House of Gnathology?

Tags

Arthrogeneous origin of TMJ pain, Asymmetry, Bruxism, Centric relation, condylar asymmetry recognition, Dentistry, Myogeneous origin of TMJ pain, Occlusal adjustment, Oral Stability, Retruded Position of the Mandible, Temporomandibular joint diagnostics, Temporomandibular joint disorder, Temporomandibular joint pain, TMJ rehabilitation, Treatment planning

A week ago I had the pleasure to attend the XXVII International AIG (Associazione Italiana di Gnatologia) Congress in Torino, Italy. Twentyseven speakers from six countries each had about 30 minutes to present their thoughts about the relationship between occlusion and temporomandibular joint disorders. In general it could be concluded that a stable occlusion would improve the function of the stomatognathic system and thereby reduce the risk for developing or aggravating a temporomandibular joint disorder. It was also underlined in several lectures that gnathology is a team work and that occlusion is one tool in the treatment of a temporomandibular joint disorder.
It was interesting to note that the speakers in general agreed in finding occlusion an important factor in the treatment of a temporomandibular joint disorder, i.e. a complete contradiction to the conclusion of several hundreds of articles and studies proclaiming that when RDC/TMD are used in the evaluation of treatment outcome occlusion is not important and should not get priority or most often not even be considered in the treatment of a temporomandibular joint disorder.

RDC/TMD were discussed and by a great part of the participants even questioned in the final round table discussion of the congress. In my opinion and in agreement with many other clinicians RDC/TMD cannot and should not be used in the clinical situation in which a specific diagnosis is to be the sound base for the treatment. Reliable criteria like maximum mouth opening, mandibular movements, the difference between dynamic and static pain and even the difference between the vertical dimensions of the two temporomandibular joint condyles visible and measurable in a panoramic X-ray exist. Therefore my suggestion to the RDC/TMD supporters is: Next time you conduct a clinical study, why not incorporate the above mentioned criteria! I am pretty convinced that the results will be different regarding the eventual link between occlusion and the temporomandibular joint disorder.

Finally I would delete the ? from the title of this blog and agree with the suggestion from Dr.Eugenio Tanteri that a forum “House of Gnathology” might come to an agreement that a correctly designed and applied occlusion is important in providing  oral stability and thereby reduce the prevalence of temporomandibular joint disorders among our patients.

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Migraine or ?

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Bruxism, Dentistry, Facial pain, Myogeneous origin of TMJ pain, Occlusal device, Occlusal splint, Retruded Position of the Mandible, Reversible treatment, Tension headache

Although the specific diagnosis of migraine is defined as a chronic neurological disorder characterized by recurrent moderate to severe headaches often in association with a number of autonomic nervous system symptoms it is often by our dental patients used as the general term for facial pain with often also no response to the prescribed medication. This experience I share with many colleagues and yet I have to tell you about the 36 years old man, who was referred for chronic left side facial pain he had suffered for 18 years, half of his life. He had visited many doctors and he had also been taking a lot of medication during the years.

The pain occurred almost every day and was described by the patient as migraine on the left side of his face covering the left side temple and cheek area. Mandibular movements were normal. A panoramic X-ray did not reveal any pathology and showed a temporomandibular joint condylar symmetry.Static pain could be provoked for closing of his mouth. During our conversation it became obvious that a left side latero-protrusion was an often used position for bruxism, which also could be confirmed by marked facets of his left side front teeth.

After information about the possibility to initially wear a stabilization splint part time ( during day time working hours )  in order to avoid his unilateral abuse of the left side mm temporalis and the deep portion of masseter he decided to try. The stabilization splint was designed around the retruded position of his mandible, inserted without any adjustments and checked after another 6 weeks. At that time the young man announced that he had been completely free from any facial pain since the day after the insertion of the splint. It had been worn during the day except for chewing. He also showed an oral stability without the splint in his mouth.

In conclusion: When the dental patient is telling about his or her migraine that is not responding to the, by the medical doctor, prescribed medication DO PERFORM A FUNCTIONAL EXAMINATION OF THE STOMATOGNATHIC SYSTEM. There might be a chance to help the patient and not only his or her teeth.

