The Effects of Dental Amalgam on the Environment
The disposal of dental amalgam, specifically the mercury component, has become a controversial topic in the past twenty years. Due to the concern this issue brings, many studies have taken place regarding the effect of mercury on the environment and in humans.
Amalgam is the most common material used in restorative dentistry due to its low cost, ease of use and stability (Chin et al., 2000). The basic ingredients include silver, tin, copper and mercury. Mercury is the most abundant component in amalgam and can be toxic in different forms, such as dust or vapor (Drummond, Cailas & Croke, 2003).
Amalgam waste is generated during placement and replacement of restorative materials. There are two types of amalgam waste: contact and non-contact amalgam. Contact amalgam includes amalgam that has been in contact with the tooth surface. Non-contact amalgam includes excess material that was either not placed in the restoration or left in the capsule that the amalgam came in. Contact amalgam accounts for the majority of the contaminants in dental waste water, while non-contact amalgam is recyclable and can be used for refinement (Drummond et al., 2003)
Non-contact amalgam is not considered to be a health hazard if stored and recycled properly. The mercury component can be hazardous in a dust or vapor form. To prevent detrimental effects from the vapor, amalgam should be stored in an airtight container. This scrap amalgam should also be stored in a liquid, which will prevent the breakdown of amalgam into its components. Water is the most common liquid used but radiographic fixer is considered to be more effective for amalgam storage and the prevention of degradation (Chin et al., 2000).
Contact amalgam is the main component of dental waste water and the primary source of concern for environmental contamination. This heterogeneous mixture of liquids and amalgam particles enters into waste water treatment plants and then into lakes and streams. Studies show that the amalgam particles settle in this heterogeneous mixture. These particles can range from 3 millimeters (mm) to 0.01mm in size (Jokstad & Fan, 2006).
There are several separating techniques based on gravitational pull that can be beneficial in removing the particles before they enter the environment via waste water (Drummond et al., 2003). The American Dental Association (ADA) recommends using amalgam separators to aid in the collection of amalgam particles. Some types of separators include filtration, centrifuge, chemical removal and sedimentation. The sedimentation technique is the most commonly used separator. This technique allows the particles to settle and then the water is removed using a low-volume pump (Jokstad et al., 2006). The specific gravity of amalgam is ten times that of water which allows this technique to work (Batchu, Rakowski, Fan & Meyer, 2006).
Amalgam separators can remove anywhere from 40-80...