In the facebook TMJ/TMD Discussion Group discussion one person posts the above picture asking if that splint will help with her TMD. It opened up an interesting discussion out of which reveals most doctors don’t have clear explanation of what causes TMD?
John Mew states that all bite splints cause the face to lengthen.
I asked Mike Mew on this matter and he agrees, one of the reason being overtime the masseter muscle will become accustomed to being lengthened and this will surely cause an increase in vertical dimensions. To me this is symptom alleviation and not addressing the cause.
The cause of all these issues is Cranial Facial Dystrophy or Maxilla that has dropped down and back.
John Mew posted in the comment section and shares his ideas on this matter.
I feel like most clinicians are so focused on looking at the problem, they only go the route of pain alleviation. Which is understandable when the patient is at their door in massive amounts of pain. They don’t have the time to ask “why?” this has happened in the patient.
The big picture that is missing and what John is trying to open people’s eyes to is that when people have forward maxilla they never have this problem in the first place.
The reason for maxilla that’s down and back? Open mouth posture & low tongue posture therefore the way to resolve TMJ & TMD is to correct your posture.
Some Rival Hypothesis for TMJ
- Occlusal disharmony precipitates TMD: Siche (1949) was one of the first to explain, if cusps clash during mastication, the two sliding surface of the joint are put under torsion and damage may result. Treatment requires grinding of teeth down. The problem is believed to be the teeth and jaw (irregular teeth contact, sliding contacts, cross bites, deviation of jaw). Clear evidence of improvement with this form of treatment is lacking and it fails to provide clear reason for development of occlusal disharmony in the first place.
- Certain types of malocclusion cause TMD: Mohlin’s (1989) findings suggest that most TMD is associated with crossbites (30%), increased overjets (20%), while least are found with deep bites (5%)and pre normal bites (2%). To some extent these numbers only reflect the distribution of malocclusion themselves. Cases of people with severe malocclusion with all types Class I, II, III without TMD indicate that malocclusoin itself is not the precipitating factor. (although it is connected to the cause)
- TMD is caused by malformed condyles: MRI allows doctors to see that TMD suffers often have condyle shapes that are not ideal, however it is not clear if this is the true cause or if this is the effect of some other underlying problem.
- TMD is result of previous trauma: This is a populate belief among many clinicians. Yet most children take a blow to the face at one time or another yet there is no global symptoms of TMD arising from this. & This theory doesn’t explain how primitive cultures didn’t have TMD when their life circumstances would allow for more incidences of receiving physical trauma. Many patients that do break the jaw or condyles which is clear physical trauma recover and do not have precipitating TMD problems after. So evidence that counter this theory is so strong, it holds no water.
- Bruxism causes TMD: Some theorize that clenching & grinding puts heavy load on the joints and damages them, yet there are many people that brux and they never have TMD.
- Stress precipitates TMD: Psychological counseling has proved to be helpful for TMD but cure rates are not there for this form of treatment to be the go-to
There are few more theories on TMD and there all lacking in any clear explanation of why TMD occurs.
Studying mouth posture is difficult so many clinicians dismiss it. You can observe if the lips are closed or not but almost impossible to know where the tongue is. Also people when in company of others may keep their mouth closed but this may not be their true resting posture when others are not around.
Peterson (1983) found that patient’s with cross bites usually posture with their teeth apart and we know that TMD patients tend to have cross bites and tooth apart resting postures (Williamson 1990).
Profits work on oral posture & tooth eruption showed that occlusal height of any individual represent the product of the period time the teeth are in contact and the biting forces applied. Interpolating from his findings and personal research, John states that if teeth are not kept in light contact for between 4 to 8 hours each day they will continue to erupt. Presumably they continue to do so until they reach the limit of alveolar support or some other obstruction such as the tongue if stored between the teeth.
The accumulated evidence leaves little doubt that both malocclusion and TMD are linked with tooth-apart-postures. -John Mew
John’s Hypothesis TMD is caused by open mouth postures.
“Joints are highly adaptable and will always remodel to suit habitual rest positions (A). If the mouth is held open continuously (B) the condyle and fossa will re-contour so that the head is in or near the center of the fossa when the jaw is in the position (C). If following this, the mouth was closed, the head of the condyle will move upwards and backwards (D) to occupy a position frequently seen in TMD cases.
This hypothesis provides a specific explanation for six of the common signs of TMD: Retroposed Condyles – Open Mouth Posture – Tongue between Teeth Posture – Occlusal Irregularities – Lingual Inclination of the teeth – Deformation of the condyle and fossa.
Crucially it also explains why a joint that at other times can reform completely is unable to adjust one or two millimeters: -It can not adapt to suit the closed mouth position if this is only intermittent. It also explains why bite splints are so successful in the short term: -rest position and the contact position become the same and why they often fail in the long term: -the joint remodels to suit the new tooth apart posture.” – John Mew
Applying the tropic premise to TMD
- There is little to suggest that our ancestors had any issues with their jaw joints.
- Mouth open postures are endemic in modern population
- All joints naturally adapt so the ball is near the center of the socket in the resting position.
- If the teeth are apart for long periods, the condyle will remodel distally and the upper incisors will move lingually.
- if they close their mouth the head of the condyle is forced distally.
- If they clench their teeth, there will be pain and damage.
Basically the condyles remodels to the resting jaw posture. Condyles should be at the position when teeth is together. But when it remodels to when teeth is apart, it is now improper placement for when the teeth actually bite down or clench.
An appliance that force the patient’s mouth closed first at the same bite-open position for 4-8 hours a day then gradually reducing the height (thickness) of appliance so the patient eventually gets to teeth together posture while the condyle remodels forwards.
The aesthetic faces of the world have horizontal jaws & small noses because of forward maxilla. These people like our ancestors do not suffer with TMJ/TMD.
This is because they have closed mouth postures with teeth in light contact that held & supported their maxilla, which allows the lower jaw to rest in a position that is further up and forwards and condyles to remodel forwards to show what people call the “nice jawline”
Therefore placing any sort of bite splint between teeth which will cause the lower jaw to rest more vertical encourages condyles to remodel further down & back, & it may provide temporary relief to condyle Joint TMD TMJ pain but facial aesthetics may decline overtime.
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