The human masticatory system is special because apart from a larger
amount of muscles than de- grees of freedom its joints do not restrict
its movements a priori. Therefore, each muscle is able to influence all
six degrees of freedom which makes the system kinematically and
mechanically indetermi- nate. Furthermore, its working space is
principally determined by the dynamical properties of its muscles and
not by passive constraints. It is concluded, that active and passive
muscle tensions through occlu- sion and condylar surfaces are in a state
of dynamical 3D equilibrium. During evolution the masticatory system
assumed a number of structural elements designed to stabilize the dental
arches to withstand powerful mastication forces which consist of
different vectors. Moreover, the perfect correlations exist between
occlusal stability and elevator muscle function, which are based on
feedback mechanisms from periodontal pressoreceptors.The perfect
geometry of the occlusal surfaces and dental arches jointly with
well-balanced occlusion, solid proximal dental contacts and structure of
the periodontal ligament guaran- tee physiologically acceptable
distribution and compensation of the mastication forces, thus ensure
long- lasting functioning of the teeth. This ideal from a functional
viewpoint system may be damaged due to periodontal disease or partial
dental loss. Restoration of the functional integrity of the dental arch
is one of the most relevant problems in clinical dentistry. Functional
equilibrium in and between the dental arches guarantee balanced
functional stimulation of the masticatory apparatus and contributes to
its harmonious development and maintenance.
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