Written by Mark W. Montgomery, DMD Friday, 10 September 2010 17:46
The urgency for taking the temporomandibular joint (TMJ) condition into account is the pervasiveness of occlusion-related disease and the recent advances in restorative and prosthetic systems. Clinical best practices would include the screening and diagnosis of the temporomandibular condition in the evaluation and treatment of the occlusion-related diseases such as abfractions, wear, mobility, periodontal damage, fractured teeth, and abnormal parafunctional muscle activity.
During routine dentistry, in the vast majority of dental practices, 2 oversimplified assumptions are made that then determine the course of occlusion, mastication, and dental anatomy decisions for the patient. These assumptions are: (1) that the asymptomatic TMJ is either healthy, or as healthy as can be expected for this patient, and (2) that maximum intercuspal position (MIP) is the most stable position in which to reference the patient’s dental care.
|Figure 1. Preoperative photo.||Figure 2. Deprogramming appliance (in anterior contact only).|
|Figure 3. Stabilized bite registration for Joint Vibration Analysis (JVA) (BioRESEARCH) testing.|| |
Figure 4. Maximum intercuspal position versus stable condylar position on the articulator.
Figures 5a and 5b. Preoperative JVA with disc derangement.
Figures 6a and 6b. Before and after JVA.
|Figure 7. Before and after case photos.|
These 2 assumptions are commonly adopted as the default scenario for dental care for several reasons. Namely, the clinical manifestations of TMJ derangements are often encountered at a later or more chronic stage that does not lend itself easily to diagnosis and/or treatment. Many of these later-stage, chronic disc derangements are often asymptomatic before and after routine dental care. Furthermore, most of these later-stage TMJ derangements are not correctable with routine dentistry.
Also, the MIP is seemingly the most easily determined position of the interface between the maxilla and mandible due to patient accommodation and preference of interdigitated teeth. Additionally, the facet-to-facet interdigitation of the teeth is routinely utilized to relate the maxillary teeth to the mandibular teeth on laboratory models of the patient’s dentition.
Relying on either or both of these assumptions creates or perpetuates the existing conditions, pathologies, and the position of the mandibular condyles and their respective disc and ligament apparatus. This perpetuation of the current status puts even the most limited restoration in jeopardy of early failure or worsening of the patient’s condition.
While the majority of patients without reported symptoms will accommodate or continue to accommodate to this condition/position of the condyles, the glaring signs of occlusal disease and pathology are staring the practitioner in the face. These signs are primarily being treated symptomatically or ignored, rather than systematically evaluated and treated at the source of the problem.
This situation is frustrating for dentists, as they often feel that they don’t have the opportunity or urgency of symptoms to be able to take control of the problems. Additionally, there has been a challenge to integrate the concepts of occlusion with the condylar position. Many dentists have studied with various occlusion “camps” only to become confused regarding the relevance of the condylar position or which condylar position is “correct.” This debate has continued for years as to the best way to define and establish what a “normal” condylar position is. As a result, the only established norms for occlusion have relied on the systems created to produce successful clinical results and idealistic concepts that are perpetuated in texts and academia.
Consequently, dentists end up discussing their “philosophy” of occlusion without regard to routine objective measurements that could establish the relative health or normality of the stomatognathic system.
This situation is also frustrating for patients, as they are at a loss as to what is normal for them. How much deterioration of their dentition is acceptable? Why, when they return to the dentist year after year, is “something wrong,” every time? And which of their symptoms are important enough to report to their dentist? They often end up years down the road with thousands of dollars of dentistry done only to discover that their wear and/or pain continues, and their condition is never truly under control, despite their best intentions and investment.
Fortunately, we currently are in a new place of discussion regarding the diagnosis and possible therapies for occlusal, masticatory, and temporomandibular care. With an objective test for TMJ condition, better treatment plans can be devised for occlusal disease.
This new place where we are is directly related to the development and usage of biometric technology that gives the doctor objective data from which to make decisions and measured documented treatment results.
The past attempts to record and/or measure the condylar position and condition included axiopath recordings of joint position and border movements, transcranial and tomographic radiography with objective and subjective interpretation, comparison of condylar position on articulators with multiple jaw position “bite” recordings, magnetic resonance imaging (MRI) and functional MRI scans, computed tomography (CT) and cone beam CT scans, contrast arthrography, computerized mandibular positions based on transcutaneous electrical nerve stimulation pulsed muscle contractions irrespective of the condylar position, face-bow mounted casts on various articulators referenced to numerous closure paths from speech to swallowing, from controlled manipulation to deprogrammed patient closure. At best, these methods were expensive and time consuming; and at worst, these techniques were dependent on the clinician’s experience and subjective analysis.
The current biometric standard with the Joint Vibration Analysis (JVA), a system of equipment and software manufactured by BioRESEARCH (bioresearchinc.com), allows the dentist to easily and objectively measure the condition of the condyles quickly, affordably, and irrespective of treatment “philosophy.” The mandate from the ADA, as stated in 1990 and 1992, calls upon the dentist “to document, assess, note, describe, evaluate, and record the presence, location, loudness, timing, consistency, and quality” of joint vibrations. This mandate then encourages us to consider biometrics that will accomplish this effectively and affordably with high levels of sensitivity and specificity. The JVA system achieves this standard and creates a 21st-century documentation of objective information that will afford the treating dentist the ability to diagnose the patient’s condition and monitor the patient throughout preventive or therapeutic care. By establishing objective measurements of the condylar condition, the dentist can evaluate the effect of future events such as injury, accident, or therapy. The doctor can also begin to correlate the condylar condition with other data, such as bite force analysis (with T-Scan) and/or electromyography (BioPAK [BioRESEARCH]) measurements of the muscles of mastication. In addition this JVA system can be overlaid on data regarding mastication analysis (BioPAK), range of motion, and mandibular position.
