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For many decades, the relationship between occlusal factors and temporomandibular disorders has been discussed controversially in the dental literature. After a brief description of current points of view about this topic, a recently published clinical trial by Le Bell et al. (2002) is summarized. The results of this study are discussed on the basis of a novel neurobiologic model, which is based on the heterogeneous activation of the masticatory musculature. This model appears to be suitable to explain the pathogenic and therapeutic effects due to occlusal management of patients with myofascial facial pain.

Over the last years, aetiological concepts have changed drastically. The role of occlusal factors in the aetiology has been overestimated in the past. The role of occlusal therapy should be aimed at restoring function. In the initial phase of treatment an occlusal splint, counseling, physiotherapy and occasionally NSAID's, leads to relieve pain and reduction of dysfunction in most patients. A repositioning splint in cases of anterior disc dislocation is not longer recommended. Selective grinding can be done in "occlusally sensitive" patients with pain or dysfunction of muscular origin. The adjustment should have a limited character, and is not indicated as preventive measure. Occlusal prosthetic reconstruction is in most patients not indicated for reasons linked to TMD because the aetiologic relationships between TMD and loss of molars has not been established. In cases of rheumatoid arthritis, osteo-arthrosis and spondylitis ankylosans, occlusal changes can occur due to the degeneration of the joint components. After the initial phase of treatment replacing the lost molars by prostheses in these particular patients, results in unloading of the joints and in decreasing recurrence of symptoms.

Frequency severity of gingival recessions was studied with Stahl and Morris indices. The results showed that the localization of gingival recession was more important on the mandible (37%) than on the maxillary (27.6%) it, also demonstrated the importance of various etiologies and particularly the association of trauma - tooth malposition (81%).

An occlusal problem can explain otologic symptoms and myofacial pains. A dental and an occlusal examination is necessary to find the true mechanism. If the occlusal examination is not immediately possible, the scheme of the biting retro incisive helps to the diagnosis, in motter to put in place a treatment. In this complete study with a backward regard of 79 patients, 62 have been treated with a total success.

The authors describe the various etiological types of periodontopathies and discuss those due to inflammatory conditions in greater detail. The original studies that enabled the role of the bacterial plaque to be demonstrated are reviewed, and new data presented which attributes a specific pathogenic action to certain bacterial strains in this particular form of the disease, without suggesting that they are the only etiological factor involved. The importance of occlusal injury in periodontal disease is then evaluated, results of clinical studies tending to confirm the role of traumatic factors in the progression of alveolysis. The occlusal factor should therefore be integrated into the stomatognathic system. The results of systematic dentofacial orthopedic examinations in patients with periodontopathies are reported, and other pathogenic factors contributing to disequilibrium of the dental organ outlined. Several clinical cases are presented. The results of these observations are employed to redefine the notion of function equilibrium which must be taken into account when treating the disease prophylactically, and to recognize those cases in which it is disturbed. Neuromuscular reeducation is then necessary to avoid recurrence of the periodontal disease.

The author point out that periodontitis is a disease of multiple aetiology and indicate two types of pitfall: traps in conceiving the plan of treatment and traps in carrying out treatment. The treatment plan may be incomplete. The authors show that the deepest types of vertical alveolysis are always related to occlusal or functional imbalance and that treatment based only upon hygiene and periodontal surgery represents a pitfall. They stress the importance of functional treatment. However such complex functional treatment itself has a number of pitfalls when it is being carried out. It is essential to restore balance of the oro-facial musculature before any treatment of occlusion. These are also types of non-occlusal musculo-dental imbalance which may plan an important role in the course of periodontitis. In conclusion, the authors note that functional treatment of the manducatory apparatus is as important as controlling inflammation. This must not be underestimated nor be allowed to go unrecognised.

The temporomandibular joints are neural structures which develop from the cephalic ectomesenchyme of the neural crests. They are analogous to the effector organs. Their lesional abnormalities have two characteristics:--pain sensation,--"foreign body". A classification is suggested on the basis of clinical characteristics and course of articular signs due to temporo-menisco-condylar stress resulting from occlusion problems, and concomitant lesions of the articular fibrocartilage: closed and open fibro-chondromalacia. Emphasis is placed upon the constant dissociation between articular clinical features and nosography. Spongialisation, or the property of regeneration of fibrocartilage from spongy bone tissue fully justifies the technique of condyloplasty to remodel the temporomandibular joints in the presence of fibro-chondromalacia. The future lies in the distinction between fibro-chondromalacia secondary to occlusive stress and that due to primary ischaemia of bone.

A quantitative study of alveolar bone resorption around the first lower rat molar has been conducted on horizontal sections. The number of osteoclasts/mm2 and the percentage of resorbing periodontal membrane surface of the socket rose through an increase in occlusal forces induced by an amalgam filling in slight occlusal overbite. The increase in resorption was significantly related to the duration of force application. The number of osteoclasts was more than tripled after 18 days. But this increase was observed in areas already previously submitted to osteoclastic resorption during bone remodeling associated with physiological tooth drift.