Flashcards in Lecture 9 Deck (26):
What are the two most commonly used occlusal appliances?
-stabilization (muscle relaxing) appliance
-anterior positioning appliance
describe the stabilization appliance
-general fabricated for the maxillary arch as it is larger and there is no tongue in the way
-it helps reduce pain of TMD by providing optimal occlusal positioning
-it also positions the condyle to be in an MSS position
-along with the MSS condyle positioning and stable occlusion (teeth contacting simultaneously and evening) --> the two factors of TMD have been rduced
-also allows canine guidance during eccentric movements
-is it rx'd for when ORTHOPEDIC INSTABILITY is the cause of TMD (or one of the causes)
how many people malocclusion?
30-40% of people have TMJ dysfunction
15% of the 30-40% seek out treatment
1 in 200 require surgery for tmd
60-90% of people have malocclusion
40-60% of the pop have TMD; 5% will seek out treatment
where are CPGs generated?
in the brainstem-->creates muscle engrams or patterns
what are the etiological factors for TMD?
occlusal factors--strongly debated
trauma--seems to affect intracapsular structures more; can have macrotrauma (large sudden force = structual changes) or microtrauma (small force over long period of time)
deep pain input--excite brainstem = protective co-contraction; body also favours the injured structure/side
emotional stress -- hypothal, RF, and limbic system influences muscle activity via gamma efferents; stress activates the hypothal-pituitary-adrenal (HPA) axis --> increases activity of gamma efferents-->cause intrafusal fibres of muscle spindles to contract (sensitizes these spindles); then any slight stretching will cause reflex contraction --> pain, increased tonicity
parafunction--clenching, grinding (bruxism); sometimes can be stopped easily by reminding the patient they are doing it
what is predisposing factor in terms of TMD?
something that increases risk for TMD
what is the initiating factor of TMD?
something that causes the onset of TMD
what is the perpetuating factor in TMD?
interferes with healing and enhances the progression of TMD
study slide 18
sometimes acute TMD can become chronic causing chronic TMD, myofascial pain, fibromyalgia, sleep disturbances, etc; and it is no longer adequate to just treat the possible etiologic factors
how can occlusal condition affect tMD?
1. affects orthopedic stability against the mand and is loads against the maxilla (can lead to overloading and injury)
2. affects mandibular function --> pain, CPGs, jaw jerk (protective reflexes)
an intracapsular disorder can develop from orthopedic instability instability, as well as amount of force exerted; the TMJ can take small instabilities with small amounts of force, but not much more
orthopedic instability is the most critical factor in assessing rel. risk factors for TMD, NOT occlusion
what is muscle hyperactivity?
associated with any increased level of muscle above the baseline not associated with functional activity; this can include bruxing and clenching but other things such as posture, habits, or stress
functional activity is greatly influenced by PERIPHERAL input (inhibitory) while parafunctional activity resides in the CNS and is excitatory in nature; acute changes in occlusal condition = protective co-contraction = peripheral inhibition, = parafunctional inhibition; if this occlusal change is not mediated, CPGs may alter muscle engrams to avoid premature contacts --> ADAPTIVE; however, once the adaptation occurs, the parafunctional activity (previously inhibited) can return
while mediotrusive, posterior laterotrusive, and posterior protrusive contacts are interferences, the main interferenes that affect muscle function are those that interfere with closure into intercuspal position
what are the advantages of occlusal appliances?
-can introduce stable occlusion
-can allow condyles to assume orthopedically stable position
-can also protect teeth and supportive structures from anormal structure and which causes breakdown or wear
initial therapy should be reversible and non-invasive, esp since etiology is often unknown (occlusal appliances satisfy both criteria)
what to consider when Rx-ing and making an OA?
-etiology of TMD (if OA will even work)
-damage to soft tissue
-make it so it actual causes desired alterations
advantages of stabilizaton appliance?
-hold teeth/condyles in MSS and stable occlusal position; relaxes muscle = decreases pain (provides optimal occlusal relationship)
-allows for canine guidance
-decreases parafunctional activity and retrodiscitis
-minimizes forces to damages tissue (AD, retrodiscal tissue?)--> better healing
-maxillary OA is good because it is bigger, less likely to break, and is flat so pts with over or underbite lack anterior guidance but can gain that back
-mnd. OA have better esthetics and easier to speak
sometimes a bite block is added to the front to holdthe jaw open slightly-- allows AD to decompress
what is an anterior position appliance?
positions the mand ant to the ICP --> good for disc derangements and adaptation and repair of inflammed retrodiscal tissue
why are partiel arch covering OAs esp dangerous in long term use?
--can cause super eruption, retrusion
what are the reasons OAs may work?
1. alteration of occlusion-->stable occlusion --> muscle acitivty-->reduce pain and symptoms
2. alteration of condyle position to a more MSS position
3. increase in VDO -->decreased muscle activity and symptoms
4. cognitive awareness --> concious of parafunctional activity --> can prevent it --> control
5. change in peripheral input to CNS --> nocturnal bruxism seems to arise from CNS and a change in the peripheral input inhibits it
6. natural musculoskeletal recover (muscles used less, recover, soreness decreases)
7. placebo--may be up to 40% of the reduction of symptoms in TMD
8. regression to the mean --> flucutation of symptoms associated w/ chronic pain; a pt's chronic TMD pain may be a 7 one day and a 3 the next; pt comes in when pain is bad and appliance is delivered as the cycle goes back to 3