Background: The purpose of this study was to investigate whether the function of stroke patients could be improved by simultaneously performing bridging and masticating exercises. And, this was tested by examining whether the effects of arousal and cognitive improvement due to mastication muscle activity could affect exercise ability. Objectives: To compare the effects, the movement of the center of pressure and the stability limit change were measured using a balance analysis platform (BT4). Design: Randomized controlled trial. Methods: In this study, 36 chronic stroke patients were randomly assigned to either single training group of the bridging exercise or combined training group that performed both the bridging exercise and the mastication exercise. The exercise was performed for thirty minutes a day, three times a week, for eight weeks. Results: In both groups, the static balance ability improved after exercise, but the dual-task training group had a better improving effect on the distance and area of the center of pressure while the eyes was open. The dynamic balance ability also improved after exercise, and the dual-task training was more effective in reducing forward, left, and right movements, but not in backward movement. Conclusion: The importance of mastication was recognized in the rehabilitation of chronic stroke patients, and it can be expected to use mastication to improve balance in stroke patients in the future.

This study were to perform for verifying the activation areas in the human's brain during mastication by using functional-MRI (f-MRI) device on the basis of hypothesis regarding anatomical-physiological parts of brain processing the information of motor and sensory function, and to perform further more for a providing basic provisional foundation about diagnosis, treatment and prognosis of abnormal occlusion as applying functional MRI. Generally healthy 10 volunteers who have a normal occlusion were selected. The half of members of volunteers was female. Age distributions were approximately alike. Before taking a f-MRI, sufficient practice was carried out as strict standards and made volunteers be not sensible to sweet taste of gum through chewing gum for 30 minutes before taking a f-MRI. Functional images for all volunteers were firstly obtained, and then anatomical images were next. The functional images consisted of echo-planar image volumes which were sensitive to BOLD (blood oxygenation level-dependent) contrast in axial orientation. The volume covered the whole brain with a 64×64 matrix and 42 slices. Images with 64 volumes were acquired under periodic mastication. The orofacial sensorimotor cortex was primary responsible cerebral part during mastication and insula. And also supplementary motor area and cerebellum in brain were intimately connected with mastication. Other numerous anatomical parts of brain were activated in each volunteer during mastication, but there was no statistical significance in this experiment. Differences according to gender and age were no significance in this study. The f-MRI device showed the accurate and detailed image in activation area of brain through valuable device. It suggested that f-MRI might be helpful to establish the basis of funtional standard occlusion depend on activation area of brain.

The aim of this study is to find out histomorphologic change and cellular activity of condyle resulted from unilateral mastication by comparison of cell proliferation and apoptosis activity. 30 adult rats were dived to 15 experimental group and 15 control group randomly. Right upper and l ower molars were gently extracted in experimental group, to make unilateral mastication environment. All subjects were sacrificed at 1 week, 2 weeks and 4 weeks by chloroform, and their tissues were prepare to observation. Streptovidin-biotin system for BrdU stanning, was used to determine cellular proliferative activity. TUNEL method was used to determine apoptotic activity. The result for cellular activity was recorded at both of anterior portion and posterior portion of condyle. Hematoxylin and Eosin stanning was used for histiomorphological change. The results were as follows. There were more change in superficial layer than deep layer of condyle in cellular activity. In anterior portion of condyle cartilage, cellular proliferative activity of experimental group was lower than control group and apoptotic activity of experimental group was higher than control group. And apoptotic activity of extracted side in experimental group is the most. In posterior portion of condyle cartilage, cellular proliferative activity of extracted side in experimental group was higher than non-extracted side and control group, And apoptotic activity of extracted side in experimental group was the low. As a result of histomorphological change, there was hyperplasia in posterior region o f extracted side c ondyle i n experimental g roup, but t here was n o change i n unextracted side i n experimental group. There was histomorphological hyperplasia in posterior condyle of experimental group as results of high cellular proliferative activity. There was mainly apoptotic change of anterior portion condyle in experimental group. But there was no histomorphologic change. In other words, there was hyperplasia by increasing of cellular proliferative activity in posterior portion of nonfunctional side condyle. In functional side condyle, there was no histomorphological change in functional condyle, but there was change in cellular activity.

