Common Misconceptions
MANY MISCONCEPTIONS REGARDING TMJ DISORDERS AND BITES are common even among dentists.
1) IF I DON'T TREAT MY TMJ PROBLEM, IT WILL KEEP GETTING WORSE - No. It's just as likely to keep getting better, because TMJ disorders are self-limiting. The acute symptoms “burn out” even without any treatment, because damaged and dislocated TMJ disks undergo adaptation characterized by fibrosis that eliminates the inflammation and restores functional capacity. Successful adaptation may require anywhere from days to decades, but it almost always occurs by middle age. Older people may experience jaw muscle pain as a subset of postural muscle pain, ear and balance symptoms that have persisted from an earlier TMJ injury, and some difficulty chewing if the TMJs and the bite don't fit together well; but they are unlikely to develop persistent TMJ inflammation. At any age, TMJ inflammation and accompanying pain can be produced by mechanics that push back on the mandible; such as a CPAP face mask or traditional headgear; extreme loss of support, such as bad dentures or sudden loss of multiple teeth; or trauma, such as a blow to the face or an excessively long dental procedure. However, the symptoms in older people almost always respond quickly to simple treatment - or even just time.
2) MY PROBLEM IS DUE TO TOOTH WEAR - Rarely. The idea that tooth wear causes TMJ disorders is intuitively appealing and was taught in dental schools for decades, even though there was no scientific evidence for it, except in extreme cases. Teeth are made for wear, and mild to moderate tooth wear is physiologic, not pathologic. In fact, teeth that show evidence of wear are healthier periodontally than teeth that do not show evidence of wear. Pre-industrial people often wore their teeth right through their crowns, leaving each molar functioning as four separate roots, but they could still chew without pain. In modern people, tooth wear is only a problem if it will prevent your teeth from lasting as long as you do, or if it occurs so rapidly that it causes the little organ inside each tooth (the pulp) to die and need a root canal.
3) IF YOU HAVE HAD ORTHODONTICS, YOU MUST HAVE A GOOD BITE - Not necessarily. You may even have very straight teeth and a very bad bite. Braces and invisalign are techniques for esthetic realigning of the teeth. They can shape the upper and lower dental arches into perfectly smooth arch shapes, but they cannot control how these dental arches fit together, the critical feature in most TMJ disorders. Also, orthodontics that leaves the teeth locked steeply together may cause the bite to become more and more strained over time during adulthood by inhibiting the differential vectors of growth in upper and lower jawbones.
4) MY PROBLEM IS DUE TO NOCTURNAL BRUXISM (CLENCHING AND GRINDING DURING SLEEP) - Nocturnal bruxism is often part of the symptom generating process, but it cannot be considered the cause of your TMJ disorder, because it occurs in everybody as a by-product of brain activity during transitions between sleep stages, therefore it has to be considered part of normal sleep. It occurs more forcefully and frequently when our central nervous systems are under stress, and it can apply a lot of force to the TMJs and teeth, but it is not found more frequently in TMJ disorder patients. In fact, TMJ disorder patients generally have weaker than normal jaw muscles, and thus they apply less force during nocturnal bruxism than average people. The bruxism itself cannot be prevented, but it can be prevented from causing symptoms by enabling your TMJs, jaw muscles, and teeth to withstand it.
5) MY ANTERIOR OPEN BITE IS DUE TO A TONGUE THRUST DURING SWALLOWING - No. The presence of a space between the front teeth that prevents you from biting things off (incising), was thought for decades to be due to the intermittent pressures of a tongue thrusting between the front teeth during swallowing, the so-called infantile swallow. Then a study using numerous force sensors in the mouths of people who had this condition found that they did not thrust their tongues during swallowing but maintained a resting posture with the tongue interposed between the teeth to protect the pharyngeal airway. In most of these cases, correcting the bite requires expanding the upper dental arch to make room for the tongue.
