The advent of adhesive dentistry in the 1950s was a boon to the dental profession. The availability of composite resin formulations, often coupled with bonding agents, enables clinicians to place tooth-colored fillings, which by most esthetic standards, beat the heck out of silver fillings. In addition, their placement is less invasive than that of amalgam, which requires the removal of enough tooth structure to allow mechanical retention.
Composite dental materials are typically based on a resin matrix — such as bisphenol A-glycidyl methacrylate or urethane dimethacrylate — with the addition of inorganic fillers. Fillers may range from silica and glass to ceramics and crystalline quartz. Since their debut on the dental scene, composite products — which may be light-cured, self-curing or both — have featured numerous variations in filler particle densities, shapes and sizes. All of these factors influence material characteristics from esthetics to polymerization shrinkage.
But nailing down the best characteristics in one formulation has been challenging. For instance, early macrofills featured large filler particles that not only lacked good polishability, but also exhibited a tendency toward “plucking,” or having particles pop out, leaving a rough, pitted surface. Not a therapeutically desirable outcome, and also not a good look for most people.
Subsequently, microfills boasted a low-filler content composed of fine particles. Unfortunately, they lacked the ability to withstand posterior compressive forces, although top-drawer polishability and stain resistance earned them favor in anterior applications.
The Nanohybrid Composite Resin
Nanohybrid composite resin incorporates nanoparticles (usually under 100 nm) of materials such as silica and zirconia — even diamonds — into more conventional fillers. Alternately, nanofilled composites are highly filled with all nanoparticles and nanoclusters of varying sizes and shapes.1Sachdeva S, Kapoor P, Tamrakar AK, Noor R. Nano-composite dental resins: an overview. Ann Dent. 2015;3:52–55. 2Pocket Dentistry. Introduction to Composite Restorations. Available at: https://pocketdentistry.com/8-introduction-to-composite-restorations/. Accessed September 10, 2018.
Joining today’s product lineup are nanohybrid composites endowed with bioactive properties. These not only are designed to deliver excellent esthetics, but also help protect teeth against caries, and foster remineralization, allowing minimally invasive treatment of early-stage caries. In fact, dental materials endowed with antibacterial properties are currently in the works.3Dental Equipment. New Dental Materials Resists Plaque and Kills Microbes. Available at: http://www.identfoshan.com/index.php?c=article&a=detail&id=20. Accessed September 10, 2018.
Numerous key opinion leaders see such materials that prevent plaque formation and help teeth rebuild themselves as the wave of the future.4Stone R. Hole truths. Mentor. 2017;8(10): 32-34.
There is still disagreement about the precise definition of “bioactive” when it comes to dental materials. Some believe that glass ionomer materials, which release fluoride ions fall into this category. Others contend that in order to earn that classification, a material must precipitate apatite through not just the release of fluoride, but also calcium and phosphate. 5Stone R. Hole truths. Mentor. 2017;8(10): 32-34.
But after several generations of composite resin materials, there’s little disagreement that when viewed through a broad lens, composite materials, placed with care, offer a wealth of patient-pleasing riches.
Speaking of care, when it comes to adhesive dentistry, following manufacturer directions is key, in addition to isolation and moisture control. In fact, many composite materials can be seriously compromised by exposure to moisture. Of course, dental dams can be of great help in this respect. But comprehensive systems, such as the Isolite 3, furnish not only moisture control and isolation of the field of operation via a comfortable yet transparent mouthpiece, but also continuous suction, illumination and retraction of oral tissues, all while preventing aspiration of dental materials by the patient. It’s almost like having an extra assistant.
Of course, each practitioner must choose the composite resin material that works best in his or her hands. But it’s easy to see that, when viewed through a broad lens, composite materials, placed with care, offer a wealth of patient benefits. Thanks to improved characteristics, they not only blend into natural dentition, but help protect it from the ravages of bacteria and time.