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.”

We've all seen temporaries fall 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


Comments

Commenter's Profile Image S. Gavin E.
March 7th, 2016
Interesting and complicated situation. If you are doing a single crown and this situation occurs how can you handle the case without redoing the occlusion throughout the mouth. Might have a hard time convincing patients to go from a single crown to a rehab. Also if the patient was asymptomatic at the beginning of treatment how come you cant just build a new crown with the same point of first contact that the natural tooth had which will then get them to slide into their previous MI.
Commenter's Profile Image John C.
March 8th, 2016
Great questions and yes it can be complicated! First off we do our best to ID this risk PRIOR to prepping. If we see this is a risk then we talk to the patient about the risks and benefits of both working with the occlusion "as is" and improving it. While improving it and reducing the risk of this means more dentistry is quite often only means an equilibration, not a full rehab. Your correct for sure that going from one crown to a bunch more stuff can be tough however IMO it is tougher to explain why problems are occurring like this if you don't have the conversation, we talk about that a lot in the occlusion workshop. As far as building in the old FPOC I am not a fan of this as not only do I feel there is no perfect way to do this, even if you digitally copy the tooth before you start, as we all know there is some level of error in everything we do but more importantly even if they are asymptomatic nearly all these teeth are beat up and breaking down due to the fact they are the FPOC so why would we want to build in early failure in a new restoration??