The purposes of this study were to estimate Brdu positive and apoptotic cells dis tribution in co ndyl ar art icular and proliferative layer. and hi stopathological evaluat ion during one sided mas t icatory condition. 15 of 30 adults Sprague Dawley male rats were experimental group, and 15 rats were control group. Experime nta l group were gen t ly extracted on all lower and upper molar teeth to make unilateral mastication. Experimental gl'Oup were divided into two group as extracted side and nonextracted side condyle. Diluted bromodeoxyuridi ne(Brdu) solution(5mg/Kg) was injected in peri toneum before sacrifice at inte rval 1 week, 2 week, 4 week Streptoavidi n-Biotin method for Brdu was used to evaluate cellular proliferat ive activity, and fluorescent TUNEL method was used to estimate the a poptotic activity. The resul ts of this experiment were recorded about anterior and posteri or condyle sepa rately On anterior condyle, contl'Ol group was sustained increased proliferative activity th roughout experiment. whi le cel lu lar proliferative activity of extracted and nonextracted s ide condyle showed more decreased than control grou p ‘ On posteri or portion of condyle‘ control group and nonextracted group showed dramatically decreased cellular pr。 liferat ive activity during all expel‘ imental period. On anterior portion of condyle, control grollp s howed decreased a poptotic activity with time passed. bllt expel'imental gl'oup(both ext l'acted and nonextracted) exhibi ted incrcased a poptotic activity. Es pecia lly extracted grollp showed prominent increased apoptotic activity. On posteri or portion of condyle. extracted group showed dec reased apoptotic activity wi th time progress. but co ntrol and nonextracted group exhibi ted increased apoptotic activity with time progress. Conclllsively. antel'ior portion of condyle on ex t racted s ide expressed hypoplasia by low cellllJar prol iferative activity and increased apoptotic activity. and poste ri or portion on extracted side showed condylar surface hyperplasia by continious proliferative cell ular activity and low a poptotic activity. a nd t hllS unmasticatol'y condyle had anLeroposLel'iorly shorter mo rph이 ogy and verti ca11y longer morphology than masticatory and nOl'mal functioning condyle

In the primary sensory neuron of the mesencephalic trigeminal nucleus (MTN), the peripheral axon supplies a large number of annulospiral endings surrounding intrafusal fibers encapsulated in single muscle spindles while the central axon sends only a few number of synapses onto single α-motoneuron₃.(α-MN₃)Therefore, the α-y linkage is thought to be very crucial in the jaw-closing movement. Spike activity in a y-motoneuron (y-MN) would induce a large number of impulses in single peripheral axons by activating many intrafusal fibers simultaneously, subsequently causing an activation of α-MN₃ in spite of the small number of synapses. Thus, the activity of y-MN₃ may be vital for modulation of jaw-closing movements. Independently of such a spindle activity modulated by y-MN₃, somatic depolarization in MTN neurons is known to trigger the oscillatory spike activity. Nevertheless, the trafficking of these spikes arising from the two distinct sources of MTN neurons is not well understood. In this short review, switching among multiple functional modes of MTN neurons is discussed. Subsequently, it will be discussed which mode can support the α-y linkage. In our most recent study, simultaneous patch-clamp recordings from the soma and axon hillock revealed a spike-back-propagation from the spike-initiation site in the stem axon to the soma in response to a somatic current pulse. The persistent Nα+ current was found to be responsible for the spike-initiation in the stem axon, the activation threshold of which was lower than those of soma spikes. Somatic inputs or impulses arising from the sensory ending, whichever trigger spikes in the stem axon first, would be forwarded through the central axon to the target synapse. We also demonstrated that at hyperpolarized membrane potentials, 4-AP-sensitive K+ current (IK₄_AP) exerts two opposing effects on spikes depending on their origins; the suppression of spike initiation by increasing the apparent electrotonic distance between the soma and the spike-initiation site, and the facilitation of axonal spike invasion at higher frequencies by decreasing the spike duration and the refractory period. Through this mechanism, the spindle activity caused by y-MN₃would be safely forwarded to α-MN. Thus, soma spikes shaped differentially by this IK₄_AP depending on their origins would reflect which one of the two inputs was forwarded to the target synapses.