Temporomandibular joint sounds.
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Cadaver↗
Biomedical subjects
S E Widmalm
Publications and source records attributed to S E Widmalm.
Temporomandibular joint pathosis related to sex, age, and dentition in autopsy material.
The purpose of this autopsy study was to test the hypotheses that temporomandibular joint (TMJ) arthrosis is more common in women than in men, increases with age, and is more common in edentulous persons than in those with natural teeth. Two hundred forty-eight TMJs removed at autopsy from 224 fresh cadavers were investigated macroscopically with dissection or cryosectioning. Age was found to be a significant factor in prediction of TMJ arthrosis (p < 0.001) and of disk perforation (p < 0.05). No significant association was found between morphologic changes in the TMJ and the factor of sex for the whole group. Disk displacement and disk perforation were, however, more common in the joints of women than men in the group of persons 80 years of age or older (p < 0.05). There were significant associations (p < 0.001) between arthrosis, disk displacement, disk deformation, and disk perforation. There were no statistically significant differences in the prevalence of morphologic changes in the joints from persons with 10 or more natural teeth in each jaw compared with those from persons without natural teeth. The results of this study showed that TMJ arthrosis is more frequent in older than in younger persons. TMJ disk displacement generally appears necessary for the development of perforations. The findings of this study indicate that sex and dentition are not major factors for the development of TMJ pathosis in elderly individuals.
Age Factors↗
Temporomandibular joint sounds: correlation to joint structure in fresh autopsy specimens.
In an attempt to better understand the cause of different types of temporomandibular joint (TMJ) sounds, we recorded joint sounds from 27 fresh autopsy specimens, displayed the time frequency distribution of the sound as a three-dimensional graph, and correlated the sound character to morphologic observations at subsequent dissection. Eleven joints elicited sounds, and 16 joints were silent. All joints with sounds had different degrees of intraarticular changes. These ranged from disk displacement with reduction to displacement without reduction and arthrosis of the articular surfaces. Reciprocal clicking occurred both in joints with disk displacement with and without reduction, as well as in joints with arthrotic changes. Crepitation only occurred in joints with arthrosis and perforation. The sample was too small to demonstrate any statistically significant association between the joint sound classified as clicking or crepitation and joint structure types of joint pathosis in this small sample. A high frequency component to the sound appeared to be associated with arthrosis of the articular surfaces. It was concluded that joint sounds indicate joint abnormality but that the absence of joint sound does not exclude intraarticular pathosis.
Aged↗
Time frequency distributions of TMJ sounds.
For analysis of time-varying signals such as the TMJ sounds, it is often desirable to know how the frequency components change with time, using methods of time-frequency analysis. The aim of this study was to compare two of the most familiar methods for energy density representation with a newly developed technique. The sounds were recorded with a microphone fastened to the subject's forehead, transformed to the time-frequency domain and displayed as 3D- and contour plots using spectrogram, Wigner distribution (WD), and the reduced interference distribution (RID) to display their time-frequency energy distributions. The spectrogram resolved only the low-frequency components. The WD provided higher resolution but also exhibited strong interference between components. The RID gave a detailed representation of the TMJ signals' relative energy distribution in the time and frequency domains, with a great reduction in the interference or cross terms. The RID therefore appears to be most useful in the application of time-frequency distributions in classification of TMJ sounds.
Analog-Digital Conversion↗
Method for identification and classification of single motor unit potentials in diagnostic electromyography.
It is important to have an objective method for recording jaw muscle capacity such as EMG before, during and after treatment of muscle dysfunction and also for oral rehabilitation with dentures, implants or other types of restorations. Because measurements of motor unit potentials (MUPs) are needed in several areas of EMG analysis, algorithms have been developed in our laboratory for use in a small computer-aided system for semi-automatic detection and pattern recognition of MUPs. Based upon the test recordings it is suggested that a characteristic 'maximal voltage increase per microsecond during the spike-phase' can be used as a supplement to the more generally used parameter 'rise-time'. Examples are given of how the programs can be useful in the study of the functional anatomy of jaw muscles by recording normative values for MUPs and their recruitment patterns.
