By Dr. Lee Ann Brady
In dental practice there are situations that we find so disconcerting that
it becomes difficult to approach them rationally and scientifically to find
a resolution. One of these is when a ceramic restoration de-bonds.
Usually when this happens I become frustrated and upset, and the patient
is frustrated and upset. This makes thinking analytically challenging, but
being able to do this is critical. What I want most is to know why the
ceramic restoration came off and how to minimize or better yet eliminate
this from happening in the future. For me there is a critical “first question”
that has to be asked.
“Where is the resin cement?”
To answer the question I need to don my loupes, and I need an explorer so I can examine the tooth and the internal surfaces of the ceramic. Often being able to visualize the resin is a challenge, especially if it is translucent, and thin. The resin will turn grey when we scratch over the surface of it with an explorer, so this test can be helpful.
If when I examine the tooth, the resin is all attached to the tooth but the ceramic interface is clean I need to think about the process of bonding to the ceramic. This may mean that the ceramic was not prepared properly. Different types of ceramic require different etching times and percentages of hydrofluoric acid, or are prepared with air abrasion. The ceramic may have been contaminated with oil from our hands, saliva, blood, try in paste or die stone and not cleaned properly. The ceramic also requires conditioning with products like silane or Monobond Plus and it is this step that may have not worked properly.
What if there is no resin attached to the tooth?
If all the resin cement is on the ceramic but the tooth is clean there is a different set of options for what happened. The tooth has to be cleaned to thoroughly remove all trace of the temporary cement. Both the enamel and the dentin need to be etched, and whether using a total etch or a self etch technique this may be where the issue occurred. I also take a second look at the prep at this point and ask myself about the amount of enamel I have versus dentin, and is it secondary dentin which can be very problematic when bonding. I also may need to look at my dentin adhesive technique, making sure we followed the steps accurately and rethinking whether the tooth could have gotten contaminated during the process due to poor isolation.
Finally, sometimes there is resin on both the tooth and ceramic. In this case I rethink the occlusal forces on the tooth and the functional design. This may be a patient who has higher functional risk, or I may have missed the mark in the precision of adjusting the final occlusion. When the resin fails under load you most often find it in both locations.
Pinpointing where exactly the resin is located gives me the opportunity to target my problem solving and decrease the risk of the same technical issue happening in the future.
If you enjoyed this article by Dr. Brady you might also be interested in her article on Determining the right amount of Occlusal Reduction or her dental hack for implant access holes!