FIT ACCURACY OF OPEN VERSUS CLOSED CAD/CAM SYSTEMS USING A SECTIONAL METHOD

INTRODUCTION: Marginal fit is critical for the success of dental restorations. Zirconia full coverage restorations can be fabricated either chair-side or in a milling center. OBJECTIVE: To evaluate the fit accuracy of all ceramic restorations fabricated by two different CAD/CAM systems using a sectional method. MATERIAL AND METHODS: A lower first molar was prepared for a full coverage restoration, it was laser scanned (Ceramill map 400) and 24 replicas were milled using acrylic CAD/CAM block (Ceramill TEMP). Half of the dies were scanned using a closed system (CEREC inLab MC X5) while the other half used an open system (Ceramill motion 2). Zirconia restorations (Monolithic Katana zirconia) were milled from each system. Sectional method where each restoration was cut into thin sections (Buehler Isomet 4000 Linear Precision Saw) after cementation by self-adhesive resin cement (RelyX™ Unicem). A stereomicroscope was used for measurement. (n=24 α= 0.05). RESULTS: There was a significant difference (t=2.387, P<0.030) as the open system was better than the closed system at the axial sites. CONCLUSIONS: within the limitations of this study, better marginal qualities were achieved using an open CAD/CAM system.