Purpose: The purpose of this study is to evaluate the trueness and fitness of machined prostheses according to drill radius setting in CAD software. Methods: For this study, standard abutment were replicated in Type IV stone. The stone abutment were scanned using a dental scanner. The CAD design software was designed using scanned abutment data. When designing, the drill radius was set to 0.3 mm and 0 mm, respectively, and saved. The saved design data was milled using a milling machine (n=13). The inner surface of the milled crown was scanned. The trueness and fitness were measured using the inner scan data of prostheses. Independent t-tests were performed to identify significant differences in each data. Results: Trueness values of the data saved with 0.3 mm and 0 mm drill radius were $18.9{pm}2.3{mu}m$ and $19.1{pm}0.9{mu}m$, respectively. There was no statistically significant difference between the groups. Fitness values of the data saved with 0.3 mm and 0 mm drill radius were $65.5{pm}0.8{mu}m$ and $33.8{pm}1.0{mu}m$, respectively. There was a statistically significant difference between the groups (p<.05). Conclusion : Setting the drill radius is important to produce clinically good fit prostheses.

Keywords: Dental CAD/CAM systems,Milling machine,Fitness,Three-dimensional evaluation,Trueness,