Algorithms↗
Anatomical and electromyographic studies of the digastric muscle.
The techniques and sites for EMG recordings from the digastric muscles are controversial. To re-evaluate old techniques for recording from the digastric muscles, especially the posterior bellies, the morphology of the muscles was studied by conventional dissections and by examination of specimens sectioned in the frontal and the horizontal planes. Based on these anatomical findings, recording sites and approaches to them were developed for the anterior and posterior bellies of the digastric muscles. EMG recordings from the two bellies of the muscle were obtained from five healthy subjects. The EMG recordings were ranked according to muscle activity level and the activity within single muscles and between muscles compared using the Wilcoxon signed rank test. The anterior and posterior bellies had synchronized activity in all mandibular movements but were silent or had negligible activity with the mandible in the rest position, when the head was rotated, and while clenching. Both bellies had marked to very marked activity during jaw opening, and moderate to marked activity during protrusion, retrusion and lateral movements. During swallowing the anterior and posterior bellies had patterns characterized by bursts of activity of high amplitude and short duration. The two bellies were not, however, always synchronously active.
Adult↗
Anatomical and electromyographic studies of the lateral pterygoid muscle.
The relationships of the lateral pterygoid muscle within the infratemporal fossa were observed by conventional dissections and by examination of specimens sectioned in the horizontal and frontal planes. The following less well-known features were noted. At the origins of the superior and inferior heads there are regions in which the fibres are interlaced or closely overlapped by fibres of either the temporalis muscle or the medial pterygoid muscle. Fibres of the superior head insert not only into the meniscus of the temporomandibular joint, but also into the pterygoid fovea at the neck of the mandibular condyle. Specimens sectioned through the origin of the inferior head of the muscle show internal tendon lamellae consistent with a pennate structure. Electromyographic (EMG) activity was recorded in five healthy subjects using concentric needle and fine-wire electrodes. Strong to very strong activity was consistently observed in the superior head during clenching and tooth gnashing. The inferior heads were silent or had negligible to slight activity most of the time during ipsilateral movements or clenching, but were co-activated bilaterally, with strong to very strong activity during jaw opening, protrusion, swallowing, tooth gnashing and during passive retrusion. They showed marked activity unilaterally during contralateral movements.
Adult↗
Clinical, radiographic, and electromyographic study of patients with internal derangement of the temporomandibular joint.
Fifteen patients with internal derangement of the temporomandibular joint (TMJ) were examined clinically, radiographically, and electromyographically. Electromyographic recordings were also obtained from 11 subjects without signs or symptoms associated with their TMJs or masticatory musculature. All the patients with internal derangement demonstrated interferences on the ipsilateral side. This was interpreted as the result of disc displacement producing a reduced joint space and, consequently, a decreased vertical dimension on the symptomatic side. Slow opening and closing mandibular movements without clenching could be performed by healthy persons without noticeable EMG activity in the temporalis and masseter muscles. In association with disc displacement, electromyographic activity of the temporalis and masseter muscles occurred when the condyle slid over the posterior band of the disc and could be interpreted as an arthrokinetic reflex caused by distraction. Continuous muscle activity could be provoked by TMJ disc displacement and ceased when the disc position was normalized on mouth opening, only to occur again every time the disc became displaced on mouth closure. Anterior disc displacement without reduction (closed lock) could cause spastic activity in the temporalis muscle on the affected side. Spastic activity of the masseter and temporalis muscles occurring on the same side as a joint with anterior disc displacement hinders or inhibits the condylar movement necessary to achieve reduction.
Action Potentials↗
The anatomy and electrical activity of the platysma muscle.
Dissection of seven cadavers showed that the platysma muscle may cover large parts of the masseter muscle. The platysma may thus be a significant source of artefact activity when recording the masseteric activity with surface electrodes. This is illustrated by a patient-case. The electrical activity of the platysma muscle was studied during jaw movements in normal, healthy subjects. Activity was regularly recorded during the latter half of large vertical jaw opening movements and, in five of the seven subjects, in the ipsilateral platysma muscle also during combined lateral-vertical jaw opening movements. The platysma may, therefore, in some individuals, have a functional role during the opening phase of chewing cycles when this has a marked lateral component.
