ORTHODONTICS AND DYSFUNCTIONS OF THE MUSCULAR APPARATUS
INTRODUCTION
The masticatory system is the seat of many functions (vital or social) including; the dental system, the bone bases, the muscles and the temporomandibular joint or TMJ. During these different functions, alterations can be observed at the level of this system; alterations which have taken several names.
These alterations called dysfunctions of the masticatory system are complex pathologies with a multifactorial etiology and multiple manifestations which make their diagnosis complicated.
Orthodontics allows for optimal occlusal function (centering, wedging and guiding of the mandible), to promote masticatory functions, to improve the aesthetics of the face and teeth, and thus to contribute to the longevity of the masticatory system. Upstream, by early diagnosis of the various anomalies which could predispose to temporomandibular disorders downstream, by eliminating these anomalies finally by carrying out occlusal equilibration we perpetuate the stability of the corrections and therefore the good health of the masticatory system.
The pathologies observed at the level of the ATM have been the subject of several names, the best known being:
- Costen syndrome
- Algo-dysfunctional syndrome of the masticatory system (Rozeicweig 1970)
- -craniomandibular disorders (Farrar, Mc Carty 1983)
- Pain and dysfunction of the masticatory system (ADAM Rozeicweig 1995)
- Dysfunctions of the masticatory system (CNO2001)
- -temporomandibular disorders
- Temporomandibular dysfunction
- Anatomical reminder
The masticatory system consists of muscles, the dental system, and finally the TMJ, which is the central element of this system. The psychosomatic component is also part of it.
fig1 The temporomandibular joint
Figure 2: The condyle
- DYSFUCTION OF THE MANDUCATORY SYSTEM
- Definition
This is the expression of a myoarthropathy of the masticatory system according to the definition adopted by the National College of Occlusodontics (CNO) or of pain and functional disorders related to a musculoskeletal anomaly of the masticatory system according to the definition proposed by Orthlieb and his colleagues.
For De Boever, these dysfunctions represent a group of musculoskeletal and joint disorders of the orofacial sphere.
For Chalon, temporomandibular disorders (TMD) group together, under this term, a set of muscular or joint pains and dysfunctions.
3. 2. CLASSIFICATION OF DAM
Several classifications have been proposed;
One is based on the elements of differential diagnosis
-Muscular DAM
-Parafunctional DAM
-Musculo-articular DAM
The 2nd based on clinical observation:
-Traumatic DAM
-Parafunctional DAM
-Psychogenic DAM
According to Orthlieb etiology (1988):
-Primitive DAMs
-Secondary DAMs
-Dysfunction of the masticatory system can manifest itself through:
-Craniofacial pain,
– joint noises (cracking, popping)
– Mandibular mobility disorders (horizontal or vertical)
- dental or periodontal alterations
- tension headaches
- tinnitus
- ETIOLOGIES OF DAM
If in the years before 1985 it was occlusion which was incriminated in DAM it currently seems accepted that these pathologies are polymorphic with numerous and multifactorial etiologies.
For Okeson several factors contribute to; there is the establishment of DAMs
-Predisposing factors; which increase the risk of developing DAM
-Triggering factors; responsible for the appearance of DAM
-Aggravating factors; which maintain its progression.
predisposing factors triggering factors
Signs and Symptoms of DAM Adaptation
structural and functional
Structural and functional adaptation
DAM
(Lokeson1996)
4. 1. Predisposing factors
These are skeletal abnormalities of the masticatory apparatus and occlusal function.
Pullinger, et al. nevertheless succeeded in isolating five “occlusal risk factors” 3
anterior open bite – incisal overjet > 6-7 mm – unilateral molar crossbite – ORC/OIM misalignment > 2 mm – posterior edentulism (> 5 teeth)
General factors are also reported such as degenerative, neoplastic, neurological diseases etc.
ATM laxity is also cited in this context
4. 2. Maintenance factors
Parafunctions would play a role in the aggravation of this pathology (bruxism, biting of nails, lips, etc.)
Stress contributes significantly to maintaining or worsening this dysfunction.
For Guyot and colleagues, nasal obstruction could also be an aggravating factor.
4. 3. Triggering factors
macro traumas such as condylar fracture or repeated application of low intensity forces on structures (teeth, menisci, muscles).
- Signs of DAM
- Joint signs
Initially, a clicking sound occurs when opening and closing the mouth. After a certain period, an acute phase may be observed, manifesting itself as sharp pain in the TMJ and trismus.
In favorable cases, joint function becomes good again (formation of a neo-disc), but in other unfavorable cases, joint noises (creaking, rubbing) appear with the presence of pain and even limitation of the amplitude of mouth opening.
5. 2. Muscle signs
Muscle spasms can be observed causing pain and trismus. The pain is located at the jugal level in relation to a spasm of the masseter, opposite the ATM. This pain can be diffuse and cause headaches, earaches, and can even affect the neck. Sensations of imbalance can also manifest themselves through cranio-spinal posture disorders.
5. 3. Additional examinations
Panoramic X-ray
MRI is currently the examination of choice for detecting joint or disc lesions.
- Malocclusions and DAMs
The consensus is currently established to say that malocclusions alone do not constitute the etiology of DAM, nevertheless they represent one of the
predisposing factors. Unilateral crossbite and anterior open bite are more involved for some authors.
- DAM therapy
Treatment is symptomatic but must also be etiopathogenic. 7.1.Symptomatic
Analgesic; non-steroidal anti-inflammatory drugs and muscle relaxants (myolastant). This treatment must be occasional during the acute phase and not continuous.
7.2. Patient education and hygiene and dietary rules
-Avoid chewing gum and bad habits such as nail biting
-Avoid hard foods
-Limit mouth opening (yawning etc.)
-Self-massage of the masticatory muscles
– Frequently put the mandible in a resting position
- 3. Physical therapy
Physiotherapy-rehabilitation with passive exercises and stretching of the masticatory muscles
Acupuncture
7. 4. Making an occlusal splint
Its objective is to reestablish the disco-condylar union, creating favorable conditions for the formation of the neodisc.
Use of an occlusal splint which allows stabilization of the mandible during its closure, muscular reconditioning, relaxation of the masticatory muscles and joint recentering
7.5. Adjuvant treatments
Grinding, orthodontic treatment, prosthetics
7.6. Other treatments
-Removal of parafunctions
-Restoration of nasal ventilation
Restoration of a harmonious posture at rest and in function
CONCLUSION
The orthodontist may be confronted at any time with DAMs for which he must carry out at least a screening if not a diagnosis . This is all the more important since the orthodontist carries out global occlusal rehabilitations , which require a valid mandibular reference position (centric relation) dependent on the musculoskeletal state. Early detection of existing dysfunctions or risk factors allows for appropriate management and modulation of orthodontic treatments for the benefit of the patient.
The orthodontist must therefore be vigilant, occluso-conscious and occluso-active, without forgetting the need to carry out a differential diagnosis to rule out pathologies.
“non-DAM” which could prove to be much more harmful.
Bibliography
- Breton-Torres I, Manon Serre M, Patrick Jammet P and Yachouh J. Dysfunction of the masticatory system: contribution of rehabilitative management. Orthod Fr 2016;87:329–339
- Manière-Ezvan A. Orthodontics and dysfunctions of the masticatory system. Dental information 2010; 33: 51-63
ORTHODONTICS AND DYSFUNCTIONS OF THE MUSCULAR APPARATUS
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