Dentists need to make many judgment calls when performing Class II restorations: Is shade-matching necessary? Is isolation critical? What types of materials should be used for fillings and as a bonding agent? All of these questions are complicated by clinical challenges, like fidgety patients and bleeding.
Fortunately, there are ways to simplify Class II restorations. Dr. Sam Simos, a dentist based in Chicago, Illinois, shared his insights recently with Henry Schein at our webinar, "Slay the Class II Restoration: Better Bonding, Better Materials, Better Strategy." Here are some key takeaways.
When confronted with sticky clinical situations, many dentists tend to look at the "top of the iceberg." It is important to start from the bottom up and understand that everything builds on itself.
Adhesives are a key part of a dentist's foundation of knowledge. Adhesion, to go back to basics, is an exchange process where minerals are removed from the tooth through etching, and then replaced by a resin monomer. This can be done by an etch lens, self-etch or glass ionomer approach. The longevity of the adhesive depends on the quality of the formed hybrid layer within the smear layer. Adhesives rely on light, with all dental curing lights being blue, so having a good curing light is essential to their longevity.
The smear layer consists of everything that lays on top of the surface of the dentin. Some dentists call the smear layer a biological Band-Aid because it covers up part of the dentin. While it does limit bond strength, it also reduces fluid from the underlying dentin.
When choosing an adhesive, it is important to consider its overall strengths and limitations, along with its compatibility with dual cure or self-cure core buildup material. Core buildup materials can be used when it is not possible to properly place a crown because there is not enough healthy tooth left. Building up the core of the tooth with a resin or plastic composite makes it easier to keep the crown in place. Dual cure materials are helpful in situations where dentists want to ensure that any material being filled too deep for light curing will still be set correctly. Self-curing materials are often used in areas inaccessible to a curing light. Let's look at two major categories of adhesives that are relevant to restorations.
Total etch adhesives: In today's dentistry, where quadrant dentistry is increasingly common, or dentists are doing deeper fillings and have to move more quickly in workflows, total etch adhesives can be very effective. Using the right adhesive can help to mitigate the challenges in using total etch in moist situations, where it "competes" with water. Dentsply Sirona's Prime&Bond elect® Universal Dental adhesive works well in these scenarios.
Self-etch adhesives: Made with acetone, adhesive and a water carrier, these adhesives are easy to use. They can be applied in all etch techniques, whether they are self-selective, or total etch, and have consistently high bond strength. The seventh generation of this adhesive is universal, meaning it can be used in both self-selective and total etch.
After you know what adhesive you will use, it is time to select your bulk-fill materials. When choosing bulk-fill materials, it is important to select one that can reach every nook and cranny and have a depth of cure. Keep in mind: A flowable material can create bubbles and leave voids in the cable surface area, so it is not ideal for the proximal box. However, in those situations, other options such as Dentsply Sirona's SureFil® SDR® flow+ work very well.
A resin-based composite or glass ionomer is an option for patients seeking an amalgam-free, natural-looking alternative. Composites can also work, but they require complete isolation, or they won't bond. However, many glass ionomers aren't indicated for permanent restorative material. There are a number of different matrix systems that dentists can use to work with them, including Palodent® 360 and Paolodent® Plus. Note: Palodent 360 is a matrix.
Selecting your capping material is the next step. The capping material TPH Spectra® ST, made by Dentsply Sirona, is a composite using micro-filler technology. Other makers of filler technology include 3M and Ivoclar. However, they use a square or oddly-shaped filler. Ivoclar introduced an oddly-shaped filler, and 3M improved on it. Dentsply Sirona improved on it even further with shade-matching, offering five universal cloud shades that match very effectively because of its filler technology. For example, you can be in the A1, B1 or C1 with just A1, which helps reduce the amount of material on your shelves to four or five shades. Plus, its product is not sticky and flows easily.
Successful Class II restorations can be challenging. Dentists need to make critical decisions about what materials to use, whether shade-matching is necessary and if isolation is needed. Having up-to-date knowledge of adhesives, bulk-filling basics and capping materials can help ease the process and save time. And, as these materials keep evolving and improving over time, many aspects of Class II restorations will become easier and easier.
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