Every TMJ patient is unique. There are three primary components that define every patient with a TMJ problem. The first of these components is the precise anatomical condition of the temporomandibular joint. Whenever there is damage to the temporomandibular joint then the bite relationship is also distorted, thereby causing the second component. Finally there are nine potential layers of pain that typically affect patients with a temporomandibular joint disorder. Let's explore each component of this Triad in more detail.
It is important to understand that TMD (temporomandibular disorder) is not an all or none injury. It is not as simple as determining whether or not the disk is displaced. TMD is a spectrum of soft and hard tissue disorders that occur together. Any classification of TMJ injury has to take into account both soft tissue injury and bone damage. Classification of the TMJ is crucial for determining both the diagnosis and the projected treatment outcome, and it is the starting point to project what type of treatment is best. MRI is the gold standard for precise diagnosis of TMJ damage.
TMJ disorders typically start with some type of trauma, such as head and neck whiplash, overstretching of the lower jaw, or trauma around the lower jaw or chin. The resulting injury to the ligaments within the TMJ results in slippage of the disk. Whenever -the disk slips out of position the joint begins to click or lock. Disk slippage is also a herniation, and it can be quite variable. The greater the degree of herniation the more likely there will be an impact on Component Two (bite instability) and Component Three (pain patterning).
Diskal displacement can also cause damage to the bone structures of the TMJ. In particular, the mandibular condyle, which is part of the lower jaw, may show loss of structure. In adult patients, the condyle may become arthritic or degenerative. In children, the condylar surface may be damaged at the growth center. In either age group, the lower jaw may become asymmetrical or receded, and the bite and profile will also distort. Whenever there is bone growth deficiency or degeneration, Component Two will be more pronounced.
The bite has several foundations. If you have ever had a high filling or crown you can relate to how precisely the teeth have to meet to stay comfortable. The function of the teeth is dependent upon very precise alignment at several levels. First of all the tooth surfaces of the bottom teeth may not properly fit the surfaces of the upper teeth. Therefore, the bite can be off center because of the anatomy of the tooth surfaces. More commonly, the teeth may be crowded or crooked, and that can alter the alignment between the upper and lower teeth as well. These two types of abnormal bite (malocclusion) can happen in anyone, and they do not necessarily mean anything is wrong with the TMJs. They are also reasonably stable, even if untreated.
The type of bite drifting that is most serious relates to a change in alignment at the level of the TMJs themselves. This can be the most serious type of malocclusion, and it is important to know whether this is the type of bite distortion that you have. Whenever there is a change in the alignment of the disk within the TMJ (Component One), there will always be a change in the bite (Component Two). Most of the time damage to the joint will cause a very specific type of bite drifting which makes the contact of the posterior (back) teeth heavier and the contact of the front teeth lighter. In more serious forms of “Joint Based Malocclusion,” the front teeth may no longer contact at all. The back teeth may become sore or loose, and they may hurt from heavy contact. The chin itself may recede, and breathing problems such as sleep apnea or snoring may occur. Remember that changes in the joint will always cause drifting of the bite, and the more serious the bite or profile change the greater the degree of TMJ damage.
For many patients, Component Two may last for a very long time. Often children who
need braces do not have a tooth surface or crowding abnormality. If a Joint Based
Malocclusion is missed before the bracework, the orthodontic treatment will not
be stable. These children may relapse and show bite drifting after their braces
are removed. Often they may be advised to have bite corrective surgery when the
orthodontics do not completely fix the bite. Such a recommendation should immediately
alert parents to the need to evaluate for a potentially unstable Joint Based Malocclusion.
Children with unstable bites are also most likely to begin to show patterns of pain
(Component Three). Unfortunately these children may carry a bite instability into
Adult patients are often told they need extensive dental work to correct their bite. They need to know precisely which type of bite abnormality they have. If the bad bite relates to abnormal tooth surfaces or tooth crowding, adult bite management may be appropriate. On the other hand, a bite that has changed or shows significant distortion may be a Joint Based Malocclusion. The best rule of thumb is to scan the TMJ foundation when there is a drifting bite or more serious bite distortion. In addition, simple dentistry such as fillings or tooth repair may not require a joint assessment, but before you spend thousands of dollars on potentially unstable bite treatment, it may be in your best interest to rule out a Joint Based Malocclusion.
