Do Your Fillings Prevent Cavities?

How often do you wish your fillings did more than fill the hole that once was a cavity? Researchers have now come up with a new preventative measure against recurrent decay.  In today’s dentistry there are several types of restorative materials used; such as gold, silver, and nickel alloys for indirect restorations and amalgam or composite resins for direct. For the sake of simplicity, the focus of this article is centered around direct restorations that utilize amalgam and composite resin.

Amalgam alloy restorations are commonly known as the metal or silver fillings. Composed of silver, tin, and mercury, amalgam has a long history of use in the field of dentistry due to its longevity and ability to withstand a wide range of clinical placement conditions.  While amalgam is a dependable restoration material, patients are increasingly turning to composite resins for aesthetic and environmental purposes.

When in comparison, composite resins or commonly known as white fillings, do not have the longevity of amalgam alloys. Advantages are found in other aspects such as reduced tooth structure loss during caries removal, aesthetic purposes as previously mentioned, and stronger bonding capabilities with the surface of the tooth.

Due to advances in the field of dentistry, composite resins are typically considered the primary choice of restorative material by many dentists for direct restorations.  In a study published December 2013 by “Reactive & Functional Polymers”, researchers explored the viability of bacteria resistant composites by adding antibacterial properties to composite resin component.  Resin material is made up of three primary components; a polymerizable resin matrix, silane coupling agents, and glass filler particles.  In layman’s terms, the polymerizable resin matrix is what holds composite material together.  If you were to look at a carbon fiber part, the resin matrix would resemble the clear material known as epoxy of which serves to give shape to the part and provide support for the carbon fiber fabric within.  The next component, silane coupling agents, are what provide a stable bond between organic and inorganic components of the composite.  Another example in layman’s terms is how silane coupling agents are similar to the adhesive effect of superglue bonding your hand to a piece of plastic.  Lastly, glass filler particles are used to strengthen the composite while reducing the amount of matrix material. 

To achieve the desired results, the researchers took two approaches.  The first approach utilized a release mechanism within the filler component that allowed antibacterial agents such as sodium fluoride to diffuse into the adjacent tissue of the filling to proactively prevent recurrent decay.  The second approach utilized silver supported fillers as a non-release mechanism.  This approach focused on the silver component of the filler disrupting the outer cell membrane of harmful bacteria.

In conclusion, the study determined that out of the two agent release mechanisms, non-released anti-bacterial agents proved most efficient.  In comparison released anti-bacterial agents often were only effective short term and often resulted in a loss of structural integrity due to leaching of material from within the filler of the composite.  Non-released agents retained structural integrity while providing long lasting antimicrobial action against several bacteria such as Streptoccus mutans, Staphylococcus epidermidis, and E. coli.  Complete inhibition of the aformention bacteria strains was accomplished by 2% w/w (mass percentage) of which was accomplished by the disruption of outer membrane of the cell thus leading to necrosis.

Beyth, N., Farah, S., Domb, A. J., & Weiss, E. I. (2013). Antibacterial dental resin composites. Reactive and Functional Polymers, 75, 81. doi:10.1016/j.reactfunctpolym.2013.11.011