Load testing is an important part of verifying centric relation. The purpose is to verify that your patient is in centric after you think they are there. In order to master this technique, it takes a solid understanding of how the masticatory system works and some practice through repetition.
The following are 2 common mistakes when load testing & how to fix them.
Mistake 1: Trying to Shove the Jaw into Centric
A very common mistake we see with load testing is when we try to shove the jaw back into Centric. We often see this happen when dentists are still learning and honing their skill.
Bilateral manipulation is not done to force the condyles into centric; it's to verify that you are there after you think you're already in CR. When you load test, if you still have muscle bracing, you'll get some tension or tenderness. If you have an intracapsular structural disorder, you might even get more than tenderness; you might get some pain. Either way, it tells you that your patient is not in centric. Remember, if you are forcing the jaw into centric you will not be able to verify centric nor will you be able to accurately identify an intracapsular structural disorder.
How to fix this problem
Instead of shoving the jaw back, you should be letting the jaw go into centric naturally. Think of centric as a gentle hinging, where the muscles want the jaw to naturally seat in this position. As the jaw starts to hinge freely, gradually start loading the joint to see if it can be totally free of any sign of tension or tenderness. When you get that result, that's when you take your bite record. You verify it.
Remember, you can't let the teeth touch. You keep the teeth apart as you're working, to find your centric. If you have any difficulty there, lay a cotton roll across the bicuspids, and just have the patient sit there for a few minutes. Just separating the back teeth takes away the trigger to the lateral pterygoid muscles and will make it easier for you to manipulate. You can also use an anterior deprogrammer, as we teach in our courses. Deprogamming the muscles makes it easy because those back teeth are separated and the jaw can slide back and forth.
Mistake 2: Manipulating with the Fingers Too Far Forward
Another mistake we often see with load testing is when Dentists’ fingers are way too far forward when performing bilateral manipulation.
How to fix this problem
Be sure that when you're manipulating, your little finger is behind the angle of the mandible. Too many times we've seen the dentist trying to manipulate with the fingers way forward. You've got to get them all the way to the back half of the mandible.
Think of that lateral pterygoid muscle, get a good picture of that in your mind. If it's in contraction and you're trying to stretch it out too fast, it's going to give you a stretch reflex contraction. And if you keep pushing on it, it's going to get sore and it's going to fight you more. This is why you need to be gentle in finding centric. Load very firmly to test it, but gently to find it.
For a patient with a really wide neck, or when you have difficulty getting your fingers in proper position, my advice is to make them an anterior deprogrammer. This will make your life much easier.
Final Words of Wisdom
Don't put pressure on yourself by thinking that centric relation can be achieved on every patient the first time you try.
What you're trying to determine is the health of the joint, and then to see if you can get a verifiable centric relation. It's not just about your skill; it's really just telling you that the patient has a problem that is preventing the condyles from completely seating up to centric relation. It is then you need to determine if it is an occluso muscle disorder or if it is an intracapsular disorder that is preventing the condyles from complete seating.
For more help with load testing, consider attending our hands-on course, Examination & Records.