Mercury vapor volatilization from particulate generated from dental amalgam removal with a high-speed dental drill – a significant source of exposure

Abstract

Background The ubiquitous use of dental amalgam for over 180 years has resulted in the exposure of millions of dental workers to mercury. Dental amalgam contains approximately 50% mercury. Dental workers, including dentists, dental assistants, and dental hygienists, have been shown to have increased levels of mercury and suffer more from health issues related to mercury exposure than the general public. Mercury is known to be absorbed via inhalation or through the skin. There are many routine dental procedures that require the removal of dental amalgam by using the dental high-speed drill, which we suspected generates an occupational mercury exposure that is not sufficiently recognized. Results We showed that drilling dental amalgam generates particulate that volatilizes significant amounts of mercury vapor generally for more than an hour after removal. The levels of mercury vapor created by this procedure frequently exceed the safety thresholds of several jurisdictions and agencies. Conclusions A significant, underrecognized source of localized exposure to mercury vapor was identified in this study. The vapor was created by microgram levels of particulate generated from dental amalgam removal with a high-speed dental drill, even when all feasible engineering controls were used to reduce mercury exposure. This exposure may explain why dental workers incur health effects when safety thresholds are not breached. The dispersion patterns for the particulate are not known, so the use of effective skin barriers and inhalation protection are required during amalgam removal to protect the dental worker from this form of occupational mercury exposure. Standard methodologies for occupational mercury exposure assessment appear to be inadequate when assessing mercury exposure during amalgam removal. Electronic supplementary material The online version of this article (10.1186/s12995-019-0240-2) contains supplementary material, which is available to authorized users.

An Emphasis on Engineering Controls and Administrative Controls in the Prevention and Control of COVID-19 in an Orthodontic Setting: Thinking Beyond Tomorrow

“…Extraoral vacuum aspiration devices, which mimic industrial fume extractors, have been used in dentistry to eliminate or reduce mercury vapor fumes in the Safe Mercury Amalgam Removal Technique, smoke plumes in electrosurgery and laser surgery, and dust in air abrasion dental procedures. 76-80 When used in conjunction with infective aerosol, there are two problems: one of infection control between patients and the other of moisture gathering at the receptacle and dripping. A simple workaround would be to use an autoclavable spittoon funnel or cup in conjunction with an extra HVE suction line.…”

“…For an operation theatre, the normal recommendation is for 12 ACH, under the assumption that the operation theatre is not going to be used for backto-back procedures. [76][77][78][79][80] When used in conjunction with infective aerosol, there are two problems: one of infection control between patients and the other of moisture gathering at the receptacle and dripping. A simple workaround would be to use an autoclavable spittoon funnel or cup in conjunction with an extra HVE suction line.…”

Sources and Toxicity of Mercury in the San Francisco Bay Area, Spanning California and Beyond

“…Elemental mercury comprises about 50% of these amalgams by weight [ 60 ]. Mercury is the only metal in a liquid state at room temperature, allowing it to bind well with the powdered alloy [ 61 ].…”

“…Studies such as the Children's Amalgam Trials suggest that exposure through dental amalgams can be deleterious to those who possess susceptible genes. In addition, there is evidence that the use of mercury containing amalgams may be affecting dentists, dental hygienists, and their assistants as well as patients: “Dental workers have higher levels of mercury as measured in blood, urine, stool, nails, hair, and organs” [ 61 ].…”

Effects of Removal Conditions on Mercury Amount Remaining in the Oral Cavity and inside Drainage System after Removing Dental Amalgams

“…In fact, the use of dental amalgam is limited in some countries [ 1 , 2 , 14 , 26 , 27 ]. However, there would be many chances to remove dental amalgams because they have been used for almost two centuries [ 28 ].…”