The Best of Both: Testing out GC America’s  2-Bottle G2-BOND System

Rohde,Jeff;

I have been using the same 2-bottle bonding system for more than 10 years. There are 2 reasons for that. The first is that I like the chemistry allowing me to have confidence in the reliability of the bond. The second is that I have zero patients coming back in to say they are sensitive from these restorations. As dentists, we rarely like changing, especially when it’s working. But we also owe it to ourselves and patients to consider new technology as it emerges, ensuring we are using the absolute best product for our patients and our practices. This was my discovery with a new 2-bottle bonding system from GC America, their G2-BOND Universal.

To understand why we made the switch at my practice, let’s look at the science behind 2-bottle systems, what G2-BOND Universal is doing differently, and what we experienced using the product in live clinical settings.

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Beyond all the hype around what “generation” your bonding system belongs to, bonding systems have essentially been distilled down to 1-bottle or 2-bottle systems. The essential challenge facing any bonding system is to get an artificial, hydrophobic material such as composite resin and bond it to a biological, hydrophilic material such as dentin. One-bottle systems certainly do well in bridging this gap, but will tend toward being either slightly hydrophilic or slightly hydrophobic. This creates a reduction in shear and tensile bond strength, with reduced interaction at the tooth for hydrophilic bonds, or reduced interaction at the composite for hydrophobic. For “Dual H” technology of G2-BOND Universal, bottle number 1 is hydrophilic to maximize its bond to dentin, while bottle number 2 is hydrophobic to maximize the bond to composite.

In choosing a bonding system, it seems like we have also gotten lost in the weeds in what etching technique we prefer to use. I have preferred self-etching systems because they reduce the chance of desiccating the dentin from drying in a total-etch technique, giving me better bonds and reduced sensitivity. The first bottle of G2-BOND Universal isn’t so much a “primer” as much as it’s a first layer of wetting, protecting the collagen for a complete bond. It also has 4-MET, MDP, and MDTP components, which allows it to act as a primer for zirconia, alumina, and most metals. This all effectively eliminates the technique sensitive application of where and how to etch, enabling a mild self-etch, or allowing for a total-etch on any unprepared enamel.

After the application of bottle 1, bottle 2 adds the chemistry of Bis-GMA and dimethacrylates for a strong interaction with composite resin. In previous bonding systems, I would still add a thin layer of flowable composite on all dentin to further seal and prevent sensitivity. With each new layer, however, there is a chance for polymerization shrinkage, creating internal stress in the restoration. The thickness of the layers of G2-BOND Universal creates a more complete seal, allowing it even to be used as a base in deeper preparations. What this does is create a shock absorbing layer that prevents debonding. I can reliably now skip the layer of flowable, and open up possibilities of using bulk fill materials as well.

One additive to many bonding systems is HEMA, or 2-Hydroxyethyl methylmethacrylate. It is often used to assist with wetting of the dentin, enabling infiltration into tooth structure after etching. It’s also used as a co-solvent when separating hydrophilic and hydrophobic stages. The problem, however, is that HEMA is often a bit too hydrophilic, attracting water to the hybrid layer in bonding. Eventually this can lead to earlier degradation of that hybrid layer, potentially causing staining along the margin or reduced flexural strength. We have all seen that Class V restoration that eventually has brown, stained margins a few years after placement. G2-BOND Universal was specifically formulated to be HEMA free to prevent this specific complication.

The system itself comes with the 2 bottles, 2 bottle covers that are clearly marked “1” and “2”, some brushes, and a disposable double dappen dish. The bottles themselves are easy to drip without over dispensing. Any end tufted brush will work but their brushes pick up a nice amount of material without globbing it on. First, apply whatever etch you feel comfortable with. You brush on the first bottle (primer) and wait for 10 seconds for the self-etching to be done. Air dry, and then brush on bottle 2 (bond) and thin with air to create a uniform layer. It coats well and you don’t need to over brush the material. Light cure for 10 seconds and you are ready to place your restoration. That is really all there is to it. Compared to a 1-bottle technique, you are trading only 10 seconds for the primer, and gaining all the benefit of the 2-bottle chemistry.

Once applied, G2-BOND Universal can be used with almost any restoration, covering direct restorations, light cured core build-ups, or cementation of indirect restorations using resin light cured cements. One of my favorite applications is to use it for immediate dentin sealing. Once prepared, place G2-BOND Universal per instructions and you get a seal over the dentin that massively reduces post-operative sensitivity and provides comfort if the patient is not anesthetized for final placement. It can also be used to perform repairs of ceramic, zirconia, composite, and metal-based restorations.

The good news is that GC has done a ton of research to prove everything from stain prevention to bond strengths. In making any decision for our patients and our practice, it is important to look at the science and make solid choices based on that science. With G2-BOND Universal, GC America has done a great job creating a product based on solid thinking and structured research. At the same time, the product is also easy to use with broad applications and very little technique sensitivity. It’s refreshing to see a product that not only is based in science but has considered the impact on the clinicians themselves.