 

 

 

 

Asymmetry Index ( AI ) for temporomandibular joint Condylar Asymmetry

Tags

Arthrogeneous origin of TMJ pain, Asymmetry, Asymmetry Index, Centric relation, condylar asymmetry recognition, Dentistry, Myogeneous origin of TMJ pain, Occlusal adjustment, Oral rehabilitation, Oral Stability, Retruded Position of the Mandible, Reversible treatment, Temporomandibular joint, Temporomandibular joint diagnostics, Tension headache, TMJ rehabilitation

For more than twenty years I have been working on a regular basis with Dr Ugo Gambardella, Medical Space in Seriate, Italy. In 1993 we founded the T.A.C. Seriate clinic, ( Team Approach to Craniomandibular disorders ) in order to optimize the diagnostics and treatment of patients suffering facial pain due to dysfunction of the stomatognathic system. Dr Gambardella was already then experienced in prosthodontics as well as in implantology.
Already at the start it became obvious to us that a large portion of the mostly referred patients showed a condylar asymmetry and a lack of oral stability. Initially our treatment aimed at a normalization of the stomatognathic system via a stabilization splint in its design compensating for the condylar asymmetry, when present, and providing at least a temporary oral stability. After 6 – 12 months several patients wanted to have permanent oral stability, which then was achieved through mostly prosthodontics , sometimes in combination with preprosthetic orthodontics.
Some years ago and then more than 5 years after completed treatment the patients were invited to have their situation evaluated and to tell how they felt and how they were functioning after treatment. The equivalent clinical examination of their stomatognathic system was executed by an Italian speaking colleague, who did not know what kind of treatment the patients had got or been exposed to. The teeth depicted in the panoramic overview X-rays were covered i.e. made not visible to the examiner while the two temporomandibular joints were shown.
The condylar asymmetry was analyzed and for each patient an Asymmetry Index ( AI ) was calculated according to the following formula: ( R – L : R + L ) x 100 i.e. the right side condylar height minus the left side condylar height divided by the sum of the right and left side condylar heights multiplied by 100. Thus an asymmetry index was expressed in percentage for each patient.
The results of the subsequent analysis showed that after more than five years with permanent oral stability no patient any longer was found with a mainly arthrogeneous origin of pain. Myogeneous origin of pain was also frequently eliminated or markedly reduced. All patients showed an increase of maximum mouth opening.
The patients were grouped and analyzed according to the asymmetry index ( AI ) . It can be concluded from the results that patients with an AI > 3 % in general benefit from reversible treatment. Patients with an AI in the range between 3 % and 10 % may do well with just a temporary oral stability in form of a stabilization splint i.e. the splint can be worn part time, which for most patients means during sleep. As the participating patients with an AI > 10 % definitely benefitted the most and also felt subjectively completely different, mostly totally pain free after the treatment it is our opinion, that when you find a condylar asymmetry > 10 % in a patient with a diagnosed facial pain, you can comfortably suggest permanent occlusal treatment after the initially reversible period in the correct mandibular position guided by the higher temporomandibular joint condyle. The permanent treatment then executed in the same mandibular position will provide oral stability.

TMJ Clicking Sound

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Arthrogeneous origin of TMJ pain, Asymmetry, Centric relation, condylar asymmetry recognition, Dentistry, Myogeneous origin of TMJ pain, Retruded Position of the Mandible, Temporomandibular joint, Temporomandibular Joint Clicking, Temporomandibular joint diagnostics, Temporomandibular Joint Disk Displacement, Temporomandibular joint pain, Temporomandibular Joint Sounds

TMJ clicking sound has been reported, discussed, investigated and even visualized in thousands of articles during the past thirty and more years with a peak of interest in 1980-s. Common knowledge is that the sound is either due to deviations in form of the articulating surfaces of the condyle and / or the temporal component ( increase of cartilage in specifically overloaded areas of the articulating surface ) or to a displacement of the disk. Disk displacement often comes and goes and it is therefore not a surprise that it is more common among patients with a mainly myogeneous origin of pain. Since the result of comprehensive epidemiological  studies in the 1970-s it is also common knowledge that  the phenomena occurs in about 40% of the adult population.

