TMJ summary Flashcards
which part of the disc is innervated?
bilaminar zone
fct of ligaments
surround joint capsule - stability, protect against extreme movements
ligaments
lateral ligament - limits AP joint movement
sphenomandibular and stylomandibular - limit lateral movements
describe the disc
fibrocartilage
avascular
biconcave
articulating surface of condyle
fibrocartilage
articular eminence
temporal bone
dictates path of condyle during mandibular movements
glenoid cavity/fossa
hollow on inferior surface of squamous temporal zone
fibrocartilage
capsule
thin fibrous CT attached to rim of fossa and neck of condyle
disc attaches to it medially and laterally
lat aspects thickened by TM ligament
blood supply
deep auricular artery
- branch of internal maxillary artery
nerve supply
auriculotemporal, masseteric, posterior temporal nerves
superior joint compartment
gliding
protrusion, retrusion, side to side
inferior joint compartment
rotation
elevation and depression
what does the disc blend with?
anteriorly blends with LP margins
posteriorly attached to bilaminar zone - loose CT and nerves
lined with synovial membrane
suprahyoids
digastric
mylohyoid
geniohyoid
stylohyoid
infrahyoids
thyrohyoid
sternohyoid
omohyoid
sternothyroid
synovial membrane
lines non-articular surfaces
produces the synovial fluid that lubricates the joints and nourishes the cartilage
when is the joint loaded?
eating or clenching
superficial MofM
temporalis
masseter
deep MofM
LP
MP
what supplies the MofM
motor branches of V3
origin and insertion of temporalis
temporal fossa
tendon onto coronoid process
fct of temporalis
elevate (anterior vertical fibres)
retract (posterior diagonal/horizontal fibres)
origins of masseter
superficial - maxillary process of zygomatic bone
deep - zygomatic arch of temporal bone
insertion of masseter
lateral surface ramus and angle mandible
fct of masseter
elevate mandible
origins of MP
superficial - maxillary tuberosity and pyramidal process of palatine bone
deep - medial aspect LP plate (sphenoid)
insertion MP
medial surface ramus/angle
fct of MP
elevates (bilateral)
swing jaw to contralateral side (unilateral)
origins of LP
superior head - greater wing of sphenoid, roof of infratemporal fossa
inferior head - lat surface LP plate
insertion of LP
tendon - joint capsule and neck of condyle. pterygoid fovea
fct of LP
protrudes and depresses - bilateral
lateral excursions - unilateral
depressing the mandible
infra and suprahyoids act together: hyoid bone stabilised
suprahyoids contract further - pulls down on mandible
LPs contract - translates condyles down articular eminence
also assisted by gravity
= forward and downward movement of mandible
initial mouth opening
hinges from centric relation up to 25mm
- aided by supra/infrahyoid contraction
- LPs relaxed
further mouth opening
to max opening - condyle translates anteriorly (forwards and downwards) along articular eminence
- bilateral contraction of LPs and contraction of supra and infrahyoids
protrusion
condyle translates forwards and downwards along the articular eminence
bilateral contraction of LPs
mouth closing
condyle held within glenoid fossa
aided by contraction of temporalis, masseter and MP
when is the jaw most stable?
