The Effect of Surface Preparation of Acrylic Teeth

Purpose: The impact of material on the adaptation of lithium disilicate inlays is poorly documented. This in vitro study aims at comparing the fit accuracy of pressed and milled inlays obtained from conventional impression and laboratory-based computer-aided design and computer-aided manufacturing. Material and Methods: A typodont molar was prepared for a mesio-occlusal ceramic inlay. The stone die generated from one conventional impression was scanned once using a laboratory scanner and the same design was used to produce 15 pressed lithium disilicate inlays from milled wax patterns (group CIDW), and 15 inlays from lithium disilicate blanks (group CICAD) with a 5-axis milling machine. Marginal and internal discrepancies were measured using the replica technique. Mixed-model ANOVA was applied to assess differences according to material and gap location at P<0.05. Results: Material and discrepancy location had a significant effect on fit measurements. Group CIDW showed significantly smaller marginal (37.4 μm) and internal (69.2 μm) discrepancies than group CICAD (59.6 μm and 93.7 μm respectively). Marginal discrepancies were significantly smaller than internal discrepancies within both groups. Conclusions: Pressed inlays generated from conventional impression and milled wax patterns yielded better fit accuracy than milled inlays obtained from conventional impression and subtractive manufacturing.