The bite registration is the most important step in any appliance that changes the relationship of the upper teeth to the lower teeth. You are in effect providing the patient with a temporary biting position that must be in harmony with all of the components of the masticatory system or the patient will not have comfort. And treatment will fail.
Every patient has a range of acceptance for treatment and it varies considerably. Some patients can accept anything you put in their mouth while others accept nothing. This is based upon a number of factors:
- Do they have pre-existing muscle problems? Conditions such as Fibromyalgia (FM) and Chronic Myofascial Pain (CMP) have tight muscles by definition! UARS patients are particularly prone to muscle pathology including CMP!
- Are they psychologically stable? Claustrophobic patients have a harder time with oral appliances than controls. Patients that deal poorly with stress are also harder to treat if they suffer from panic attacks in the night
- Do they have healthy TMJ? You really need to check and document this before placing an appliance! But what should you be concerned with? If a patient opens 45mm -52mm with a straight opening pathway (mandible does not deviate to one side when open wide) you are fine to treat them. They should have 1/4 of this measurement in lateral movements to left and right as well as in protrusive. In protrusive, the mandible should slide forward without deviating to one side.
- Clicking TMJ are a fact of life. More than 85% of a given population have clicking in their TMJ yet only about 10-15% are symptomatic. What Is important is the timing of the click. An early click indicates that the disk is dislocated when biting, but quickly reduces to normal positioning when they open, and remains in normal position throughout most of the opening/closing cycle, only to slip off just before the teeth occlude. The later the click, the more damaged the ligaments that hold the disk onto the condyle are stretched. Patients with late opening/ early closing clicks are the riskiest to treat. When the bite registration is taken, great care must be made to ensure the disks are on the condyles or at least in a passive position. Don’t forget as well that disks do not just dislocate posteriorly, they also go medially.
- Are they taking a SSRI or SSNRI type medication? These meds have been shown to exacerbate Sleep-Related Bruxism and will increase the length of the treatment plan by 4-6 weeks.
The following guide to taking a bite registration that is balanced and accurate, the following is a step-by-step guide on how to accomplish this.
Step One: Know What You Are Treating
Your examination of the patient is critical. Assuming you have completed your examination and all indications are that this patient can be treated with an oral appliance, you can go to step 2. Do they suffer from OSA? Sleep-related Bruxism? Both?
Step Two: The Bite Registration
This is the most important step as the treatment appliance will be made to this positioning. There are a number of registration devices available. I have always used the George Gauge as I found it worked well in my hands. Any 3D registration will work.
Correct Use of a George Gauge:
The first step is to fit the gauge without a bite fork to the lower incisors ensuring it is stable. Tighten the lower thumb screw to lock the position
Remove and place the appropriate bite fork into the gauge. Ensure you have enough posterior opening to accommodate the appliance.
Place the assembled gauge, with the grey upper thumb screw for the upper loose (allowing free movement of the mandible anteriorly and posteriorly) onto the patient’s teeth.
Ask the patient retrude as far as possible and record this number:
The ask the patient protrude as far as possible and record this number:
Add the two numbers together. This is your protrusive range (11 mm in the example above)
A guide for the Luco Hybrid OSA Appliance:
- Sleep Bruxism: 75% advancement with 4mm anterior opening is the most effective treatment position
- Sleep Apnea: 70% advancement with 4mm anterior opening is the most effective treatment of mild to moderate OSA
- Sleep Apnea with Sleep Bruxism: 75% 4mm treats both
It should be noted here that a pilot study provided to the FDA in the 510(k) application for sleep bruxism, the 75% 4mm was used on 51 patients, all of which demonstrated a significant reduction in sleep bruxism, tension/migraine headaches and muscle pain by the 14 day reassessment. This included TMJ pain and an increase in range of mandibular motion, all within 14 days. Some patients have been in treatment over 14 years with the device and have remained symptom free. The Luco Hybrid OSA Appliance is the only FDA cleared treatment of sleep bruxism and the only OSA appliance FDA cleared to use in OSA patients who suffer from both conditions.
(Please note: any bite registration may be used at any advancement)
Set the George Gauge to the desired protrusion and tighten the upper (grey) thumbscrew to lock the position:
This example sets the protrusion at 75% (a severe OSA/SRB patient).
Place into the patient’s mouth. Ask them how it feels. They should report that their jaw feels forward but they should not report and muscle discomfort. Inject fast set vinylpolysiloxane bite registration material between the teeth above and below the bite fork and stabilize until set.
Remove the registration and inspect for accuracy:
IMPORTANT NOTES ON BITE REGISTRATIONS:
- Make sure to inject enough VPS to fully record all of the teeth. This ensures an accurate mounting of the casts when constructing the appliance.
- Hold the George Gauge level while the VPS is setting to ensure accuracy. Patients will often try to shift their mandible forward or backward trying to help. TMD patients will often try to force their mandible back into their clenching position. If the George Gauge is raised, the mandible comes forward. If it is lowered it goes back. Your 85% can quickly go to 90% or 75% simply by not holding the gauge level.
- Instruct the patient to gently bite. I have lost many lower blue bite sticks to patients that bite on it like there was no tomorrow only to hear a crack! I always keep a half dozen spares on hand.
- Make sure that when they are biting, both upper and lower incisors are seated fully into the grooves of the bite sticks. Sometimes patients will open slightly allowing the mandible to retrude or open too wide. This would result in a very poor fitting appliance.
- As they say in woodworking, measure twice, cut once. Make sure your protrusive position locked into the George Gauge is what you intend it to be. Check your calculations carefully!
- Always remember that the bite registration is the most critical step in designing the appliance. After all, they will be wearing this every night for years!
- Don’t forget to document these numbers in the patient’s file, this provides documentation of how you treated your patient, as well as a reference if you ever have to make a new appliance in the future.