when mouth closed and teeth in occlusion
lateral excursion
mandible moves to left
left condyle pulled backwards slightly by the temporalis and rotates but sits within the glenoid fossa
R condyle moves forwards, downwards and inwards along articular eminence - R LP contracts
posterior fibres of L temporalis contract
TMD definition
collective term “a group of conditions that cause pain and dysfct in the jaw joint and muscles that control jaw movement’
- masticatory muscles
- TMJ and associated structures
- both
basic classification
disorder of the MofM
disorder of the TMJ
headache attributable to TMD
= often they co-exist
basic classification - disorder of the MofM
usually caused by parafct habits
basic classification - disorder of TMJ
disc displacement +/- reduction osteoarthritis osteoarthrosis hypermobility subluxation adhesions
Groups of TMD
Group 1 - muscle disorders
Group 2 - disc displacement
Group 3
Group 1 - muscle disorders
1a - myofascial pain
1b - myofascial pain with limitations in aperture
Group 2 - disc displacement
2a - disc displacement with reduction
2b - disc displacement without reduction and no limitations in aperture
2c - disc displacement without reduction and with limitations in aperture
soft end feel
pt guarding against opening due to pain
hard end feel
can’t open any further
Group 3
3a - arthralgia (pain)
3b - osteoarthritis of TMJ
3c - osteoarthrosis of TMJ
masticatory muscle disorders
local myalgia (pain felt locally within muscle) myofascial pain (pain felt within and referred outside of the muscle)
common cause of masticatory muscle disorders
parafct activity
- clenching, grinding, biting nails, chewing gum
can be thought of as overworking the muscles almost causing a sprain-like injury
S+S of MM disorders
tender muscles on palpation
pain with jaw activity i.e. speaking, chewing
pulling, tight or achey sensation
disc displacement with reduction tx
no pain = no tx tx - advice - limit opening - BRA - occ surgery
disc displacement with reduction pathogenesis
ideal disc position no longer maintained in relation to the condyle throughout range of motion
disc initially displaced anteriorly by the condyle during opening until disc reduction (relocation) - click
S+S of disc displacement with reduction
click on opening and closing
deviation of jaw to affected side (same side) on opening
if left untxed may eventually progress to OA
disc displacement without reduction pathogenesis
disc anteriorly displaced and no longer reduces (relocates)
S+S of disc displacement without reduction
“closed lock” - limited opening 25mm - disc displacement without reduction with reduced mouth opening
deviation of jaw to same side on opening
limited contralateral excursion i.e. if left joint is affected there is limited jaw movement to right
if chronic the joint can become stretched and allow a nearly full range of movement
- history of limited opening but not anymore and MRI showing remodelling
- disc displacement without reduction without limited mouth opening
get pain as bilaminar zone innervated
osteoarthritis
deterioration of joint, often relating to condyle
S+S of osteoarthritis
pain and crepitus (grating/grinding)
radiographic features
- joint space narrowing
- osteophytes
osteoarthrosis
same signs and changes as osteoarthritis but no pain, just crepitus
moth eaten condyles
hypermobility
excessive range of movement which may lead to subluxation
subluxation
dislocation of joint - condylar process beyond articular tubercle
subluxation causes
excessive mouth opening
yawning
trauma
prolonged dental tx/intubation
presentation of subluxation
malocclusion
open bite
empty articular sockets - palpate as pre-tracheal hollowing
if unilateral - chin shifted to contralateral side
click palpated at max opening
open lock may result - jaw is ‘stuck open’
- MofM spasm and hold mandible in this position
subluxation preventive aftercare
support chin
limit opening
can use circular fixation bandage for 24hrs
subluxation - when should you not relocate?
if you suspect any facial fractures
subluxation relocation
ASAP as may avoid need for additional measures i.e. muscle relaxants/sedation/GA
chair with head support
one side at a time
put downward pressure on L molars with thumb and grip mandible with rest of hand (fingers buccal sulcus)
increasing force until you feel condyle move
then hold in position with non-dominant hand by one finger in front of condyle
relocate other side
verify normal occlusion
complications of subluxation
unable to reduce
subcondylar fracture
early repeat redislocation
adhesions
limit extensibility of joint capsule
- chronic inflammation
- history of trauma/surgery
- immobilisation
- chronic disc displacement without reduction
S+S of adhesions
limited opening
deviation to same side on opening
limited contralateral excursion
multifactorial aetiology - biopsychosocial model
biological: inflammation
- local factors: secondary to parafct, trauma, infection, tooth loss, prolonged dental procedures
- systemic factors: arthritis, fibromyalgia, hypermobility (EDS)
psychological: anxiety, depression, thoughts, beliefs
social: work, finances, family, relationship
HPC key points
pain - associated pain elsewhere e.g. neck, shoulders clicking other noises e.g. grating limitation of opening locking altered occlusion sensory disturbance history of trauma parafct activity what have they prev tried and did it help? opening/closing aggravating/relieving factors temp/persistent timing and duration - morn bruxism - day habits
MH key points
arthritis prev malignancy immunosuppression mental health fibromyalgia hypermobility syndromes
SH key points
occupation stress home circumstances sleeping pattern recent family difficulty or bereavement relationships
DH key points
recent tx (in particular lengthy or difficult appts) surgical procedures (recent 3rd molar removal) denture wearers
why should you palpate the neck?
