Initial characterisation of TMJ TMJ sounds and osteoarthritis Detailed analysis of TMJ sounds
Oullette, (1974), was the first to categorise TMJ sounds in an objective manner. The diagnostic significance of TMJ sounds had traditionally been a controversial subject. It was acknowledged that TMJ sounds existed but no classification of these sounds was made. The very fact that sounds were present varied from one authors interpretation to another warranted further investigation, according to Ouellette. He wanted to record the sounds emitted from the TMJ and divide them into groups on examination.
In his work, sounds were recorded by use of a microphone placed over the temporal bone-zygomatic bone, with the participant seated in a straight backed chair and with her/his head in the normal position. The recordings were made stereophonically as the participants ‘opened their mouths to the maximum unstrained intrincisal, distance and to complete closure, with maximum intercuspation’. At least five opening-closing movements were recorded at each sitting.
Each recording was analysed for frequencies in the 40 Hz to 4 kHz range. This provided both total sound amplitudes and the main frequencies making up the sounds. Oullette analysed the sounds recorded and categorised the people involved according to the categories of sounds. Initial categories of TMJ sounds.
Group 1. low frequency sounds with similar components in both opening and closing stages,together with the noise made by teeth contact as a single peak or burst of frequencies.
Group 2. a combination of low and high frequencies. Most of the frequencies were in the 2 kHz to 4.5 kHz range.
Group 3. staccato characteristic’ or irregular, abrupt, staccato bursts of sound energy in the high and low frequency ranges. (Low amplitude spikes were said to be related to crepitus clicking ).
Group 4. little or no sound recorded, except for the characteristic spike of the teeth contact. (Most participants in this group were of small stature and had flaccid or frail musculature.)
Ouellette’s conclusions, were that participants with symptoms of TMD had a tendency towards ectomorphic somatotype and dolichocephalic facial type. No significant differences were evident for participants of different age, weight, sex, height, maximum inter-incisal distances or decibel levels during the opening-closing movement or during the contact of the teeth in centric occlusion.
Participants in the group of symptomatic patients tended to have more signal bursts or a higher amount of noise in the recorded sounds. No significant difference in teeth contact was exhibited between those that were symptomatic and asymptomatic.
He also concluded that although the sounds from the left and right side of the TMJ of a given individual were broadly similar yet slight differences were noted. Therefore, each joint should be examined separately even though it is possible that sound from one side of the joint could affect the analysis of the opposite side by travelling through the bones and tissue matter of the jaw and cranium. Top of the page
In 1976 Sigvard Kopp, at the University of Gothenburg, analysed a comprehensive questionnaire completed by one hundred and twenty patients referred to a clinic for mandibular dysfunction. Kopp was particularly interested in Osteoarthrosis , (OA), . He divided those surveyed into three groups as described below.
1. those with TMJ Crepitation. These people exhibited both clicking but more importantly grinding noises while opening-closing their mouth The sounds emitted whilst the mouth was opened and closed were polyphasic, i.e. made up of several frequencies. He considered this to be an indication of structural damage to articular surfaces, that is, the presence of OA and even Rheumatoid Arthrosis . These were mostly female and with the greatest incidences in the 61-68 year age group.
2. people with Palpatory Tenderness. Here mostly clicking sounds were emitted from the jaw during opening-closing motion of the mouth, although a few also had grinding noises. This TMD was deemed to originate from muscle attachment near the joint or bony tissue of the joint and this was common in the 21-30 age group.
3. those without either of the above symptoms.
All three groups complained of having headaches at least once a week, feeling of stiffness in the TMJ, pain in the TMJ/masticatory muscles, difficulty in opening the mouth and suffered from tooth clenching while awake. However, those with palpatory tenderness also had symptoms of tooth clenching while asleep but those of the fist group did not. Both groups 1 and 2 had also indicated stiffness, pain or difficulty in moving their hands and fingers. Top of the page
Probably the most significant classification of TMJ sounds was carried out by David Watt in 1980. He proposed a classification of the TMJ sounds which would take into account the nature of the sound, (click or crepitus), its quality, (hard or soft), its dependence on position relative to mandible movement, (near/middle/far) and whether the sound occurs on opening or closing of the jaw.
