The Front Flat Plate Appliance
SUMMARY
The front flat bite plate appliance covers all the upper teeth and contacts just the lower 6 front teeth on a bite plate which is so flat and smooth that it allows the mandible (the lower jawbone) to glide around freely in all directions and to grind or clench in any position the muscles choose. Worn nightly, it diminishes the strength of the nocturnal clenching and grinding by about half, deprograms the jaw muscles so we can see if they prefer a different bite position more compatible with body posture, and redirects the nocturnal clenching and grinding forces (that everyone experiences) to gradually reduce overbite. These effects are described in more detail below. The front flat plate appliance is a muscle treatment rather than a joint treatment, so it is not suitable for inflamed TMJs. The cost of the appliance is $1000. A temporary comfortable version, which will last for at least a few weeks, can be made chairside for $100.
REDUCING THE FORCES USED IN NOCTURNAL GRINDING AND CLENCHING - Nocturnal bruxism (grinding and/or clenching) is not itself a pathology, because it occurs in everybody during transitions between sleep stages, and it always gets more severe when they are under stress, but it can be destructive. Clenching compresses the vessels that supply circulation to the teeth. That can make teeth temperature sensitive by impeding circulation to their pulps. Eventually it can strangle them, causing them to die and need root canals. Grinding exacerbates gum disease by loosening the teeth like rocking a fence post. Grinding can also cause the teeth to bend a little just above the socket rim, which can break away little bits of the thin layer of brittle enamel there and leave V-shaped gumline defects called abfractions.
A front flat bite plate appliance eliminates some of those bruxism forces and reduces others. It eliminates all forces on the molars and premolars, because they cannot even contact while the appliance is worn. It reduces the bruxism forces applied to the canines and incisors, because the jaw muscles are wired in a positive feedback loop that requires stable contacts on the back teeth to provide a proprioceptive "go ahead" from the neuromuscular system before they can fire strongly, and the appliance prevents that "go ahead" signal. As a result, the front flat bite plate appliance reduces the forces of nocturnal bruxism by about half every night you wear it. Thus it performs the same function as Botox without damaging the muscles that are needed for regulating facial growth, the failure of which is at the root of TMJ disorders, as explained in the ETIOLOGY files.
HEADACHES are often reduced or eliminated by the reduction in the strength of nocturnal bruxism. We still don't understand the mechanisms behind headaches, but we know that pressure on the head is controlled by jaw muscle activity. In monkeys, forceful biting bends the skull. Human jaw muscles are not as strong, but our craniofacial skeletons are much more delicate, therefore it should come as no surprise that excessive jaw muscle tension can produce enough pressure to interfere with circulation to and from the cranium. The jaw muscles are such important regulators of cranial circulation that normalizing their tensions often relieves headaches from unrelated sources.
DEPROGRAMMING THE BITE - The upper front flat plate detects bite strain by deprogramming the jaw muscles so they stop automatically closing the mandible into the one place where all the back teeth fit. Once they are deprogrammed, the jaw muscles can hold the mandible in any position they choose all night long. If they choose a new position consistently, the old position was strained. Some people describe feeling like their jaw has been freed. Others describe feeling like their bite has been disrupted, because the freed jaw doesn't want to go back to where the teeth fit.
The time needed to deprogram the jaw muscles depends on the health of those muscles. Children and young people often deprogram overnight. They may even have trouble finding the old strained bite in the morning, because the deprogrammed jaw muscles quickly become used to operating in the new more comfortable mandibular position, and they can hold that position for some time in spite of the teeth not fitting there. The average TMJ disorder patient requires a few weeks of nightly front flat bite plate appliance wear to fully deprogram. Some patients with longstanding severe TMJ disorders may require months of appliance wear along with bite stabilization, jaw muscle exercises, physical therapy, or massage to help rehabilitate those jaw muscles before they can demonstrate a healthy natural unstrained jaw closing trajectory.
STRETCHING THE JAW MUSCLES - The height of the front flat bite plate determines the amount of stretch it applies to the jaw closing muscles. If the bite plate starts out too tall, it may be difficult to tolerate for 8 hours at first due to the compressive forces generated by the passive stretch of the jaw closing muscles. It can be shortened at a follow-up appointment, or you can start out with shorter wearing times, taking it out for a bit after a few hours. If the bite plate starts out too short, it may not provide enough jaw muscle stretching to eliminate the symptoms; and its height can be increased during a single appointment for a small lab fee.
