Comparison of the Accuracy of Fit of Metal, Zirconia, and Lithium Disilicate Crowns Made from Different Manufacturing Techniques

Abstract

Purpose:To evaluate the accuracy of fit of metal, lithium disilicate, and zirconia crowns, which were produced using different manufacturing techniques. Materials and Methods: Ten patients in need of a molar crown were recruited. Eight crowns were fabricated for each patient: 2 zirconia, 3 lithium disilicate (e.max), and 3 metal-ceramic crowns using conventional, conventional/digital, and digital techniques. Marginal, axial, and occlusal gaps were measured using a replica technique. Replicas were sectioned mesiodistally and buccolingually and were observed under a stereomicroscope. A total of 32 measurements for each crown replica at 3 different points (12 marginal, 12 axial, and 8 occlusal) were performed. Statistical analysis was performed using two-way ANOVA and Tukey HSD tests. Results: Marginal means ranged from 116.39 ± 32.76 µm for the conventional metal-ceramic group to 147.56 ± 31.56 µm for the digital e.max group. The smallest axial gap was recorded for the digital zirconia group (76.19 ± 23.94 µm), while the largest axial gap was recorded for the conventional e.max (101.80 ± 19.81 µm) and conventional/digital metal-ceramic groups (101.80 ± 35.31 µm). The conventional e.max crowns had the smallest occlusal mean gap (185.59 ± 59.09 µm), while the digital e.max group had the largest occlusal mean gap (295.38 ± 67.80 µm). Type of crown had no significant effect on marginal (p = 0.07, f = 2.71), axial (p = 0.75, f = 0.29), or occlusal fit (p = 0.099, f = 2.4), while fabrication method had a significant effect on axial gap only (p = 0.169, f = 1.82, p = 0.003, f = 6.21, and p = 0.144, f = 2 for marginal, axial, and occlusal fit, respectively). Digital fabrication produced significantly smaller axial gaps than the conventional method (p = 0.02), and the conventional digital method (p = 0.005). Conclusions:The type of crown and method of manufacturing had no effect on the marginal and occlusal gap of single posterior crown, while the method of manufacturing had a significant effect on the axial gap. The digital method produced the smallest axial fit in comparison with the other methods, while the type of crown had no effect on the axial gap.

Color matching of full ceramic versus metal-ceramic crowns - a spectrophotometric study

“…In order to achieve clinical validation, it is essential to analyze the clinical performance of restorative materials. Metal-ceramic crowns were considered as the golden standard, combining mechanical resistance with esthetics [11][12][13]. However, nowadays, full ceramic crowns are becoming most often the solutions of choice for protection and/or replacement of altered dental structures, especially in anterior dental areas due to their advantages over metal-ceramic restorations: improved esthetics because of their increased translucency and light transmission [14,15], minimal tooth reduction [14,16], low thermal conductivity [17], less periodontal damage because of the supragingival placement of margins [18][19][20] and less susceptibility to metal allergies [14].…”

Comparison of three-dimensional digital technique with two-dimensional replica method for measuring marginal and internal fit of full coverage restorations

“…8 The results of this study revealed that the theory of acceptable marginal discrepancy within 120 µm was not applied for all of the tested restorations, particularly for absolute marginal discrepancies values. De Almeida et al 28 and Al Hamad et al 29 also reported marginal gap of lithium disilicate crowns greater than 120 µm and some other studies presented much lower values. [30][31][32][33] Defining a standard value of marginal and internal gap for recently restorations made by advance technology is a necessity.…”

Application of multi-directional forged titanium for prosthetic crown fabrication by CAD/CAM

“…Pure titanium processed by CAD/CAM is being used clinically and the accuracy of these components has been reported to be equivalent to that of cast components 28,29) . However, it is difficult to evaluate the fit accurately using conventional methods as it is difficult to stabilize measurement points; the conventional analog method measures distances microscopically using silicone impressions [30][31][32][33][34][35][36][37][38][39][40] . Furthermore, it is not objective and poor in reproducibility.…”