We rely on our teeth for chewing several times a day, everyday of our lives. Many of us also subject our teeth to harsher habits such as clenching and grinding or chewing unforgiving materials like ice. Of course, our teeth may also become damaged during accidents. As if that wasn’t enough, our teeth are also vulnerable to the biological breakdown that occurs when bacterial plaque creates acid that degrades tooth structure (i.e. tooth decay).
Any dental intervention designed to reestablish tooth structure lost to any of these risks falls under the broad category of Restorative Dentistry. Restorative Dentistry is defined as the study, diagnosis and integrated management of disease of the teeth and their supporting structures and the rehabilitation of the dentition to the functional and aesthetic requirements of the individual.
How are teeth restored?
Dental restorations fall into 2 main categories:
Direct Restorations are fillings that are directly attached to surrounding tooth structure in a prepared cavity or adjacent to a chipped/fractured surface during a single dental appointment. Fillings are made from 2 different substances: dental amalgam (silver fillings) and composite resin (tooth-colored fillings).
Dental amalgam has been used for more than 150 years throughout the world. It consists of liquid mercury (50% by weight) and a powdered alloy composed primarily of copper, silver and tin. The chemical properties of elemental mercury allow it to react with and bind the copper/silver/tin alloy particles together to form an amalgam.
Benefits: Dental amalgams are strong and long-lasting.
Potential Risks: Dental amalgams require more tooth reduction than composite fillings. Analogous to concrete, amalgam is vulnerable to cracking if it’s thin. Therefore, to be used at a successfully adequate thickness, a dentist must create a larger hole to retain the material and in the process, remove even healthy tooth structure adjacent to the decay. This removal, in turn, weakens overall tooth structure and increases the need for future dental work. This material also tends to expand and contract and thus can cause teeth to fracture, especially when the fillings are large and the surrounding tooth structure has become thin. Because dental amalgam consists of elemental mercury, there has been a growing concern regarding the toxicity of this material in the body.
Are Dental Amalgams Safe?
Historically, this material was considered inert, not releasing mercury vapor once the filling was placed. In recent years, this has been shown to be incorrect. Small amounts of mercury vapor are released during placement and removal of these fillings, as well as during chewing or teeth grinding. This vapor is then ingested or absorbed by the body and bioaccumulates. Mercury is a neurotoxin and pro-amalgam dentists are placing it approximately one inch from the brain. High levels of mercury vapor exposure are linked to adverse effects in both the brain and kidneys.
Children, the fetuses of pregnant women, hypersensitive individuals, and people with kidney impairments are particularly vulnerable to the neurotoxic effects of dental mercury. In 2010, the U.S. Food and Drug Administration warned against the use of amalgam in vulnerable populations and insisted that they had a duty to disclose amalgam’s risks to consumers. Many countries around the world are working to protect vulnerable populations, especially children, from amalgam exposure and several countries have already banned its use.
From an environmental standpoint, dental offices are the second largest consumer of mercury, and this toxin pollutes:
- WATER, not only via dental offices, but also human waste (amalgam is by far the largest source of mercury in our wastewater);
- AIR, via body cremation, dental clinic emissions and sludge incineration;
- LAND, via landfills, burials, and fertilizer.
Once in the environment, dental mercury converts to its even more toxic form, methylmercury, and finds its way into the fish people eat. More and more U.S. lakes and rivers have posted warnings regarding dangerous mercury levels in fish.
Our Dental Amalgam Philosophy
Even with all of the substantiated science supporting the health risks of dental amalgam, the American Dental Association still claims that there isn’t enough evidence to conclude it’s harmful. We believe that this stance is politically driven. Regulatory agencies require that this material be safely stored in hazardous waste containers and when we remove it from our patient’s mouths, it must again be safely stored in hazardous waste containers. Even the amalgam sediment in our vacuum lines is filtered into a separate storing cartridge and thus reduces the amount that ends up in our wastewater. How can the storage and disposal of this material have such strict guidelines, yet once in the mouth, it’s deemed not hazardous?
We believe that there are safer materials that can be placed more conservatively and esthetically than dental amalgam. Therefore, we haven’t placed a dental amalgam filling since 2004 and do not store this material in our office. We believe that all patients owe it to themselves to get educated about dental amalgam and to make informed choices regarding this material. We respect our patient’s decisions to keep or remove their dental amalgam fillings based on their individual beliefs regarding the effect of this material on their overall health.
Composite is a combination of plastic and glass components that produce a tooth-colored filling.
Benefits: With continued technological advances, composite is more and more esthetic and bonds better to adjacent tooth structure. Unlike amalgam, it doesn’t require a bulky preparation site and thus it makes for a much more minimally invasive option. Because it’s chemically bonded to tooth structure, it can be used to repair chipped teeth and even to cosmetically enhance appearance by closing spaces between teeth or by reshaping teeth.
Potential Risks: Because fillings in general are a mechanical fix in a biological environment, they are vulnerable to the effects of bacterial invasion and decay. Because composites are chemically bonded to tooth structure, those bonds can break down with time and these fillings can begin to leak and be reinvaded by bacteria, leading to recurrent decay.
Indirect restorations include inlays, onlays, crowns, bridges and veneers. These restorations are made of materials that tend to be much more durable than direct filling material. They are composed of ceramics (porcelain) and gold alloys. Most inlays, onlays , crowns and bridges are made of ceramics (porcelain) or gold alloy-reinforced ceramics. They can also be fabricated totally of gold alloy. Where gold is know for its resiliency and biocompatibility, it’s fallen out of favor for a lot of patients due to its compromised esthetics.
Inlays are similar to fillings and fit inside the cusp tips (top edges) of the tooth;
- Onlays are more extensive and extend over the cusps of the treated tooth, much like crowns, but don’t extend to the gumline as crowns do;
- Crowns are tooth-shaped “caps” that are placed over teeth to cover the tooth to restore its shape, size, strength and often their appearance. When cemented into place, crowns fully encase the entire visible portion of a tooth that lies at and above the gumline;
Bridges serve to bridge the gap between one or more missing teeth. They are typically composed of two or more crowns for the teeth on either side of the gap with the false tooth/teeth in between and the entire unit is cemented in place;
Veneers are thin laminates, typically of porcelain, that are bonded over the front surface of teeth much like a press-on fingernail. To be bonded successfully, there must be an adequate amount of remaining enamel after preparing the tooth. Therefore, veneers serve as conservative options to restore primarily front teeth to a preferred shape, color and overall beauty and to improve smile appearances.
Indirect restoration procedure
During the first visit, Dr. Schweifler prepares the tooth/teeth, makes an impression (mold) of the area to be treated and then fabricates a temporary restoration to seal the prepared areas. The impression is then sent to a dental laboratory where a technician fabricates the final restoration. At a second visit, typically 2-3 weeks later, Dr Schweifler cements or chemically bonds the restoration to the prepared tooth/teeth and adjusts as needed.