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Erschienen in:
01.03.2012 | review article
Tooth clenching as a risk factor for temporomandibular disorders
A synthesis of recent publications
Erschienen in: international journal of stomatology & occlusion medicine | Ausgabe 1/2012
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Tooth clenching, more than tooth grinding, is considered one of the most detrimental oral parafunctional activities and has been implicated as an important factor in the etiology and maintenance of temporomandibular disorders (TMD). This frequent parafunctional behavior is of major concern to dentists because of its possible consequences on the different components of the stomatognathic system as excessive occlusal forces are able to cause dental restoration and/or hard dental tissue breakdown (wear, cracks), periodontal breakdown (mobility) or TMD.
The aim of this paper was to present a synthesis of recent publications (published during the last 10 years) dealing with some aspects of tooth clenching and its relationship to TMD: methods for the evaluation of tooth clenching, epidemiological data, effect of tooth clenching on the temporomandibular joint (TMJ) and the masticatory muscles, relationship between tooth clenching, stress and psychological factors and biological function of tooth clenching.
A search in the National Library of Medicine PubMed database was performed using the association of the two key words “tooth clenching” and “temporomandibular disorders”. However, although tooth clenching and tooth grinding are considered two different disorders, it appeared in most papers that these two parafunctional activities are often associated so that it was not always possible to systematically separate the data relevant to tooth clenching from those relevant to tooth grinding.
Awake clenching is reported by about 20% of the general population and by 50–80% in TMD populations. This oral parafunction is responsible for excessive mechanical stress in the TMJ which may lead to disk displacement and/or joint damage with internal derangement or osteoarthritis. Experimental low-level tooth clenching in pain-free individuals has been shown to produce symptoms sufficiently severe to meet the diagnostic criteria for TMD myofascial pain. However, the masticatory muscle pain is usually short-lasting and self-limiting which questions the nature of the relationship between tooth clenching and TMD. The etiology of the muscle pain can be ascribed either to damaged muscle fibers or to a reduction in blood supply.
Although there is strong evidence that some TMD patients are characterized by high levels of distress, anxiety and somatization, conflicting evidence still exists regarding the causality of the relationships between tooth clenching or grinding, stress and TMD. On the other hand, tooth clenching or grinding could be considered as a useful prophylactic behavior for stress-related psychosomatic diseases, such as stomach ulcer and/or neuroses, by down-regulating the limbic system, the autonomic nervous system and the hypothalamic-pituitary-adrenal axis.