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Journal of Technologic Dentistry 2024; 46(3): 73-83

Published online September 30, 2024

https://doi.org/10.14347/jtd.2024.46.3.73

© Korean Academy of Dental Technology

적층 빌드 방향이 가철성 국소의치 금속 구조물의 정확도와 내부 다공성에 미치는 영향

함건희1, 김지환1,2

1고려대학교 일반대학원 보건과학과 치의기공학전공, 2고려대학교 L-HOPE 공동체-기반 토탈 러닝헬스시스템 교육연구단

Received: August 1, 2024; Revised: September 5, 2024; Accepted: September 19, 2024

Effect of build orientation on the accuracy and internal porosity of removable partial denture metal frameworks

Geon Hee Ham1 , Ji-Hwan Kim1,2

1Department of Dental Laboratory Science and Engineering, College of Health Science, Korea University Graduate School, Seoul, Korea
2L-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: August 1, 2024; Revised: September 5, 2024; Accepted: September 19, 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 aimed to investigate whether the accuracy and internal porosity of removable partial denture frameworks differ depending on the build direction in the selective laser melting method.
Methods: A partially edentulous maxillary study model was scanned, and the anterior–posterior palatal bar was then digitally designed. The angles formed between the z-axis and the path of the insertion and removal were divided into five groups: –60°, –30°, 0°, 30°, and 60°. For each group, three removable partial denture metal frameworks were fabricated and used as specimens. The inner surface of each sample was scanned and superimposed on the design file to obtain the root mean square (RMS) value, and the average RMS value of each group was measured. One sample was randomly selected from each group, and the equivalent diameter and sphericity of the pores were analyzed using industrial X-ray three-dimensional computed tomography. To compare statistical differences between groups, the Kruskal–Wallis test of SPSS Statistics ver. 27.0 (IBM) was used (α=0.05).
Results: The average RMS values of the whole inner surface accuracy of the specimens were in the order of –60°<0°<–30°<30°<60° (p<0.05). The equivalent diameter and sphericity of internal pores were significantly different among groups (p<0.001).
Conclusion: The build orientation of the selective laser melting method influences the accuracy and internal porosity of removable partial denture frameworks.

Keywords: Accuracy, Porosity, Removable partial denture, Selective laser melting

Article

Original Article

Journal of Technologic Dentistry 2024; 46(3): 73-83

Published online September 30, 2024 https://doi.org/10.14347/jtd.2024.46.3.73

Copyright © Korean Academy of Dental Technology.

적층 빌드 방향이 가철성 국소의치 금속 구조물의 정확도와 내부 다공성에 미치는 영향

함건희1, 김지환1,2

1고려대학교 일반대학원 보건과학과 치의기공학전공, 2고려대학교 L-HOPE 공동체-기반 토탈 러닝헬스시스템 교육연구단

Received: August 1, 2024; Revised: September 5, 2024; Accepted: September 19, 2024

Effect of build orientation on the accuracy and internal porosity of removable partial denture metal frameworks

Geon Hee Ham1 , Ji-Hwan Kim1,2

1Department of Dental Laboratory Science and Engineering, College of Health Science, Korea University Graduate School, Seoul, Korea
2L-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: August 1, 2024; Revised: September 5, 2024; Accepted: September 19, 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 aimed to investigate whether the accuracy and internal porosity of removable partial denture frameworks differ depending on the build direction in the selective laser melting method.
Methods: A partially edentulous maxillary study model was scanned, and the anterior–posterior palatal bar was then digitally designed. The angles formed between the z-axis and the path of the insertion and removal were divided into five groups: –60°, –30°, 0°, 30°, and 60°. For each group, three removable partial denture metal frameworks were fabricated and used as specimens. The inner surface of each sample was scanned and superimposed on the design file to obtain the root mean square (RMS) value, and the average RMS value of each group was measured. One sample was randomly selected from each group, and the equivalent diameter and sphericity of the pores were analyzed using industrial X-ray three-dimensional computed tomography. To compare statistical differences between groups, the Kruskal–Wallis test of SPSS Statistics ver. 27.0 (IBM) was used (α=0.05).
Results: The average RMS values of the whole inner surface accuracy of the specimens were in the order of –60°<0°<–30°<30°<60° (p<0.05). The equivalent diameter and sphericity of internal pores were significantly different among groups (p<0.001).
Conclusion: The build orientation of the selective laser melting method influences the accuracy and internal porosity of removable partial denture frameworks.

