Abstract
Introduction: This study was conducted to evaluate the effect of different impression and wax pattern fabrication methods on the marginal and internal adaptation of pressed lithium disilicate inlays.
Methods: A mandibular first molar extracted due to poor periodontal prognosis was prepared for lithium disilicate mesio-occlusal inlay restoration with 1.5-mm pulpal depth, 5–8° divergence of internal walls, a 3-mm occlusal isthmus width, and a 2.5-mm proximal box width. Three groups were defined according to the impression and wax pattern fabrication method. In Group 1, conventional impressions were made with heavy- and light-body polyvinyl siloxane impression material, and stone dies were made using type IV dental stone. In Group 2, stone dies obtained in Group 1 were scanned using a laboratory scanner before application of the die hardener, and wax patterns were fabricated using computer-aided design (CAD) technology. In Group 3, the prepared tooth was scanned using an intraoral scanner, and wax patterns were made using the same CAD workflow. All the wax patterns were subsequently invested and processed using the press technique. The marginal and internal gaps of the inlays were evaluated using micro-computed tomography. The obtained data were analyzed using one-way analysis of variance (ANOVA) at a significance level of 0.05.
Results: The mean internal gap in Group 3 was significantly lower than that in Group 2 (P<0.001) but significantly higher than that in Group 1 (P=0.003). In addition, Group 2 exhibited a significantly greater internal gap than Group 1 (P<0.001). No statistically significant differences were observed among the three groups in terms of marginal gap values (P>0.05).
Conclusion: The impression and wax pattern fabrication methods did not significantly influence the marginal adaptation of pressed lithium disilicate inlays. However, the conventional impression technique combined with hand-made wax patterns resulted in the smallest internal gap among the evaluated methods.