The Concept of the Complete Examination
Five diagnostic components for predictable restorative success
Proper and complete clinical evaluations are the basis of proper and complete diagnoses, which in turn lead to relevant and predictable treatments. Patients require restorative dentistry for reasons such as decay, tooth breakage or weakening, wear, or complete tooth loss. It is very predictable to diagnose and treat issues related to bacteria; there, cause and effect are clear, and both the patient and the doctor are often comfortable with such a scenario.
The most common yet under-diagnosed dental condition today is excessive tooth wear. While patients often seek cosmetic rehabilitation due to excessive chipping and wear of both posterior and anterior teeth, many cases are treated without a clear understanding or diagnosis of what caused such severe loss of tooth structure. This is unfortunate, because if the cause of the wear to the natural dentition is not remedied during treatment, the restored teeth will likely suffer the same prognosis.
Examining the System
It is important to understand that the teeth are functioning within a system. This system is composed of the temporomandibular joint (TMJ), the muscles of mastication, the posterior teeth, the anterior teeth, and their connection to the central nervous system. These components, which comprise the stomatognathic system, must function in harmony for the patient to have comfort and long-term stability. A lack of harmony will show up as signs and symptoms in one or more components of the system. These could include wear, migration, and mobility of the teeth; soreness in the muscles of mastication; and pain, tension, clicking and popping, and crepitus in the TMJ.
To address these symptoms, the restorative dentist must have a system by which to evaluate and examine the components of the stomatognathic system. The dentist must also possess the training to interpret this data and formulate a complete diagnosis. This will lead to a treatment plan to address any instability in the system.
The following components of the complete examination are discussed in detail below:
1. Palpation of the muscles of mastication.
2. Evaluation of the range of motion of the mandible.
3. Evaluation of the dentition for sign of instability.
4. Evaluation of the occlusion and requirements of occlusal stability.
5. Determination of the restorability of the TMJ.
Palpation of the Muscles of Mastication
The muscles of mastication should be free of inflammation and capable of palpation without discomfort. The dentist must identify soreness to palpation in the superficial masseter, deep masseter, anterior temporalis, posterior temporalis, and the medial pterygoid. Patients should be asked about muscular discomfort. If they are experiencing any aching in the muscles, they should describe its intensity, duration, and frequency, as well as whether there is any cramping or knotting. The doctor should examine the masticatory muscles for signs of hypertrophy. Most patients have never had their masticatory muscles examined and are often unaware of the level of muscle knotting and soreness that is commonly present. Patients with headaches are also often unaware of possible occluso-muscular causes and implications. Many people have adjusted to a "baseline" of muscle discomfort and may be unaware of what it feels like to be muscularly comfortable.
Evaluation of the Range of Motion of the Mandible
Much information can be obtained by observing the range of motion of the mandible. The dentist should be aware of the effects of muscle hyper-contraction and intracapsular joint derangement. The mandible should rotate (condyles in the glenoid fossa) approximately 20 to 25 mm. Opening larger requires translation of the condyle to a maximum normal opening of 40 to 60 mm. The mandible should be capable of protruding more than 8 mm and moving laterally left or right at least 8 mm.1 These measurements can be made using a range-of-motion ruler (Figure 1 and Figure 2).
Movement to maximum limits should be asymptomatic, smooth, unrestricted, and symmetrical. Deviations and restrictions should warrant further investigation to determine a muscular or intracapsular origin.
Evaluation of the Dentition for Signs of Instability
The signs of instability in the dentition would include abnormal wear, tooth movement that is not wanted, broken teeth, and teeth with excessive mobility (Figure 3 and Figure 4). A normal amount of tooth wear occurs slowly, following a minimally progressive course. In an adult, tooth wear averages 10.7 µm per year. Exposed dentin is not normal and should be evaluated to determine its cause. Because dentin wears at a rate far greater than enamel, this can cause wear and breakdown to accelerate.2
Tooth movement that is unwanted is the result of excessive force on a tooth or breakdown of its supporting structures. Normal teeth have 50 to 100 µm of mobility that varies by time of day and amount of force applied. Numerous factors can lead to increased tooth mobility. Periodontal disease is a common cause of mobility; however, excessive load and lateral forces found in occlusal trauma can also cause this condition to exist.3 Thankfully, the mobility can be resolved to pre-trauma levels once the cause is removed.4 Patients can exhibit varying degrees of some or all the signs of instability.
A complete exam will also identify a centric relation/maximum intercuspation discrepancy–ie, hit on inclines and slide into full or maximum intercuspation (Figure 5). If there is a discrepancy, these questions should be considered: Is the deviation in the arc of closure or line of closure? Is the patient able to chew all food on both sides without pain? Does the bite seem to be changing or unstable? In addition, does the wear on the teeth indicate functional patterns? Horizontally functioning patients often have flat tabletop wear present (Figure 6), while vertically functioning patients often exhibit constricted wear patterns of anterior chipping and lingual wear of maxillary anterior teeth (Figure 7 and Figure 8).
Once the data are collected, there remains the challenge of how to proceed. When the signs or symptoms of instability are recognized in the teeth, joints, or muscles, further investigation is warranted before beginning restorative care. That would include patients with a positive load test, muscular symptoms, people with tooth wear or mobility that is excessive, and patients with a hit and slide into maximum intercuspation, who should undergo a further diagnostic evaluation that includes face-bow mounted diagnostic casts in centric relation.
