Wednesday, June 13, 2012
For a long time, composites were seen as second best in restoring posterior teeth. Pressing in a silver amalgam was the gold standard, with superior strength and wear resistance. Over the last decade, this idea has been challenged by many of the new entries to the hybrid composite market. These filling materials are stronger than ever, and actually look like tooth enamel. Flowable composites also showed promise for smaller restorations or lining a cavity preparation.
The problem was that no single type of filling material ever did the job perfectly. Silver fillings were great because they could be quickly condensed in one bulk application, no matter how deep or wide the cavity was. The problem was that you needed to further remove tooth structure to allow for proper dimensional strength of the filling. And as these fillings got larger, many seemed to turn into crowns later on in life.
Composite fillings allowed you to be more conservative with tooth structure, as well as offer a bonded, esthetic, mercury-free alternative to amalgam fillings. The problem here was that they were more technique sensitive, and, done properly, took a lot more time to place. Flowable composites certainly solved that dilemma, but were still limited on size. Tooth large and the filling suffered from excessive wear or shrinkage at the application.
Looking at all these considerations from a clinical aspect, I was drawn to a new product from Kerr called Sonicfill. At first glance, it's hard to tell if it’s a new device or a new material. In a basic sense, it is both. The idea behind the system is that you have a handpiece that connects to your existing delivery system that uses ultrasonic vibration to essentially liquefy composite resin filling material. In a very basic sense, it works like the flat vibrator you use when pouring up a stone model of an alginate impression. Shake the stone fast enough, and it begins to flow.
SonicFill Bulk Fill Dental Composite Instructional Video
While the handpiece itself is an important component, the technology behind the composite itself is the most interesting part of the system. The formulation is proprietary, but we do have some clues as to what they did when making this material. First, there are modifiers added to the composite that allow it to more easily reach that super-viscous state. This allows it to be dispensed from unidose tips with the ease of a flowable composite.
Second, they tweaked the optical properties to allow you to cure the material up to 5mm deep. While you may not do an occlusal composite that deep, you would see that depth when doing a large build-up over a root canal, or class II filling. This matters because it eliminates the need for incremental layering. Plus, less time filling means less worry of moisture contamination if you aren’t using an Isolite i2 or rubber dam.
Third, there did not seem to be a compromise on the properties of a good filling material. The resin is highly filled, has very little shrinkage (1.6%) and excellent flexural strength according to Kerr studies. This means that it will perform well without having to put a secondary capping layer to prevent excessive wear.
Of course, I am always skeptical of studies done internally at a particular manufacturer without having any backing from independent third party resources. In classic Kerr fashion, they have gone the extra mile to establish several third party clinical studies that have been able to corroborate their own findings about the material. They put it all together in a great article that has abstract summaries of all the research done to date.
Keep in mind this is only indicated for posterior restorations, but it does seem to match up with many of the best attributes we look for in other filling materials. It allows you to easy flow the material into the cavity preparation similar to a flowable composite. You can bulk fill the entire cavity the same way you would with an amalgam filling. Further, you have the ability to place a bonded, esthetic restoration without compromising on wearability or strength. Kerr has also set up a great demo program, so you can try it in your own office yourself.