Composites, Matrix Systems, and Curing Lights
Amanda Seay, DDS, AAACD
Together, composites, matrix systems, and curing lights allow clinicians to give patients the durable, high-quality restorations they need, but there are multiple variables that can affect the longevity of the restoration. By fully understanding and considering the options for each, clinicians can choose the ones that work best together and also benefit the patient the most.
Composite resins are a popular restorative option in dentistry today. Although the effort to create the “perfect” material is ongoing, significant improvements have been made in composite resin systems.
Today’s composites have dozens of shade options, including opaque and translucent shades. The end result is the ability to create highly esthetic composite restorations that disappear within the tooth structure.
Another essential improvement is their filler particles. While composites with smaller particles have more wear, the combination of different size particles in the new nanofilled composites have low-wear properties. In addition, modern composites have significantly lower polymerization shrinkage, the ability to maintain a high polish, and improved handling properties.
Microfilled composites are translucent and very polishable, making them highly esthetic. They are most commonly used as a veneering material, acting as the last thin layer placed over a microhybrid composite.
Microhybrid composites demonstrate excellent physical characteristics with improved handling and less wear than microfilled composites. They are used for anterior and posterior restorations, and have long been considered a “universal” composite material.
Nanofilled composites offer properties similar to microhybrid composites, and have similar polish and gloss retention to microfilled composites. Nanofilled composites have demonstrated excellent strength and wear properties, have favorable handling characteristics, and are highly esthetic. Some manufacturers are now incorporating nanosized particles into their formulations, resulting in the creation of another composite category, the “nanohybrid.”
While polymerization shrinkage can be a concern with composite resins, most current microhybrid and nanohybrid composites only have a polymerization shrinkage from 2% to 3.5%. With the goal to minimize shrinkage to the greatest possible extent, some manufacturers are introducing low-shrinkage materials. With further research to find new chemistry and improve composite resin restorations, their clinical use will likely increase as well.
An excellent matrix system is critical for the clinical success of a Class II composite restoration. Composite matrix bands have varying thickness, width, size, and contour, and can allow you to work more quickly and effectively.
Advanced matrix systems, which enable a more predictable Class II composite restoration, consist of a sturdy ring clamp that helps to obtain close adaptation of the matrix to the prepared tooth and provides separation between the teeth. This allows for a consistently tight proximal contact. In addition, these systems provide an anatomically correct matrix band that allows for proper emergence angles and placement of the proximal contact in the proper area of the tooth.
New-generation systems may include wedges, adjacent tooth guards, instruments, and retainer rings or clips, which hold the bands in place during the procedure and can also be used as a rubber dam clamp.
System selection depends on location within the mouth and the amount of remaining tooth structure. Circumferential matrix systems are suited for larger restorations that extend buccally or lingually beyond the line angles of a cusp. Sectional matrix systems may be preferred for smaller restorations because they offer visibility and access, reduced flash, and don’t require forced wedging. Additional features include bands that are translucent to allow use of a curing light, or those that are non-reflective and high-contrast, which is advantageous under bright light sources.
Balancing flexibility with rigidity, the technological improvements offered by today’s matrix bands enhance adaptation and predictability—the foundation for optimal results.