Adolescent↗
The refractory period of the masseteric cutaneous silent period.
Silent periods were elicited in the electromyographic activity of the masseter and temporalis muscles from six normal subjects, by electrical stimulation of the skin over the contralateral masseter during clenching. Pairs of suprathreshold square pulses with varied time intervals were delivered using surface electrodes. It was found that the silent periods, which were mostly of the long latency (about 53 ms) type, had a refractory period, during which a new silent period could be evoked only by increasing the strength of the second stimulus. This refractory period could last for up to 1.5 s. During the first 200 ms after the first stimulus a second silent period was almost impossible to evoke with the moderately painful stimuli used in the present experiments. It is suggested that the refractory period should be considered as significant for the methodology when recording the silent period duration. It is also suggested that the long latency silent period should be recorded as a separate parameter and differentiated from the short latency (10-12 ms) silent period. This may be of special importance to recognize when a short latency silent period and a long latency silent period merge.
Adolescent↗
The influence of eye closure on muscle activity in the anterior temporal region.
In the experiments reported here the influence of eye closure upon the muscle tone in the region of the anterior temporal muscles was studied during mandibular rest in four patients with TMJ dysfunction and in four healthy subjects. The muscle activity as well as the cortical activity (EEG) of the patients was influenced by changes in visual stimulation. EMG (the anterior temporal region) and EEG (parieto-occipital region) were recorded with needle electrodes. Ongoing EMG activity was present in all patients when their eyes were open. Closure of both eyes reduced the muscle activity by 50-100%. Closure of one eye could also abolish all activity but the degree of this influence was variable. Opening of the eyes blocked the alpha rhythm in the EEG. Simultaneously, increased activity was observed in the region of the temporal muscle. The activity level in the temporal region of the healthy subjects was very low and could easily be reduced to noise level using ordinary relaxation manoeuvres without eye closure. The results reported here indicate that visual stimulation may increase muscle tone in the temporal region probably as part of an arousal reaction. It is, however, possible that the activity might stem not from the temporalis muscle but from the temporoparietalis.
Blinking↗
Maximal bite force with centric and eccentric load.
Premolar bite force was measured conventionally with a pressure transducer. During biting the tips of the buccal cusps made contact with the transducer. It was shown that the maximal bite force increased significantly if the eccentric load on the upper premolar was made centric and axial with respect to the transducer by covering the whole occlusal surface of the tooth with a plastic filling. Possible neurophysiological explanations of the difference in bite force are discussed. It is concluded that biting on a pressure transducer with an eccentric load cannot give a fair estimation of the true value of the maximal bite force during clenching in the position of intercuspidation.
Adult↗
Long latency components of the jaw jerk and blink reflex in man.
In the present study, the electromyographic (EMG) activity in the masseter and temporal muscles during about 200 ms after chin taps (jaw jerk response) was compared with the EMG activity in the orbicularis oculi after glabella tap (blink reflex). In two of ten subjects components with long latency and duration, analogous to blink reflex components BR2 and BR3, were found in the masseter and temporal muscles. They may represent the mechanical contraction which results in jaw closure. In two of the subjects chin taps were found to elicit late responses in the orbicularis oculi with the same latencies (25-30 and 80-100 ms) as BR2 and BR3 associated with glabella tap.
Adult↗
A new method for recording temporomandibular joint sounds and electrical jaw muscle activity in relation to jaw opening degree.
A system for continuously quantifying of jaw movements in terms of jaw angle was tested in combination with a previously tried method for simultaneous recording of temporomandibular joint (TMJ) sounds and electromyographic (EMG) activity. The system was used to measure the degree of rotation of the lower jaw in the sagittal plane in relation to the upper jaw. It was tested on a group of healthy subjects and patients with TMJ clicking and found useful to record EMG activity and TMJ clicking in relation to opening degree and velocity of jaw movement in open-close cycles.
Adult↗
Trend analysis of jaw jerk action potential-amplitude data.
