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Journal of Technologic Dentistry 2024; 46(4): 133-140

Published online December 30, 2024

https://doi.org/10.14347/jtd.2024.46.4.133

© Korean Academy of Dental Technology

석고제품을 이용한 보철물 제작 시 발생되는 폐수에 대한 수질시험 결과

오선미

동남보건대학교 치기공학과

Received: August 20, 2024; Revised: October 5, 2024; Accepted: October 25, 2024

Water quality test results on wastewater generated from the making prosthetics using plaster products

Seon Mi Oh

Department of Dental Technology, Dongnam Health University, Suwon, Korea

Correspondence to :
Seon Mi Oh
Department of Dental Technology, Dongnam Health University, 50 Cheoncheon-ro 74beon-gil, Jangan-gu, Suwon 16328, Korea
E-mail: smoh@dongnam.ac.kr
https://orcid.org/0000-0003-0321-6344

Received: August 20, 2024; Revised: October 5, 2024; Accepted: October 25, 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: The purpose of this study was to identify the source of specific pollutants in dental laboratory wastewater and to suggest management methods for wastewater in such settings.
Methods: Test samples (81 types) were created from wastewater generated during prosthetic fabrication using plaster products. The water quality of these samples was tested three times by an authorized testing agency, and the results were categorized based on plaster manufacturer and the prosthesis-making method.
Results: In the model plaster group and related samples, lead (Pb) was not detected. In the dental stone group, Pb was detected in sample 50 at 152 times more than the water quality standard, and in sample 51, Pb was detected at a level below the standard. In the high-strength stone group, Pb was detected in two out of three samples. In the high-strength stone test group, after trimming, the concentrations of copper (Cu) and Pb in the gypsum sludge increased. In the mixed gypsum group, after 30 days, the concentrations of mercury (Hg) and hexavalent chromium (Cr6+) increased.
Conclusion: Some of the tested gypsum samples exceeded hazardous substance standards, indicating that these gypsum products should not be used in prosthetic fabrication. Additionally, the concentration of hazardous substances increases before and after plaster trimming, necessitating a thorough management of plaster trimming machines. Since the concentration of hazardous substances in wastewater from the plaster trap increases over time, it is critical to maintain cleanliness in the plaster trap at all times.

Keywords: Dental laboratory wastewater, Dental technicians, Gypsum hazardous substances, Gypsum traps

Article

Original Article

Journal of Technologic Dentistry 2024; 46(4): 133-140

Published online December 30, 2024 https://doi.org/10.14347/jtd.2024.46.4.133

Copyright © Korean Academy of Dental Technology.

석고제품을 이용한 보철물 제작 시 발생되는 폐수에 대한 수질시험 결과

오선미

동남보건대학교 치기공학과

Received: August 20, 2024; Revised: October 5, 2024; Accepted: October 25, 2024

Water quality test results on wastewater generated from the making prosthetics using plaster products

Seon Mi Oh

Department of Dental Technology, Dongnam Health University, Suwon, Korea

Correspondence to:Seon Mi Oh
Department of Dental Technology, Dongnam Health University, 50 Cheoncheon-ro 74beon-gil, Jangan-gu, Suwon 16328, Korea
E-mail: smoh@dongnam.ac.kr
https://orcid.org/0000-0003-0321-6344

Received: August 20, 2024; Revised: October 5, 2024; Accepted: October 25, 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: The purpose of this study was to identify the source of specific pollutants in dental laboratory wastewater and to suggest management methods for wastewater in such settings.
Methods: Test samples (81 types) were created from wastewater generated during prosthetic fabrication using plaster products. The water quality of these samples was tested three times by an authorized testing agency, and the results were categorized based on plaster manufacturer and the prosthesis-making method.
Results: In the model plaster group and related samples, lead (Pb) was not detected. In the dental stone group, Pb was detected in sample 50 at 152 times more than the water quality standard, and in sample 51, Pb was detected at a level below the standard. In the high-strength stone group, Pb was detected in two out of three samples. In the high-strength stone test group, after trimming, the concentrations of copper (Cu) and Pb in the gypsum sludge increased. In the mixed gypsum group, after 30 days, the concentrations of mercury (Hg) and hexavalent chromium (Cr6+) increased.
Conclusion: Some of the tested gypsum samples exceeded hazardous substance standards, indicating that these gypsum products should not be used in prosthetic fabrication. Additionally, the concentration of hazardous substances increases before and after plaster trimming, necessitating a thorough management of plaster trimming machines. Since the concentration of hazardous substances in wastewater from the plaster trap increases over time, it is critical to maintain cleanliness in the plaster trap at all times.

