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Introduction

The dental functional diagnostic procedure determines the functional condition of the structures of the masticatory system. For patients with functional disturbances it serves to arrive at a specific diagnosis. For medical and legal reasons, it is necessary for all patients who are facing dental restorative or orthodontic treatment, even for those who are assumed to have no malfunction. Often no connection can be established between the clinical findings discovered through conventional methods (testing of active movements and muscle palpation) and the symptoms reported by the patient. For that reason, specific manual examination methods for the masticatory system have gained prevalence during the past 15 years. These focus on the so-called loading vector and recognize the capacity of biological systems for adaptation and compensation. A cause-targeted treatment is then indicated only when the caregiver knows which structures are damaged (loading vector) and the cause of the damage (the harmful influences).

1 Possible causes and consequences of an altered occlusion

Idiopathic or iatrogenic alterations of the static or dynamic occlusion can influence the neuromuscular programming, and thereby affect other structures of the masticatory system. The same sequence of events can also be precipitated by intrinsic factors or other extrinsic factors. Usually during a clinical examination the changes listed in the right-hand column receive the most attention. But to plan a cause-targeted therapy it is necessary to determine what the specific causes of the altered neuromuscular programming are. A differentiated investigation protocol could set aside the old superficial philosophical discussion of the causes of functional disturbances within the masticatory system (“occlusion versus psyche”) in favor of an individualized patient analysis.

The Masticatory System as a Biological System

Every biological system, from a single cell to an entire organism, is continuously exposed to many influences. It overcomes these through two mechanisms:

• adaptation as a reaction of the connective tissues;

• compensation as a muscular response to an influence (Hinton and Carlson 1997).

Influences on the one hand and the capacity for progressive adaptation on the other may achieve a physiologic state of equilibrium. If, however, the sum of harmful influences during a given period of time exceeds an individually variable threshold, or if the adaptability of a system becomes generally diminished, the system will fall out of equilibrium. This condition has been referred to as decompensation or regressive adaptation (Moffet et al. 1964) and is accompanied by more or less severe clinical symptoms. Regressive adaptation of bone can be seen on radiographs (Bates et al. 1993), and in soft tissues it is expressed as pain.

Because the adaptability of a system is primarily a genetic factor and decreases with increasing age, the most effective therapeutic measures are those aimed at the reduction of the harmful influences.

2 Fundamentals of the etiology of symptoms in the masticatory system

Every biological system is subjected to harmful influences of varying severity. The ones listed here represent only a selection of those which the dentist can demonstrate simply and repeatedly. These influences are assimilated by the system through progressive adaptation (connective-tissue reactions) or compensation (muscular reactions). As long as a system remains in this state, the patient will report no history of symptoms or functional disturbances. Only when the damaging factors exceed a certain threshold does regressive adaptation, or decompensation, accompanied by destructive morphologic changes and/or pain begin. By the time a patient comes to the dental office with symptoms, not only must severe influences already be present, but the mechanisms for adaptation and compensation must already be exhausted.

3 Equilibrium between influences and adaptation/compensation

A healthy biological system can be compared with a balanced set of one side are countered by the individual’s capacity for adaptation and compensation. The adaptive and compensatory mechanisms are genetically determined and therefore remain relatively constant, except for a gradual decline with age. For this reason, the equilibrium can only be disturbed by change on the side of the influences.

Progressive/Regressive Adaptation and Compensation/Decompensation

The patient population of a dental or orthodontic practice can be divided into three groups:

• “Green” group: The masticatory structures are either physiological or have undergone complete progressive adaptation. These patients have no history of problems, nor do they experience symptoms during the specific clinical examination.

• “Yellow” group: These patients have compensated functional disturbances and no history of problems. However, symptoms can be repeatedly provoked by specific manipulation techniques.

• “Red” group: Patients with complaints whose symptoms can be repeatedly provoked through specific examination methods suffer from a decompensated or regressively adapted functional disturbance.

In young patients, adaptation is based upon growth, modeling, and remodeling (Hinton and Carlson 1997). Modeling (= progressive adaptation) is the shaping of tissues by apposition and results in a net increase of mass. Remodeling (= regressive adaptation) is usually accompanied by a net decrease of mass. In adults adaptation depends primarily upon remodeling processes (de Bont et at. 1992).

4 Functional status of biological systems

A functional analysis should always be carried out before any dental restorative or orthodontic treatment is initiated. The patient’s most urgent needs are determined by which group of the patient population he/she is classified under. For patients with complaints (red group) a functional analysis should be performed to arrive at a specific diagnosis and to determine whether or not treatment h indicated and possible, and if so whether it should be cause-related or symptomatic. All other patients (green and yellow groups) have no history of complaints. If during a specific functional analysis with passive manual examination techniques, compensated symptoms can be repeatedly provoked in an otherwise symptom-free patient, the patient is classified in the yellow (caution!) group. Identification of these “yellow” patients is extremely important because of the therapeutic and legal implications. They make up between 10% and 30% of the patients in an orthodontic practice. Patients with compensated functional disturbances are also of special interest because tooth movement or repositioning of the mandible is always accompanied by stresses which increase the harmful influences on the system.

When faced with a compensated functional disturbance, the clinician has three basic options:

1. Referral of the patient because of the complexity of the problem.

2. Dental treatment without provoking decompensation. Here the dentist must be aware of the loading vector acting upon the system.

3. Treatment directed at the cause with subsequent definitive dental treatment monitored through on going functional analysis.

