Use of mercury-containing dental restorations (Dental Amalgam) in Pakistan Dr. . Fe Feroze oze Ali Kalhoro lhoro BDS, S, FC FCPS S Assoc ociate iate Profe ofessor ssor (Operative perative Dent ntistr stry) y) Principal, ncipal, Instit titut ute e of Dentistry tistry LUMHS HS Ja Jamsh shoro oro SDPI's seventeeth Sustainable Development 10/12/2014 1 Conference
Introduction & background Dental amalgam has been used for over 150 years for the treatment of dental cavities and is still used world-wide in particular, for the treatment of larger cavities due to its: • Excellent mechanical properties • Durability, • Cost-effectiveness • Less technique sensitive. • Long service • Bharti R et al. Dental amalgam: An update. J Conserv Dent. 2010 Oct-Dec; 13(4): 204 – 208. SDPI's seventeeth Sustainable Development 10/12/2014 2 Conference
Dental amalgam is a combination of silver alloy particles and mercury and contains about 50% of mercury in the elemental form. SDPI's seventeeth Sustainable Development 10/12/2014 3 Conference
Use of Dental Amalgam It constitutes 75% of all restorative materials used by dentists worldwide. • Bharti R et al. Dental amalgam: An update. J Conserv Dent. 2010 Oct-Dec; 13(4): 204 – 208 SDPI's seventeeth Sustainable Development 10/12/2014 4 Conference
About 180 million Americans are having more than one billion restored teeth and majority of these are dental amalgam • Richardson GM, Wilson R, Allard D, Purtill C, Douma S,Gravie`re J (2011) Mercury exposure and risks from dental amalgam in the US population, post-2000. Sci Total Environ 409(20):4257 – 4268 SDPI's seventeeth Sustainable Development 10/12/2014 5 Conference
Mercury issue and Dental Amalgam SDPI's seventeeth Sustainable Development 10/12/2014 6 Conference
Amalgam war In 1845, the American society of dental surgeons condemned the use of all filling materials other than gold as toxic, thereby igniting 1 st Amalgam war. • Dodes JE. The amalgam controversy-an evidenced based analysis; JADA vol.132; march 2001. SDPI's seventeeth Sustainable Development 10/12/2014 7 Conference
Controversy on the use of dental amalgam reappeared again in 1926 and into the 1930’s , when a German physician Dr. Alfred stock, demonstrated that mercury escaped from fillings in the form of dangerous vapour that could cause significant medical damage. This led to the 2 nd Amalgam war. • Dodes JE. The amalgam controversy-an evidenced based analysis; JADA vol.132; march 2001. SDPI's seventeeth Sustainable Development 10/12/2014 8 Conference
A neurobiologist Mats Hanson in 1981, started the fight against authorities and had led the 3 rd Amalgam war. • Dodes JE. The amalgam controversy-an evidenced based analysis; JADA vol.132; march 2001. SDPI's seventeeth Sustainable Development 10/12/2014 9 Conference
The Amalgam war continues to range on today. SDPI's seventeeth Sustainable Development 10/12/2014 10 Conference
Due to its common use in dental practice amalgam is major source of Hg usage. It emits the mercury and emission takes place during: • Mixing/trituration (mercury vapors) • Condensation of amalgam filling into cavity (releasing of mercury vapors into environment/air) • Chewing (increases body burden of mercury of patient) • Removal of old amalgam filling ( increases body burden of mercury of the patient) • Disposal in waste ( increases level of Hg in water, soil and air) • Autoclaving/heat sterilization of amalgam-contaminated instrument • Horsted-bindslev P. Amalgam toxicity-environmental and occupational hazards. J dent,2004.:32:359-65 SDPI's seventeeth Sustainable Development 10/12/2014 11 Conference
Among these, two are more critical situations in terms of release of mercury from dental amalgam 1. During mixing of Hg with alloy 2. During removal of old amalgam Both lead to high exposures to respirable amalgam particulate and as well as to mercury vapor • Richardson GM (2003) Inhalation of mercury-contaminated particulate matter by dentists: an overlooked occupational risk. Hum Ecol Risk Assess 9(6):1519 – 1531 SDPI's seventeeth Sustainable Development 10/12/2014 12 Conference
These vapors of mercury released from the dental amalgam can be inhaled and rapidly absorbed and distributed through out the body, accumulating in organs and fetus also. • Lorscheider FL, Vimy MJ, Summers AO (1995) Mercury exposure from ‘‘silver’’ tooth fillings: emerging evidence questions a traditional dental paradigm. FASEB J 9(7):504 – 508 SDPI's seventeeth Sustainable Development 10/12/2014 13 Conference
