A better understanding of individual susceptibility to dental disease and variation in treatment outcomes will allow the dental field to move forward. Image: Shutterstock

A new study suggests that personal patient factors influence the chance of dental filling failure, rather than the choice of filling material.

— By Conn Hastings

New research shows that people who drink alcohol or men who smoke are more likely to suffer a failed dental filling. The research team also found that a genetic difference in some patients is associated with increased filling failure rates. In contrast, no major difference in filling failure rates were observed between traditional amalgam and newer composite resin fillings. The results, published in open-access journal Frontiers in Medicine, suggest that genetic analysis might help dentists to personalize treatments for their patients, which could lead to improved outcomes.

Most people will have had a tooth filled at some point. While many patients dread the dentist, having to go back again because a filling has failed, can quite literally be a pain. Fillings can fail for a variety of reasons, including reemergence of the initial tooth decay or the filling becoming detached. So, how can we prevent filling failure? Does it depend on the filling material?

Dentists commonly use two different types of filling material. One is the amalgam filling, commonly used for over 150 years and composed of a mixture of metals including mercury, which is toxic. While there is no conclusive evidence that amalgam fillings cause health problems in patients, several countries have banned them nonetheless.

A newer alternative is the composite resin filling. Composite fillings are more expensive and more difficult for dentists to insert, but they look better, and are non-toxic.

So far, the jury is out on whether composite fillings are as durable as amalgam fillings, but could differences between patients themselves, such as lifestyle choices and even genetic differences, also affect filling failure?

To investigate this, researchers from America and Brazil accessed a large repository of dental records from a dental school in Pittsburgh, which contained information on patient fillings, and rates of failure up to five years after the filling procedure. The repository also contained information about patient lifestyles, including smoking and drinking habits, and a DNA sample from each patient.

By analyzing the data, the team found that overall, there were no major differences between patients receiving amalgam or composite fillings in terms of filling failure rates. This suggests that composite fillings are at least as durable as amalgam fillings, and offer a viable alternative with no toxic ingredients.

The team went on to investigate patient lifestyle factors that could affect the failure rate of composite fillings. They found that within two years of the procedure, fillings failed more often in patients who drank alcohol, and the overall filling failure rate was higher in men who smoked.

Finally, using the patient DNA samples, the researchers looked for genetic differences between patients whose composite fillings had failed and those whose hadn’t. Strikingly, they found that a difference in the gene for matrix metalloproteinase (MMP2), an enzyme found in teeth, was linked to increased filling failure. The researchers hypothesize that MMP2 might be able to degrade the bond between the filling and the tooth surface, potentially leading to failure.

While this link and preliminary hypothesis are intriguing, the researchers have not yet confirmed if these differences in the MMP2 gene are responsible for failed fillings, and will need to investigate this further. However, 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.

“A better understanding of individual susceptibility to dental disease and variation in treatment outcomes will allow the dental field to move forward,” says Alexandre Vieira, a researcher involved in the study. “In the future, genetic information may be used to personalize dental treatments and enhance treatment outcomes.”

Original research article: A Pragmatic Study Shows Failure of Dental Composite Fillings Is Genetically Determined: A Contribution to the Discussion on Dental Amalgams

Corresponding author: Alexandre Vieira

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