A patient presented to our office with severe occlusal-related disease. Examination revealed abfractions, anterior wear into the dentin, and periodontal attachment loss. The patient desired a long-term restorative solution that would include aesthetic enhancement of the smile (Figure 1).
The case was designed with a mock-up of the anterior smile zone, followed by a determination that the envelope of function would be well controlled without having to restore the vertical dimension. The development of the anterior envelope of function was accomplished by first deprogramming the avoidance pattern muscle engrams with an anterior contact (only) appliance. In the deprogrammed patient, the mandibular position is determined by an anterior contact composite ball bite (open-bite centric). This open-bite registration is then tested with the JVA and compared to the preoperative JVA. By testing the stability of the TMJs at the time of bite registration, we can be confident that our diagnostic wax-up will be designed not only to the desired aesthetic result, but also that the provisionals and final restoration will be accomplished with the condyles in a more smooth and stable position (Figures 2 and 3).
The patient’s preoperative casts and mock-up casts were mounted, and cross mounted, at the most stable condylar position allowing for the desired smile design and functional anterior zone. This mounting with the apex of force centric open-bite registration can then be studied on the articulator for a comparison of the condylar position with the condylar position that is associated with the preoperative MIP interdigitation (Figure 4).
Commonly, the cases that have avoidance-related anterior wear and muscle engrams also show a condylar position discrepancy between the MIP condylar position and the stabilized mandibular restorative position. These small dislocations of the condyle in the MIP are frequently associated with disc movement and subtle changes in the morphology of the posterior band of the meniscus. This increases the frequency of inflammation in the joint and the likelihood that the patient will suffer a partial- or full-disc displacement, along with the associated popping and possible retrodiscal impingement and pain (Figures 5a and 5b).
The condyle position discrepancy between stable/normal and the MIP dislocation can be in almost any direction and position. The clinical manifestation of this discrepancy is usually referred to as a “slide,” or as a “closure” interference. Rarely does this dental “slide” actually show up as the condyle being on the disc and downward and forward on the eminence. Rather, the abnormal MIP condyle is pulled downward and away from the disc and eminence, thus destabilizing the disc and allowing for the disc movement that is observed on the JVA.
Consequently, we now pay very close attention to any joint vibration that occurs during the time that the teeth are sliding into MIP, or in the timeframe just before closure. These are the early, subclinical vibrations that can be easily treated by elimination of the closure interferences and/or re-establishing the normal vertical dimension of occlusion. Certainly, the treatment plan does not have to include a change in vertical dimension or a full-mouth rehabilitation; however, it must ensure that the closure interferences (slides) are eliminated and that any hyperactivity of the lateral pterygoid muscles related to working or nonworking interferences be controlled with appropriate occlusal therapy. This occlusal therapy can include subtractive coronoplasty on the interferences, but more frequently depends on appropriate additive coronal enhancement of the anterior and canine teeth.
The use of the JVA during treatment design and provisionalization as well as postoperatively gives us the assurance that we are not only aware of any pretreatment problems or red flags, but most importantly, that in the course of any dentistry that influences tooth contact or occlusion patterns, we have not made changes that result in a more unstable TMJ apparatus than we noted before treatment. We would always like the patient to finish our care better off than when we first started (Figures 6a to 7).
Regardless of other biometrics or treatment philosophy, the JVA provides objective information to the treating doctor as to the stability or instability of the TMJ condylar apparatus. This information can be easily utilized in the decision as to whether (or not) MIP would be the best choice in making dental treatment plans for the best long-term patient prognosis. Certainly, an unstable condyle being present in the attempt to treat occlusal disease would necessitate the treating doctor to consider and document the effect of his or her treatment of the dentition on the stomatognathic system, including the TMJs. In the author’s experience, in utilizing the JVA system in literally hundreds of full-mouth rehabilitations during the last 11 years, several conditions of the patient bring this technology to bear.
The most enlightening finding from JVA recordings has been the diagnosis of subclinical problems that represent “early” or “unstable” condyle-disc problems that are not perceptible with any other technology, especially palpation or auscultation. This condition shows up as disc movement, joint laxity, and/or TMJ inflammation. The ability to diagnose this subclinical condition has revealed that appropriate treatment of the dentition can result in stabilizing or correcting the problem in the condyle disc apparatus. This is the missing link in the conversation of the connection between the occlusion and the TMJ condition.
If problems can be detected before they become permanent ligament or disc damage, then stabilization through effective occlusal therapy will afford the patient the best possibility for long-term health and function.
The benefit of having baseline JVA recordings on all of our patients gives the patient the assurance that we will have something to compare to should an injury or jaw trauma occur. It also allows the patient to know that he or she is in the right place for care should any signs or symptoms occur. Many patients are considering snoring or sleep apnea appliances that modify the position of the jaw and joints at night. The JVA allows us to follow their therapy with appropriate care giving and monitoring.
Only by having appropriate biometrics with the JVA we can ensure that we are in control of the TMJ condition for our patients. Screening, diagnosing, recording, and monitoring with JVA provide affordable, noninvasive, and objective data that we have needed for effective routine TMJ management, even for our asymptomatic patients.
Disclosure: Dr. Montgomery has no financial interest in any of the companies mentioned in this article and received no compensation for writing this article.
Disclosure: Dr. Shuman reports no conflicts of interest.
Disclosure: Ms. Morgan reports no conflicts of interest.
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