TMD 2015, Condylar Asymmetry?

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Arthrogeneous origin of TMJ pain, Asymmetry, Asymmetry Index, Bruxism, condylar asymmetry recognition, Dentistry, Occlusal device, Retruded Position of the Mandible, Temporomandibular joint diagnostics, Temporomandibular joint disorder, Temporomandibular joint pain, TMJ rehabilitation, Treatment planning

Reflecting back on the interesting information given by eighteen well known international speakers at the Quintessence International Symposium on TMD & FACIAL PAIN and HEADACHE, Bridging the Gap Between Current Research and Clinical Practice in Scottsdale Arizona ( February 6-7,2015, Co-Chaired by Drs Daniel M.Laskin and Charles S.Greene ) I once again would like to stress the importance to recognize a temporomandibular joint condylar asymmetry when present. Several speakers stressed the overloaded temporomandibular joint as the cause of TMD and advised to pay less attention  to the masticatory muscles initially at  the examination of TMD pain. Lack of synovial liquid and mini ruptures or even nano ruptures of the joint tissues are to be looked upon as causes for cartilage degeneration with osteoarthritis / osteoarthrosis as the end result.

It is my opinion that in combination with bruxism a temporomandibular joint condylar asymmetry needs to be acknowledged and addressed. The shorter condyle side joint is in its morphology unstable and easily develops internal derangement of its articulating parts.  The well known phenomenon of disk displacement is thereby a fact and the first step in joint break down with the diagnosis Arthritis microtraumatica art.temp.mand. In this perspective occlusion becomes extremely important . The shorter condyle side joint needs to be supported with the correct vertical dimension of occlusion. What is missing in vertical dimension inside that joint needs to be compensated for at the level of the teeth of the ipsilateral side. In my mind this is the only possibility to create a stable occlusion with the maintenance of improved joint function after the initially reversible approach with an orthotic device.

Finally a statement/question that might need some thoughts: How much longer are we as a profession going to talk about occlusion without considering the vertical dimension of the two temporomandibular joints!?

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.

TMJ Clicking Sound

Tags

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!

Cutting Temporomandibular Joints

Tags

Asymmetry, condylar asymmetry recognition, Dentistry, Implantology, Occlusion, Orthodontics, Preprosthetic occlusal adjustment, Prosthodontics, Radiography, Temporomandibular joint, Temporomandibular joint disorder, Temporomandibular joint pain, Treatment planning

occurs in surgery. Thank God it does not happen too often, as responsible, well trained and experienced oral / maxillofacial surgeons are utmost cautious. They know it is involved with major draw backs. However, under certain circumstances and with the correct indications it is  necessary. I do not mind that at all, but what I do mind is all the cutting of temporomandibular joints in the panoramic x-rays we are exposed to in the literature and thus unconsciously gives us the message that the joints are not so very important.

It does not matter whether it is in a professional journal of prosthodontics, orthodontics, implantology, periodontics or even in a presentation at a congress it could be estimated that 8-9 out of 10 panoramic x-ray photos presented do not show the entire picture of the two temporomandibular joint condyles. The majority of condyles are cut totally  or at least partially while all the teeth are nicely depicted and aligned in the perfect occlusal plane  often before as well as always after treatment.  Is a vertical condylar asymmetry present in such a patient most likely the teeth are not aligned in the shown or anticipated correct occlusal plane. With a high probability the smile of that patient is tilted which is observed in the clinical situation and which often also might be the reason for the complaint of  the not satisfied patient.

In rehabilitation priority is supposed to be given to the whole stomatognathic system and not only to one third of it. As the other two thirds of the system ( the masticatory muscles and the two temporomandibular joints ) are dependent on the teeth it is my advice that the teeth must be aligned in such a way that they vertically compensate for what is missing in the vertical dimension of the shorter condyle when present. Addressing the vertical condylar asymmetry, when present, is of utmost importance and  in my opinion it should be done already at the time of treatment planning regardless specialty of the therapist. To incorporate an index, preferably via Maaxloc, between the models already at the initial analysis of the ” study ” models instead of just manually having the models to occlude will definitely contribute to a bigger certainty in reaching the goal of treatment. It makes the whole planning easier and it decreases the risk of unnecessary difficulties during treatment. In not accepting cut temporomandibular joint condyles in the panoramic x-ray and instead  only accepting  the picture when it is  complete i.e. picturing  both the temporomandibular joint condyles we most probably will be  expanding our clinical success and consequently patient satisfaction.

Uneven Front Teeth Wear

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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

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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.

The Mandibular Position and The Hinge Axis

Tags

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

It is impossible for me not to repeat the importance in every clinical situation to recognize a temporomandibular joint condylar asymmetry, when present. In not doing so the treatment cannot be correctly predicted. The treatment will not be as successful as was expected . Unnecessary adjustments of oral devices or, even worse, adjustments of permanent dentistry will disappoint the patient as well as the dentist with also the risk that the treatment will never be fully accepted despite tremendous efforts from both parties involved.

In the clinical situation or in the dental laboratory the conventional axis of mandibular rotation should never penetrate the centers of the two temporomandibular joint condyles at a condylar asymmetry.One condyle, the ” higher one “must determine the axis of rotation. If not, the axis of rotation could not be parallel to the horizontal plane, used as the reference at general rehabilitation.

                                                  Wrong axis of rotation at a condylar asymmetry.

CORRECT AXIS OF ROTATION AT A CONDYLAR ASYMMETRY.

It is my opinion that the definition and the application of the generally used retruded position of the mandible ( RPM ),based upon the assumption that the two temporomandibular joints are equal, therefore needs to be reconsidered and slightly adjusted Clinically I have always worked with the retruded position of the mandible as my reliable position of reference.However for the past 25 years I  have advocated that the retruded position of the mandible ( RPM ) is ( should be ,if not yet ) determined and guided by the normally developed and functioning temporomandibular joint condyle. When the right side is the higher side RPM is to be written RPM (R). When the left side is the higher side RPM is to be written RPM (L) and when the two condyles are of equal height RPM is to be written RPM (=).In addition, when the two condylar heights are measured in the panoramic ( over view ) x-ray and the magnification factor  of the machine is compensated in the calculation the RPM(R) or RPM(L) at an asymmetry can be written i.e. RPM(R)1,5mm or RPM(L) 0,5 into the clinical documents. In that way the almost true difference between the two condylar heights easily can be compensated for in the necessary index to be used in the phase of rehabilitation clinically or at the laboratory via the Maaxloc device (info@dentatus.se)

In general the higher condyle determines what side is to be the guiding side for RPM. However, there is one exception under rare circumstances.At a ramus asymmetry when the total vertical dimensional difference between the two mandibular sides is determined by a major difference in height of the two rami, the vertical dimensional difference determined by the condyles is overruled.Then the biggest total mandibular vertical height may direct even the “shorter condyle” to be the guide in the registration of the retruded position of the mandible and the center of the hinge axis rotation. In this context “disturbing” precontacts or interferences enter a completely new perspective. Unilateral tooth contacts on the “higher condyle” side may indicate the correct vertical dimension of the occlusion. The lack of tooth contacts on the “shorter condyle” side may indicate the occlusal dimension that needs to be increased.Only interferences or precontacts on the “shorter condyle” side will then remain as traditional interferences i.e.disturbing tooth contacts.