Determination of Mercury in Dental Hard Tissue: An in Vitro Study

ORIGINAL ARTICLE
Nexhmije Ajeti, Violeta Vula, Miranda Stavileci, Lindihana Emini

 
International Journal of Biomedicine. 2022;12(4):601-605.
DOI: 10.21103/Article12(4)_OA14
Originally published December 5, 2022

Abstract: 

The purpose of this study was to determine the levels of mercury in hard tissue from dental amalgam fillings under in vitro conditions.
Methods and Results: The study included 30 human teeth that were extracted for various clinical reasons. The teeth were stored in a physiological solution until they were used. The teeth were divided into 3 experimental groups: Group 1 (n=10) – occlusal surface cavity preparation (class I according to Black); Group 2 (n=10) – proximal-occlusal surface cavity preparation (class II); and Group 3 (n=10) – mesio-occlusal-distal [MOD] surface cavity preparation. Each of these groups was divided into 2 subgroups: subgroup 1 (n=5) – amalgam fillings were not polished, and subgroup 2 (n=5) amalgam fillings were polished. The teeth were filled with amalgam, and those in subgroups 2 were polished after 24 hours. The amount of mercury released from the amalgam fillings was determined 9 months after the teeth were filled. Before chemical analysis, the teeth were irrigated 4 times over a period of 10 minutes in an ultrasonic bath. From each tooth, 250mg of the powder was mineralized with royal water (HCl+HNO3 in a ratio of 1:3) in a microwave oven, for 54 minutes. After mineralization, the samples were filtered and analyzed with inductively coupled plasma optical emission spectrometry. The average mercury level after polishing the amalgam filling was significantly smaller (P=0.032) only in Group 1. The average mercury levels in the 3 groups revealed significant differences between both the unpolished samples (one-way ANOVA F = 69.54, P < 0.001) and the polished samples (one-way ANOVA F = 110.54, P < 0.001). Group 3 with MOD surface cavity preparation was characterized by the highest mercury levels.
Conclusion: The teeth with an MOD amalgam restoration are characterized by the highest mercury levels. The more mercury is released from unpolished amalgam fillings than from polished amalgam fillings in teeth with occlusal surface cavity preparation (class I according to Black).

Keywords: 
dental fillings • amalgam • mercury • polishing
References: 

