x-ray analysis of vertical tmj Condylar Asymmetry

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Asymmetry, Bruxism, Centric relation, Condyle (anatomy), Dentistry, Health, Radiography, Retruded Position of the Mandible, Temporomandibular joint, Temporomandibular joint disorder

Dental students are normally taught about the necessity of an overview radiograph in the screening for and in the early detection of undiagnosed hard tissue changes of the maxilla and of the mandible (neoplasms, tumors or any strange lesions). Most dental students have also been told the questionable value of the panoramic radiograph because of the superimposition of the structures due to the construction of the X-ray machine with its two axes of rotation ( focus and film in opposite directions). On the other hand the panoramic radiograph is the only routinely used radiograph in the dental practice in which comparisons between the right and the left sides of the jaws can be made, as both side are projected in the same film without any change of head position.
However,comparisons of horizontal dimensions are not possible due to the superimposition of structures.Vertical dimensions can be compared as the focus of the X-ray machine is long and narrow. From this point of view the panoramic radiograph therefore shows its strength and its unquestionable clinical value in assisting the dentist in finding the correct vertical and frontal relations between the two jaws. In other words, in evaluating the occlusion from a functional point of view the panoramic radiograph is an aid of utmost importance.

Panoramic radiograph / Orthopantomogram, randomly chosen. Note the vertical dimensional difference between the two condyles.

Steps in determining the vertical condylar / ramus  asymmetries:

1. Determine the most posterior point of the two condyles and the mandibular angels.

2. Draw a line through the two points of each mandibular side. This line we have named ” the ramus tangent “.

3. Draw new lines through the points perpendicular to ” the ramus tangent” and do so also between the most superior point of the condyle and  “the ramus tangent “.

4.Measure the condylar heights ( CH )and measure the ramus heights( RH ).

At a vertical mandibular asymmetry you most often will find a difference in vertical height between the two condyles as the ramus portion of the mandible is a most stable part of the mandible and is less reacting on traumata etc during growth and development.

In evaluating the condylar asymmetry it was suggested ( Habets LLMH,Bezuur JN,Naeije M, Hansson TL. The Orthopantomogram,an aid in diagnosis of temporomandibular joint problems 2. The vertical symmetry. J Oral Rehabil 1988;15:465-471) to measure the condylar heights on ” the ramus tangent “. The condylar asymmetry,expressed in percentage is calculated accordingly, ( Right-Left/Right+Left)x100%. An asymmetry bigger then 3% is to be considered a true morphological asymmetry.

If you want to estimate the  vertical difference in mm between the two condylar heights you absolutely need to adjust for the magnification of the machine used.

From many years of daily clinical experience it seems as if a condylar asymmetry might be a major reason for an asymmetrical stomatognathic system and its asymmetrical function. The ” shorter condyle ” side is most often found on the mediotrusive side  at laterotrusive  bruxing. When there is a lateral slide between the retruded contact position of the mandible ( RCP } or the centric relation ( CR ) and the intercuspal position ( ICP ) or the centric occlusion ( CO ) the slide seems to be most often directed towards the ” shorter condyle “side. It seems consequent that a condylar asymmetry most likely will result in an asymmetrical function, bruxism with orofacial pain of either mainly arthrogeneous origin or of mainly myogeneous origin.

To recognize a condylar asymmetry, when present, is therefore in my opinion of utmost importance for the registration of the mandibular position used in diagnostics and in the treatment ,topics to which I will return within shortly.

HAPPY NEW YEAR!

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Functionally induced facial pain

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Temporomandibular joint pain

can always be provoked by orthopedic tests. It is of utmost importance to distinguish between a mainly arthrogenous origin of pain ( dynamic pain dominant ) versus a mainly myogenous origin of pain ( static pain dominant ) at every visit as the origin of pain may change during time of treatment. The two different origins of pain demand completely different approaches from a clinical / therapeutical point of view. If a change in origin of pain is not being addressed or taken into account by the dentist i.e. the dentist does not change his/her initial mind set to treatment, the management / treatment of the functional pain is doomed to fail. This might be the reason why so many patients with CMD /TMD become chronic victims of too many unsuccessful procedures, unnecessary expenses and not to say oral invalidity that detrimentally affects their quality of life.

