In the child and adolescent this pathology reaches considerable and probably underestimated orders of frequency, when one takes into account subclinical pathologies and those predisposing to these conditions such as subluxation ( hypermobility) and alteration of joint shape associated with noxious parafunctional habits (onicophagia, bruxism etc.).
The main interest to the clinician in an early diagnosis and treatment of juvenile forms of these conditions, rests in their relative reversibility, even in those cases which present with a marked alteration in joint shape and a severe symptoms of painful dysfunction.
This reversibility, due to the regenerative potential typical of the plasticity of tissues during early growth, is indirectly proportional to it, thus decreasing significantly as growth nears termination.
While the study of craniomandibular arthropathies in infants and during growth is a subject of much current interest, it still requires substantial progress on the clinical therapeutic level. Verification of, and diagnostic and therapeutic procedures for these same conditions in the case of an adult population, are decidedly more substantiated.
Until now, a difference of opinion over the etiology of this pathology has posed a limiting factor to any progress. Our school, in agreement with part of the Scandinavian one, believes it to be primarily due to intrinsic damage to the joint, the musculature being involved only secondarily.
A series of clinical-symptomatological and radiological verifications and long-term studies, along with a huge mass of experimental data from similar pathological conditions studied in other areas (e.g. knee pathologies) allow the following considerations with respect to syndromes associated with craniomandibular dysfunctional arthropathy (algicodisfunction of the TMJ, myofacial syndrome, Costen’s syndrome, dysfunctional craniocervicomandibular pathologies, craniomandibular disorder, etc.):

1. It is very common, and is found through objective verification (clinical examination) in such high frequency as to merit consideration as an “anthropologically phylogenic disorder” rather than a pathology (as with the eruptive pathology of the wisdom tooth);

2. It presents many factors which predispose and extend the condition (congenitally oversized joint, noxious parafunctonal habits, bad fillings, etc.);

3. It has a multifaceted etiology (miopragia of the tissues, malformation of the joint parts, acute traumas, repeated chronic microtraumas);

4. It corresponds to the model of chronic degenerative illnesses (multifaceted etiology, acute phases alternating with remissions, tendency to evolve, impossibility of a complete cure);

5. Muscular involvement is usually only secondary to joint damage (dystrophic and inflammatory changes, myosites / arthromyosites, tenosinovites);

6. It usually presents with a degree of clinical evidence (signs and symptoms) and of objective (instrumental) data that is proportional to the degree of joint involvement (index of arthropathy);

7. It can be helped by many therapeutic approaches, none of which is effective in resolving chronic symptoms (pain, joint noises, deviation of movement):
· the use of sedatives and anti-inflammatory drugs;
· the application of occlusal splints;
· selective grinding and the reorganisation of the occlusal model;
· psychological support;
· physiotherapy;

8. Its progress tends to level off completely into adulthood;

9. It can be completely resolved by a few specific therapeutic interventions in the acute stage (locking, acute condylar/meniscal/temporal subluxation or dislocation, pain associated with hypofunction and arthritis), and especially useful are specific physiotherapeutic exercises for the mandible.

Structural Development of the TMJ

The structure of the temperomandibular joint develops from the 1 brachial arch, differentiating itself from Meckel’s cartilage during the 2nd month of gestation.
At birth, the anatomy of the TMJ is rather rudimental, while the appearance of the first teeth (central and lateral incisors), begins a process of structural differentiation, mainly in the articular eminence of the temporal bone, that gives the anatomy of the TMJ a functional structure dependent on occlusion.
The factors determining the anatomy of the TMJ (posterior determinants of occlusion), stem from both genetic forces and functional exogenetic stimuli. The latter are generated by multiple activities, both physiological (sucking, swallowing, mastication and phonation), and parafunctional (bruxism), already present in the deciduous tooth stage.
The functional anatomical structure that is established during the deciduous tooth stage, tends to be preserved into the phase of change of dentition, with few variants, as is demonstrated by the sequence of eruption of the permanent teeth. The change of the deciduous molars happens only after the stability of the occluding structure has been assured by the additional eruption of the first molars that maintain the vertical component of the occlusion stable, and by the appearance of new incisors that guarantee the continuity of the closing function.