• Bilateral balanced occlusion: all teeth remain in contact during laterotrusion.
The bilateral balanced occlusion is difficult to achieve in the natural dentition. Nevertheless, balancing contacts can offer protection for the joints in some cases.
132 Canine guidance
With canine guidance, not only should all the other teeth disclude (vertical disclusion), but only the distal slope of the lower canine should slide against the mesial slope of the upper canine. This called “sagittal protection.” This is important from a prophylactic standpoint because it helps keep the condyle from impinging upon the sensitive bilaminar zone during lateral movements (see p. 48).
133 Group function (unilateral balanced occlusion)
Group function involves multiple teeth on the laterotrusive (working) side including the canines, premolars, and sometimes also the molars. There are no contacts on the contralateral (nonworking) side during the lateral movement. Clinically, patients find a moderate canine guidance to be the most comfortable. Surprisingly, this does not correlate with the measured EMC activity of the muscles of mastication (Soneda 1989).
134 Balancing contact
Canine guidance on the laterotrusive side during right lateral movement of the mandible.
Right: Simultaneous tooth contacts on the contralateral side are referred to as balancing contacts. If the contralateral contacts hinder guidance on the laterotrusive side, they are called hyperbalancing contacts, or nonworking interferences. In specific functional disturbances balancing contacts can be advantageous to treatment (see p. 318).
Manual Functional Analysis
Manual examination techniques for systematic testing of the musculoskeletal system can be traced back to the London orthopedist Cyriax. His 1933 textbook describes specific techniques for examining the temporomandibular joint. During recent decades, conventional functional diagnostics in dentistry was based primarily upon the study of active movements and muscle palpation (Dworkin et al. 1988, Fuhr and Reiber 1989, Siebert 1996). The system used was derived mostly from the examination techniques of Krogh-Poulsen (1966). Hansson et al. (1980, 1987) were the first to advocate applying the examination methods from orthopedics and manipulative therapy (Cyriax 1947; Mennell 1949; Maitland 1964; Wolff 1970; Mennell 1970, 1978; Kaltenborn 1976L; Cyriax 1947, 1979; Frisch 1987) to examination of the temporomandibular joint.
Over the years many other authors adopted various orthopedic tests and described their diagnostic potential (Friedman and Weisberg 1982, 1984; Palla 1986; Solberg 1986; McCarroll et al. 1987; Roller 1989; Hesse et al. 1990; Steenks and de Wijer 1991; De Laat et al. 1993; Lobbezoo-Scholte et al. 1993, 1994; Hesse 1996; Hesse et al. 1996, 1997).
By itself, however, the application of the “new” examination techniques to complement the conventional evaluation of active movements and muscle palpations still did not represent a decisive advance in clinical functional diagnostics.
The multitude of examination techniques available were taken up in 1988 by G. Groot Landeweer and A. Bumann and further developed into a systematic, practice-oriented examination concept. The term manual functional analysis was introduced to describe the new concept (Groot Landeweer and Bumann 1991, Bumann et al. 1993, Bumann and Schwarzer 1995, Bumann and Groot Landeweer 1996a, b) and to differentiate it from instrumented functional diagnostics, which was highly rated at that time, and from the term clinical functional analysis, which was used for the conventional procedures.
After a few years of intensive clinical experience, the initial concept (Groot Landeweer and Bumann 1992, Bumann and Groot Landeweer 1992) of the basic examination and the expanded examination-associated with the spiritual father of manipulative medicine-was abandoned in favor of a systematic, goal-oriented testing of the individual anatomical structures (joint surfaces, bilaminar zone, capsule and ligaments, muscles of mastication), in addition, specific techniques for differentiating various clicking phenomena in the human temporomandibular joint were described (Bumann and Groot Landeweer 1993), and the reliability of these for diagnosing partial and total disk displacements was demonstrated (Bumann and Zaboulas 1996).
The introduction of the so-called loading vector represents a major advance in manual functional analysis. This describes the direction of any load that is responsible for an area of tissue damage within the joint and provides a better understanding of malfunctions of the system. A determination of the specific loading vector is important if one is to follow an effective procedure for arriving at a diagnosis and treatment plan. Therefore the current concept of manual functional analysis takes the following aspects into consideration:
• A search for the loading vector at any given time
• Tests for any possible restrictions to movement
• Determination of various harmful influences
The Masticatory System as a Biological System
The introduction contains a brief discussion on how influences, mechanisms of adaptation and compensation, and the emergence of symptoms are interrelated. Whether or not symptoms will arise in the masticatory system depends primarily on the equilibrium between the harmful influences and the patient’s capacity for adaptation. The resultant influence is a combination of the number, duration, amplitude, and frequency of all the individual influences (static and dynamic occlusion, parafunctions, and dysfunctions). The dentist can alter this equilibrium only to a very limited extent. Because the patient’s individual adaptability cannot be influenced directly, one who treats a biological system such as the masticatory system can only indirectly help the organism to adapt by reducing the sum total of the harmful influences. For the dentist, this means that he/she can bring about a positive influence on a disrupted functional system only if the functional disturbance is at least partially the result of a nonphysiological static and/or dynamic occlusion.
135 Biological systems
Influences within biological systems are processed through two mechanisms. When a system has the ability to assimilate the acting stimulus passively without a further increase of its inherent energy, an adaptive condition exists. The second mechanism is compensation, in which there is an increase of the system’s inherent energy with either an absence or a decrease in adaptation. With persisting un-physioiogical loading the system can lose its ability to compensate (decompensation) and undergoes collapse, usually with the appearance of clinical symptoms. It is essential during examination of the masticatory system that the clinician is able to differentiate between these two conditions, adaptation on the one hand and and loss of adaptation or loss of compensation on the other. Systems that are in an adaptive state require no treatment. When adaptation becomes lost, treatment is necessary; the treatment goal is the restoration of an adapted condition.
The first part of the manual functional analysis procedure determines the patient’s complaints and the degree of damage of the relevant tissue. The principle of the examination is similar to that of a stress EKG: the structures of the masticatory system are loaded to the maximum in a specified sequence. A patient may react to this in one of three ways:
• The stress on the tissue provokes no pain or other symptoms. This is a physiological response and is a sign that the structures