Hopefully in not contributing to the too often clinically existing confusion of how to handle the sound I would rather suggest the following: Check the panoramic x-ray i.e. check specifically the temporomandibular joint condylar heights before you take any further steps in your attempt to help your patient!

Most probably you will find a shorter condyle of the joint with the registered clicking sound. Try to guide a mandibular rotation movement around the higher condyle and most likely the clicking sound disappears or at least gets a reduced  magnitude, when it is due to a latent disk displacement. If there is no discomfort or pain to be registered there is no real indication for intervention. However, if discomfort or a mainly myogeneous origin of pain is reported by the patient there is a need for an initially reversible treatment in form of a stabilization splint that compensates for the difference in vertical dimensions between the two condyles. The splint is to be worn part time . The patient is supposed to find a seemingly fast relief.  When the clicking sound is found in combination with a mainly arthrogeneous origin of pain the splint needs to be worn as much as possible for at least 6 months before additional permanent treatment is considered.

In addition , even if the clicking sound is due to a deviation in form ( of the condyle and / or of the temporal component )  the clicking sound may over time get reduced as a smoothening out of the articulating surfaces can be expected at a consequent long term  wearing of the correctly designed splint. Therefore I once again would suggest the use of the Maaxloc instrument in producing the index  which will be used in mounting the models into the articulator before the construction of the stabilization splint. The splint absolutely must compensate for the registered difference in vertical condylar height between the two joints in providing a symmetrical oral stability in order to eliminate the  painful and bothersome  tmj clicking.

Sleep Apnea Oral Devices

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Arthrogeneous origin of TMJ pain, Asymmetry, condylar asymmetry recognition, Dentistry, Myogeneous origin of TMJ pain, Occlusal device, Sleep Apnea, Sleep Apnea Device, Temporomandibular joint, Temporomandibular joint diagnostics, Temporomandibular joint dysfunction, Temporomandibular joint pain, Treatment planning

Nowadays MAD, the mandibular advancement device, seems to be delivered from almost every dental office in an effort to assist the medical profession fighting sleep apnea, a major problem for many of our patients. The device is supposed to direct the mandible forward and inferiorly in order to increase the air flow through the mouth. However, a standardized method in making the device seems lacking and many patients suffer discomfort or pain after wearing the device after various lengths of time. Dentists regularly also register changes of occlusion, most often posterior open bites.

As the device shall position the mandible forwards the most often clinically achieved index accompanying the impressions to the laboratory must be taken in a protruded mandibular position. But how much protrusion seems to be left at random. There are studies concluding that it does not matter whether the protrusion is 75% of maximum protrusion or only 25%. Nevertheless it seems accepted to allow a rather large amount of protrusion as additional protrusion as adjustment of the device  often is recommended in the cases where the originally designed device has not given the expected relief.

At a vertical temporomandibular joint condylar asymmetry an excessive and prolonged protrusion definitely puts the comfort of the patient and a  harm free function of the stomatognathic system at risk. At a vertical condylar asymmetry most likely the clinically taken index does not register the mandible in a symmetrically protruded mandibular position. Most likely the mandible is deviating towards the ” shorter ” condyle side. To then have this position maintained during six to eight hours of sleep with thus an awkward  and asymmetrical muscle function and temporomandibular joint condylar positions may be one reason for discomfort or facial pain at awakening.

One way to avoid the problem is to use the Maaxloc ( following the analysis of the vertical condylar heights in the panoramic x-ray ) in constructing the index which is to be used in the mounting of the models in the articulator. It is then easy to bilaterally just set the amount of individually determined protrusion to be applied in the fabrication of the device. A symmetrical protrusion is thereby achieved resulting in a more comfortable device.