1. Mutter J, Naumann J, Sadaghiani C, Walach H, Drasch G. Amalgam studies: disregarding basic principles of mercury toxicity. Int J Hyg Environ Health. 2004 Sep;207(4):391-7. doi: 10.1078/1438-4639-00305.
2. Mercury Air Quality Guidelines - Second Edition. WHO Regional Office for Europe, Copenhagen, Denmark, 2000. Available from: https://www.euro.who.int/__data/assets/pdf_file/0004/123079/AQG2ndEd_6_9...
3. US Food and Drug Administration. Information for Patients About Dental Amalgam Fillings. Content current as of: 09/24/2020 Available from: https://www.fda.gov/medical-devices/dental-amalgam-fillings/information-...
4. Skare I, Engqvist A. Human exposure to mercury and silver released from dental amalgam restorations. Arch Environ Health. 1994 Sep-Oct;49(5):384-94. doi: 10.1080/00039896.
5. Sweeney M, Creanor SL, Smith RA, Foye RH. The release of mercury from dental amalgam and potential neurotoxicological effects. J Dent. 2002 Jul-Aug;30(5-6):243-50. doi: 10.1016/s0300-5712(02)00040-4.
6. Berglund A. Release of mercury vapor from dental amalgam. Swed Dent J Suppl. 1992;85:1-52.
7. Bahari M, Alizadeh Oskoee P, Savadi Oskoee S, Pouralibaba F, Morsali Ahari A. Mercury release of amalgams with various silver contents after exposure to bleaching agent. J Dent Res Dent Clin Dent Prospects. 2016 Spring;10(2):118-23. doi: 10.15171/joddd.2016.019.
8. Rotstein I, Dogan H, Avron Y, Shemesh H, Steinberg D. Mercury release from dental amalgam after treatment with 10% carbamide peroxide in vitro. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2000 Feb;89(2):216-9. doi: 10.1067/moe.2000.102160.
9. Azarsina M, Kasraei Sh, Masoum T, Khamverdi Z. Effect of surface polishing on mercury release from dental amalgam after treatment 16% carbamide peroxide gel. J Dent (Tehran). 2011 Winter;8(1):33-8.
10. Mutter J. Is dental amalgam safe for humans? The opinion of the scientific committee of the European Commission. J Occup Med Toxicol. 2011 Jan 13;6(1):2. doi: 10.1186/1745-6673-6-2.
11. Neghab M, Choobineh A, Hassan Zadeh J, Ghaderi E. Symptoms of intoxication in dentists associated with exposure to low levels of mercury. Ind Health. 2011;49(2):249-54. doi: 10.2486/indhealth.ms1214.
12. Leopold K, Foulkes M, Worsfold P. Methods for the determination and speciation of mercury in natural waters--a review. Anal Chim Acta. 2010 Mar 24;663(2):127-38. doi: 10.1016/j.aca.2010.01.048.
13. Brune D, Eoje DM. Man’ mercury loading from a dental amalgam. Sci Total Environ. 1985; 44(1): 51-63. doi: 10.1016/0048-9697(85)90050-6
14. Toledo Bello L, Aparecida du Ana P, Santos D. Mercury Amalgam Diffusion in Human Teeth Probed Using Femtosecond LIBS. Appl Spectrosc. 2017;4:659-69. doi: 10.1177/0003702816687572
15. Toumelin-Chemla F, Lasfargues JJ. Unusual in vivo extensive corrosion of a low-silver amalgam restoration involving galvanic coupling: a case report. Quintessence Int. 2003 Apr;34(4):287-94.
16. Marek M. Dissolution of mercury from dental amalgam at different pH values. J Dent Res. 1997 Jun;76(6):1308-15. doi: 10.1177/00220345970760061101.
17. Rotstein I, Avron Y, Shemesh H, Dogan H, Mor CH, Steinberg D. Factors affecting mercury release from dental amalgam exposed to carbamide peroxide bleaching agent. Am J Dent. 2004:17(5):347-50.
18. Brownaell AM, Brent S, Brent RL, et. al. The potential adverse health effects of dental amalgams. Toxicol Rev. 2005;24:1-40. doi: 10.2165/00139709-200524010-00001.
19. UNEP 2008 annual report. Available from: https://www.unep.org/fr/node/12277
20. Harris HH, Vogt S, Eastgate H, et. al. Migration of mercury from dental amalgam through. J Synchrotron Radiat. 2008; 15(2): 123-8. doi: 10.1107/S0909049507061468.
21. Han DH, Lim SY, Sun BC, Janket SJ, Kim JB, Paik DI, Paek D, Kim HD. Mercury exposure and periodontitis among a Korean population: the Shiwha-Banwol environmental health study. J Periodontol. 2009 Dec;80(12):1928-36. doi: 10.1902/jop.2009.090293.
