Broken fillings, fractured teeth, the bite is out of balance. The dentistry bills make a substantial part of this person’s family budget. He/she has come to my office because of having learned somewhere that I should know something about the bite issues. I’m supposed to belong to the cognoscenti, can I help?
These patients go in two categories – the ones with good TMJ-joints and the ones with bad joints. Both categories receive the same treatment. I adjust the bite forces as explained in my previous article “The Soundbites of Sound Bites”. I am quite confident that with a micrometer or two grindings here and there, guided by frequent Tscan recordings, I am capable to create a perfect, digitally verified match between the teeth of the upper and lower jaw. I would not touch my diamond bur if I would not have a Tscan in my office. It is so many times that I have fooled myself to rely only to the looks and appearance of bite foil markings. The digital data of occlusion forces is so much better a tool to accurately level out the high force contact points. I change the shape of the occluding dentition so that when the patient closes the teeth, I can hear a nice relaxed click of the upper and lower jaw teeth meet each other almost simultaneously. If I can make the jaw closing relaxed and easy, I am assured that the jaw joints are lying in the condylar fossa in their most favorite and stable position. The power-clenching phase of jaw-closing produces a stable total force curve close to the 100%
Despite my efforts to equilibrate the shape of occluding surfaces I frequently meet patients whose lower jaw has trouble to meet the upper jaw. It is not only the shape of the occluding teeth that makes a difference. The next video is from a patient with problems with his joints. Despite repeated efforts I have not been able to completely cure his problems. However, during the last 6 months of my repeated interventions we both agree that there has been improvement. Here’s how the jaw-closing looks like for him:
In this recent video, it takes 0.59 seconds from the first, initial tooth contact “A” until the time point “B”, where the maximum amount of contact points has been attained. Looking at the video you see how the jaw-closing muscles are working on to do the adjustment. The pillars demonstrating the actual forces in different points of occlusion are pumping up and down in each 3-microsecond timeframe of the movie. There must be slight translation of the condyle joint surfaces during the final millimeters of rotational closing of the mandible so that the teeth would fit together. We are hoping that his joints gradually get better and better. Before and after I perform any intervention on the teeth of my patients, I always palpate the jaw-joints by putting my finger-tip into the ear canals. For some individuals, I can feel the synovial tissues moving and bulging the wall of the ear canals while patient closes the jaw. For some I can feel the “click” sound of the synovial disk, sometimes there might be crepitus or excessive lateral deviations of the joint during the closing movement. I try to make a verbal description of what I am feeling with my fingertips. Very often the fingertip feel of the joints can be perfectly normal, but the digital data produced by electronic pressure sensors between the teeth reveals that the joint can’t be rotating normally. My experienced fingertips give me some idea what is going on, but my fingers are not a tool reliable enough to assess the quality of jaw joint.
Nevertheless, I can make almost everybody to close their jaw smoothly, with a minimal time elapsing between the initial, first contact until the maximum amount of tooth contacts in maximum intercuspal position. The patients themselves usually immediately recognize an improvement of their bite. Their usual comment is that now they are biting more “freely”. However, I can’t get a perfect stable 100% total force curve for every one of my patients. The jaggedness and wobble of the total force curve reveals that there still is muscle strain oscillating between different groups of jaw-closing muscles during the clenching period. These are the patients with a bad bite, an underlying joint problem. Instead of a stable rotation, there happens a slide of the joint surfaces during the last millimeter of jaw-closing. Instead of a rotational final stage of the closing movements, there is a subtle translational component in their joint movement. Despite that there is a stable occlusion in the tooth-to-tooth-end of the jaw-swivel-system, the muscles are strained to keep the joint-ends stable during the power-clenching phase of jaw-closing. The sliding of the joint surfaces produces a total force curve that is unstable, jagged and wobbly.
After I have finished working on the jaw closing, an equally essential step in my treatment protocol is to ascertain that the lateral excursions should be strain-free for the muscles. This is important both for those with stable joints as well as for those with problems in their joint function.
Normally, I reshape the canine teeth to make the premolar and molar teeth disclude immediately as the mandible starts to glide laterally. Some grinding down of the cusp inclines of the back teeth are usually also needed. For individuals with a healthy TMJ-joint system, it is relatively easy to attain a beautiful Tscan recording, with a characteristic appearance.