A good friend of mine, Dr Staffan Lindholm, Stockholm, Sweden, is probably one of the most experienced dentists in Scandinavia when it concerns oral devices  in fighting sleep apnea. His expertise and unusual self criticism already several years ago  motivated him to compare the outcome of 59 conventionally and from just clinically taken indices  oral devices with another  59 devices constructed from articulator set protrusion of the models mounted with the Maaxloc registration. Six patients of the first group suffered pain and discomfort from  their devices while only 1 patient of the second group showed a minor dissatisfaction, but tolerated the splint. The 6 not successful devices in the first group of  patients were later adjusted according to a Maaxloc registration resulting in patient satisfaction.

In many discussions with fellow dentists and dental technicians Dr. Lindholm  proclaims the superiority of the Maaxloc instrument in constructing a more comfortable  and successful oral device. He is happy to generally tell about his continuing success with a 80-90% reduction of the risk to develop discomfort or pain in the patients who are forced to wear an oral device fighting sleep apnea by using the Maaxloc registration in mounting the models before its fabrication in the laboratory . In conclusion, please do consider a correct index in protrusion for the construction of any anti sleep apnea device at your choice and thereby enjoy a major increase of clinical success!

Uneven Front Teeth Wear

Tags

Asymmetry, Bruxism, Centric relation, condylar asymmetry recognition, Dentistry, Occlusal device, Occlusal splint, Occlusion, Orthodontics, Preprosthetic occlusal adjustment, Retruded Position of the Mandible, Reversible treatment, Temporomandibular joint, Temporomandibular joint disorder, Temporomandibular joint pain, Treatment planning

may very well denote a temporomandibular joint condylar asymmetry and may therefore indicate the necessity of a panoramic x-ray in order to avoid negative consequences of a dental treatment. It is my experience that very often the front teeth ( the central and the lateral incisors ) of the quadrant of the ” higher condyle ” side are more worn than the equivalent teeth of the contra lateral side. The ” higher condyle ” side seems with a far more higher prevalence be used as the laterotrusive side ( working side ). The contra lateral side of the face then also looks bigger or thicker, most probably due to the unilateral hyperactivity of the superficial masseter muscle of that side. When this kind of an observation is made there is an absolute indication to proceed with a clinical examination in order to rule out whether pain or discomfort are involved.

If pain is present the stomatognathic system needs to get normalized. This is easily accomplished with the insertion of a correctly designed stabilization splint. The splint preferably already at the dental laboratory is  fabricated in the correct relation between the models i.e. the models have been mounted in an articulator according to the index ( registration ) made in the Maaxloc and thereby based upon the difference between the two condylar heights. Within a couple of weeks, not to say surprisingly often within a couple of days, the patient returns with markedly reduced pain or completely without pain. Also without any difficulties the patient normally finds his / her natural way in getting his / her teeth together. However,on the ” shorter condyle ” side tooth contacts are missing. This most often results in a slide between the mandibular reference position, RPM, and the intercuspal position and therefore often indicates a need for extended dental treatment or at least a change of direction of your earlier planned treatment.  The empty space between the teeth of the ” shorter condyle ” therefore needs to be filled in or the teeth of the ” shorter condyle ” side need to be built up. After four to six months and with a reversible approach in form of a partial and casted metal splint cemented on the not occluding teeth of the ” shorter condyle ” side oral stability is achieved. Personally I always have that splint casted in gold and made for the lower premolars / molars. The earlier worn stabilization splint is being adjusted to the new and reversible occlusion and is used part time, during sleep for an individually determined length of time. Finally permanent treatment can be considered at the choice of you and your patient.

Uneven front teeth wear occurs and is also sometimes observed in young patients.In these individuals it may be even more important to analyze the vertical dimensions of the two temporomandibular joint condyles. At a condylar asymmetry an index via Maaxloc may serve as an adequate guide to relate the upper and lower models of the teeth, indicating the correct vertical dimensions of the jaws after completed treatment and thereby contribute to the best outcome of the orthodontic treatment. In not addressing the condylar asymmetry, when present, in the initial phase of treatment planning there is always the risk to deliver a yet perfect occlusion but in a not perfect occlusal plane, i. e. a perfect smile what concerns the teeth but less perfect what concerns the smiling mouth of the whole face.

