The effect of superficial anesthesia of lips on masticatory movements was examined from an electromyographic (EMG) viewpoint in eight adult male subjects. Surface EMG activity from the masseter and anterior digastric muscles was recorded simultaneous to tracking of jaw movement with the MKG (Model K-5) in a period of pre-anesthesia to 40- minute post-anesthesia divided in six different stages during which the subjects performed thirty masticatory strokes in their habitual side with chewing gum for each stage. The time duration and integral value of the EMG activity, and time-lag between the onset of of muscle activity and mandibular movement were analyzed. The mean values from each stage were calculated, the differences compared and then interpreted. The time duration and integral value of the masseter muscle in both pre and post-anesthesia stages did not change significantly in for most of the subjects; but the digastric muscle's decreased in the post-anesthesia stages. Concerning the time-lag between the onset of muscle activity and mandibular movement, we observed in six subjects that the time-lag between the start of the closing phase and the onset of masseter's activity was shorter in the post-anesthesia stages, whereas in seven subjects the time-lag between the start of the occlusal phase and the onset of digastric's activity was longer for the post-anesthesia stages too.
From these results we conclude that there is a strong possibility that the somato-sensory input studied - lips' sensibility to touch or pressure has more effect on jaw-opening movement than on jaw-closing movement during mastication in man.

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We have developed a new system that allows a simultaneous recording and analyzing of the function of stomatognathic components associated with the mandibular movement.
The system consists of two units that are capable of simultaneous processing 15 signals generated by the mandibular movement. One unit is for recording of three dimensional mandibular movements, and another unit is for recording of analog data such as EMG activities, TMJ sounds, occlusal contact sounds relate to the mandibular movement.
Mandibular movement analyzing unit can measure the movements of any selected point in the mandible in three dimensions as six degrees of freedom. This unit has two charge coupled device (CCD) cameras that detect the position of LEDs fixed to the head frame and mandibular face bow by using a stereo image processing method.
The operator can select the recognition points in the mandibule by employing a handy pointer equipped with two LEDs. The measurement error for the mandibular movement is less than±0.15 mm.
This multifunctional system can be of practical use for both synthetic and analytic evaluation of simultaneously recorded data on various functional components related to the mandibular movement. This new system of ours can supply us with multi-angled diagnostic information that will help us to make more efficient treatment plannings and decisions.

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The purpose of this study was to establish a simple clinical method for the diagnosis of stomatognathic dysfunction through analyzing the volume of the range of mandibular border movements at the incisal and kinematic condylar points.
Eleven normal subjects and three patients with restricted mandibular movement (two of them due to closed lock of the TMJ and one to coronoid hyperplasia) participated in this experiment. Twelve different mandibular border movements (MBM) were recorded using a six degree of freedom digital jaw movement tracking device (MM-JI-E, SHOFU Co.) : protrusive MBM, left and right lateral MBM, posterior MBM, and two intermediate movements between each consecutive pair of these four movements.
The volume surrounded by the MBM was calculated with a personal computer. The relationship between the vol-ume at the incisal point and the parameters of mandibular movements was also analyzed. The following results were obtained:
1. The volume could be calculated by a previously reported method of modeling of the range of mandibular border movements.
2. The normal range of the volume was considered to be large, because the mean volume at the incisal points was 3848.0±1543.2mm³, and the mean volume at the kinematic condylar point was 12.0±5.2mm³. Individual variations were thought to be due to anatomical differences and kinematical differences in normal subjects.
3. Analysis of the volume at the incisal point in the patients before and after treatment showed that as function improved, the volume increased. The degree of improvement could be predicted from the increase in volume.
4. The newly calculated volume data at the incisal point in this study was a useful parameter for the diagnosis of stomatognathic dysfunction. But the volume data at kinematic condylar points were considered to examine more detailed.
5. The back and forth width of the range in the parameters of mandibular movements was highly correlated with the volume at the incisal point. The product of the distance of maximal opening, distance of back and forth tooth sliding movement and distance of lateral tooth sliding movement showed the strongest correlation to the volume at the incisal point.

