The marginal fit of selective laser melting–fabricated metal crowns: An in vitro study

doi:10.1016/j.prosdent.2014.05.018

The Journal of Prosthetic Dentistry

Volume 112, Issue 6, December 2014, Pages 1437-1440

https://doi.org/10.1016/j.prosdent.2014.05.018 Get rights and content

Statement of problem

The selective laser melting technique is attracting interest in prosthetic dentistry. The marginal fit is a key criterion for fixed restorations.

Purpose

The purpose of the study was to evaluate the marginal fit of cast cobalt-chromium alloy crowns versus the fit of selective laser melting–fabricated crowns.

Material and methods

The marginal gap widths of 36 single crowns (18 selective laser melting–fabricated cobalt-chromium metal crowns and 18 cobalt-chromium cast crowns) were determined with a silicone replica technique. Each crown specimen was cut into 4 sections, and the marginal gap width of each cross section was evaluated by stereomicroscopy (×100). The Student t test was used to evaluate whether significant differences occurred in the marginal gap widths between the selective laser melting–fabricated and cast cobalt-chromium metal crowns (α=.05).

Results

The mean marginal gap width of the cast crowns (170.19 μm) was significantly wider than that of the selective laser melting–fabricated crowns (102.86 μm).

Conclusions

Selective laser melting–fabricate cobalt-chromium dental crowns found improved marginal gap widths compared with traditional cast crowns.

Section snippets

Material and Methods

Thirty-six single crowns were examined in this study (18 SLM-fabricated CoCr metal crowns and 18 CoCr cast crowns). To fabricate the metal crowns, a maxillary premolar crown preparation was simulated by using a stainless-steel die with a height of 6.0 mm (with assuming a 2-mm flat occlusal reduction), a uniform heavy chamfer finish line of 1.0 mm in width, and a total occlusal convergence of 5 degrees (Fig. 1). The die was manually prepared by using tungsten carbide burs (MANI Inc) and trimmed

Results

The mean (standard deviation) of the marginal gap width for the SLM-fabricated crown group was 102.86 ±40.54 μm (95% confidence interval [CI], 54.55-185.94 μm). The corresponding values for the cast crown group were 170.19 ±66.17 μm (95% CI, 96.17-337.63 μm). The marginal gap widths differed significantly between the 2 groups (P>.05 by the Anderson–Darling test; P<.05 by the Student t test) (Table I).

Discussion

This study compared the marginal fits of SLM-fabricated and cast CoCr metal crowns. The mean marginal gap width of the cast crown group (170.19 μm [95% CI, 96.17-337.63 μm]) was significantly wider than that of the SLM-fabricated crown group (102.86 μm [95% CI, 54.55-185.94 μm]). Therefore, the null hypothesis of the study was rejected. In the present study, restorations fabricated by CAD/computer-aided manufacturing SLM and the traditional lost-wax technique were both fabricated with a gypsum

Conclusions

According to the results of this laboratory study, compared with traditional cast crowns, the SLM-fabricated CoCr dental crowns had significantly smaller marginal discrepancies. Within the limitations of this study, the mean marginal fit of SLM-fabricated CoCr crowns seems to meet the requirements for clinical dental applications. More studies are needed to verify the suitability of this technology, and future in vivo studies that deliver the cast into the mouth with a detector are planned.

Acknowledgments

The authors thank researchers from Shanghai Jiao Tong University School of Materials and technicians from Shanghai Foshion and BEGO CAD/CAM Center, Shanghai Foshion Dental Division.

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Electronic (PubMed, Cochrane, EBSCOhost, and Google Scholar) and manual searches were conducted for articles published from January 2010 to December 2020 to identify relevant studies evaluating the effect of different finish line preparations (chamfer, deep chamfer, shoulder, rounded shoulder) on the marginal and internal adaptation of cobalt-chromium metal alloy copings fabricated by using CAD-CAM technology.
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: Supported by Shanghai Leading Academic Discipline Project (Project Number: T0202, S30206) and the Science and Technology Committee of Shanghai (08DZ2271100, 12441903001, and 13140902701).

View full text

The marginal fit of selective laser melting–fabricated metal crowns: An in vitro study

Statement of problem

Purpose

Material and methods

Results

Conclusions

Section snippets

Material and Methods

Results

Discussion

Conclusions

Acknowledgments

J Mater Process Tech

Int J Mac Tool Manu

Appl Surf Sci

J Dent

J Prosthet Dent

J Prosthet Dent

J Endod

J Prosthet Dent

J Prosthet Dent

Dent Mater