Keywords: Accuracy, Porosity, Removable partial denture, Selective laser melting

Fig 1.

Figure 1.Schematic diagram of the build orientation of five groups.
Journal of Technologic Dentistry 2024; 46: 73-83https://doi.org/10.14347/jtd.2024.46.3.73

Fig 2.

Figure 2.Support structure installation in Magics 21.0 (Materialise). (A) Bottom view, (B) side view.
Journal of Technologic Dentistry 2024; 46: 73-83https://doi.org/10.14347/jtd.2024.46.3.73

Fig 3.

Figure 3.(A) Split mesh by component and (B) area selected during optimal alignment.
Journal of Technologic Dentistry 2024; 46: 73-83https://doi.org/10.14347/jtd.2024.46.3.73

Fig 4.

Figure 4.Color map of the differences in the inner shape of the five groups.
Journal of Technologic Dentistry 2024; 46: 73-83https://doi.org/10.14347/jtd.2024.46.3.73

Fig 5.

Figure 5.Pore distribution in five groups.
Journal of Technologic Dentistry 2024; 46: 73-83https://doi.org/10.14347/jtd.2024.46.3.73

Fig 6.

Figure 6.Position of support attachment on the polishing surface of the five groups and line support attachment area viewed from the bottom in Magics (a).
Journal of Technologic Dentistry 2024; 46: 73-83https://doi.org/10.14347/jtd.2024.46.3.73

Fig 7.

Figure 7.Frequency of equivalent diameter for five groups.
Journal of Technologic Dentistry 2024; 46: 73-83https://doi.org/10.14347/jtd.2024.46.3.73

Table 1 . Mean±SD of RMS in five groups (unit: µm).

ComponentNumberMean±SDp-value

–60°–30°30°60°
#14 Mesial occlusal rest3219.6±12.6186.6±19.3104.5±16.9126.3±23.6117.5±23.60.023*
#15 Distal occlusal rest366.5±4.967.9±19.358.9±10.0106.7±16.1123.0±26.10.029*
#24∙25 Interproximal occlusal rest393.6±11.4109.6±15.071.3±3.8143.9±6.5315.5±21.30.010*
#17 Mesial occlusal rest380.3±11.475.7±39.2141.2±47.3117.4±13.560.7±6.40.082
Major connector380.7±7.8114.1±16.883.6±5.586.3±4.7113.1±8.60.032*
Whole inner surface394.3±8.3110.8±19.2109.9±10.6112.7±6.8149.7±8.50.045*

Determined significance by Kruskal–Wallis test (α=0.05)..

SD: standard deviation, RMS: root mean square..

*Mean difference significant (p<0.05)..


Table 2 . Porosity in five groups.

–60°–30°30°60°
∑Pore volume (µm3)3E+10
(≒2.66×1010)
2E+10
(≒1.66×1010)
1E+10
(≒1.25×1010)
3E+10
(≒2.70×1010)
2E+10
(≒2.46×1010)
Material volume (µm3)2E+12
(1.76×1012)
2E+12
(1.66×1012)
2E+12
(1.74×1012)
2E+12
(1.67×1012)
2E+12
(1.64×1012)
Porosity (%)1.511.000.721.611.50

Table 3 . Mean±SD of equivalent diameter and sphericity in five groups.

–60°–30°30°60°p-value
Number31,05623,45915,39732,54632,186
Equivalent diameter (µm)104.92±36.35100.26±32.49100.56±40.80105.39±34.47102.88±33.02<0.001
Sphericity0.65±0.070.66±0.070.70±0.080.65±0.070.65±0.07<0.001

Determined significance by Kruskal–Wallis test (α=0.05)..

SD: standard deviation..


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