6) MY PROBLEM IS DUE TO TONGUE TIE (TIGHT LINGUAL FRENUM) - Doubtful. This is an occasional problem which is being routinely overdiagnosed and overtreated today. It is certainly reasonable to expect that ankyloglossia (tongue tie) could result from lack of breastfeeding, because it requires a wider range of tongue functional movements than bottle feeding. The long recognized problem with tongue tie is that it can prevent normal breast feeding, which is the primary condition for treating it in infancy. If a tongue tie is not treated in infancy, it can make it difficult later for children to pronounce consonants and sounds like “r, s, z, t, d, l, j, zh, ch, th, dg, or to roll Rs; another good reason for treating it. However, tongue tie is rarely a problem in adults, unless it impairs the tongue's normal functional range of motion. Low tongue posture is associated with airway obstruction, because narrow palates do not allow adequate space for the tongue and thereby force the tongue to posture down and back, which forces the tongue base posteriorly into the pharyngeal wall. In response to the problem of low tongue posture, a number of dentists have promoted the idea that the cause of low tongue posture is tongue tie, and they have popularized a minor surgery (lingual frenectomy) to cut the lingual frenum in order to improve the airway passage. They even developed a scoring system for tongue mobility (Kotlow score) based on the belief that tongue should be able to maintain a seal against the palate as the mouth opens wide. However, there is no evidence or even reason to think that the tongue needs to be free to move beyond its normal range of motion. The low tongue posture that is found with constricted or obstructed airways is almost always caused by an upper jaw that is too narrow to house the tongue up higher in the palate where it belongs - not by a tight frenum. If you can lick your lips, you do not have a clinically significant tongue tie. In addition, tongue tie surgery could later exacerbate snoring or sleep apnea, because it removes one of the mechanisms that normally prevents the tongue from shifting backwards into the pharynx.
7) ADOLESCENT CONDYLAR RESORPTION (AKA CHEERLEADER SYNDROME) IS IDIOPATHIC - No, This condition (also known as condylar atrophy, idiopathic condylysis, and progressive condylar resorption) is not actually idiopathic but is the result of a rapidly backwardly rotating lower jawbone growth pattern, which drives the condyles (on the other end of the center of the rotation) upward and forward into the temporal bones so forcefully that they resorb the bone there. Even before this condition was named, it was recorded by a researcher who studied a set of identical twins, one of whom had severe right side TMJ pain. His records (below) show that the monozygotic twin with the TMJ pain (dotted line in the left side X-ray) had a mandibular condyle that had rotated upward and forward into the temporal bone as the first molar on that side had shifted down and back due to the backward rotation of the mandible.
HEALTHY TMJ DAMAGED RIGHT TMJ
Idiopathic condylar resorption is usually treated surgically just because of the severity of the condition; but it should be treated with functional orthodontics that promotes horizontal facial growth and exercises that strengthen the jaw muscles. A study of schoolchildren who had a backwardly rotating jaw growth pattern showed that using exercise gum for a year changed the direction of their facial growth to a forward rotation, until they stopped chewing the exercise gum, which allowed their mandibles to revert to backward rotation again.
8) JAWBONE GROWTH STOPS AT ADULTHOOD WHEN OTHER BONES STOP GROWING - No. Unlike our other bones, our jawbones are programmed to keep growing throughout life; because the teeth of our ancestors kept wearing down throughout life, and the few people who lived into old age in our ancestors used to be an important resource. Therefore, our jaw systems are designed to to maintain a stable bite table throughout life and to keep functioning, even as the teeth wear down to their root tips. To accomplish this bite stability, continual jawbone growth was needed to keep compensating for continual tooth wear. Today, it slows down about 90% after the second decade; but then it continues throughout life. If a deep or steep overbite prevents this adult mandibular growth from continuing to advance the mandible, its growth pattern often gets redirected vertically, and it rotates down and back into the space needed for the pharyngeal airway.
9) TMJ DISORDERS AROSE WHEN HUMANS STARTED EATING GRAINS - No, they didn't arise until we started processing those grains into highly refined foods which require so little chewing that they deprive our jaw muscles of the exercise they need to maintain a healthy harmonious facial growth pattern. As can be easily seen from museum skulls, early humans sometimes wore out their TMJs when they also wore out their teeth, but they did not experience the types of TMJ disorders that have become common today. Modern TMJ disorders arose when our diets became so soft that they deprive our jaw muscles of the exercise they need to regulate our facial growth. A detailed comparison between craniofacial growth in our recent pre-industrial ancestors and modern people can be found in chapters 3 and 4 of ETIOLOGY.