Functional Diagnostic Examination Procedures...

Besides a thorough case history, a modem treatment-oriented functional diagnostic concept is composed of three parts:

• Examination to determine the extent of destruction of the different structures of the masticatory system. This part determines conclusively whether or not there is a loading vector (= overloading of one or more structures in a specific direction).

• Treatment-oriented examination to reveal any structural adaptations (= progressive adaptations). Here thought must be given to distinguishing between progressive adaptation in the loaded structures and adaptation of the surrounding structures. As a rule, the former are desirable and require no treatment, whereas adaptations in the surrounding structures usually result in an increase of the load and restriction of movement. Adaptations of surrounding structures are always oriented in the direction of the loading vector and therefore impede treatment. Within the framework of an interdisciplinary treatment, it is the duty of the physical therapist to eliminate any adaptive conditions in the surrounding structures through manual therapy and measures to increase mobility. Without a permanent modification of habitual functional patterns, physical therapy will not be successful.

5 Schematic representation of the treatment-directed examination sequence

To establish a function-based, problem-oriented treatment plan, it is first absolutely necessary to gather specific information in a rigidly defined sequence. Our current concept has been tested and validated by more than 10 years of clinical experience. The three elements at its core are the reproducible determinations of destruction (= loading vector), structural compensations (= adaptations) and etiological factors (= influences). The first two elements require the examination techniques of manual functional analysis. At this time there is no practical alternative available to test for loading vectors and evidence of adaptations in the masticatory system. Because of their multiplicity and variety of origins, the influences can be only partially clarified within a dental practice. For this the dentist has at his/her disposal the techniques of clinical occlusal analysis and instrumented functional analysis (in the articulator). In functional diagnostics the latter serves only as a test of the inclusive information without knowledge of the individual loading vectors that may be present.

...and their Therapeutic Consequences

• The third part of the examination process seeks to identify all possible harmful influences, and for the dentist this is the most important part. It deals especially with finding evidence for causal relationships between any loading vector and the occlusion. The findings provide information as to whether or not the static and dynamic occlusions are contributing to the overloading of affected structures. In the discussion of whether treatment should be solely dental or interdisciplinary there are two basic points to consider: On the one hand, isolated treatment of the masticatory system also affects the structures that allow movement (Lotzmannetal. 1989. Gole 1993), while on the other hand, treatment of the movement apparatus may also resolve problems in the masticatory system (Makofsky and Sexton 1994, Chinappi and Getzoff 1996). Patients with chronic pain can benefit significantly from a thorough, specific, interdisciplinary treatment [Bumann et al. 1999).

6 Evaluation of the destruction

The extent of intraoral destruction is determined by the traditional dental primary diagnostic methods. Damage to the individual structures of the temporomandibular joint and the muscles of mastication can be detected only through manual functional analysis. In some cases additional imaging procedures are necessary.

Left: Example of a clinical examination technique (posterosuperior compression) to detect destructive changes in the masticatory system.

7 Identification of the impediments

Identification of musculoskeletal impediments is very important for treatment planning. If existing impediments are not diagnosed, the treatment goal will be reached much later, if at all. Furthermore, the treatment result is likely to remain unstable.

Left: A histological slide shows anterior disk displacement with disk deformation as an example of an impediment in the anterior treatment direction.

8 Identification of the influences

The search for causes is aided by asking why the symptom arose. From the dental point of view, the question arises as to whether the with the symptom or the loading vector (see p. 124ff). If this is not the case then the patient in question will not be helped by modifications of the occlusion.

Left: Example showing use of the Mandibular Position Indicator to help diagnose a static occlusal vector(see p. 128).

The Role of Dentistry in Craniofacial Pain

Polarizing discussions during the past 10 years have made the role of the dentist in diagnosing and treating pain in the head and neck region increasingly obscure rather than more clear. In the academic debate concerning the etiology-predominantly psychological factors versus predominantly occlusal factors—the practitioner facing the problem of treating a patient has been largely ignored. The argument of multicaiisal genesis was previously taken as an excuse to regard the multiple causes as an inseparable bundle rather than to dispel at least a certain amount of confusion by specifically testing the individual factors.

It is our opinion that every patient with head and neck pain should be seen by a dentist in order to clarify the following questions:

• Do the symptoms arise from a structure in the masticatory system (presence of a loading vector)?

• Is the loading vector related to the occlusion?

• Can the occlusion-related portion of the total loading vector be reduced with reasonable effort and expense?

• Would symptomatic treatment in the dental office be reasonable?

9 Differential diagnosis of head and neck pains

A pain classification scheme modified from those of Bell (1990) and Okeson (1995). The colors of the backgrounds of the different diagnoses indicate which disorders are outside the realm of dental treatment and which require the inclusion of Other disciplines for diagnostic assistance or for ruling out certain conditions. In addition, colors indicate which diagnoses can be arrived at through which steps in the dental examination. As clearly shown by the overview, dentistry covers a significant part of the differential diagnosis of head and neck pain. This does not mean, however, that dentistry should be the leading discipline in treating every case of head and neck pain. There are, for example, areas in which the dentist cannot intervene with primary cause-related treatment, or even with interdisciplinary secondary support. The primary goal of a tissue-specific diagnostic process for identification of loading vectors is to differentiate between conditions that can and cannot be treated by a dentist. Except in the latter instance, the decision must then be made whether dentistry is to provide the sole treatment of the diagnosed conditions or is to be part of an interdisciplinary approach.