Asymmetry Index ( AI ) for temporomandibular joint Condylar Asymmetry

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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.

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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!