22. Mahler DB, Adey JD, Fleming MA. Hg emission from dental amalgam as related to the amount of Sn in the Ag-Hg (gamma 1) phase. J Dent Res. 1994 Oct;73(10):1663-8. doi: 10.1177/00220345940730101201.
23. Boyer DB. Mercury vaporization from corroded dental amalgam. Dent Mater. 1988 Apr;4(2):89-93. doi: 10.1016/s0109-5641(88)80097-6.
24. Marek M. The effect of tin on the corrosion behavior of the Ag-Hg phase of dental amalgam and dissolution of mercury. J Dent Res. 1990 Dec;69(12):1786-90. doi: 10.1177/00220345900690120101.
25. Berdouses E, Vaidyanathan TK, Dastane A, Weisel C, Houpt M, Shey Z. Mercury release from dental amalgams: an in vitro study under controlled chewing and brushing in an artificial mouth. J Dent Res. 1995 May;74(5):1185-93. doi: 10.1177/00220345950740050701.
26. Warwick R, O'Connor A, Lamey B. Mercury vapour exposure during dental student training in amalgam removal. J Occup Med Toxicol. 2013 Oct 3;8(1):27. doi: 10.1186/1745-6673-8-27.
27. Dérand T. Mercury vapor from dental amalgams, an in vitro study. Swed Dent J. 1989;13(5):169-75.
28. Bolsoni LE, Almeida RP, Viniia D, Panzeri H. [Emission microspectrometric study of the amalgam restoration-tooth interface]. Rev Odontol Univ Sao Paulo. 1990 Oct-Dec;4(4):289-92. [Article in Portuguese].
29. Pleva J. Mercury poisoning from dental amalgam. J Orthomolecular Psych. 1983;12:184-193.
30. Gay DD, Cox RD, Reinhardt JW. Chewing releases mercury from fillings. Lancet. 1979 May 5;1(8123):985-6. doi: 10.1016/s0140-6736(79)91773-2.
31. Canay S, Cehreli MC, Bilgiç S. In vitro evaluation of the effect of a current bleaching agent on the electrochemical corrosion of dental alloys. J Oral Rehabil. 2002 Oct;29(10):1014-9. doi: 10.1046/j.1365-2842.2002.00934.x.
32. Björkman L, Lind B. Factors influencing mercury evaporation rate from dental amalgam fillings. Scand J Dent Res. 1992 Dec;100(6):354-60. doi: 10.1111/j.1600-0722.1992.tb01086.x.
33. Oyapero A, Awotile A, Adenuga-Taiwo O, Enone L, Menakaya I. Managing Amalgam Phase Down: An Evaluation of Mercury Vapor Levels in a Dental Center in Lagos, Nigeria. Journal of Dental Research and Review. 2017; 4(1):4-8.
34. Marshall SJ, Marshall GW Jr. Dental amalgam: the materials. Adv Dent Res. 1992 Sep;6:94-9. doi: 10.1177/08959374920060012401.
35. Fredin B. Mercury release from dental amalgam fillings. Int J Risk Saf Med. 1994;4(3):197-208. doi: 10.3233/JRS-1994-4303.
36. Shinada K, Ueno M, Konishi C, Takehara S, Yokoyama S, Zaitsu T, Ohnuki M, Wright FA, Kawaguchi Y. Effects of a mouthwash with chlorine dioxide on oral malodor and salivary bacteria: a randomized placebo-controlled 7-day trial. Trials. 2010 Feb 12;11:14. doi: 10.1186/1745-6215-11-14.
37. Siblerud R, Mutter J. An Overview of Evidence that Mercury from Dental Fillings may be an Etiological Factor in Many Health Disorders. Journal of Biomedical Research & Environmental Sciences, Environmental contamination atmospheric chemistry. 2021;2(6): 472-85.
38. Haley BE. The relationship of the toxic effects of mercury to exacerbation of the medical condition classified as Alzheimer’s disease. Med Verit. 2007;4:1510-24. doi: 10.1055/s-2007-959237.
39. Paknahad M, Mortazavi SM, Shahidi S, Mortazavi G, Haghani M. Effect of radiofrequency radiation from Wi-Fi devices on mercury release from amalgam restorations. J Environ Health Sci Eng. 2016 Jul 13;14:12. doi: 10.1186/s40201-016-0253-z.
40. Hahn LJ, Kloiber R, Vimy MJ, Takahashi Y, Lorscheider FL. Dental "silver" tooth fillings: a source of mercury exposure revealed by whole-body image scan and tissue analysis. FASEB J. 1989 Dec;3(14):2641-6. doi: 10.1096/fasebj.3.14.2636872.

Download Article
Received October 4, 2022.
Accepted November 12, 2022.
©2022 International Medical Research and Development Corporation.