Then Watt claimed that sounds that occurred less than 30 ms before the closing occlusal sound may not actually be TMJ sounds but could be premature contact of the teeth. Sounds occurring greater than 30 ms before occlusion should be considered as TMJ sounds, especially if the sound is obtained during the motion of the jaw opening. When a sound is emitted on closure of the mouth and there is a sudden arrest of the mandibular movement, then the sound is likely to be occlusal. If there is no arrest, then that sound should be considered as a joint sound. Top of the page
Watt’s classification of TMJ sounds is as follows.
Soft Click Soft Crepitius Hard Clicks Hard Crepitius
1. Soft Clicks. These sounds being produced at the middle-wide opening, (greater than 1 cm), are often described as a ‘popping click’ by the sufferer and can often be heard in individuals who do not suffer from any TMJ trouble but probably due to muscle incoordination. These sounds are usually short bursts of low frequency and low amplitude.
2. Soft Crepitus: Here the sounds are emitted at the wide opening position of the mouth, (greater than 2 cm), sounding like knuckles being rubbed over each other. This sound was found to be predominant in young women about the time of the advent of the third molars. The sounds emitted were of low frequency and low amplitude. Often these sounds would come and go and even change position in the opening-closing cycle.
3. Hard Clicks: These TMJ sounds which occur in the near-middle parts of the opening cycle, (approximatly from 1 cm to 2 cm), can be described as ‘cracking or grating clicks’. Their presence suggests some specific defects of joint surfaces. The sounds detected are sharp and contain a number of high amplitude peaks, meaning that the surfaces of the TMJ are abrasive.
4. Hard Crepitus: Produced in the near opening, (less than 1 cm), and closing section of the cycle this sound is comparable to ‘footsteps on gravel’. The very presence of this sound is ‘strongly indicictive of arthritic changes in the TMJ. The classification was then taken into the next stage by categorising the sounds with respect to the position of the mandible to the upper jaw. Here, Watt, defined three positions of the jaw in which he described the TMJ sounds.
Near Clicks Middle Clicks Wide Clicks Top of the page
a. Near Clicks: Sounds occurring in a position of less than 1 cm are sometimes the result of arthritis. These clicks are usually more trouble to the person than wide clicks as they are often indicitive of damage to the articular surfaces such as arthitis changes.
b. Middle Clicks Soft or low amplitude sounds emitted between 1 cm and 2 cm are often caused by separation of the joint surfaces or by the snapping of the TM ligament over the lateral pole of the condyle.
c. Wide Clicks Soft clicks which take place at the maximum jaw opening may be symptomless. However clicks occurring before the maximum, greater than 2 cm, could be the result of the condyle translating onto the anterior band of the meniscus. People with this may often experience partial dislocation of the jaw while in the opening cycle. The sound emitted is usually only audible to the person with the problem.
Very little had been done previously to quantifytmj sound amplitudes, background noises and to determine the spectrum of heallthy TMJs. Work to this effect was carried in 1993, [Gallo, Airoli, Ernst & Palla.]. Their aim was to record acoustically the sound emittes by health TMJs with and without mandibular movement to determine baseline spectra.
Spectra were recorded from 40 subjects, (17 females and 23 males, ageing from 18 upto 46 years old), with healthy TMJs. Each participant had to complete a questionaire in order to eliminate subjects with craniomandibular disorders from the study. All those with a negative history where then given a clinical examination including ausculation of the TMJs with a stethoscope, the lateral and intrameatalpalpation of the TMJs, the palpatation of the masticatory, neck and shoulder muscles and the measurement of the unassisted mandible mobility. Tenderness to palpatation was considered positive when it elicited a reflex or the participant stated that it produced pain or discomfort.
The sounds were recorded using a miantur capacitor microphone inserted into the end ear-pieces of a medical stethoscope, then placed in the mentus of the audatory canal. Recordings were made fistly with no mandible movement followed by three consecutice opening and closing mandible movements.
The recorded signals were then bandpass filtered, 50 Hz to 2 kHz. The frequencies at which 10, 25, 50, 75 and 90 % of the total power occured, (F10, F25, F50, F75 and F90), as well as the bandwidths between 10-90% and 25-75% of the total power were calculated in order to characterise the shapes of the spectra and to analyse whether the shapes of the group average spectra differed with statistical eignificance between the two sides, (the recordings without mandible movement and that withmandible movement).
WORK IN PROGRESS....