TMD Flashcards
TMD can split into which 2 groups
masticatory muscle disorders and the TMJOINT disorder itself
what is the biomechanics of the TMJ (4 parts)
1) at rest - closed mouth position
- condyle is situated at the thinner intermediate zone of the disc and the disc is located along the anterosuperior aspect of the condyle
2) hinge movement
- first 20-25mm of mandibular opening is a pure rotational movement in the inferior joint cavity
- articular disc rotates on the articular surface of the condyle
3) translational movement
- after the first 25mm, the condyle cant rotate further and hence it moves down and forward across the articular eminence
- the intermediate zone of the articular disc is maintained against the condyle and the free sliding movement occurs in the superior joint cavity
4) mouth open position
- condyle assumes a position beneath the articular eminence
- articular disc is positioned between articular eminence and the condyle with the intermediate zone situated directly above the condyle
2 types of internal derangement of TMJ
internal derangement refers to a breakdown of the normal rotational function of the disc on the condyle
- disc displacement with reduction
means at rest, disc is displaced anteriorly and during opening, condyle moves over the posterior band, producing a click sound - disc displacement without reduction
means at rest, disc is displaced anteriorly but on opening, disc cannot be reduced. forward translation of the condyle merely jams the disc forward in the joint
what is disc displacement without reduction without limited opening
it is a separate diagnosis under expanded taxonomy of TMD (Peck et al 2014)
-is a physiologic adaptation within the joint
- continued stress on the retrodiscal tissue (aka bilaminar zone) causes fibrosis and creation of a new functional disc
and so theres this phenomenon whereby some patients experience a gradual progression of increased opening and decreased discomfort even without treatment
how to diagnose internal derangements
- joint sounds on function
- TMJ pain
- limited ROM
- deviation on opening
what are the ways to manage internal derangement
CONSERVATIVE
- patient education
- physiotherapy
- splint therapy
- medication
MINIMALLY INVASIVE
- intraarticular injection (hyaluronic acid, corticosteroid)
- arthrocentesis
- arthroscopy
INVASIVE
- disc plication
- disectomy (surgical removal of a damaged portion)
- arthroplasty (surgical procedure to replace some or all of a joint)
what sort of imaging to indicate for TMD
- MRI is gold standard for soft tissue evaluation. can evaluate articular disc location and morpho and presence of tissue effusion
- therapeutic arthroscopy is another option
defn of TMJ dislocation
dislocation of the mandibular heads anterior to the articular tubercles without spontaneous reduction
what are some risk factors for TMJ dislocation
multifactorial
single episode of dislocation attributed to
- trauma
- aberrancy in masticatory movemetns
- prolonged mouth opening during lengthy dental procedre
- dislocation secondary to epileptic seizures, facial trauma
recurrent dislocation due to
- capsular weakness
- ligamentous laxity in Ehlers danlos syndrome
- anatomic: steep eminence, abnormal condylar shape, atypical disc position
- myospasm (duchenne muscular dystrophy, epilepsy)
immediate management for locked jaw
bimanual intraoral traction
LA: auriculotemporal nerve block
- alternative is intra articular anesthetic distribution into the empty glenoid fossa, aimed at minimizing myospasm prior to digital manipulation
- in some cases, acute myospasm is significant enough that GA or IV paralytics are required
technique:
- place thumbs at retromolar pad/ external oblique ridge and press inferiorly then posteriorly, manipulating condylar head over preglenoid plane, seating it back in the articular fossa
when will open joint surgery be needed?
severity of condition:
- chronic (when joint has been out of fossa for 6months or longer)
- acute recurrent
other minimally invasive techniques should have been explored, and only when there is persistent relapse of TMJ dislocation then consider surgery
risks and complications of arthroscopy
general surgical risks apply eg inflammation, pain, swelling, infection
excessive fibrosis can lead to trismus
nerve and vascular risks
how to reduce locked jaw
manual reduction technique
1) traditional hippocractic technique
- stand in front of patient and place thumbs on lower molars/ external oblique ridge and ask patient to open such that elevator muscles are relaxed then apply downward and backward pressure to guide condyle back into joint
2) wrist pivot method
3) syringe metod (place 10ml syringe between posterior teeth and ask patient to roll back and forth gently to allow spontaneous reduction)
what are some minimally invasive therapies/ non surgical methods of managing CHRONIC TMD
1) autologous blood transfer
- patients venous blood is injected into superior joint space and pericapsular tissues
- the injected blood will coagulate and trigger inflammatory response, leading to fibrosis and tightening of joint capsule, reducing excessive mobility
2) botulinum toxin injection
- to reduce excessive mobility
3) arthroscopy
- can lavage and flush inflammatory mediators and debris from joint, reducing pain and inflammation
- mechanical breakdown (lysis) of adhesions, restore joint function
4) lateral pterygoid myotomy
- myotomy involves cutting and dividing muscle,
- lateral pterygoid depresses mandible and opens the mouth with assistance of anterior belly of digastric and mylohyoid
what are some surgical interventions for CHRONIC TM dislocations
1) eminectomy (anatomic modification of eminence)
2) glenotemporal osteotomy
3) titanium mini plate