The total force curve raises steeply after the time point “A” -the first contact point – to the time point “B”, where all the contact points have met. The three-dimensional graph of occlusion shows the bite forces evenly divided on all teeth and a stable total force line appears close to the 100% level all through power-clench phase of occlusion from the time points little after “B” and lasts until the time point “C” on a Tscan -graph. The lateral excursions happen quickly and smoothly between the time points “C” and “D”. The pillars showing the amount of relative force on premolars and molars disappear. The total force falls to zero as soon as all the force is subjected only to the working side pair of canines. There are now wobbles, nor jaggedness in the total force curve. Each group of muscles seem to know what to do and when to do. There are no disputes between the differently oriented motor unit fibers.
Again, with individuals with joint problems, it may be impossible to make their back teeth to disclude in lateral excursions. The joints seem to be sliding off their axis during the rotation, which can be seen on the Tscan as the contact force hops off the canine to move over to the back teeth.
All the data is saved in my computer files, easy for display. I can explain and inform my patient that I can see what the problem is. With the interventions explained above, I can relieve the muscular strain that has been damaging not only for the dentition, but also to the joint tissues. Effortless jaw-closing and relaxed anterior guidance in lateral excursions of the mandible relieves the strain to the joint tissues.
The healing of damaged joint function takes time and it requires regular, repeated follow-up of my patients. However well I adjust the bite of these individuals with the Tscan, it is not uncommon to see signs of attrition and tooth wear already months or only weeks later. Like a door with broken hinges, the door frames wear out quickly. Likewise, the wear-out of the anterior guidance must be regularly assessed and repaired in individuals with slackness in their jaw-joint-hinges. I also advise my patients to avoid chewing anything unilaterally, but always to pay attention to share the bolus of food to be chewed equally with both sides of the dentition and do the chewing by up and down movements only, because the lateral excursions would strain the working side condyle and might eventually slide it off its rotational axis.
The description of patients above falls in to the broad category of what clinician dentists call bruxism.
A search through PubMed database of scientific journal article abstracts dealing with bruxism shows that the overwhelming majority of present day authors reject the idea that occlusion should have any critical role in this entity. Actually, the International Code of Diagnosis (ICD-10) for bruxism, F45.82, is classified in the chapter V, which deals with mental and behavioral disorders.
In my previous article “The Legend of Spooky Bites” I criticized the prevalent attitude of the mainstream of occlusion scientists. Surely, we all agree that muscles do not operate like if magic, just by themselves, without any reason. The activity of jaw muscles is a result from efferent motor nerve activity from the ganglia of the brain stem. What makes the ganglia vibrate, we would like to know.
Basically, the question is whether it is a simple mechanical reflex or would there be higher spirits that make the jawbone move. I question the view, that the jaw-moving muscles would essentially be guided by some complicated phantomlike actions of our psyche. By no means, there may be some truth there – just think about it. You enter a music club, where the beat of rhythm overwhelms your soul and the music syncopates your nervous system so that the agitation can make you tap your feet and clap your hands. A good piece of music surely can make your jawbone jerk, but really, the instability of the occlusion and jaw-joint is a much better explanation for this perplexing jaw-muscle hyperactivity.
As of yet, most of the data in studies of occlusion is not based on digital measuring of occlusion forces. With a Tscan in my disposal, I can see things that have not been recognized earlier. New technology has opened up new avenues of understanding the tooth grinding phenomenon. I present a hypothesis for discussion that an unstable and jagged total force curve during clenching period in a Tscan recording is a physical demonstration of pathology in the jaw joint system and most likely it is a common feature for patients with pathological tooth grinding. The unstable joints slide and translate during the jaw-closing. As a result,the perfect occlusion is lost and the muscles are activated for a search of a better and more secure hold between upper and lower jaw. The rapid actions of different sets of jaw-moving muscles are projected as a jagged total force curve with notches and peaks of opposite force directions oscillating back and forth within microseconds of intervals.
The jagged total force curve in Tscan recording reflects of a tug-of-war going on between different groups of jaw-moving muscles, a feature that is typical for a subset of patients that suffer from excess teeth grinding. Any dentist with a Tscan can see these signs. The prevalent thinking by the mainstream of occlusion scientist, that bruxism is a mental or a behavioral disease should be challenged. Bruxism should be regarded as a reflex or as a symptom of failure in occlusion, not as a disease itself.