusal and interproximal contacts was not influenced by CAD/CAM design modes. Preop presented the most similar tooth morphology to master unprepared crowns.