 

Occlusal ” interferences ” at condylar asymmetry

Tags

Asymmetry, Centric relation, condylar asymmetry recognition, Dentistry, Occlusal adjustment, Occlusal device, Occlusal splint, Occlusion, Preprosthetic occlusal adjustment, Retruded Position of the Mandible, Temporomandibular joint, Temporomandibular joint disorder, Temporomandibular joint pain

must be carefully evaluated before any action is taken. It is as important and necessary to realize as it is absolutely wrong to adjust occlusal  pre contacts in the acute situation of functional facial pain.The latter  ” interferences ” may not be real as they might not exist under normal or pain free circumstances. They might be due to changed muscular conditions in the dysfunction of the stomatognathic system and most probably they will disappear with a normalization of the function. In my opinion it is therefore an absolute necessity to always normalize the muscle function via reversible means before any change of the occlusal surfaces takes place. This is done through the insertion of a stabilization splint made in the correct mandibular position, based upon the findings of the condylar heights visible in the panoramic x- ray, and worn according to the preliminary diagnosis during 4-6 months . Not until then an occlusal adjustment can be considered.

Although occlusal pre contacts cause an oral instability with mostly a slide between the retruded position of the mandible ( RPM ) and the intercuspal position ( ICP )  pre contacts on the ” higher condyle ” side may indicate the true vertical dimension of the occlusion ( the static relation between the teeth of the maxilla and of the mandible ).Therefore these contacts will function as the guide  for an increase of the vertical dimensions of the teeth not in contact  on the opposite side in equivalent regions. Thus ,it is my advice that, occlusal pre contacts on the ” higher condyle ” side should not be removed. If so, there is a major risk that the vertical dimension will get decreased and problems due to a too low vertical dimension of the occlusion will occur.

Occlusal pre contacts on the ” shorter condyle ” side  in the retruded position of the mandible ( RPM ) most likely are true interferences and can therefore be removed after a normalization of the muscle function. They should also be removed prior to the introduction of new elements into the occlusion via prosthodontics.

At condylar symmetry i.e. when the two condylar heights are of equal size, pre contacts in the retruded position of the mandible ( RPM ) should be removed pre prostodontically. If no further rehabilitation is planned or indicated these pre contacts can be left unless they produce a  major lateral slide between the retruded position of the mandible ( RPM ) and the intercuspal  position (ICP ).The general rule remains: DO NOT CONTRIBUTE TO UNNECESSARY CHANGES OF THE OCCLUSION IN A PATIENT WITHOUT PAIN !  NEVER APPLY  OCCLUSAL ADJUSTMENT AS A PURE PREVENTION !

Reversible Oral Stability, One Splint and that’s it

Tags

Asymmetry, Bruxism, Centric relation, condylar asymmetry recognition, Condyle (anatomy), Dentistry, Occlusal device, Occlusal splint, Radiography, Retruded Position of the Mandible, Temporomandibular joint, Temporomandibular joint disorder, Temporomandibular joint pain

Through the insertion of a stabilization splint fabricated in the correct mandibular position i.e. in RPM(=),RPM(R) or RPM(L) it is easy ,not to say the only way, to confirm or justify the preliminary diagnosis of the complaint of facial pain.Needless to say , I take for granted that the mandibular position is determined from the analysis of the vertical dimensions of the two temporomandibular joint condyles visible in the panoramic x-ray. The values conclude with the difference in mm provided the technician with the impressions of the upper and lower jaws. Via Maaxloc you or your technician produce the index with which the models are mounted into the articulator of your choice. The splint is fabricated in hot curing acrylic and at a condylar asymmetry it will be somewhat thicker at the ” shorter condyle ” side ,as it is compensating what is missing in the vertical dimension of that condylar height. The splint does not need to be adjusted if your measurements and impressions/models are correct. It fits directly into the mouth of your patient. There are many hard and good working technicians who perfectly provide excellent splints. My opinion is that if the dentist needs to adjust a splint the error most likely must have happened in the clinical situation as the technician is working with the models of non changeable materials and correctly mounted in the articulator.

