Reliable Adhesion to a Non-Retentive Preparation
The groundbreaking 3M Scotchbond Universal Plus Adhesive and 3M RelyX Universal Resin Cement work together to provide exceptional bond strength
There was a time not too long ago when root canal treatment would automatically lead to a crown restoration. That's because we didn’t know any better or have today's adhesive materials. Today, we have the ability to work with advanced materials that allow us to treat cases more conservatively and confidently. The case featured here is a good example of one where there was simply no need to grind away at existing tooth structure unnecessarily to seat a crown.
A 26-year-old healthy female presented with several older restorations that needed to be replaced. Tooth No. 18, in particular, was a challenge. The patient had extremely tall pulp horns and the restoration had affected the pulp.
To begin treatment, a root canal treatment was performed by an endodontist, and the patient then presented to me for the restoration. Instead of seating a crown over the root canal, we decided to take a more conservative approach with an onlay. Had we chosen a crown, we would have had to remove about twice as much tooth structure, and that would only weaken the tooth. With the right adhesive materials and technique, we would be able to keep most of the existing enamel and bond a ceramic onlay in place that blends in with the other natural teeth and functions perfectly.
A Conservative Restoration
After sealing off the root canal and preparing the tooth, you can see that most of the buccal side is gone. On the lingual side, I tried to maintain as much tooth structure as possible during preparation. (Figure 1) Next, I etched the enamel with the 3M Scotchbond Universal Etchant. (Figure 2) I then applied 3M Scotchbond Universal Plus Adhesive over the composite base on the etched enamel. I used a Teflon tape to protect the adjacent tooth from sticking to the onlay, per the instructions for use. (Figure 3)
I seated the onlay with 3M RelyX Universal Resin Cement. I typically remove the excess with a Benda Brush (Centrix) because the long bristles don’t get into the margin space. (Figure 4) After wiping off the excess, I compressed it in place and then light-cured before removing excess cement. (Figure 5) Here, you'll see the final restoration after cementation (onlay courtesy of ceramist Aram Torosian, CDT, MDC). At this point, I typically use a No. 12 scalpel for finishing because it provides an easy access between teeth. The cement has a consistency that is easy to flick off with the scalpel blade. After flossing for verification, we’re good to go. (Figure 6)
A New Level of Adhesion
As you can see, I rely completely on the adhesion provided by the bonding agent and the cement, because there is zero retention on that preparation. With a non-retentive surface, it is critical to use a bonding system that is predictable—I know it will bond every time, and I know that it will give me enough bond strength. I can say with confidence that the next time the patient eats something chewy, for example, this restoration will be strong enough to hold. The patient can be expected to enjoy a strong, natural-looking restoration that will endure for years to come.
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GO-TO PRODUCTS USED IN THIS CASE
