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Orthodontic therapies for asymmetrical musculo-articular dysfunctions
Algies and dysfunctions of the manducatory tract come in various forms with multiple etiologies. When occlusal causes are today largely understated by most authors, it is nevertheless admitted that asymmetries represent a risk factor for appearance and development of dysfunctional pathologies of the manducatory tract. When such dysmorphoses are present, it is essential to detect potential dysfunctions and - possibly - to perform a special clinical assessment of the manducatory tract, and - if necessary - additional examinations. This step allows making the mandatory diagnosis, assessing the adaptive capacities and proposing a coherent therapeutic attitude that will always start with reversible treatments that can be continued, if necessary - after re-assessment - by stabilizing the occlusal relationship, a phase when orthodontics will often be an actor.
1 Therapeutic process
• Taking care of a patient with an asymmetrical musculo-articular dysfunction demands a practitioner's reflection about the "therapeutic process".
• Prior any proposal for a treatment indication, it is essential to make a careful assessment of the benefits the patient will get from our action. The clinical interview, the clinical examination and the ensuing prognosis are major elements for therapeutic decision making (treating or not treating, with whom, how?). After this step, the practitioner can move to the next question: what kind of therapeutic procedure?
• Epidemiology shows that articular dysfunctions are most frequently asymmetrical. A frequent pathognomonic sign is a discrepancy between bilateral importance of molar and canine Class II, with a midlines' offset. This clinical picture is far from rare and is a reminder for a closer search of asymmetrical musculo-articular dysfunctions.
• The clinical interview must be accurate and must analyze circumstances of appearance, possible etiologies, etc.
• The clinical examination aims to establish a differential diagnosis in order to differentiate muscular from articular problems (disk dysfunction - reducible or not) and from pain concerns.
• The ensuing prognosis must allow an early listing of the different kinds of cases: muscular problems, intra-articular problems and mixed cases which are frequent. This prognosis is analyzed according to several major factors: the first one will assess both short term and long term; the second one will compare the therapeutic option (invasive) to a non intervention strategy.
• This much formatted procedure allows - for example - establishing an indication for a treatment that will include a recapture of the disk (treatment on the disk) when a reducible disk dysfunction recently appeared, with a special clinical picture showing a distinct early projection in the condylar path at the opening. At the opposite, a therapeutic centric relation, without disk recapture (treatment off the disk) will be proposed when the projection is ancient et more belated in the condylar path of opening.
• Management of pain problems depends upon the examination of patient-reported spontaneous signs, and upon clinical examination-induced signs. Then, a prognosis can be considered.
The therapeutic decision making process comes only after this diagnosis and prognosis step.
To summarize, diagnosis will highlight a clinical picture in order to analyze such notions as "pain" or "absence of pain". Specifically, it is the prognosis that will allow making a choice between therapeutic intervention and abstention. S. PALLA made a good description of this progression. The remaining question is "when do we treat, when don't we treat?" In the literature opinions differ about the use of either reversible or invasive therapies. But therapeutic protocols remain relatively close.
2 Therapeutic protocols
• First, let's state that the manducatory tract can have its articular movements modified or limited by internal or external TMJs' etiologies, especially by remote muscular or pain problems.
• Intra-articular disorders are a large part of TMDs, through their most frequent clinical signs: reducible or non reducible disk shifts and arthrosis-induced joint remodeling.
• It is important to determine the etiology of internal problems before assessing the relevance of any usual treatment (orthopedic stabilization with an orthosis, repositioning, decompression, exercises, manual positioning) that will often be followed by a stabilization of tooth-size relationships.
• Also, elements to be taken into consideration are the ancientness of the pathology and the assessment of adaptive capacities.
• Parafunctional habits, known or unknown from the patient, may not only generate especially aggressive and pathogenetic, but - also - difficult-to-manage muscular troubles.
• Mechanical phases are well known and need to be aimed at the reduction of signs and symptoms, using an interocclusal test-orthosis.
• This testing step must be reversible. Following this first step, a re-assessment of the clinical big picture and of the prognosis is mandatory, in order to confirm the improvement.
• Then, a decision should be made: either stabilization of this asymptomatic cranio-mandibular relationship, or non-intervention. Protocols for this stabilization are codified, but few many articles are featuring any iconography of clinical results.
• Cases differentiation is possible: muscular disorders, intra-articular disorders (reversible or not) and pain problems will be considered separately for technical reasons.
Faced to pain, first we relieve.
Face to dysfunction, first we assess the clinical improvement.
In this short first part, we chose to give some rules for the reader to select a therapeutic option. A second part will present this protocol through a case presentation.
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