The amplitude of the jaw jerk action potential (MSP) is a parameter with potential diagnostic value. It has apparently a large and irregular variation which has not yet been subjected to a thorough analysis. It is important to know if samples of MSP contain trends. The occurrence of trends indicates that the average value is influenced in a principally different way by changes in the number of observations per sample than if trends do not occur. If, for instance, there is a positive linear trend in the data, this means that the average value is larger if the number of observations is small. Samples of MSPs therefore were recorded, using surface EMG electrodes in the masseter and the anterior temporal muscles of young and elderly subjects, and subjected to trend analysis. Trends of the 1--4th grade occurred in 51% of the samples. Both positive and negative linear trends were found and had about the same frequency. The trend components were, however, randomly distributed. Comparisons between groups may therefore be made without the claim of trend-free samples. This significantly facilitates the use of the parameter MSP-amplitude, since it is difficult to obtain samples which have a normal and identical distribution.
Action Potentials↗
Standard values of the amplitude of jaw jerk action potential and differences due to age, sex and L-dopa treatment.
The amplitude of the jaw jerk action potential (MSP) is a parameter with possible diagnostic value. Standard values have, however, not yet been established. MSPs were recorded using surface EMG electrodes in the masseter and the anterior temporal muscles of young and elderly healthy males and females. The group means ranged from 0.26 to 2.11 mV in the masseter and from 0.17 to 0.81 mV in the anterior temporalis. The amplitude of MSP was higher in females than in males, decreased in elderly subjects and lower in the temporalis than in the masseter. The jaw jerk action potentials also were recorded in four subjects before and after L-Dopa administration. The amplitude increased by about 90%. It is concluded that the parameter MSP amplitude can be useful in the studies of muscle spindle sensitivity and the influence of various physiological, pathophysiological and pharmacological factors on the nervous regulation and muscle function in the masticatory system.
Action Potentials↗
Tooth tapping ability of young and elderly males and females.
The ability to perform high frequency tooth tapping movements was studied in young dentulous, elderly dentulous and elderly edentulous subjects of both sexes as a possible test of the overall efficiency of the masticatory motor apparatus and related structures. Tapping frequency was measured during a test period of 90s by counting the number of taps per 5 s intervals. It was found that observed values of tapping frequency could be fitted to an exponential equation with a high degree of fit for 90% of the young subjects and for 60% of the elderly subjects. The values of the remaining elderly subjects were best fitted to straight lines. The elderly subjects could thus be regarded as belonging to two different populations which were differently affected by advanced age and loss of teeth regarding their tooth tapping ability. Young dentulous subjects had the highest starting frequency (6-1 Hz) followed by elderly dentulous (5-5 Hz) and elderly edentulous subjects (4-9 Hz). The lower limits were 4-6 Hz for young dentulous subjects, 4-1 Hz for elderly dentulous and 3-7 Hz for elderly edentulous subjects. The average group means pointed all in the same direction that increased age and loss of teeth change the functional ability by deteriorating it.
Adult↗
Kinematics of the tooth tapping movement.
Electrical activity in the masseter muscles and tooth contact vibrations were recorded simultaneously from subjects tapping their teeth slowly into maximal intercuspidation and again with maximal frequency. High speed cinephotography was also used with four of the ten subjects. Three main parts could be distinguished on the obtained graphical representation of the tooth tapping movement: tooth contact phase (TCP), opening phase (OP) and closing phase (CP). Tapping frequency was increased by decreasing the jaw opening degree and the durations of TCP, OP and CP. The jaw velocity immediately before tooth contact, which may be of significance for the reflex response, was however not increased. The average jaw speed was nevertheless increased from 10 to 15 cm/s since the turning from OP to CP was more abrupt in high than in low frequency tapping. The duration of electrical activity after tooth contact was significantly shorter at tapping with high than with low frequency. The teeth maintained contact without detectable rebound between each open-close cycle. The OP started about 100 ms after the cessation of electrical activity both at low and high tapping frequency. The time between end of electrical activity and the start of a new OP was supposed to be dependent upon the relaxation time of the masseter muscles.
Adult↗