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Journal of Technologic Dentistry 2024; 46(4): 150-156

Published online December 30, 2024

https://doi.org/10.14347/jtd.2024.46.4.150

© Korean Academy of Dental Technology

Selective laser melting 방식과 lost-wax casting 방식으로 제작된 메탈코핑의 내면과 변연의 정확성 평가

김희령1, 노미준1, 이완선2, 김지환1,3

1고려대학교 일반대학원 보건과학대학 치의기공학전공, 2부천대학교 치기공과, 3고려대학교 L-HOPE 공동체-기반 토탈 러닝헬스시스템 교육 연구단

Received: November 8, 2024; Revised: December 6, 2024; Accepted: December 22, 2024

Evaluation of the accuracy of internal and marginal surfaces of metal copings manufactured using selective laser melting and lost-wax casting methods

Hee-Ryung Kim1 , Mi-Jun Noh1 , Wan-Sun Lee2 , Ji-Hwan Kim1,3

1Department of Dental Laboratory Science and Engineering, Graduate School, Korea University, Seoul, Korea
2Department of Dental Technology, Bucheon University, Bucheon, Korea
3L-HOPE Program for Community-Based Total Learning Health Systems, Korea University, Seoul, Korea

Correspondence to :
Ji-Hwan Kim
Department of Dental Laboratory Science and Engineering, Graduate School, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 02841, Korea
E-mail: Kjh2804@korea.ac.kr
https://orcid.org/0000-0003-3889-2289

Received: November 8, 2024; Revised: December 6, 2024; Accepted: December 22, 2024

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Purpose: This study was conducted to evaluate the accuracy of the internal and marginal surfaces of metal copings manufactured using lost-wax casting (LWC) and selective laser melting (SLM) methods.
Methods: A prepared upper left incisor on the master model was selected as the abutment tooth and scanned using a model scanner. Copings were fabricated by casting with cobalt– chromium (Co–Cr) alloy or three-dimensional (3D) printing with Co–Cr powder (n=20). The manufactured specimens were scanned and saved in standard tessellation language format. Accuracy was measured using a 3D analysis program. Statistical analyses were conducted using the SPSS (IBM). Significant differences were evaluated using the Shapiro–Wilk test. The Mann–Whitney U-test, a nonparametric method, was used because normality was not satisfied (α=0.05).
Results: The mean root mean square (RMS) values of trueness of the internal and marginal surfaces in the LWC method were 37.12±1.21 and 59.92±4.48 μm, respectively, which were higher than the values of 20.73±1.07 and 44.61±2.67 μm, respectively, in the SLM method, with the difference being statistically significant (p<0.001 and p=0.023, respectively). The internal surface mean RMS values of precision in the LWC and SLM groups were 22.39±2.87 and 21.16±1.25 μm, respectively, which showed no statistically significant difference (p=0.872); however, the marginal surface mean RMS values were 50.97±2.24 and 22.11±1.19 μm, respectively, indicating a statistically higher precision in the SLM group (p<0.001).
Conclusion: The internal and marginal surfaces of metal copings manufactured using LWC and SLM methods showed significantly different accuracy, except for internal surface precision. Both methods yielded clinically acceptable values.

Keywords: Accuracy, Lost-wax casting, Metal coping, Selective laser melting, Subtractive manufacturing, Three-dimensional printing

Article

Original Article

Journal of Technologic Dentistry 2024; 46(4): 150-156

Published online December 30, 2024 https://doi.org/10.14347/jtd.2024.46.4.150

Copyright © Korean Academy of Dental Technology.

Selective laser melting 방식과 lost-wax casting 방식으로 제작된 메탈코핑의 내면과 변연의 정확성 평가

김희령1, 노미준1, 이완선2, 김지환1,3

1고려대학교 일반대학원 보건과학대학 치의기공학전공, 2부천대학교 치기공과, 3고려대학교 L-HOPE 공동체-기반 토탈 러닝헬스시스템 교육 연구단

Received: November 8, 2024; Revised: December 6, 2024; Accepted: December 22, 2024

Evaluation of the accuracy of internal and marginal surfaces of metal copings manufactured using selective laser melting and lost-wax casting methods