WHAT TO EXPECT - In the morning, when you wake up with the appliance still in your mouth and your jaw muscles deprogrammed, your mandible swings open and closed along a trajectory that fits those light steady background tensions of your whole postural system. If this unstrained postural jaw closing trajectory brings your mandible directly into a stable natural bite, your natural bite is probably healthy, at least in its central area (although it could still restrict your mandibular range of motion in chewing). However, if the unstrained postural jaw closing trajectory brings your mandible into contact with only one or two teeth before sliding backward or to the side into your full natural bite, that slide is the cause of your bite strain; because it forces your mandible to slide away from its proper position. Identifying the source of the slide maybe difficult at first, because initially your jaw muscles will become reprogrammed as soon as they make contact. However, as your jaw muscles become healthier over the following weeks, the location of the prematurely contacting areas should become clear. These are the contacts that drive your mandible away from its optimal postural position, and identifying them tells us how to improve your bite.
IMPROVING YOUR BITE may or may not be necessary. Many people can live comfortably with a strained or unstable bite, especially if they can wear an oral appliance which relieves the strain and provides bite stability every night or if they have good adaptive capacity. If your bite is causing symptoms, it can be stabilized or moved. High spots can be drilled down, low spots can be built up, and/or teeth can be shifted orthodontically. The techniques for improving bites are explained in THE ROLE OF THE BITE under TMJ DISORDERS.
IMPROVING BODY POSTURE – If your postural system is healthy, the posture of your mandible should be made to fit your head posture mechanism, which may require adjusting your bite. If your postural system is strained, your mandibular and spinal posture should be improved together. In these cases, deprogramming your jaw muscles can provide a window of time for postural work to realign your mandible into a harmonious fit with the rest of your postural system before locking in that mandibular posture with permanent dental work such as crowns. Any improvement in body posture requires changing the natural posture of the mandible, which requires altering the bite. Subsequently, stabilizing the bite in a location just above the new improved mandibular postural position will stabilize the new improved mandibular posture, just as stabilizing the old bite stabilized the old mandibular posture. The connection between the bite and body posture is described in detail with extensive footnotes in BITES AND POSTURE under the heading FOR DOCTORS.
REDUCING OVERBITE - The vertical overlap of the teeth, the overbite, is often at the root of TMJ disorders and postural problems; because it can keep the mandible locked back and therefore unable to naturally advance in order to keep reducing resistance in our airways as we age. Our jaws are programmed to keep growing slowly during adulthood by forward translation (advancement) of the front half (the tooth containing half) of the lower jaw (the mandible), which gradually eliminated overbites and overjets during adulthood; however, this natural mandibular advancement and the reduction of overbite are stimulated by chewing forces, which have reduced by half in the last few centuries. As a result, natural mandibular advancement it is often blocked by deeply and/or steeply overlapping overbites. When the mandible can’t grow horizontally, it grows vertically. When the advancement of the mandible is prevented or blocked, its growth gets redirected down and back, bringing the chin into the pharyngeal airway.
The front flat plate appliance encourages advancement of the mandible by reducing restrictive overbites by redirecting the forces of nocturnal bruxism, which we all apply anyway, upward on the upper front teeth and downward on the lower front teeth. The effect is to gradually shorten the front teeth by intruding them a little back into their basal bones while lengthening the back teeth by allowing them to get taller and extrude from their basal bones due to their natural eruption process. In this manner, the appliance uses the forces generated by your nocturnal bruxism to perform the orthodontics you need. It only reduces overbite slowly, usually at the rate of about ½ mm per year; but that rate is more than adequate to accommodate the slow mandibular advancement that naturally occurs during adulthood.
Because the overbite will keep reducing only until the back teeth start to make contact with the appliance, the target reduction in overbite can be controlled by adjusting the relative heights of the front and back portions of the appliance. When the bite plate portion of the appliance has worn down far enough, the back teeth begin to contact, and the appliance then becomes a stabilization appliance, with biting contacts spread out more evenly among all the teeth and at least including some of the back teeth. At that point, if muscle symptoms recur, the bite plate portion of the appliance should be stabilized.