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The purpose of the this study was to observe through serial ultrasonic images the vertical motion of the tongue during mastication. Six male subjects with an average age of 28.7 and no evidence of neurological disorders volunteered for this experiment. The subjects were comfortably seated with the head straight and F-H plane parallel with a floor. A continuous, real-time image of the tongue was obtained using a 7MHz mechanical scanning transducer. The ultrasonic transducer was fixed below the chin to make gentle contact with the skin in relaxed position. Real-time B-mode ultrasonic observation of the tongue was made in the median sagittal plane of the mandible. Thereafter, karsol was established on the line that linked right and left first molars and the vertical motion of the tongue was recorded as M-mode. This transducer produced good quality images of the dorsal surface during mastication. Due to the small size and lightness of the transducer, image were continuously recorded without manipulation from the operator.
Results were as follows:
1. With visual inspection, it was confirmed that the vertical motion of the tongue has two stages; Which were interpreted as the sorting out phase (SO-phase), and the bolus formation phase (BF-phase) .
2. The most upper and lower points during mastication and the resting position were invariable within individuals.

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The purpose of this study was to examine functional muscular adaptation through analysis of the shortterm morphological and functional changes induced by the use of the Herbst appliance.
Four patients with Angle Class II Division 1 malocclusions, age range 9y6m-lly2m were chosen as subjects. Lateral cephalograms were taken to evaluate morphological changes. The electromyographic (EMG) activity of the inferior head of the lateral pterygoid (ILpt) muscle was recorded with an intraoral surface electrode.
A similar pattern of cephalometric changes was observed in all patients. Immediately after wearing the appliance, the condyles of all patients translated antero-inferiorly and the EMG activity of the ILpt muscle was significantly increased. After several months, the condyles of three patients were still positioned antero-inferiorly as compared to their original positions; however, the EMG activity of the ILpt muscle had decreased to the pre-treatment level in all patients. Just after removal of the appliance, the EMG activity of the ILpt muscle significantly increased in response to minor morphological changes. Two weeks after removal of the appliance, the EMG activity decreased again to the pre-treatment level.
These data indicate that the functional muscular adaptation is established within a short period, prior to compensatory morphological adaptation.

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Severe habitual snoring is thought to bea pre-stage of obstructive sleep apnea syndrome (OSAS) . Recently, dental treatment for OSAS and snoring has become common in Japan. The aim of this experiment was to study the efficacy of a linked analysis of apnea and snoring as a simple diagnostic method. A 49 year-old male diagnosed with OSAS volunteered to participate as study subject. A dental splint was used as therapy, the nights before and after wearing the splint, linked recordings of an Apnomonitor II (which includes pulsoximetry) and of snoring sounds were carried out. Wearing of splint the brought about decrease in both the apneaindex (from 22.8 to 9.7 times/h), and in the disaturation time of hypoxia (from 38.8% to 14.6%) . After therapy with the splint we confirmed that snoring had disappeared. The linked analysis made it possible to study the relationship between apnea and snoring sounds. These results suggest that linked analysis with an Apnomonitor II and snoring sounds is useful for simple diagnosis of OSAS and snoring noise level.

