Cutting Temporomandibular Joints

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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

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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

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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

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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.