The mercury can also be transferred to breast milk in proportion to maternal dental amalgam load • Richardson GM, Wilson R, Allard D, Purtill C, Douma S, Gravie`re J (2011) Mercury exposure and risks from dental amalgam in the US population, post-2000. Sci TotalEnviron 409(20):4257 – 4268 SDPI's seventeeth Sustainable Development 10/12/2014 14 Conference
In the body mercury mostly target the neuron specially developing neurons and may impair the neonatal growth of the infants of mothers having amalgam restoration . • Kern JK, Geier DA, Audhya T, King PG, Sykes L, Geier MR (2012) Evidence of parallels between mercury intoxication and the brain pathology in autism. Acta Neurobiol Exp (Wars) 72:113 – 153 SDPI's seventeeth Sustainable Development 10/12/2014 15 Conference
Germany and Canada advised against the use of dental amalgam in pregnant women and children • PHS (US Public Health Service) (1993) Dental amalgam: a scientific review and recommended public health service strategy for research, education and regulation. US Department of Health and Human Services, Washington, DC • PHS (US Public Health Service) (1997) Dental amalgam and alternative restorative materials: an update report to the Environmental Health Policy Committee. US Department of Health and Human Services, Washington, DC SDPI's seventeeth Sustainable Development 10/12/2014 16 Conference
Chronic mercury exposure The mercury is excreted from the body through urine and feces. With the time the elimination may be slow down due to disturbance in the function of detoxification enzyme this lead to increase retention of mercury in the body and may cause unpredictable toxicity. • Mutter J, Naumann J, Sadaghian C, Walach H, Drasch G (2004) Amalgam studies: disregarding basic principles of mercury toxicity. Int J Hyg Environ Health 207(4):391 – 397 • Mutter J, Naumann J, Guethin C (2007) Comments on the article , ‘the toxicology of mercury and its chemical compounds’ by Clarkson and Magos (2006). Crit Rev Toxicol 37:537 – 549 SDPI's seventeeth Sustainable Development 10/12/2014 17 Conference
• There is no question that dental amalgam release Hg. But whether the amount of released mercury is at safe level or not ? • And whether the safety threshold differs among subpopulations? • Berlin M, Zalups RK, Fowler BA(2007) Mercury. In:Nordberg G, Fowler RA, Nordberg M, Friberg LT (eds) Handbook on the toxicology of metals, 3rd edn. Academic Press, Burlington SDPI's seventeeth Sustainable Development 10/12/2014 18 Conference
Risk assessment According The World Health Organization the typical absorbed dose of mercury from amalgams is 1 – 22µ per day ,and most of people are suffering from less than 5 micrograms per day • IPCS (International Programme on Chemical Safety) (2003) Elemental mercury and inorganic mercury compounds: human health aspects. World Health Organization, United Nations Environment Programme SDPI's seventeeth Sustainable Development 10/12/2014 19 Conference
The FDA believes that the actual exposure is 1 – 5 µg/d in its current amalgam rule [PHS 1993 (as cited in FDA 2009)]. The level is well below to cause any adverse effect SDPI's seventeeth Sustainable Development 10/12/2014 20 Conference
The Exposure variables may include: • Total amalgam surface area. • Physical and chemical composition of the amalgam. • Mechanical stresses of chewing and bruxism • Oral conditions of temperature & pH SDPI's seventeeth Sustainable Development 10/12/2014 21 Conference
Mercury vapors US Environmental Protection Agency (EPA) provides a reference concentration (RfC) for chronic mercury inhalation of 0.3µ/m3 or /day, which was set in 1995 (EPA 1995). • EPA (US Environmental Protection Agency) (1995) Mercury, elemental: reference concentration for chronic inhalation exposure (RfC). In: Integrated risk information system. US Environmental Protection Agency.http://www.epa.gov/iris/subst/0370.htm#revhis. Accessed 26 Dec 2013 SDPI's seventeeth Sustainable Development 10/12/2014 22 Conference
Mercury vapors Where as the California Environmental Protection Agency (CaLEPA) gives the reference exposure level (REL) for chronic mercury inhalation of 0.03 µg/m3 or /day — which was set in 2008, • CalEPA (California Environmental Protection Agency) (2008) Mercury. In: Mercury reference exposure levels: technical support document for noncancer RELs, Appendix D.1.F. Office of Environmental Health Hazard Assessment SDPI's seventeeth Sustainable Development 10/12/2014 23 Conference
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