Part I and Part II of this series reviewed the four common uses for the leaf gauge, separating the intent and use for each. In Part III, I will review the overlap and hopefully help the practitioner embrace the versatility of all four tools – which just happen to look exactly the same: A bunch of skinny pieces of plastic, attached at one end.
Loading the TMJ
For the TMJ to be truly loaded, the lateral pterygoid must be completely released. If any tension, tenderness or discomfort is present while using the Joint Loader Tool, one of the possible etiologies is the lateral pteryoid not releasing. But remember, if the result is a “negative load test” (no findings), there is no need to deprogram the muscle. You are done using the Joint Loader Tool and there is no need to use the Muscle Releasing Tool. If there is a “positive load test,” indicated by tension, tenderness or discomfort after having the patient move forward, backward and squeeze while keeping back teeth apart, the muscle might be the source. Yes, it is simultaneously being deprogrammed, by default, but not with intention… yet. Regardless, put the Joint Loading Tool away and get out the Muscle Releasing Tool, with intention.
Deprogramming the Lateral Pterygoid
It’s time to attempt to differentiate between the two possible etiologies of discomfort noted while using the Joint Loading Tool: Internal derangement of the joint and/or lack of release of the lateral pterygoid. But before you can, there must be an intentional attempt to deprogram. One tool that we have at our disposal (usually our first line of testing) is the Muscle Releasing Tool. So, use it. Keep the back teeth apart and have the patient slide forward and backward several times over several minutes. There’s really no need to squeeze on the Muscle Releasing Tool. You might even imagine that tool doesn’t even come with an option to squeeze. After using it, put the Muscle Releasing Tool away and get out the Joint Loading Tool again. Use as previously directed. As you can see, those two tools are often on the tray at the same time. Imagine your assistant having to pass them back and forth to you, just like the amalgam plugger and condenser, back and forth, as needed. Do you remember those? They are two different tools used for two different things that have been intentionally placed on the tray for one procedure. The Joint Loading Tool and Muscle Releasing Tool are no different.
Identifying First Point of Contact in Centric Relation
The Tooth I.D. Tool is very different from the two tools previously discussed. It can help
identify the first tooth contacting even if there is a positive load test and/or the lateral pterygoid is not deprogrammed. When “leafing down” the patient, you will eventually get to a first point of contact. I promise. It is important to acknowledge that the first point of contact may not be in a fully-seated condylar position but the tool is doing its job, facilitating the identification of the first point of contact. You now know what tooth or teeth touch first, on that day, and can continue to evaluate the degree and direction of slide from that first point and help the patient see that the system is being required to compensate. What a gift! If you want to identify a predictable repeatable first point of contact, you have two other tools that you have already used and can revert back to for further deprogramming and evaluation, or use the next tool to take a bite record. Why move to the next tool if the last three still leave some ambiguity or lack of predictability? It will allow you to better evaluate the system using an articulator and/or to fabricate an appliance to continue the evaluation and diagnosis.
Obtaining Centric Relation Bite Records
When using the Bite Holder, by default the TMJ is being loaded. At least as much as the patient’s joint anatomy, pain tolerance and lateral pterygoid will allow. The lateral pterygoid is also being deprogrammed, by default, as long as the back teeth stay apart. And that’s great news if you want a bite record that is in a fully-seated condylar position, right? Even better, when taking the record, we can verify a more predictable record by asking the patient if there is any tension, tenderness or discomfort while practicing with the patient and refining the number of leafs for the proper thickness of material. Yes, the Bite Holder can slice, dice, chop and grind. It’ll even do your dishes. But wait, there’s more! If there is no tension, tenderness, or discomfort, the odds that our models that will accurately represent the first point of contact, that the Tooth I.D. Tool helped us capture, will dramatically increase. After all, isn’t that really what this is all about?
When the leaf gauge is used intentionally for any of the four specific jobs intended and the practitioner differentiates each, it really does become one tool that can do so many things (or at least the four described in this article). But just like the Mix-o-matic (or whatever it was called), you don’t want it to slice when you push dice or chop when you want it to grind. That makes for a messy, unpredictable recipe. Keeping that in mind should make TMJ diagnosis, muscle diagnosis, occlusal diagnosis, and bite records more fun, accurate and predictable. Want to dive even deeper into clinical topics like this? Check out our clinical categories in our Course Library. Not yet a member of Spear Online? Click here to learn more.