Have you ever had issues with your temporaries? Of course the answer is "yes," but hopefully not too often. Not long ago, I had a patient come to me stating, “Doctor, I am really hoping YOU can get my temporary to stay on! I am here from out of town and you are the third dentist I have seen in three days, because this temporary keeps coming off.”
Interestingly, when the patient handed me the temporary, I noticed that, while it seemed thick enough, it was also cracked - which of course got me thinking, “I wonder why this is cracked and keeps coming off?”
Sure, I had some suspicions. It could have just been bad luck. Maybe he was eating things he should not be, or there was a lack of occlusal clearance.
Unfortunately, my fear that there was a lack of occlusal clearance was immediately found to be the least of the issues, as the tooth preparation was nearly in contact with the opposing tooth.
So what happened here? While we can never be 100 percent sure, I think it’s a safe bet that prior to preparation, the patient's first point of contact (FPOC) in centric relation (CR) was #31 (the tooth with the problem temporary) and #2 (the opposing tooth). Once this first point of contact was eliminated, the condyle seated more superiorly and caused a loss of occlusal clearance. Interestingly, the opposing tooth was also in a temporary, which raised the question in my mind of, “I wonder how much room there is between the two preparations?”
Unfortunately, when the upper temporary – which was actually a three-unit temporary – was removed, we found that there was not enough clearance for one crown, let alone two, as you can see in the photo.
So the question, of course is: “What the heck do we do now?”
The first thing that is clear (while very unfortunate) is that even though final impressions had been taken and the crowns made, using them would likely lead to more problems and frustration. The likely issues would include not only occlusal issues but also very thin, if not perforated, restorations by the time the crowns were adjusted. Clearly, the safest path forward would be to first find CR or at the very least a stable, repeatable and comfortable condylar position to build to.
For me, this means taking the patient through splint therapy as taught in Spear’s Occlusion in Clinical Practice workshop. Once a stable, comfortable condylar position has been found (ideally CR) we would then mount diagnostic models in that position and proceed with evaluating the models to determine just what needs to be done occlusally to move forward in a predictable manner. It’s worth noting that this evaluation could be as simple as a trial equilibration, but could also involve an orthodontic set-up and/or a diagnostic wax-up. You really just don’t know until you have the models mounted and start looking at them.
If this sounds like a bit of a nightmare, you are right. it can be, if no one - especially the patient - knew or was advised this was likely to happen. Have you ever gotten a call from your lab saying you did not reduce enough, or perhaps adjusted your temporary to the point where you created a hole and you KNOW you reduced enough tooth structure? If so, this is likely what happened.
This is EXACTLY why I like to look for a patient's FPOC - to avoid finding myself in this situation. While I am certainly NOT saying that you must always treat every FPOC and CR/CO (centric occlusion) discrepancy, I do believe that knowing the levels of risk in treating these types of cases is important.
John R. Carson, D.D.S., P.C., Spear Visiting Faculty and Contributing Author www.johncarsondds.com