10) THE CAUSE OF TMJ DISORDERS IS MULTI-FACTORIAL - No. That fallacy persisted for years as a result of patients reporting a variety of different types of events that appeared to immediately precede their symptoms, but those events were just triggers. For example, the cause of your TMJ injury was not that time you bent incorrectly or chewed a stale bagel, the cause was an ongoing facial growth strain that required constant adaptation to prevent damage and thereby made you vulnerable to injury. When your body is healthier, your adaptation is usually more successful and better able to prevent the strain from producing cell damage leading to symptoms. When your adaptive capacity is reduced, symptoms are likely to arise. As a result, stress frequently triggers symptoms, and anything that increases adaptive capacity frequently relieves symptoms. In response to the multiple factors that seem to cause or relieve symptoms, some TMJ departments at dental schools employ psychologists and a dual axis treatment approach to treat patients psychosocially as well as physically, as if TMJ disorders had some unique relationship with pain; but all pain conditions have a psychosocial component.
11) X-RAYS SHOW THAT MY TMJ PROBLEM IS TOO SEVERE FOR NON-SURGICAL TREATMENT. Nonsense. X-rays can show changes that have occurred in the shape of the bones at the TMJs, but they cannot tell us if those changes happened last week or many years ago, or if they have any relevance to your current clinical condition. Many TMJs of older people have undergone extensive damage and remodeling, which makes them look bad on X-ray, but the remodeling was part of a successful anatomical adaptation of the TMJs, and they are no longer the cause of the symptoms.
12) BOTOX IS A GOOD SOLUTION TO MY PROBLEM - Botox is one way to temporarily reduce the forces used in nocturnal bruxism. It has recently become a popular management tool for treating muscle pain; but it weakens the jaw muscles, which need strength promote healthy facial growth; and there are better ways to treat jaw muscle pain. Botox is marketed as a means to "soothe and relax tense muscles". However it is actually a paralytic toxin that works by temporarily damaging the muscles, which weakens them through atrophy - muscles that are used less get weaker. The jaw muscles regulate jawbone growth, and unregulated jawbone growth is the root cause of most TMJ disorders, so damaging the jaw muscles makes TMJ disorder symptoms likely to return later. Wearing a front flat bite plate appliance is a better way to reduce the forces used in nocturnal bruxism, because it promotes jaw muscle health by providing an unrestricted range of motion for their exercise, it promotes horizontal facial growth, and the effect lasts as long as the appliance is worn - instead of wearing off after three months, like Botox treatments.
13) BITE CHANGES ARE AN ADVERSE SIDE EFFECT OF MANDIBULAR ADVANCEMENT APPLIANCES - The bite changes that commonly occur after wearing mandibular advancement appliances to treat sleep apnea cause great confusion among dentists, because they are due to the mandible shifting forward, which must be accomodated by a forward shifting of the teeth; however, dental schools in the past have only taught dentists how to shift bites backward, not forward. As a result, dentists generally try to prevent the bite changes that frequently occur due to wearing a mandibular advancement device. However, these bite changes can be managed to benefit our treatment, as described in the last few pages of MULTILEVEL ORAL APPLIANCE TREATMENT OF SLEEP APNEA under the tab FOR DOCTORS.
14) ADJUSTING BITES BY DRILLING ON TEETH (EQUILIBRATION) LEAVES THEM MORE SUSCEPTIBLE TO DECAY - No, toothpaste commercials have convinced the average person that the enamel on teeth is there to protect the dentin beneath from decay, but that's not how teeth work in mammals. Evolution combined enamel and dentin to produce tooth structures that wear down in a manner that produces and maintains effective chewing surfaces. The enamel on the sides of the teeth wears slower than the dentin around it, leaving edges that cut and tear the food, but it does not protect the tooth from cavities. Cavities form wherever food gets stuck or plaque is allowed to accumulate, whether that area is covered by enamel or dentin.
15) DUAL BITE IS A PATHOLOGY - No, dual bite is simply the result of the basal bones outgrowing a backwardly strained centric bite. Initially the patient usually develops one biting platform on the back teeth and another biting platform further forward on the premolars or the front teeth. This type of bite was considered a pathology when dentists assumed that the only correct bite was the one at the very back of the dentition, also know as centric relation (CR). However the additional bite platform is usually adaptive and prevents the development of symptoms.