The patient is then to wear the splint depending upon the preliminary diagnosis. Full time use, 24 hours a day, except at eating at arthrogeneous origin of pain as the anatomical joint structures need support. Part time use of the splint, day OR night, at myogeneous origin of pain as the masticatory muscles needs to be interrupted in their hyperfunction  i.e. given the possibility to rest. I do think that the reason why even  perfectly fit splints do not give the patient any relief is that the splint is worn at the wrong time of the 24 hours. To wear a splint during sleep when bruxing occurs during the day does not make any sense to me. Just a change in the way the patient is wearing the splint may result in complete relief.

Personally I never prescribe soft splints. In my opinion they function as chewing gum due to their resilience and should be avoided in any bruxing situation. In conclusion, there is only one splint that also can be looked upon as universal . That is the conventionally made stabilization splint  ( the old Michigan splint ) fabricated around the correct mandibular position in RPM. No problem All continents !

 

Maaxloc, the mandibular axis locator

Tags

Asymmetry, Bruxism, Centric relation, condylar asymmetry recognition, Condyle (anatomy), Dentistry, Occlusion, Radiography, Retruded Position of the Mandible, Temporomandibular joint, Temporomandibular joint diagnostics, Temporomandibular joint disorder, Temporomandibular joint pain

Several years ago I met with and was introduced to Kenneth Wallenholm, an experienced dental technician in Stockholm, Sweden. I was giving a lecture and he was in the audience. I had talked about the recognition of temporomandibular joint condylar asymmetry, when present, and its importance for a correct registration of the mandibular position to be used as the reference position for optimal dental work clinically as well as in the dental laboratory. He had immediately understood my message and for a long time also realized that most “wax bites”, indices or ” Registrat ” accompanying dental impressions into the laboratories most frequently ended up in the trash can, never being used. The reason was that these ” wax bites ” did not provide any information about the workable intermaxillary relation. The technicians therefore rather related the upper and lower models of the jaws by hand i.e. they just tried to find the best stability between the models,maybe sometimes the intercuspal position, before they started their technical procedures to establish an acceptable occlusion. We were  both of the same opinion that such unfortunate events outside the mouth of the patient are the major reasons  for clinically unwanted adjustments of dental work before its  insertion into the mouth.

It did not take us long time until we met again and started to brain storm how to come up with a device in order to facilitate for the dentist / technician team to ascertain and improve the registration of the correct mandibular position to be used by both the professions. After many hours, many different measurements, several different drawings and a certain number of pieces of ” metal constructions ” the patent was approved and the prototype for the Maaxloc  was completed by Dentatus ( info@dentatus.se : dentatus@dentatus.com )

The Maaxloc determines the clinically correct mandibular position. The Maaxloc is not an articulator even if it is described under articulators in the list of products from Dentatus. The Maaxloc is a device to assist in finding the correct mandibular position of reference at a recognized condylar / mandibular asymmetry. The registration index produced in the Maaxloc can be  used in any articulator of your choice and can comfortably be applied in cases of craniomandibular or temporomandibular disorders,as well as in any case of prosthetic rehabilitation or orthodontic analysis. Determining the correct mandibular position of reference is of utmost importance and will help to avoid unwanted occlusal features. This includes achieving the correct incline of implants into the jaws and improving the occlusal analysis before an orthodontic treatment is initiated.

The Maaxloc is time saving and reduces pain because:

1.Symmetry in occlusal contacts between the jaws decreases the risk of failure in providing bilateral load to the stomatognathic system.

2.Less time is spent on adjustments and on remakes due to fractures in veneers and crown & bridge work, including supra structures on successfully accepted implants.

3.Shorter sessions for repetitive registrations of the mandibular positions.

4.A stable occlusion compensates a morphological asymmetry, improves the general adaptation of tissues and is especially beneficial to the edentulous patient wearing removable prostheses, with less dislocation of the prostheses.

5.Last but not least, once the individually correct mandibular position has been found, the patients immediately acknowledge their natural way of achieving and sensing oral stability

It  is my convinced opinion that the measurements of the condylar heights in a panoramic ( overview ) x-ray and  the difference between the two sides transferred into  the Maaxloc will further your clinical success and confidence.

x-ray analysis of vertical tmj Condylar Asymmetry

Tags

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!