In Component Two, it is useful to look at the statistical chance of having a bad TMJ. Clinical research has shown that TMJ injury is exceedingly rare in infants and very young children. However, in tracking and scanning sequential age groups, the prevalence of TMJ injury increases by 1% per year until the mid-thirties. Therefore 12-14% of middle school children, 18-22% of college students, and 33% of patients in their thirties will suffer from some type of TMJ damage. The older you are the higher the probability that Component Two is affecting you and your bite.
Most conditions in the body ultimately result in pain, and when pain develops it is a warning that the condition has become more advanced. In heart disease, the coronary arteries may become progressively plugged until the lack of circulation to the heart causes pain such as angina. However, the atherosclerotic heart disease in most people starts years or even decades before the angina. Autopsies during the Vietnam War era confirmed many of our young casualties were already showing cardiac artery damage at least two decades before someone would normally expect to have cardiac pain. Cancer is often missed because clinical signs such as lumps or swollen lymph nodes are missed, and it is not until pain starts that the real clinical diagnosis is established through advanced testing.
In many respects the TMJ is the same. Dentistry has made this a pain condition, and most of the therapy is focused on treating pain. Successful outcome is likewise measured by the reduction or the elimination of pain. While pain reduction is important, it is also critical to confirm the structural damage is not progressive. That is why Component One and Component Two must be included in a TMJ assessment. Failure to control pain is a warning that damage is progressing, but likewise if the bite is unstable (Component Two) there is even more reason for concern.
As in all diseases in the body, pain typically represents progressive tissue damage. Pain is also more severe during active phases of damage. At the Piper Clinic, we classify pain according to systems of complexity. The simplest pain in the TMJ population relates directly to injury of joint structures. We refer to these layers as Pain Pie One, and these pain problems are relatively, predictably controlled with specific joint and bite management. The three layers in Pain Pie One are:
When the pain is limited to Pain Pie One, symptoms are expected to improve whether the joint remains unstable or not. These pain layers cycle often, and when Component One or Component Two are more active, the pain layers of Pain Pie One are often more active.
When TMJ problems start with a physical trauma, these injuries may also harm other areas as well. For example, the teeth, the cervical spine, or even facial sensory nerves may also suffer damage. Pain Pie Two includes layers of pain that are caused by traumatic damage to structures other than the TMJs. Hence, trauma to the jaw may injure the teeth and sensitivity or swelling may occur within individual or multiple teeth. Both the cervical spine and the TMJ may be damaged in a whiplash trauma, and headaches could then develop from one or both regions. Likewise neuralgia pain may develop in sensory nerves that lie outside of the TMJ. This type of pain can include dental and trigeminal neuralgias. The key point about Pain Pie Two is that these layers must be diagnosed and treated separately from Pain Pie One. Patients with layers from Pain Pies One and Two generally are more complex to manage.
For the more unfortunate patients there is development of pain that is exacerbated or caused by other sources of injury or pain. These layers form Pain Pie Three. Conditions such as fibromyalgia, secondary migraine, and reflex sympathetic dystrophy may develop if the layers in Pain Pie One and Pain Pie Two are not appropriately addressed. Keep in mind that these layers occur because of failed pain management of the pain layers of the first and second pies, and if not treated appropriately early, then these most debilitating Pain Pie Three layers may become more dominant. Patients with any of the three conditions in Pain Pie Three may become worse either with or without TMJ management. The layers in Pain Pie Three require their own separate management.
As you can see there is significant variability from one TMD patient to the next. Some patients may have more bite changes and less pain while others may have simpler joint injury but more complicated pain layering. The bottom line is that all three components have to be completely diagnosed to know where each patient fits in this highly variable disease. Likewise, when pain is present it can be divided into individual layers that may be more amenable to treatment.