some pts can present with tenderness of SCM
how to palpate masseter
bimanual palpation
- one finger inside cheek and one EO over masseter
- clench then slightly part teeth
- palpate inferior, mid and superior aspects
- presence/absence of tenderness/pain
TMJ examination
palpation
listening on opening and closing
observe lateral excursions and protrusion (10mm)
mouth opening - interincisal distance 35-50mm
mandibular position - posturing habits
ideal lateral excursion and protrusion
should be smooth unobstructed movement
observe for deviation, restrictions and abnormal sounds
what should you do if the pt is guarding due to discomfort/trismus?
ask if they can open any further - sometimes use gentle finger pressure
ST exam
buccal mucosa - linea alba
cheek biting - morsicatio buccarum
bony prominences - tori - associated with overload on teeth
tongue - scalloping
examining teeth
wear facets attrition occlusion high spots teeth present/absent interfering contacts occ NCTSL
palpating MP
one finger inside mouth - slide it posteriorly along your lower teeth past the last standing molar
push finger into the tissues and gently close - you will feel MP contract
differential diagnoses
odontogenic pain sinusitis temporal (giant cell) arteritis ear pathology salivary gland (parotid) pathology referred neck pain headache atypical facial pain trigeminal neuralgia angina/MI burning mouth syndrome condylar fracture
should you routinely image?
no - only in special circumstances, not routine investigations
plain film
mouth open (allows better visualisation of condyle - can show arthritic changes)/closed OPT only if joint pathology suspected e.g. arthritic changes
CBCT
more accurately demonstrates bony anatomy and changes
arthrography
radiopaque dye injected into joint space using videofluoroscopy
used when meniscal tears suspected
MRI
ST anatomy inc disc
can detect anterior disc displacement
US
muscle/ST pathology overlying joint
nuclear imaging - technetium 99
use for suspected hyperplasia
isotope picked up in areas of increased cell turnover
exclude any red flags
history of malignancy
lymphadenopathy (persistent/unexplained)
neurological symptoms (headache/CN abnormalities)
facial asymmetry (mass/swelling/profound trismus)
severe unilateral TMJ pain can indicate malignancy
recurrent epistaxis, nasal discharge, anosmia or reduction in hearing (ipsilateral) - nasopharyngeal carcinoma
unexplained weight loss/fever - malignancy, infective, immunosuppression
change in occlusion (neoplasia, RA, trauma etc)
new onset unilateral headache/scalp tenderness, jaw claudication, general malaise, esp if >50yrs - may indicate temporal arteritis (systemic inflammatory vasculitis)
broad management categories
reassurance and education conservative advice reversible therapies - BRA, physio, acupuncture, hypnosis, clinical psychology, pain clinic, TENS, replacement of missing teeth (esp if lacking posterior support) meds surgery
meds
simple analgesics
BZDs - if seen early during acute exacerbation as muscle relaxant
amitriptyline/nortriptyline (muscle relaxants)
intra-articular steroid injection
surgery
botox high condylar shave arthrocentesis arthroscopy joint replacement disc repositioning/repair/removal
arthrocentesis
flushing out joint, often in combination with steroids to break down adhesions
arthroscopy
visualises joint, can simultaneously remove adhesions/flush joint
joint replacement
last resort
v rarely used
if no other option and gross pathology present i.e. tumours
management of trismus
usually resolves spontaneously
identify and tx underlying cause e.g. infection/trauma
improve mouth opening gradually by stretching the muscles and ligaments over weeks/months
physio
- esp H+N radio pts
- therabite, trismus screw, tongue spatulas
a few pts with severe trismus refractory to conventional measures may undergo surgical intervention e.g. coronoidectomy
why should a splint always be full coverage?
to prevent overeruption
when is split therapy offered?
