One of the most common defenses of mercury amalgam fillings you still hear these days is that they last so much longer than tooth-colored composites. This statement from Delta Dental is typical:
With more durable resin material available for only a decade, resins haven’t stood the test of time in teeth where grinding and chewing result in heavy wear; by contrast, the durability of amalgam fillings is well documented — the average life span of amalgams is 8 to 10 years, but many last 20 years or more.
Considering that those fillings continuously release toxic mercury vapor, longevity is hardly a virtue here.
But we digress.
While this durability argument may have held true back in the early days of composite, new research shows that today’s materials can hold their own against amalgam.
Consider the study on fillings published just last week in Frontiers in Medicine. Wanting to see why some fillings fail, researchers screened nearly 5000 patient records from the University of Pittsburgh School of Dental Medicine and looked at the outcomes of over 8000 fillings.
A few factors seemed to make failure more likely: smoking , tobacco use, alcohol use, and a difference in the gene for matrix metalloproteinase (MMP2). This is an enzyme found in teeth that can degrade all kinds of proteins in the extracellular matrix secreted by cells. The new research suggests that it may be able to degrade the bond between a filling and its tooth surface, as well.
Either way, as noted in a news release on the study,
the results suggest that personal factors for each patient appear to influence their chance of filling failure, rather than the filling material their dentist used.
And here’s where things get interesting. “Our data,” note the authors,
also show that direct composite resins perform similarly (and maybe slightly better) to amalgam in posterior teeth up to 5 years and are suitable substitutes for their metallic counterparts, making it feasible to completely replace amalgam in dentistry. The justification of using amalgam due to its lower costs alone in contrast to the potential of eliminating an environmental hazard has become harder to support now that direct composite resins can perform at acceptable levels.
They go on to emphasize that most of the composites placed were by beginning dentists – a fact that also speaks to the virtues of modern composites.
The statistically significant lower failure rate of posterior composite resin versus amalgam restorations with 5 years follow-up in our study, despite the fact that direct composite resins are more technique sensitive than amalgam, further suggest that the first can replace the latter.
In our view, toxicity concerns alone are enough of a reason to stop using this out-of-date material, with respect to personal and environmental health alike. These latest findings only stress the fact that there’s no good reason to stick with this material. There are better options out there.
Those are the ones we choose to use in our practice.
Originally posted 2017-11-16 07:01:34.