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Amalgam Economic, durable, debatable

Most general practitioners continue to place amalgam restorations, and think amalgam is safe and poses no health risk to patients. They are, however, responding to widespread patient concerns and inquiries, according to recent survey results.

By Gail Weisman


Posted by dentalproducts.net. Originally published in the December 2002 Dental Products Report.

Nearly four in five general practitioners in the United States place amalgam restorations, according to the results of a September DPR survey.l That said, more than two-thirds of these dentists said they have decreased their use of amalgam during their careers (see "Amalgam use" chart). A nationwide survey by the ADA Health Policy Resources Center showed that the number of amalgam restorations placed dropped 28% from 1990 to 1999, while the number of composite restorations placed jumped nearly 80% during the same time period.

The reasons for this drop-off, and for a fifth of U.S. GPs having discontinued the use of amalgam altogether, are varied. By far, however, the most overwhelming motivation for the shift away from amalgam is esthetics—more than nine in 10 survey respondents cited patient preference for esthetic materials as a reason for decreasing or stopping amalgam use. An upcoming issue of Dental Products Report will feature an in-depth look at the profession's opinions on the amalgam controversy, examining specific issues such as mercury toxicity, waste disposal concerns, and where dentists are getting their information. The survey results highlighted here focus on amalgam usage patterns and patient viewpoints.

Amalgam still popular

It bears repeating—79% of the GPs who responded to our current survey said they offer amalgam restorations in their practices. In fact, just over one-quarter (27%) of these practitioners said that amalgam is used in more than half of the direct restorations they place (see "Amalgam caseload" chart, below). Interestingly, the next largest single group of respondents (21%) said that less than 10% of the direct restorations they place are amalgam. So while amalgam is still used in many practices, it is being used with less frequency in individual practices.

Greg Warsow, product manager for Kerr Dental's line of amalgam alloys, offered a simple explanation. "The decline in amalgam use is directly related to the rise in composites," he noted. The survey responses bear this out; 92% of those who said they stopped using or decreased their use of amalgam indicated doing so because "patients prefer composite resin for esthetic considerations."

Amalgam's pros (and con)

Warsow's statement also implies that, other than esthetics, there is nothing inherently wrong with amalgam as a restorative material. Again, our survey results show that doctors agree. Amalgam is touted most highly for its durability and more than four in five survey respondents gave amalgam an "Excellent" or "Very Good" rating in this category (see "Rating amalgam" chart below). Interestingly, the category that received the next highest rating from respondents was biocompatibility, relating to the very issue that naysayers are criticizing. The only category in which amalgam did not score highly was esthetics, which 91% of the respondents described as "Poor."

Patient concerns

While the survey respondents appear to be resolute in their support of amalgam safety, patient concerns are more prevalent. More than three-quarters of the responding GPs said one or more of their patients had asked to have functional amalgams removed for safety reasons (see "Requests to remove amalgam" chart below).

Additionally, nearly all (98%) of the respondents said that they had patients, albeit a small number, who had expressed concern over the safety of mercury in their mouths (see Are patients concerned? chart below).

What's the problem?

The basic formulation of amalgam has remained unchanged for decades. "Silver, tin, copper, and mercury," Warsow said. "It's been the same for years, with slight variations in the different percentages of these metals."

So, why hasn't a suitable replacement been found for the offending component?

"It's not for lack of trying, because there has been a lot of research done," Warsow said. "But there is no known substitute for mercury that we have found. The one non-mercury alloy that actually came to market expanded so much that it fractured teeth."

Why, then, can't the amount of mercury be reduced?

"A certain ratio of mercury to the rest of the mix is necessary to ensure the proper expansion rate and marginal seal as well as to impart a plastic, workable consistency," Warsow said.

The bulk of dental amalgam research and development efforts, Warsow noted, has had nothing to do with trying to reduce the mercury content. "Most of the science has been focused on changing the ratio of silver, tin, and copper, as well as adding other metals, such as palladium, to improve polishability and create a material with optimal, controlled expansion."

Thumbs up

"Because of its history, we believe amalgam is safe," Warsow said. "Toxicity testing is a very exact science. If a product is expected to cause some type of health problem, is it tested to rigorous standards prior to 510K approval. There has never been any scientific evidence to show that mercury-containing dental amalgam has caused any ill effects in patients."

Judging from these survey results, apparently most dentists agree. nDPR


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