as second line tx - if advice is not enough
education and reassurance
condition usually non-progressive, symptoms may fluctuate but should improve
often self-limiting
can often be managed with simple conservative management
address biopsychosocial aspects
all pts unique so need to find strategies which work for them
- will be trial and error to find right strategies
- can take a couple of weeks to see any benefit
conservative advice
soft diet
reduce caffeine
avoid parafct activities that may exacerbate symptoms - wide yawning, teeth grinding, clenching, chewing gum or pencils, nail biting
avoid using incisors to slice food
ensure chewing on both sides
keep teeth at least 2mm apart when at rest
limit mouth opening to 2 fingers width
consider simple analgesia for short-term use e.g. paracetamol/NSAID
consider local measures for pain relief - covered ice/warm flannel/heat pad, massaging affected muscles
try to identify sources of stress
- give advice on relaxation techniques, setting realistic targets, pacing activities, getting social support, counselling
support mouth on opening
jaw exercises - physio helps some pts
BRAs theory
exact mechanism unknown, little scientific evidence to support use
can make better/worse/no effect
theoretically
- stabilise occlusion
- improve fct of MofM
- therefore reduce abnormal activity and protect teeth in cases of grinding
despite lack of evidence, may feel that due to their relative inexpense, non-invasive nature and historical benefit to a significant number of pts, their use is justified
soft splint advantages
quick, easy, cheap
preferable for clenchers
can be used in teenagers whose occlusion may still be developing
vacuum formed (simple construction)
soft splint disadvantages
may need regular replacement
may exacerbate condition
difficult to adjust
bilaminar splints
soft inner, hard outer
slightly more £ but can be simply made by any dental lab
may be better for those who are chewing through soft splints, or where it promotes clenching
Wenvac
cheap, some chew through/bounce on it as soft and rubbery
splint instructions to pt
may need to wear splint for several weeks before benefit felt
wear every night
wear at time of parafct - usually sleep, may be driving, using computer, other times of stress
if v severe symptoms wear continuously apart from eating
use may then decrease as symptoms improve, and recommence as symptoms worsen
but many pts continue to wear long term
pt may still clench/grind with splint in situ, but hopefully splint will act as habit breaker
occ splints may worsen a pts problem in which case they should be reassessed
soft splints may occ promote clenching leading to worsening of discomfort - may consider a hard splint
which type of splint to use?
evidence doesn’t favour any particular splint
- soft and bilaminar ‘go to’
- Lucia jigs may be used, particularly in Rx dentistry
- hard splints may be favoured by those with Rx experience but are rarely constructed in primary care
anterior bite plane - Lucia jig
discludes posterior teeth to allow relaxation of MofM
used as a v short term measure during acute exacerbations, prior to more definitive splint
may also be used as diagnostic tool for TMD pts
simple to construct chairside - cold cure acrylic or greenstick (can also buy preformed)
airway risk, get dahl effect
stabilisation splint
Michigan splint U
tanner appliance L
full coverage to prevent over-eruption
creates
- uniform contact in centric relation
- canine guidance to separate posterior teeth in eccentric excursions
- anterior guidance to separate posterior teeth in protrusion
i.e. the splint creates an artificial ‘ideal’ occlusion
complex construction - imps, jaw reg in centric relation, facebow and adjustments at fit appt required
preferable for bruxers
pathogenesis
inflammation of MofM or TMJ secondary to parafct habits
trauma either directly to joint or indirectly e.g. sustained opening during tx
stress (parafct)
psychogenic
occlusal abnormalities (v rare)
- no evidence, but a Rx that is significantly ‘high’ may cause muscle pain due to posturing
common clinical features
F>M
most common 18-30yrs
intermittent pain of several months/years duration
muscle/joint/ear pain, particularly on wakening (clenching overnight)
trismus/locking
‘clicking/popping’ joint noises
headaches (temporalis)
crepitus indicates late degenerative changes
anterior repositioning splint
a maxillary appliance
often used for those with disc derangements
- promotes a more harmonious condyle-disc relationship by capturing an anteriorly displaced disc
directs mandible anterior to ICP
causes of TMD
myofascial pain
disc displacement (anterior +/- reduction)
degenerative disease
- localised: osteoarthritis (often asymptomatic)
- generalised/systemic: RA
chronic recurrent dislocation
ankylosis
hyperplasia - one condyle larger, asymmetry
neoplasia - osteochondroma, osteoma, sarcoma
infection - rare, usually from ear
reversible tx
education
meds
physical therapy
splints
irreversible tx
occlusal adjustment
- DON’T do, no benefit
surgery