In the above mentioned perspective I once and for all would like to express my serious concern regarding the use of the world wide recommended diagnostic indices to be used in the individual patient in the clinical situation. Indices may serve in an epidemiological study, but in my opnion they are without any value in the clinical evaluation of the single patient. It is also my opinion that the use of these indices in many clinical studies is one reason why the outcome of dental treatment has not shown any permanent success.  However, in A 5-Year Follw-Up of Temporomandibular Disorder Treatment Emphasizing Condylar Asymmetry (Cranio ,October 2006,vol.24.no 4,pp 265-273 ) of our patients in T.A.C. Seriate,Italy we used the orthopedic tests to initially distinguish the origin of pain. We were able to show that our dental treatment was successfull . The results were permanently stable. The patients showed an increase in mouth opening and a significant decrease of dynamic and static pain. The patients also showed a permanent reduction of their initial facial pain. The patients with a condylar asymmetry> 10% and who underwent dental treatment aiming at permanent oral stability, showed the greatest improvement.

MERRY CHRISTMAS!

temporomandibular joint condylar (A)SYMMETRY

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Temporomandibular joint

Before discussing condylar (a)symmetry, “to be or not to be” my opinion is that in the examination and treatment of orofacial pain the initial step must be to distinguish between a neurological origin of pain versus a functional origin of pain i.e. a functionally induced facial pain.

As dentists and as clinicians we should stay away from the neurological pain. Our education has not given us the information that will make us capable in pin-pointing a neurological diagnosis. We are supposed to know how to examine,to diagnose and to treat the stomatognathic system.  Diagnostics and treatment of neurological origin of pain belongs in the field of pharmacology or in the field of neurosurgery.The functional origin of pain in the stomatognathic system can successfully be dealt with in the fields of dentistry,physical therapy and sometimes psychology.

When treating the functionally induced facial pain the function that causes the pain needs to be changed. Besides, a functional change is also a reversible change.When the initially adequate information to the patient and the following reversible approach result in a reduction of pain we are heading in the right direction.When the proper function is normalized the pain remains reduced or sometimes it is even completely gone. Not until the pain is at the 0-level for at least 4-6 months permanent treatment should be concidered if necessary. Very often, when the pain is gone, the function of the stomatognathic system has returned to its normal conditions. The patient has benefited from the nature of adaptation. However, there are also patients who need additional dentistry, some of them even full mouth rehabilitation. Thus, dentistry plays an important role in the maintenance of restored function.

In restoring function the clinicians need to look out for mandibular/ VERTICAL temporomandibular joint (tmj) CONDYLAR (A)SYMMETRY. To focus the vertical condylar (a)symmetry in the clinical approach or management of a craniomandibular disorder / temporomandibular disorder ( CMD / TMD ) is in my opinion a must. It is also my opinion that, if there was not an asymmetrical function or in other words, if there was not one side of the bilateral stomatognathic system that constantly was too much or too little used, there would hardly be any patients with functionally induced pain, except the ones who are bruxing their teeth in an abused protrusion.Therefore, when it concerns the clinical diagnostics of the masticatory muscles and the temporomandibular joints, LOOK FOR ASYMMETRY! When it later concerns the management and treatment of the same muscles and joints ,GIVE PRIORITY TO SYMMETRY!

Team Approach in tmj Condylar Asymmetry Recognition and rehabilitation( TACAR )

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condylar asymmetry recognition, Temporomandibular joint diagnostics

For many years during and after given lectures and courses I have been asked to guide and to assist in the diagnostics and treatment of facial pain and often facial asymmetry due to a vertical temporomandibular joint condylar asymmetry.Often dentists do not consider the phenomenon, a possible vertical temporomandibular joint condylar asymmetry, when their utmost perfect occlusal rehabilitation fails. It is not that strange as mostly the two temporomandibular joints were not considered in the planning and design of the prosthodontics or orthodontics.There may be several explanations and  reasons.Some of them may be ascribed to facts like:

1. The temporomandibular joints are often pictured in a sagittal plane and one at the time,

2.The two temporomandibular joints are learnt and conceptualized as being identical,

3.An occlusal adjustment is something that is considered almost “normal “, when ” the work ”  returns from the dental laboratory before it’s permanent insertion into the mouth,

4.Occlusal devices need to be adjusted as the patient might be a tooth grinder or a tooth clencher,

5.The two temporomandibular joints may not be or were not visible in the panoramic radiograph (if even taken ) or

6.The dentist was taught that the panoramic radiograph is not reliable and that all dimensions in the pictureare are not trustworthy and so on.

From January 2014 on I will try to provide an exchange of experience and ideas through this blog on at least a weekly basis. The blog will address clinical and practical problems . My intention is to share my experience of more than 30 years in dealing with tmj condylar asymmetry.The readers are most welcome to ask questions and hopefully the blog will stimulate to new discoveries and even to convince the very conservative part of the dental profession to recognize and to compensate for an existing temporomandibulr joint condylar asymmetry when it is confirmed to be the cause for the facial pain in the patient.