Exacerbating and lasting sleep bruxism should not be considered solely as a problem of the oral cavity or the related area, but it should be thought of as a major problem of a living body relating to sleep and autonomous function. Also it is indispensable that the dental approach towards sleep apnea syndrome should be in cooperation with medical specialists and that the problem be dealt with much care and caution. All the researches and the clinical knowledge presented here suggested strongly the possibility that oral sensation was playing a major role in various parts of sleep bruxism and sleep apnea. And if these clinical knowledge and researches were to be investigated thoroughly in connection with the mechanism of brain, sleep and pain, and the analysis kept on going, then the results should give us valuable materials in elucidating sleep bruxism and sleep apnea.

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Purpose: To establish a simple and reliable method for assessment of sleep bruxism (SB) in clinical dentistry, we have developed an ultraminiature cordless electromyogram system, BMS. We have examined the validity of the BMS in an awake state in the daytime and the influence of motion of simulated sleep-turning and scratching motion on the device. In the present study, as a preliminary step to practical application of the device to SB assessment, we examined whether EMG activities could be properly recorded without significant trouble by using the BMS in an actual home sleep environment.
Methods: The subjects were nine bruxers and nine non-bruxers. EMG activities of the masseter muscle during sleep were measured by using the BMS for two days in the subjects' homes. The data obtained during the second night were analyzed and compared between the two groups. EMG bursts with amplitude of 20% of maximum voluntary contraction (MVC) or more and with duration of 0.25s or more were selected. Start and end of the sleep period were detected by using an actigraph. (AMI Ltd.)
Results: All subjects could set up and operate the BMS by themselves. The EMG bursts obtained by using the BMS during sleep could be properly recognized and analyzed. Artifact signals with a linear-spike shape, which were thought to be radio wave communication errors, were occasionally observed, but the signals could be distinguished from actual muscle activities and were eliminated. The number of bursts, burst time and integration of bursts per hour of sleep period of bruxers were significantly larger than those of non-bruxers, and the mean values in bruxers were 6.3-times, 3.2-times and 2.5-times larger, respectively, than those in non-bruxers. The duration per burst of bruxers was significantly smaller than that of non-bruxers. There was no significant difference between the two groups in the average of RMS values of burst and sleep time.
Conclusion: It was confirmed that masseteric EMG burst during sleep in the home environment could be properly recognized and analyzed both in bruxers and non-bruxers in BMS measurement. The BMS is thought to have capacity for practical use as a monitoring device of masseteric activity during sleep.

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In orthodontics and pedodontics, parafunction including oral breathing and tongue thrusting are considered to be factors that lead to malocclusion including maxillary protrusion and open bite. In order to correct these parafunction, oral myofunctional therapy (MFT) is commonly used.
There are several MFT training regimens for lips, which include button pull exercises (pulling a button with the lips closed tight) and the use of the Patakara, a mouth rehabilitation instrument. However, there has been limited research to objectively evaluate training methods to improve the strength and endurance of the orbicularis oris muscle.
Our previous studies measuring oxygenation dynamics in the orbicularis oris muscle by using near-infrared spectrometry indicated that performing 5 or 10 sets of 5 seconds load at 80% 1-RM (1 repetition maximum) and 5 seconds rest was effective for the orbicularis oris muscle to enhance muscle strength as a result of the hypoxic conditions in the muscle. These studies also indicated that repetition of 15 sets of 5 seconds load at 50% 1-RM and 5 seconds rest was effective as the endurance of the orbicularis oris muscle as a result of the aerobic conditions in the muscle. The aim of this study was to validate the effectiveness of hypoxic and aerobic conditions for improving the strength and endurance of the orbicularis oris muscle, respectively.
Subjects consisted of 15 adults from both sexes with normal stomatognathic function and no interference with lip closure. Traction plates were inserted in the upper and lower oral vestibules, and 1-RM was measured by pulling against the plates using a universal testing machine. Subjects were assigned to three groups: Group A subjects completed 20 sets comprised of load of 50% 1-RM for 5 seconds and rest for 5 seconds; Group B subjects completed 5 sets comprised of load of 80% 1-RM for 5 seconds and rest for 5 seconds; and Group C subjects completed 5 sets comprised of load of 50% 1-RM for 5 seconds and rest for 5 seconds. Maximum tension and duration of contraction of the orbicularis oris muscle were measured 14 and 28 days after the loading. The results revealed that for orbicularis oris muscle training, 5 sets with load of 80% 1-RM was more effective for improving muscle strength, whereas 20 sets with load of 50% 1-RM was more effective for improving endurance.

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