Keywords: Dental laboratory wastewater, Dental technicians, Gypsum hazardous substances, Gypsum traps

Fig 1.

Figure 1.Research process.
Journal of Technologic Dentistry 2024; 46: 133-140https://doi.org/10.14347/jtd.2024.46.4.133

Fig 2.

Figure 2.Test process.
Journal of Technologic Dentistry 2024; 46: 133-140https://doi.org/10.14347/jtd.2024.46.4.133

Fig 3.

Figure 3.Test sample.
Journal of Technologic Dentistry 2024; 46: 133-140https://doi.org/10.14347/jtd.2024.46.4.133

Table 1 . Classification of samples and characteristics.

Classification of samplesSamples no.Sample characteristic
Basic water sample groupSample 1Tap water
Sample 29Wastewater (hand cream+soap+tap water)
Sample 2Mixing gypsum (model plaster+dental stone+high strength stone) made by company(A)
Sample 30Sample 29+mixing gypsum
Sample 31Density change test of sample 2 for 30 day later
Mixing gypsum groupSample 41Model plaster sample made by company(A)
Sample 44Model plaster made by company(N)
Sample 47A model plaster made by company(O)
Sample 48B model plaster made by company(O)
Sample 63Model plaster made by company(N) (7 test item)
Model plaster group (type II)Sample 42Yellow dental stone sample made by company(A)
Sample 45Yellow dental stone sample made by company(N)
Sample 50Yellow dental stone sample made by company(P)
Sample 51White dental stone sample made by company(P)
Sample 52Brown dental stone sample made by company(R)
Dental stone group (type III)Sample 53Green dental stone sample made by company(R)
Sample 62Yellow dental stone sample made by company(N) (7 test item)
Sample 66Yellow dental stone sample made by company(P) (7 test item)
Sample 70Yellow dental stone sample made by company(U)
Sample 43High strength stone sample made by company(A)
High strength stone test group (type IV)Sample 46High strength stone sample made by company(N)
Sample 49High strength stone sample made by company(PA)
Sample 61High strength stone sample made by company(N) (7 test item)
Sample 68High strength stone sample made by company(A) (7 test item)
Sample 28Trimming mixing gypsum made by company(A)
Trimming test groupSample 64Trimming model plaster sample made by company(N)
Sample 65Trimming high strength stone sample made by company(N)
Sample 67Trimming dental stoner made by company(P)
Sample 69Trimming high strength stone sample made by company(A)
Sample 71Trimming dental stone sample made by company(U)

Table 2 . Test item to water quality.

Test itemWater quality standard (mg/L)
Cu0.100
Pb0.010
As0.010
Hg0.001
CN0.010
Cr6+0.050
Cd0.005
Sb0.020

Cu: copper, Pb: lead, As: arsenic, Hg: mercury, CN: cyanide ion, Cr6+: hexavalent chromium, Cd: cadmium, Sb: antimony..


Table 3 . Test result table of basic water group.

Basic water sample (standard)Cu
(0.100)
Pb
(0.010)
As
(0.010)
Hg
(0.001)
CN
(0.010)
Cr6+
(0.050)
Cd
(0.005)
Sb
(0.020)
Sample 10.001600.000200.00030-0.003000.00200-0.00010
Sample 290.015400.003300.00020-0.004000.00200-0.00030

Cu: copper, Pb: lead, As: arsenic, Hg: mercury, CN: cyanide ion, Cr6+: hexavalent chromium, Cd: cadmium, Sb: antimony, -: not detection..


Table 4 . Pb-test result table of gypsum kind.

