THE JAW JOINT - TMJ - TMD - CMD

 

X-Ray of Jaw Joint at Full Closure

TMJ or Tempero Mandibular Jaw Joint problems - are far more widespread than generally realised , mainly because the chronic head and neck pain, the pain behind the eyes, pain in front of the ears, pain at the back of the head, muzziness, difficulty in clearing the ears , even Tinnitus and vertigo - associated with this dysfunction syndrome - are rarely linked to the Jaw joint or the Teeth . People usually visit their Doctor first with TMJ (not so difficult to understand when the symptoms above are reviewed) and are prescribed pain killers +/or tranquillisers; when these do not work - they get referred on to first , Neurologists , then ENT Specialists - because of the ear symptoms.

A sketch of a Normal TM Joint with the disc in position….plenty space superior and posterior to condyle.

The problem ........ very few Doctors know anything about TMJ PAIN and DYSFUNCTION and most Dentists and many Orthodontist never even test for it - ‘ignore it and hope it will go away.’ seems to be the widely held approach.

Sketch of Joint with disc displaced forward and medially …. Condyle Up & Back; Much reduced posterior & superior space

 

Yet - it is an easily understood phenomenon or condition - The cause of the pain and dysfunction is the pressure caused by the condyle (head of the mandible) which is driven up and back off its disc in the articulator fossa, constricting the posterior connective tissues filled with important blood vessels (nerves,veins and arteries to tissues inside and outside the skull) causing inflammation and pain and forcing the disc itself more downwards and forwards, and sometimes inwards also. In the early days of this relentlessly progressive condition - on opening, the condyle recaptures the disc and makes the ‘click’ that many people are aware of . Over time this ‘click’ gets later and later in the opening cycle - and then it disappears altogether . At which point the disc has been driven fully forward and is bunched up ahead of the translating/moving condyle -- thereby LIMITING the amount of Jaw opening (The normal opening of 48 - 52mm (+/-2mm) can be reduced to as little as 34mm or even less - the simple measurement test (combined with side to side measurements) for TMJ Dysfunction)

A 15 Year Old ….. at Full Opening ……. Only 34mm !

What McDonald’s think it should be … NORMAL - NOT less than 48mm in Adults Young People 52mm+/-2mm

Because the Mandible is driven Up and Back off the disc the Muscles that control the mandible are then working at a foreshortened length , but doing so 24 HOURS a day - in contrast to the healthy situation when the muscles are working at their genetically determined length , BUT in a rhythmic fashion of alternating muscle bundles contracting and relaxing. This constant & heavier muscular contraction intrudes the posterior teeth over time so the mandible goes ever more up and back, also thus extending , perpetuating & intensifying the pain & dysfunction as the muscles are further foreshortened .

A typical FHP …. Neck ‘ extended’ forward

There is often an accompanying - compensating- forward positioning of the head, (known as FHP) - as the neck muscles are progressively recruited - leading then to spasms in these neck muscles. Because these are then also forced to overwork and at a different length than nature intended - with consequent pain in the Neck , the base of the skull & even the top of the shoulders.

If a TMJ Dysfunction goes untreated - the condition goes on over the next 10 to15 years to result in true Osseo-Arthritic Degeneration of the head of the Mandible and the articular surface of the Temporal Bone itself.

One study in 1998, in Sweden, where MRI Scans were used to definitively show displaced discs - 45% of a ‘healthy’ group (who were unaware of TMJ problems) were shown to have one or both discs displaced .......... Showing, on the one hand how prevalent ‘TMJ’ is, and on the other hand - how many people can have TMJ Syndrome and not be aware of it .

You see, true TMJ Pain-Dysfunction Syndrome is NOT a Disease … its a CONDITION - with 2 Consistent Findings - occurring singly or together - i.e. Dysfunction, with or without the Pain , …… and because we all have different ADAPTIVE capacities , many people have this condition without actually suffering ............. just yet !

Figures also show that Women suffer from ‘TMJ’ more than Men - in a ratio of 4:1 ... some studies have this as high as 7:1 !!!!

And it affects most age groups ........ we have in our practice 6, 7, 8 and 9 year olds who have TMJ Dysfunction ...... they come in for Orthopaedic Orthodontics and when we measure the Range of Motion (ROM) of the Mandible , we find there is dysfunction .....then Mother usually says ‘Oh yes, Mark is always complaining of headaches - at least twice a week- and we have had his eyes tested for the headaches , but they are ok ...... and yes, his jaws used to click - but he doesn’t have that any more ......! ’

Sketch of Joint with Disc ‘bunched up‘ Ahead... Limiting further opening

And this brings us to the cause of it all ....... - what Dr. John Witzig and Dr.Terrence Spahl 2 of America’s greatest Functional Orthodontists and TMJ experts refer to as ‘ The Distal Driving Occlusion’ and ‘The Reduced Vertical Dimension’ When we close our lower jaw (Mandible) to the point of first contact of the lower teeth against the upper teeth - when everything is functionally correct - the mandible closes ‘on plane’ , without deviation - into maximum interdigitation of the teeth - with the disc between the mandibular condyle and the Glenoid fossa...... but, if - to close the jaws - with the teeth in maximum intercuspation - the mandible has to deviate back and up (‘distally driven’) then over time, at the joint level the condyle is driven back and up off the back end of the disc … and the disc gets ‘squirted’ forwards.

