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 GET WORSE - No. It's just as likely to get better, because TMJ disorders are self-limiting. The symptoms eventually “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 unless exposed to extreme or ongoing trauma; and even then the symptoms almost always respond quickly to simple treatment - or 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 a few rare cases of extreme wear. 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. In fact, you may 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 teeth 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 together with steeply interdigitating cusps 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 is part of normal sleep. It occurs in everybody as a by-product of brain activity during transitions between sleep stages. 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.
5) MY ANTERIOR OPEN BITE IS DUE TO A TONGUE THRUST DURING SWALLOWING - No, it's due to an advanced tongue resting posture. The presence of a space between the front teeth that prevents you from biting things off (incising) is called an open bite, and it was thought for decades to be due to the intermittent pressures of a retained infantile tongue thrust, when the tongue pushes forward during swallowing. 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, usually 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 to rest up high in the palate, where it belongs.
6) MY PROBLEM IS DUE TO TONGUE TIE (TIGHT LINGUAL FRENUM) - Doubtful. A tight lingual frenum can be a serious problem in babies when it prevents them from nursing or later in young children who cannot pronounce consonants and sounds like “r, s, z, t, d, l, j, zh, ch, th, dg, or to roll Rs. However, tongue tie is rarely a problem in adults, unless the frenum is so tight that it prevents normal swallowing which begins with pushing the tongue tip up against the front of the palate to form a bolus. A number of dentists have promoted the idea that the cause of the low tongue posture that seems to accompany sleep apnea and other facial growth pathologies is tongue tie, and they have popularized lingual frenectomy as a means to treat these conditions. 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, the frenum is only pathological if it impairs the tongue's normal functional range of motion, which does not include holding the tongue in the palate during opening. In adults who can speak normally and lick their lips but have low tongue posture, the cause of low tongue posture is the narrow palate, not a tight frenum; and the only benefit of lingual frenectomy is to better enable natural cleaning of the teeth with the tongue. 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 simply the result of a rapidly backwardly rotating lower jawbone growth pattern. The center of rotation of the human mandible is in its ascending ramus, far below the condyles. Therefore, as the chin rotates down and back due to excessive vertical growth at the front of the face, it drives the condyles (on the other end of the center of the rotation) upward and forward into the temporal bones at the front of the TMJs. The condyles can get driven up and forward so forcefully that they resorb the bones where they contact at the TMJs (condylar resorption). 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 by reducing or intruding the posterior teeth with temporary anchorage devices (TADs) or functional orthodontics that promotes horizontal facial growth and strengthens the jaw muscles.
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 were an important resource. To preserve them, our jaw systems are designed to to maintain a stable bite table even as the teeth wear down to their root tips, by continuing to grow in a manner that continually carries the lower tooth roots upward and forward into the upper teeth slowly throughout life. The mandible rotates upward in front while translating forward due to growth from behind. If a deep or steep overbite prevents that growth, it gets redirected vertically, and the mandible rotates down and back into the space needed for the pharyngeal airway.
9) TMJ DISORDERS AROSE WHEN HUMANS STARTED EATING GRAINS - No, they arose when we started processing those grains into highly refined foods which require so little chewing that stopped getting the exercise they need to make them strong enough 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. They often wore out their dentitions, while we often don't wear ours in. 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 adaptive capacity is reduced. Stress diminishes adaptive capacity. 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 the healed TMJs are no longer the cause of symptoms.
12) BOTOX IS A GOOD SOLUTION TO MY PROBLEM - Botox is one way to temporarily reduce the jaw muscle forces used in nocturnal bruxism; but it does so by damaging the jaw muscles, which need strength to promote healthy facial growth. The jaw muscles are responsible for regulating 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. A safer way to reduce the jaw muscle forces used in nocturnal bruxism is by wearing a front flat bite plate appliance, because the effect lasts as long as the appliance is worn, and the appliance promotes jaw muscle health and horizontal facial growth.
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 managing them effectively requires adjusting bites forward, and dental schools in the past have only taught dentists how to adjust bites backward. As a result, dentists go to great lengths to try and prevent the bite changes that almost always occur in people wearing mandibular advancement devices. However, these bite changes can be easily managed to benefit our treatment and long-term health, as described in 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, Many people believe that the enamel on teeth is there to protect the dentin beneath from decay, and therefore that any defect in the enamel increases the susceptibility to decay; but that's not how teeth work in mammals. Evolution didn't cover dentin with enamel to protect it from decay. It combined enamel and dentin to produce tooth structures that wear down in a manner that creates effective grinding surfaces, because the enamel on the sides of the teeth wears slower than the dentin around it, leaving edges that cut and tear the food. Cavities form wherever food gets stuck or plaque is allowed to accumulate, whether that area is covered by enamel or dentin. In cavity formation, the acid produced by the bacteria drills a funnel shaped hole right through the enamel.
15) DUAL BITE IS A PATHOLOGY - No, dual bite is a successful adaptation to a backwardly strained centric bite involving 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 known as centric relation (CR).