Do you prefer cement-retained or screw-retained restorations?
Chances are you have a strong preference for one or the other. While both have their own advantages and disadvantages, the truth is you really need to be comfortable with both.
There is a simple reason for this: While you may love screw-retained restorations, they just are not always esthetically acceptable. Picture trying to close a screw access hole for a restoration in the maxillary anterior that comes through the facial. On the other hand, picture trying to remove the cement around a cement-retained restoration on a maxillary second molar on a patient with limited access.
So what’s the problem with cement and implants? It really boils down to the fact that if your patient is susceptible to her or his plaque, then any residual cement you leave behind may result in peri-implantitis. If you are saying, “Yes, but I have been doing cement-retained implant restorations for years and not had a problem,” you need to realize it can take eight years for peri-implantitis associated with cement to become evident. Add to this the fact that studies show that as a whole we as dentist are not nearly as good as removing residual cement as we think. Now we really have trouble.
(Click here for a course on treatment planning for implants.)
So what are we to do? Here are some tips to help:
1. Do screw retained restorations when you can.
Yes, they can take longer to delivery, but the screw access hole can be closed esthetically. There is no real downside other than this, and the gains are huge in eliminating any chance of residual cement. Also, your restoration will be much easier to retrieve should you ever need to remove it.
(Click here to see why implant restoration screws become loose.)
2. Keep your margins shallow when you have to cement.
Never place your margins more than 1 mm sub-gingival and, if possible, make them supra-gingival.
3. Use cement that’s easy to remove and radiopaque.
For me this means I do not want to use any resin cement. The easy ones (at least the ones I have tried) are harder to clean up than a RMGI. The key here is to wait until the right time to remove the cement. I would rather start a little late than start too early. If you start too early, you just end up smearing it around and making a mess that’s even harder to clean up.
4. Take post-operative radiographs.
The idea here is to both look for any residual cement and document the bone levels at the time of delivery.
5. Make your restoration cleansable.
If you can’t get to your cement, not only can you not clean it but your patient can’t either. If your patient is susceptible to his or her plaque, you and your patient are doomed. Take for example the cement-retained restoration here that I removed from a patient's mouth.
Even though the patient and dental office had a chance to get around things to clean, it is evident they still did not get a great job done.
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Now imagine how bad things could be if you had a non-cleanable cement-retained restoration. You might be left with stuff like this around your restoration.
(For more articles by Dr. John Carson, click here.)
John R. Carson, DDS, PC, Spear Visiting Faculty and Contributing Author www.johncarsondds.com