title: Optimizing the procedure for mercury recovery from dental amalgam.
abstract: Mercury, as any other heavy metal, may cause environmental damages due to its accumulation and biotransformation. Dental offices, whether private or institutional, use dental amalgam as a restorative material on a daily basis. Dental amalgam is composed of mercury (50%), silver (30%) and other metals. Approximately 30% of the amalgam prepared in dental offices (0.6 g per capsule) are wasted and inadequately discarded without any treatment. Methods for mercury recovery have been proposed previously, using high temperatures through exposure to direct flame (650 degrees C), long processing time, and hazardous reagents as potassium cyanide. The purpose of this study was to develop a method to replace the direct flame by an electrical mantle in the process of mercury recovery. Results showed an average mercury recovery of 90% from 2 kg of amalgam after 30 minutes of processing time, thus optimizing the procedure. The proposed modifications allowed a significant reduction in processing time and a mercury recovery with high purity. The modified process also provided minimization of operator exposure to physical, chemical and ergonomic hazards, representing a technological advance compared to the risks inherent to the original method. It also provided environmental health and economy of energy resources by replacing a finite energy source (fossil and organic) by a more environmentally appropriate electric source, resulting in significant improvement of the procedure for mercury recovery from dental amalgam.
authors.affiliation: School of Dentistry of Bauru, University of São Paulo, Bauru, SP, Brazil.
authors.forename: Flávia Godoy
authors.initials: FG
authors.lastname: Iano
authors.forename: Ovídio dos
authors.initials: Od
authors.lastname: Santos Sobrinho
authors.forename: Thelma Lopes da
authors.initials: TL
authors.lastname: Silva
authors.forename: Marlus Alves
authors.initials: MA
authors.lastname: Pereira
authors.forename: Paulo Jorge Moraes
authors.initials: PJ
authors.lastname: Figueiredo
authors.forename: Leny Borghesan Albertini
authors.initials: LB
authors.lastname: Alberguini
authors.forename: José Mauro
authors.initials: JM
authors.lastname: Granjeiro
mesh_terms: D001938:Brazil; D003723:Dental Amalgam / Q000737:chemistry*; D003770:Dental Offices; D003793:Dental Restoration, Permanent; D018057:Dental Waste / Q000032:analysis*; D004781:Environmental Exposure / Q000517:prevention & control*; D004782:Environmental Health; D004784:Environmental Monitoring; D004785:Environmental Pollutants / Q000032:analysis; D006256:Hazardous Waste / Q000032:analysis; D006801:Humans; D017744:Medical Waste Disposal / Q000379:methods*; D008628:Mercury / Q000032:analysis* / Q000302:isolation & purification; D008630:Mercury Poisoning; D018570:Risk Assessment; D018505:Waste Management / Q000379:methods*
chemical_list: D018057:Dental Waste; D004785:Environmental Pollutants; D006256:Hazardous Waste; D017744:Medical Waste Disposal; D003723:Dental Amalgam; D008628:Mercury