Evaluation of the Occlusion and Requirements of Occlusal Stability
Just as it is important to recognize the signs of instability during an examination, it is equally important to recognize the signs of stability. A patient may exhibit numerous signs of stability and only few signs of instability or vice versa. The signs of stability are even, stable holding contacts on all teeth with the joints in centric relation; anterior guidance that immediately discludes the posterior teeth in excursive and protrusive movements; harmony with the envelope of function; and teeth in harmony with the neutral zone.1 By knowing the signs of stability, they can be incorporated into future restorative treatment.
Through even tooth contact (no contact on cusp inclines) with the TMJs in centric relation, true stability can be maintained or reintroduced. According to Peter Dawson, DDS, "Centric relation is the only condylar position that allows an interference-free occlusion."1 Centric relation is a natural, stable axial position from which the jaw can anatomically function. When the elevator muscles contract and the lateral pterygoids release, this stable axial position will be reached. This fixed position is in the most superior part of the glenoid fossa with the condyles being braced by their medial poles.5 A tripod of stability is reached when both condyles are fully seated and even anterior contact exists. It is from this relationship that an interference-free occlusion can be derived. It becomes clear that a clinician must also verify a lack of pathology or alteration in the joint structures to allow proper joint function. Centric relation is a position achieved only with the proper condyle disc assemblies in proper anatomic position.
The effect of proper anterior guidance on muscle activity has been well documented in the literature for decades. By having immediate disclusion of the posterior teeth in excursive and protrusive movements, the elevator muscles are shut down, which lessens the force on the teeth.6-9 Posterior teeth should only be loaded along the long axis of their roots.3 When posterior teeth remain in contact during excursive movement (working and non-working side interferences), the elevator muscles remain active. This causes muscular functional disharmony between the muscles of mastication. Proper guidance eliminates lateral forces on posterior teeth, thus reducing wear to normal levels (Figure 9 through Figure 12).
Teeth respond to force by changing their position, unless there is an equal balancing force. For this reason, teeth must be restored or placed in harmony with the neutral zone, which is a peri-oral complex established facially by the muscles of the lips and soft tissue and lingually by the muscles of the tongue. Teeth will move naturally to find a neutral spot between these forces.10
Determination of the Restorability of the TMJ
It is necessary to examine the TMJ to establish its current condition and the effect this may have on proposed treatment. Information may be gathered through physical examination, oral history, or radiographically. Discussion of a patient's history will often reveal information helpful in diagnosis of the TMJ; this would include any history of injury such as blows to the face, sports injuries, or automobile accidents. The clinician should ask whether the patient has ever experienced pain in the joints, noise such as clicking or popping, or if there is a history of the jaw locking in any position.
The joints must be capable of loading under firm pressure in centric relation without tenderness, tension, or pain11 (Figure 13). If this response is positive, further investigation must be undertaken, as the joint is not in centric relation with the proper disc condyle assembly. Tenderness and pain may indicate displacement of the disc from its proper position. Tension may indicate that a lack of muscular release is preventing the condyle from seating in the glenoid fossa.
Another useful tool to aid in joint diagnosis is Doppler auscultation (Figure 14). It offers a fast, reliable method to listen for joint derangement, and when combined with load testing, can be highly diagnostic.12 From a radiologic standpoint, the gold standard of imaging is magnetic resonance imaging (MRI). As opposed to standard radiographs or CAT scans, MRI can image and determine the disk position with certainty. Due to the expense associated with MRI imaging, it is often solely employed for patients in severe dysfunction or pain. For this reason, a clinician must be able to reasonably determine the health of the TMJ using less expensive and invasive diagnostic tools. Although a discussion of possible TMJ conditions, which are quite specific, is well beyond the scope of this article, the joint will be in three possible conditions with varying degrees of derangement. These conditions would be structurally intact, altered at the lateral pole, or altered at the medial pole.1 The pertinent point not to be missed can be summed up by this quote from Dawson, "If the TMJs are not stable, the occlusion will not be stable, so it is a risky proposition to undertake occlusal changes without knowing the condition of the TMJs."1
Moving Forward with Treatment?
One of the first decisions to be made is whether it is safe or risky to begin restorative treatment. In the opinion of this author, a "risky" patient will exhibit three characteristics. First among them is active temporomandibular dysfunction (TMD). Although this topic is beyond the scope of this article, the most pertinent point is that TMD patients often have altered and/or changing joint anatomy. A second situation to be concerned about is a severe bruxism, which can be the result of numerous causes, many which are multi-dimensional13 and difficult to treat. If a patient's problems can destroy teeth, they can destroy restorative dentistry. When a patient's problems are beyond the scope of a clinician's ability, caution is warranted. Lastly, people with psychological issues should raise a note of concern. The clinician's review of a patient's medical and dental history should include screening for psychological functioning and distress. This could include screening patients for a history of seeing multiple dentists, self-image issues, sleep disorders, fatigue, and patients with uncompleted care in their mouth.14
The good news is that most patients can be safely restored, and conditions identified in patients given a complete examination can often be resolved before commencing treatment. The purpose of completing a thorough exam before treatment is to recognize whether patients have instability in their teeth, muscles, or TMJ. When instabilities are recognized, treatment options can be created to achieve resolution.
Conclusion
Achieving success in restorative dentistry is an ever-evolving challenge. No two patients are alike; all have their own combinations of signs and symptoms. It is the clinician's responsibility to properly examine and diagnose in order to make sound restorative decisions. This begins with a complete examination that will provide the necessary information to determine the current condition of the stomatognathic system. By following a simple, yet thorough, standardized diagnostic approach, predictability can be achieved.
About the Author
Leonard A. Hess, DDS
Senior Faculty
The Dawson Academy
St. Petersburg, Florida
Private Practice
Monroe, North Carolina
References
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