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Temporomandibular (TMJ) surgery is a common option in the treatment of chronic condylar dislocation, but some authors have reported disappearance of its symptomatology after occlusal therapy.
A case in which condylar dislocation (CD) disappeared by changing the location of anterior guidance is presented. The patient was an 18 year-old male with an Angle class III malocclusion who had been suffering-one year - from condylar dislocation of the right TMJ upon waking up. Initially, he did not seek medical assistance for he was able to reduce it by himself. Clinical inspection showed that the mandibular right second molar was guiding mandibular eccentric movements. A stabilization splint was successfully used as therapy; within 24 hours most of the symptomatology had disappeared. Thereafter, we made removable metal appliances which fixed anterior guidance either on the canine tooth of the afflicted side or on the healthy side, and requested the patient to wear them alternately in order to determine whether changing the location of anterior guidance would contribute to the cure of CD. Moreover, we recorded jaw and condyle movements with a 6-degree-of-freedom measuring device during lateral excursions with and without wearing of the splints. By shifting anteriorly the location of tooth guidance, the range of mandibular border movements increased; and the condylar range of motion decreased during parafunctional grinding tasks. The condyle's rotation and movement became smoother and smaller within the confines of the glenoid fossa. CD of the right TMJ disappeared by shifting anteriorly the tooth guidance. We conclude that correction of anterior guidance is a non-invasive alternative therapy in some cases of condylar dislocation.

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Involuntary clenching is common during physical exercise, therefore this study was aimed to elucidate the relationship between the stomatognathic system's neuromusculature and physical exercise with elbow flexion as model.
In twelve healthy, fully dentate males (mean age: 27.9±1.8), mandibular position, electromyographic (EMG) activity from jaw closing (JM), sternocleidomastoid (SCM) and biceps brachial (BB) muscles, and elbow flexion strength were simultaneously recorded during elbow flexion tasks. The factors subject to analysis were: 1) EMG activity and mandibular position during the exercise, 2) time coordination of the stomatognathic and biceps brachial muscles, 3) elbow flexion strength allowing or not, involuntary clenching. Following the criteria whether the subjects involuntary clenched or not during the task, they were divided into two group: the Clenching group (8 subjects) and the Non-clenching group (4 subjects) . Results:
1) Clenching group: Mandibular position was located in the intercuspal position (ICP) . Onset of EMG activity in the JM occurred prior to that of the BB in 5 subjects, but in the whole group the BB's EMG onset occurred prior to the SCM's. These data indicate that involuntary clenching during the task was not implemented by reflexive or feed-back mechanisms, but by the so called feedforward mechanism. When the subjects were instructed to avoid clench-ing during the task, elbow flexion strength significantly decreased (p<0.05) .
2) Non-clenching group: The mandible shifted horizontally without occlusal contacts. Elbow flexion strength was not significantly different (p>0.05) for either clenching or not during the task.
From these results, we conclude that the stomatognathic system's neuromusculature and physical exercise are closely related and that involuntary clenching may play an important role in the execution of physical exercise in some individuals.

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Measurement of mandibular movement and electromyographic activity of masticatory muscles have improved remarkably with computer technology. I have developed a new system to analyse stomatognathic function which can be used by dentists in private practice. To test it clinically, evaluation of function of old and new dentures in two patients and their ability to chew different foodstuffs were made using this system.
The results were as follows:
1) this new system proved to be effective for evaluation of function of old and new dentures
2) chewing ability and biting force improved with new dentures.

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The purpose of this study is to analyze biological signals associated with nocturnal bruxism during sleep. Polysomnographic recordings were obtained with the multi-telemeter system from 5 male subjects (mean age 33.8) . Bruxism events were detected when elevations of masseter EMG activity exceeded 5%MVC level.
A total of 660 bruxism events were recorded and divided into clenching (24.1%), grinding (58.9%) and combined (17.0%) types according to jaw movement patterns. Changes in sleep stage, heart rate, and FFT of EEG were analyzed for all the bruxism types. Results are as follows;
1) Mean masseter's EMG activity of all bruxism events was 9.3% MVC, with a mean duration time of 9.1 seconds. The mean EMG activity of the clenching type was significantly higher than that of the grinding type. However, there was no significant difference between mean durations of clenching and grinding type bruxism events.
2) Sleep stage generally became lighter after bruxism event occurred. This tendency was typical in the clenching type.
3) FFT analysis of EEG revealed an increase of mean power frequency after bruxism events. EEG mean power frequency of the grinding type was higher than that of the clenching type.
4) Heart rate increased gradually at least 8 seconds before the onset of bruxism events and its peak was observed right after the offset of bruxism events.

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