The Pros and Cons of Dental CementsBy John Carson on April 11, 2023 | comments
Do you ever stop and think about the cements you use? Understanding the pros and cons of dental cements will allow you to pick the right cement for the right application.
While I am sure most of us have our go-to dental cement (I am all for simplifying and streamlining things, too), it is good to revisit our choices from time and time and think about what cement we are picking, why, and the ramifications of our choices — choices that can affect outcomes not only when we are delivering restorations but also down the road. Those “down the road” consequences can include things like restorations coming loose, sensitivity, or even restoration failure.
In this article, I will cover the pros and cons of the three main dental cement categories and some of the things to think about with each. Keep in mind, however, that there is no “magic” cement that can eliminate all the possible issues you may have from time to time, as many issues stem from other causes like improper isolation (moisture control), occlusion issues, or preparation design. While some cements can help make up for shortcomings in areas like these, they can’t fully overcome them.
The Pros and Cons of the “Main Three” Dental Cements
Let’s look at what I would consider the three main groups of definitive or “permanent” cements:
1. Luting Cements
These are cements like Resin Modified Glass Ionomers (RMGIs) such as RelyX luting™ or FujiCEM 2™ and zinc phosphate cements. Yes, I know the mention of zinc phosphate dates me, but it is still in use. In my opinion, the clear choice in this category is almost always an RMGI, as it is much simpler to use. Also, since the liquid in zinc phosphate is acid, there is a higher potential for sensitivity, especially if not mixed ideally.
- Very easy to use, especially in the case of RMGIs that use auto-mix tips.
- Moisture tolerant, at least more so than some other choices.
- Easy clean-up, especially with RMGIs.
- Low sensitivity potential with RMGIs.
- Easiest removal of restorations in the future should they require replacement.
- Works well on altered tooth structure.
- The least retentive of the three categories; requires the most preparation.
- Not indicated for use with lower strength all-ceramic restorations—feldspathic, for example.
- Limited working time.
2. Self-Adhesive Resin Cements
These are cements like RelyX ™; Unicem 2 or PANAVIA™ SA Cement Universal. They are typically supplied in an auto-mix delivery system of some sort and require no separate etching, priming, or bonding of the tooth preparation.
- Very easy to use — nearly, if not as easy, as the easiest RMGI cements.
- Moisture tolerant like RMGI cements.
- Low sensitivity potential but perhaps more sensitivity potential than RMGI cements.
- In most cases, easier clean-up than resin cements that use separate adhesive components.
- Easier removal of restorations in the future should they require replacement compared to resin cements that use separate adhesive components.
- Perhaps slightly less preparation retention required compared to luting cements.
- Tend to work well on altered tooth structure, but perhaps not as well as luting cements.
- Not indicated where the highest bond strengths are desired, for instance, with veneers.
- Typically, more difficult clean-up than with luting cements.
- Harder removal of restorations in the future should they require replacement than with luting cements.
- Good preparation retention is still needed for the best outcomes.
- Limited working time.
- May not be color-stable.
3. Resin Cements That Use Separate Adhesive Components
These are resin dental cements like RelyX ™ Veneer Cement or PANAVIA™ Veneer LC. These come in both dual-cure and light-cure-only options. Typically the light-cure-only options are used for thinner, more translucent, restorations like veneers while the dual options are for thicker, more opaque, restorations in which you may not get adequate light penetration to fully set light-cure-only options.
- The most retentive option.
- Indicated for all all-ceramic restorations.
- Unlimited working time with light-cure-only options.
- Light-cure options are typically color-stable (some dual-cure options are as well).
- Greatly affected by altered tooth structure.
- Require excellent moisture isolation.
- Some are very technique sensitive.
- Working time can end abruptly.
- Clean-up can be difficult.
So, if we look at these pros and cons (and yes, I am sure we could come up with some more in each group), how do we pick? If most of the marketing out there is to be believed we need the “strongest” or “easiest” every time, right? Putting aside the fact that typically “strongest” and “easiest” do not often go together (despite our wishing they did), I am going to argue that maybe we do not always have to opt for “strongest”— in fact, many times we are better off not to. In many cases, maybe we need to think more about our choices.
For example, do we really need to use a resin cement (from either of those categories discussed above) with a gold crown? I would say in nearly every case the answer is no. I am sure we could come up with an instance when it might make some sense, but at best such a situation would be rare. In most cases, we would be making things much harder than we have to, for no real gain.
Another example is when we are thinking about zirconia that is a high-strength variant. (I specify a high-strength version because not all zirconias are the same strength — in fact some are only about as strong as e.max from Ivoclar or GC Initial® LiSi Press, and we have to treat those differently.) But for the high strength zirconias, I would say that since physically they are much like gold restorations, we are often better off luting them, as it is a simpler process at delivery and makes things easier if we ever have to remove or cut off the restoration to re-treat the tooth.
I mentioned lower-strength zirconia, e.max, and LiSi Press — so what about those? If we know luting these is out, then that leaves us with a resin cement from one of the other two categories. This is where we really owe it to ourselves to think about our options. I would argue that if we have good preparation resistance and retention, coupled with proper restoration thickness, then we are typically better off with a self-adhesive resin cement. Not only will this make things simpler now, but it will also make replacing the restoration in the future slightly easier if that becomes necessary. And let’s face it — if the patient lives long enough, restorations will likely have to be replaced at some point.
That leaves us with the option of when to use resin cements with a separate adhesive. For me, this is typically done in the case of a minimal thickness restoration and/or with non-retentive preparations such as veneers.
Now that you know the pros and cons of dental cements, it doesn’t have to be about using the same go-to choices every time. I hope this article has given you some fresh insight and new things to think about.
John R. Carson, D.D.S., is a member of Spear Visiting Faculty and a contributor to Spear Digest.