Effect of Different Wax Pattern Manufacturing Techniques on the Marginal Fit of Lithium Disilicate Crowns

Purpose: The present study evaluated the marginal gap of lithium disilicate crowns fabricated through three different wax pattern techniques; Conventional, Milling and 3D-printing. Materials and Methods: Thirty stone models were replicated from a stainless-steel model representing a prepared tooth; ten were sent to make conventional wax patterns while the remaining were sent to a digital dental scanner. The computer aided design was completed and STL (Standard Tessellation Language) files were sent to either milling or 3D-printing machines. All wax patterns (n = 30) were pressed, and a stabilizing instrument was used to secure the crowns on the master model. The marginal gap was measured at 18 points for each crown using a digital microscope (mu m) (n = 540) and compared using One-way ANOVA (p <= 0.05). Results: There was a significant difference in the marginal gap value between all three groups (p < 0.01) where the milled group showed the least mean gap (28.87 +/- 30.18 mu m), followed by 3D printed (47.85 +/- 27.44 mu m), while the highest mean marginal gap was found in the conventional group (63.49 +/- 28.05 mu m). Conclusion: Milled and 3D-printed wax patterns produced better fitting crowns compared to conventional techniques.