Comparison of the Fit of Lithium Disilicate Crowns made from Conventional, Digital, or Conventional/Digital Techniques

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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.

Section: Discussionsupporting

confidence: 66%

Section: Discussionmentioning

confidence: 99%

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

Hamad

Quran

AlJalam

et al. 2019

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“… Multiple recent studies examined the marginal fit of ceramic restorations fabricated using digital impression systems. Many of these studies, compared the marginal fit using digital and conventional impressions and concluded that both protocols result in clinically acceptable marginal adaptation for the fabrication of indirect all ceramic dental restorations . Nonetheless, another area that require further investigation is the validity of various digital workflows currently being utilized for digital crown fabrication.…”

Section: Introductionmentioning

confidence: 99%

Marginal Fit Evaluation of CAD/CAM All Ceramic Crowns Obtained by Two Digital Workflows: An In Vitro Study Using Micro‐CT Technology

Duqum

Brenes

Mendonça

et al. 2019

Purpose:To evaluate the marginal fit of CAD/CAM all ceramic crowns made from lithium disilicate and zirconia using two different fabrication protocols (model and model-less). Materials and Methods: Forty anterior all ceramic restorations (20 lithium disilicate, 20 zirconia) were fabricated from digital impressions using a CEREC Bluecam scanner. Two different digital workflows were used: a fully digital model-less approach and a printed model digital approach. The crowns were cemented on the respective prepared typodont teeth and marginal gap was evaluated using Micro-CT. Each specimen was analyzed in sagittal and trans-axial orientations, allowing evaluation of the marginal fit (vertical and horizontal) on each surface. Logarithmic transformation was used with a significance of 0.05. After that a reliability analysis was performed by re-measuring four randomized selected images for each specimen and performing intraclass correlations to determine any systematic bias in the measurements. Results: Vertical measurements in the lingual, distal and mesial views had an estimated marginal gap ranging from 101.9 to 133.9 µm for lithium disilicate crowns and 126.4 to 165.4 µm for zirconia. No significant differences were found between model and model-less techniques. Conclusions: Both workflows are valid protocols for the fabrication of monolithic ceramic restorations. The use of a printed model did not improve the marginal fit of lithium disilicate or zirconia crowns. Both materials are also clinically acceptable, no matter which workflow was used to obtain the restoration.

“…The predictability of the final restoration, its reproducibility, and improved precision with less time and effort are the main benefits of CAD/CAM technology . The advantage of digitally designing the prosthesis prevents the build‐up of excessive strains on the restoration, which are encountered during the conventional fabrication process .…”

mentioning

confidence: 99%

Internal Adaptation of Implant‐Supported, Polymer‐Infused Ceramic Crowns Fabricated by Two CAD/CAM Systems

Talic

Alfadda

2018

Purpose: The aim of this in vitro study was to compare the internal 3D adaptation of polymer-infused ceramic crowns fabricated using two CAD/CAM systems: CEREC inLab MC XL and Ceramill Motion 2 (5X). Materials and Methods: Twenty-five implant-supported metal-ceramic crowns were fabricated conventionally using the lost-wax technique, and the outer contour was scanned to serve as a guide for designing the polymer-infused ceramic CAD/CAM crowns. Twenty-five crowns were fabricated using CEREC, and 25 crowns were fabricated using Ceramill. The cement space was set to 20 μm. The Zeiss Accura Microsystem Coordinate Measuring Machine (CMM), Calypso, and Geomagic software were used to measure the 3D accuracy of fit of all crowns to their respective implant abutments. To test for the statistical significance between groups in terms of 3D total distortion, a one-way ANOVA was conducted. The Kolmogorov-Smirnov test was used to investigate the differences in the x, y, and z coordinates. A p-value of 0.05 or less was considered statistically significant at an alpha level of 0.05. Results: Comparing the 3D misfit of metal-ceramic crowns to those of CAD/CAM crowns fabricated using CEREC revealed no significant difference (88.20 ± 36.59 μm vs. 102.45 ± 36.58 μm, p = 0.161). Similarly, no significant difference in 3D total distortion was identified between metal-ceramic crowns and crowns fabricated using Ceramill (88.20 ± 36.59 μm vs. 78.40 ± 31.03 μm, p = 0.336); however, the 3D total distortion of polymer-infused crowns made by Ceramill was significantly reduced compared to that of crowns fabricated by CEREC (78.3 ± 31.0 μm vs. 102.4 ± 36.5 μm, p = 0.019). Conclusions: Polymer-infused ceramic crowns fabricated using CEREC exhibited the least accurate 3D fit. All misfit values of the tested groups were within clinically acceptable levels.