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
오선미
동남보건대학교 치기공학과
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
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.
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
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.
오선미
동남보건대학교 치기공학과
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
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.
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
Table 1 . Classification of samples and characteristics.
Classification of samples | Samples no. | Sample characteristic |
---|---|---|
Basic water sample group | Sample 1 | Tap water |
Sample 29 | Wastewater (hand cream+soap+tap water) | |
Sample 2 | Mixing gypsum (model plaster+dental stone+high strength stone) made by company(A) | |
Sample 30 | Sample 29+mixing gypsum | |
Sample 31 | Density change test of sample 2 for 30 day later | |
Mixing gypsum group | Sample 41 | Model plaster sample made by company(A) |
Sample 44 | Model plaster made by company(N) | |
Sample 47 | A model plaster made by company(O) | |
Sample 48 | B model plaster made by company(O) | |
Sample 63 | Model plaster made by company(N) (7 test item) | |
Model plaster group (type II) | Sample 42 | Yellow dental stone sample made by company(A) |
Sample 45 | Yellow dental stone sample made by company(N) | |
Sample 50 | Yellow dental stone sample made by company(P) | |
Sample 51 | White dental stone sample made by company(P) | |
Sample 52 | Brown dental stone sample made by company(R) | |
Dental stone group (type III) | Sample 53 | Green dental stone sample made by company(R) |
Sample 62 | Yellow dental stone sample made by company(N) (7 test item) | |
Sample 66 | Yellow dental stone sample made by company(P) (7 test item) | |
Sample 70 | Yellow dental stone sample made by company(U) | |
Sample 43 | High strength stone sample made by company(A) | |
High strength stone test group (type IV) | Sample 46 | High strength stone sample made by company(N) |
Sample 49 | High strength stone sample made by company(PA) | |
Sample 61 | High strength stone sample made by company(N) (7 test item) | |
Sample 68 | High strength stone sample made by company(A) (7 test item) | |
Sample 28 | Trimming mixing gypsum made by company(A) | |
Trimming test group | Sample 64 | Trimming model plaster sample made by company(N) |
Sample 65 | Trimming high strength stone sample made by company(N) | |
Sample 67 | Trimming dental stoner made by company(P) | |
Sample 69 | Trimming high strength stone sample made by company(A) | |
Sample 71 | Trimming dental stone sample made by company(U) |
Table 2 . Test item to water quality.
Test item | Water quality standard (mg/L) |
---|---|
Cu | 0.100 |
Pb | 0.010 |
As | 0.010 |
Hg | 0.001 |
CN | 0.010 |
Cr6+ | 0.050 |
Cd | 0.005 |
Sb | 0.020 |
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 1 | 0.00160 | 0.00020 | 0.00030 | - | 0.00300 | 0.00200 | - | 0.00010 |
Sample 29 | 0.01540 | 0.00330 | 0.00020 | - | 0.00400 | 0.00200 | - | 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 kind | Model plaster | Dental stone | High strength stone | Mixing 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) | - | - | - | - | - | - | 1.5298 | 0.0043 | - | - | - | 0.0022 | - | 0.0002 | 0.0700 |
Pb: lead, -: not detection..
Table 5 . Test result table of gypsum kind by maker.
Test item (standard) | Model plaster | Dental stone | High strength stone | Mixing 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) | - | 0.00300 | 0.00300 | 0.00200 | 0.00200 | 0.0050 | 0.00490 | |||
As (0.010) | - | - | - | - | - | - | 0.00004 | |||
Hg (0.001) | - | - | - | - | - | - | 0.00011 | |||
CN (0.010) | - | - | - | - | - | - | - | |||
Cr6+ (0.050) | 0.01100 | 0.00400 | 0.00900 | 0.00400 | 0.01000 | 0.0040 | 0.01100 | |||
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 plaster | Dental stone | High strength stone | Mixing gypsum | |||||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Before | After | Before | After | Before | After | Before | After | Before | After | Before | After | ||||||||||||
Sample 63 | Sample 64 | Sample 66 | Sample 67 | Sample 70 | Sample 71 | Sample 61 | Sample 65 | Sample 68 | Sample 69 | Sample 2 | Sample 28 | ||||||||||||
Cu (0.100) | - | 0.0040 | 0.0030 | 0.0290 | 0.0020 | 0.0030 | 0.0020 | 0.0040 | 0.0050 | 0.0180 | 0.0049 | 0.0022 | |||||||||||
Pb (0.010) | - | - | 1.5298 | 2.7300 | - | 0.0100 | - | 0.0100 | 0.0022 | 0.0100 | 0.0670 | 0.1345 | |||||||||||
As (0.010) | - | 0.0100 | - | - | - | - | - | - | - | - | 0.0004 | 0.0017 | |||||||||||
Hg (0.001) | - | - | - | - | - | - | - | - | - | - | 0.0001 | –0.0004 | |||||||||||
CN (0.010) | - | - | - | - | - | - | - | - | - | - | - | 0.0060 | |||||||||||
Cr6+ (0.050) | 0.0110 | 0.0090 | 0.0090 | 0.0130 | 0.0040 | 0.0030 | 0.0100 | 0.0100 | 0.0040 | 0.0030 | 0.0110 | 0.0070 | |||||||||||
Cd (0.005) | - | - | - | - | 0.0002 | - | - | - | - | - | - | - | |||||||||||
Sb (0.020) | - | - | - | - | - | - | - | - | - | - | 0.0020 | 0.0086 |
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) | 0.01540 | 0.00490 | 0.02030 | 0.00770 | 0.01260 |
Pb (0.010) | 0.00330 | 0.06700 | 0.07030 | 0.08570 | –0.01540 |
As (0.010) | 0.00020 | 0.00040 | 0.00060 | 0.00120 | –0.00060 |
Hg (0.001) | 0.00046 | 0.00011 | 0.00057 | –0.00046 | 0.00100 |
CN (0.010) | 0.00400 | - | 0.00400 | 0.00100 | 0.00300 |
Cr6+ (0.050) | 0.00200 | 0.01100 | 0.01300 | 0.01400 | –0.00100 |
Cd (0.005) | - | - | - | - | - |
Sb (0.020) | 0.00030 | 0.00200 | 0.00230 | 0.00120 | 0.00110 |
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) | 0.0049 | 0.0041 | –0.0008 |
Pb (0.010) | 0.0670 | 0.0487 | –0.0183 |
As (0.010) | 0.0004 | - | –0.0004 |
Hg (0.001) | 0.0001 | 0.0004 | 0.0003 |
CN (0.010) | - | - | 0 |
Cr6+ (0.050) | 0.0110 | 0.0170 | 0.006 |
Cd (0.005) | - | 0.0002 | 0.0002 |
Sb (0.020) | 0.0020 | 0.0003 | –0.0017 |
Cu: copper, Pb: lead, As: arsenic, Hg: mercury, CN: cyanide ion, Cr6+: hexavalent chromium, Cd: cadmium, Sb: antimony, -: not detection..
Sun-Kyoung Lee
Journal of Technologic Dentistry 2024; 46(4): 182-188 https://doi.org/10.14347/jtd.2024.46.4.182Sun-Kyoung Lee
Journal of Technologic Dentistry 2024; 46(4): 174-181 https://doi.org/10.14347/jtd.2024.46.4.174Jae-Kyung Ryu, Nam-Joong Kim, So-Min Kim, Sun-Kyoung Lee
Journal of Technologic Dentistry 2024; 46(2): 42-48 https://doi.org/10.14347/jtd.2024.46.2.42