Treatment Concept Mandible Down & Forward Teeth realigned in Corrected position

In other words there is a positional mismatch between
a)the condyle of the mandible - disc - Joint complex and
b)the maximum interdigitation of the teeth and
c) the healthy Neuro-Muscular position of the Mandible in space - the result- - - the mandible is driven up and back off the disc - working dysfunctionally - just a question of time ………………….. until it is followed by the pain.

So, how do we reverse the process , well ......... ‘- simply bringing that condyles down and forward again on the disc and then rearranging the teeth so that it stays there - at rest and in function - without mandibular deviation - in all but the most rare and bizarre cases , relieves the TMJ PAIN DYSFUNCTION problem ‘ ….. in the words of Dr Terrence Spahl - the great American TMJ clinician referred to earlier.

Treatment is usually carried out as a two phase treatment - the first involving the wearing of a small lower jaw splint : to simply bring the mandible down - and to hold it there until all the symptoms have subsided, the inflammation has disappeared , adhesions broken down ,and the disc recaptured - with full range of movement again …..…….. which can take many months, and longer even in some severe cases. - then the second phase begins......... moving the jaws & teeth by Orthopaedic Orthodontics, so that the mandible closes directly on plane with maximum intercuspation in this new position - without being driven backwards or upwards - with the disc ‘in position’ at all times.

A typical case The ‘Distal Driving’ Occlusion with Deep Overbite

This treatment modality is the same in concept , whether the TMJ patient is a 7 year old , or is 70 years old !

Upper ‘ALF’ to Develop & a Lower Splint

And of course this is where the advent of the newer ALF Appliances has improved things so fantastically ..............

Up to now, it required a high degree of motivation by adults (including yours truly) to wear the FORMER bulky plastic appliances and Active Plates --- especially with the speech embarrassments that went with them - to achieve the twin goals of arch developments and mandibular repositioning necessary - before the teeth are realigned at the finish with the conventional bands and brackets - to hold. Now, however - the lower splint, - all arch development - and most tooth movements, can be achieved by these newer ALF appliances - without the patients life being disturbed .... - except in a most minimal way --- A totally different world altogether - opening up treatment for all but the most unusual of cases My own case was a proof in point - see below - at start of Tx 10/12/99…..watch this space !!

Typical TMJ Occlusion-Deep overbite

Upper ALF to develop

Lower ALF Splint

Both appliances in the mouth !

 

Two important Implications of TMJ Dysfunction need to be Highlighted.
1. If conventional orthodontic corrective movements of teeth are carried out on young patients who have an existing UNDIAGNOSED TMJ - this can well result in the FIXING of the mandible in the ‘dislocated’ position - to the long term detriment of that person.

----- we now realise that before any Orthodontic movement of the teeth is carried out we must first test for the presence of a TMJ dysfunctional joint , and if one is present - then that mandible MUST be repositioned in the correct neuro-muscular position - with the condyles on the disc - before moving the teeth to the better aesthetic alignment .

Sometimes Orthodontists are accused incorrectly of causing a TMJ problem that appears subsequent to their realigning the teeth ........ the truth is more likely to be that the TMJ problem existed, at an asymptomatic level, BEFORE the Orthodontics was carried out.

2. The FJO (Functional Jaw Orthopaedics) treatment modality for TMJ Pain & Dysfunction Syndrome is not the only treatment modality available for this CHRONIC condition - the other one is the Medication one - where TMJ & Facial Pain specialists treat the symptoms with drug therapy, which, by the nature of the condition , usually has to be long term.

Apart from the fact that we would personally be very unhappy to have to live with long term drug therapy - this modality ( while it relieves the symptoms ) does nothing to halt the on-going destructive effects of TMJ on the teeth , the alveolar bone or the Osseo-degeneration of the articular surfaces of the joint itself .

The Name ..... TMJ - TMD - CMD
At the beginning we referred to this condition as TMJ - Tempero Mandibular Joint problems ........ so-called, because it involves the jaw joint with its two bones - the temporal bone of the Skull which houses the Glenoid Fossa ..... the ‘socket’ part of the joint; and the Mandible which has the condyle or ‘ball ‘ of the joint .

This condition is also referred to as TMD - Tempero Mandibular Dysfunction ....a better name perhaps .... More recently, however , with the new thinking about this whole area , and in particular the role of the Cranial bones, which we are now recognising are not quite as ‘fixed’ as had been thought , some clinicians (at the forefront of advances) are tending towards referring to this whole syndrome as CMD ..... Cranio Mandibular Dysfunction. I like that idea myself, as it introduces the concept s of the CRANIUM , and the interaction of it’s different bones , as a significant ENTITY .

Visit our ‘What’s New’ page on this web site for more on this topic.