Gypsum kindModel plasterDental stoneHigh strength stoneMixing gypsum





Sample no. (maker)41
(A)
44
(N)
47
(O)
48
(O)
42
(A)
45
(N)
50
(P)
51
(P)
52
(R)
53
(R)
70
(U)
43
(A)
46
(N)
49
(PA)
2
(A)
Pb (0.010)------1.52980.0043---0.0022-0.00020.0700

Pb: lead, -: not detection..


Table 5 . Test result table of gypsum kind by maker.

Test item (standard)Model plasterDental stoneHigh strength stoneMixing gypsum




Sample 63
(N)
Sample 62
(N)
Sample 66
(P)
Sample 70
(U)
Sample 61
(N)
Sample 68
(A)
Sample 2
(A)
Cu (0.100)-0.003000.003000.002000.002000.00500.00490
As (0.010)------0.00004
Hg (0.001)------0.00011
CN (0.010)-------
Cr6+ (0.050)0.011000.004000.009000.004000.010000.00400.01100
Cd (0.005)---0.00020---
Sb (0.020)------0.00200

Cu: copper, As: arsenic, Hg: mercury, CN: cyanide ion, Cr6+: hexavalent chromium, Cd: cadmium, Sb: antimony, -: not detection..


Table 6 . Test result table compare before trimming with after trimming.

Test item (standard)Model plasterDental stoneHigh strength stoneMixing gypsum




BeforeAfterBeforeAfterBeforeAfterBeforeAfterBeforeAfterBeforeAfter












Sample 63Sample 64Sample 66Sample 67Sample 70Sample 71Sample 61Sample 65Sample 68Sample 69Sample 2Sample 28
Cu (0.100)-0.00400.00300.02900.00200.00300.00200.00400.00500.01800.00490.0022
Pb (0.010)--1.52982.7300-0.0100-0.01000.00220.01000.06700.1345
As (0.010)-0.0100--------0.00040.0017
Hg (0.001)----------0.0001–0.0004
CN (0.010)-----------0.0060
Cr6+ (0.050)0.01100.00900.00900.01300.00400.00300.01000.01000.00400.00300.01100.0070
Cd (0.005)----0.0002-------
Sb (0.020)----------0.00200.0086

Cu: copper, Pb: lead, As: arsenic, Hg: mercury, CN: cyanide ion, Cr6+: hexavalent chromium, Cd: cadmium, Sb: antimony, -: not detection..


Table 7 . Test result table of washing water and mixed plaster group.

Test item (standard)Washing water,
sample 29
Mixing gypsum,
sample 2
Predicted result,
sample 30 (2+29)
Acture result,
sample 30 (2+29)
Difference result,
sample 30
(predict - acture)
Cu (0.100)0.015400.004900.020300.007700.01260
Pb (0.010)0.003300.067000.070300.08570–0.01540
As (0.010)0.000200.000400.000600.00120–0.00060
Hg (0.001)0.000460.000110.00057–0.000460.00100
CN (0.010)0.00400-0.004000.001000.00300
Cr6+ (0.050)0.002000.011000.013000.01400–0.00100
Cd (0.005)-----
Sb (0.020)0.000300.002000.002300.001200.00110

Cu: copper, Pb: lead, As: arsenic, Hg: mercury, CN: cyanide ion, Cr6+: hexavalent chromium, Cd: cadmium, Sb: antimony, -: not detection..


Table 8 . Test result table of sample 2 being left 30 days.

Test item
(standard)
Sample 2
(test result of mixing gypsum)
Sample 31
(test result of sample 2 being left 30 days)
Difference
Cu (0.100)0.00490.0041–0.0008
Pb (0.010)0.06700.0487–0.0183
As (0.010)0.0004-–0.0004
Hg (0.001)0.00010.00040.0003
CN (0.010)--0
Cr6+ (0.050)0.01100.01700.006
Cd (0.005)-0.00020.0002
Sb (0.020)0.00200.0003–0.0017

Cu: copper, Pb: lead, As: arsenic, Hg: mercury, CN: cyanide ion, Cr6+: hexavalent chromium, Cd: cadmium, Sb: antimony, -: not detection..


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Journal of Technologic Dentistry

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