Hee-Ryung Kim1 , Mi-Jun Noh1 , Wan-Sun Lee2 , Ji-Hwan Kim1,3

1Department of Dental Laboratory Science and Engineering, Graduate School, Korea University, Seoul, Korea
2Department of Dental Technology, Bucheon University, Bucheon, Korea
3L-HOPE Program for Community-Based Total Learning Health Systems, Korea University, Seoul, Korea

Correspondence to:Ji-Hwan Kim
Department of Dental Laboratory Science and Engineering, Graduate School, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 02841, Korea
E-mail: Kjh2804@korea.ac.kr
https://orcid.org/0000-0003-3889-2289

Received: November 8, 2024; Revised: December 6, 2024; Accepted: December 22, 2024

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Purpose: This study was conducted to evaluate the accuracy of the internal and marginal surfaces of metal copings manufactured using lost-wax casting (LWC) and selective laser melting (SLM) methods.
Methods: A prepared upper left incisor on the master model was selected as the abutment tooth and scanned using a model scanner. Copings were fabricated by casting with cobalt– chromium (Co–Cr) alloy or three-dimensional (3D) printing with Co–Cr powder (n=20). The manufactured specimens were scanned and saved in standard tessellation language format. Accuracy was measured using a 3D analysis program. Statistical analyses were conducted using the SPSS (IBM). Significant differences were evaluated using the Shapiro–Wilk test. The Mann–Whitney U-test, a nonparametric method, was used because normality was not satisfied (α=0.05).
Results: The mean root mean square (RMS) values of trueness of the internal and marginal surfaces in the LWC method were 37.12±1.21 and 59.92±4.48 μm, respectively, which were higher than the values of 20.73±1.07 and 44.61±2.67 μm, respectively, in the SLM method, with the difference being statistically significant (p<0.001 and p=0.023, respectively). The internal surface mean RMS values of precision in the LWC and SLM groups were 22.39±2.87 and 21.16±1.25 μm, respectively, which showed no statistically significant difference (p=0.872); however, the marginal surface mean RMS values were 50.97±2.24 and 22.11±1.19 μm, respectively, indicating a statistically higher precision in the SLM group (p<0.001).
Conclusion: The internal and marginal surfaces of metal copings manufactured using LWC and SLM methods showed significantly different accuracy, except for internal surface precision. Both methods yielded clinically acceptable values.

Keywords: Accuracy, Lost-wax casting, Metal coping, Selective laser melting, Subtractive manufacturing, Three-dimensional printing

Fig 1.

Figure 1.Measurement range of accuracy. (A) Internal surface, (B) margin surface.
Journal of Technologic Dentistry 2024; 46: 150-156https://doi.org/10.14347/jtd.2024.46.4.150

Fig 2.

Figure 2.Formula for calculating root mean square (RMS).
Journal of Technologic Dentistry 2024; 46: 150-156https://doi.org/10.14347/jtd.2024.46.4.150

Fig 3.

Figure 3.Representative color-difference maps of trueness and precision for lost-wax casting (LWC), selective laser melting (SLM) groups.
Journal of Technologic Dentistry 2024; 46: 150-156https://doi.org/10.14347/jtd.2024.46.4.150

Table 1 . Mean±SD of trueness RMS values for marginal and internal surface for LWC and SLM groups (n=10, unit: μm).

No.GroupMean±SD95% CIp-value

MinMax
1LWC internal surface37.12±1.2134.3739.87<0.001
2SLM internal surface20.73±1.0718.3123.15
3LWC marginal surface59.92±4.4849.7970.050.023
4SLM marginal surface44.61±2.6738.5850.64

SD: standard deviation, RMS: root mean square, LWC: lost-wax casting, SLM: selective laser melting, CI: confidence interval, Min: minimum, Max: maximum..


Table 2 . Mean±SD of precision RMS values for marginal and internal surface for LWC and SLM groups (n=45, unit: μm).

No.GroupMean±SD95%CIp-value

MinMax
1LWC internal surface22.39±2.8716.6028.180.872
2SLM internal surface21.16±1.2518.6523.68
3LWC marginal surface50.97±2.2446.4755.48<0.001
4SLM marginal surface22.11±1.1919.7224.50

SD: standard deviation, RMS: root mean square, LWC: lost-wax casting, SLM: selective laser melting, CI: confidence interval, Min: minimum, Max: maximum..


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Journal of Technologic Dentistry

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