Experimental Occlusal Interference Research Articles

Descending serotonergic modulation from rostral ventromedial medulla to spinal trigeminal nucleus is involved in experimental occlusal interference-induced chronic orofacial hyperalgesia

BackgroundDental treatment associated with unadaptable occlusal alteration can cause chronic primary myofascial orofacial pain. The serotonin (5-HT) pathway from the rostral ventromedial medulla (RVM) exerts descending modulation on nociceptive transmission in the spinal trigeminal nucleus (Sp5) and facilitates chronic pain. The aim of this study was to investigate whether descending 5-HT modulation from the RVM to the Sp5 is involved in the maintenance of primary myofascial orofacial hyperalgesia after persistent experimental occlusal interference (PEOI) or after delayed removal of experimental occlusal interference (REOI).MethodsExpressions of 5-HT3A and 5-HT3B receptor subtypes in the Sp5 were assessed by immunofluorescence staining and Western blotting. The release and metabolism of 5-HT in the Sp5 were measured by high-performance liquid chromatography. Changes in the pain behavior of these rats were examined after specific pharmacologic antagonism of the 5-HT3 receptor, chemogenetic manipulation of the RVM 5-HT neurons, or selective down-regulation of 5-HT synthesis in the RVM.ResultsUpregulation of the 5-HT3B receptor subtype in the Sp5 was found in REOI and PEOI rats. The concentration of 5-HT in Sp5 increased significantly only in REOI rats. Intrathecal administration of Y-25130 (a selective 5-HT3 receptor antagonist) dose-dependently reversed the hyperalgesia in REOI rats but only transiently reversed the hyperalgesia in PEOI rats. Chemogenetic inhibition of the RVM 5-HT neurons reversed the hyperalgesia in REOI rats; selective down-regulation of 5-HT in advance also prevented the development of hyperalgesia in REOI rats; the above two manipulations did not affect the hyperalgesia in PEOI rats. However, chemogenetic activation of the RVM 5-HT neurons exacerbated the hyperalgesia both in REOI and PEOI rats.ConclusionsThese results provide several lines of evidence that the descending pathway from 5-HT neurons in the RVM to 5-HT3 receptors in the Sp5, plays an important role in facilitating the maintained orofacial hyperalgesia after delayed EOI removal, but has a limited role in that after persistent EOI.Graphical

Neuronal Activities in the Rostral Ventromedial Medulla Associated with Experimental Occlusal Interference-Induced Orofacial Hyperalgesia.

The imbalanced conditions of pronociceptive ON-cells and antinociceptive OFF-cells in the rostral ventromedial medulla (RVM) alter nociceptive transmission and play an important role in the development of chronic pain. This study aimed to explore the neuroplastic mechanisms of the RVM ON-cells and OFF-cells in a male rat model of experimental occlusal interference (EOI)-induced nociceptive behavior reflecting orofacial hyperalgesia and in modified models involving EOI removal at early and later stages. We recorded the mechanical head withdrawal thresholds, orofacial operant behaviors, and the activity of identified RVM ON-cells and OFF-cells in these rats. EOI-induced orofacial hyperalgesia could be relieved by EOI removal around postoperative day 3; this effect could be inhibited by intra-RVM microinjection of the κ-opioid receptor agonist U-69593. EOI removal around postoperative day 8 did not relieve the orofacial hyperalgesia, which could, however, be reversed by intra-RVM microinjection of the NK-1 (neurokinin-1) receptor antagonist L-733060. The activity of ON-cells and OFF-cells did not change during both the initial 3 and 6 d of EOI. When EOI was removed on postoperative day 3, OFF-cell responses decreased, contributing to the reversal of hyperalgesia. When EOI lasted for 8 d or was removed on postoperative day 8, spontaneous activity and stimulus-evoked responses of ON-cell increased, contributing to the maintained hyperalgesia. In contrast, when the EOI lasted for 14 d, OFF-cell responses decreased, possibly participating in the maintenance of hyperalgesia with persistent EOI. Our results reveal that adaptive changes in the RVM were associated with orofacial pain following EOI placement and removal.SIGNIFICANCE STATEMENT A considerable proportion of patients experience chronic orofacial pain throughout life despite the therapies given or removal of potential etiologic factors. However, current therapies lack effectiveness because of limited knowledge of the chronicity mechanisms. Using electrophysiological recording, combined with a behavioral test, we found that the prevailing descending facilitation in the rostral ventromedial medulla (RVM) participates in the maintenance of orofacial hyperalgesia following late removal of nociceptive stimuli, while the prevailing descending inhibition from the RVM may contribute to the reversal of orofacial hyperalgesia following early removal of nociceptive stimuli. Thus, variable clinical outcomes of orofacial pain may be associated with descending modulation, and an optimal window of time may exist in the management of chronic orofacial pain.

17β-Estradiol Exacerbated Experimental Occlusal Interference-Induced Chronic Masseter Hyperalgesia by Increasing the Neuronal Excitability and TRPV1 Function of Trigeminal Ganglion in Ovariectomized Rats.

Pain symptoms in temporomandibular disorders (TMD) predominantly affect reproductive women, suggesting that estrogen regulates pain perception. However, how estrogen contributes to chronic TMD pain remains largely unclear. In the present study, we performed behavioral tests, electrophysiology, Western blot and immunofluorescence to investigate the role and underlying mechanisms of estrogen in dental experimental occlusal interference (EOI)-induced chronic masseter mechanical hyperalgesia in rats. We found that long-term 17β-estradiol (E2) replacement exacerbated EOI-induced masseter hyperalgesia in a dose-dependent manner in ovariectomized (OVX) rats. Whole-cell patch-clamp recordings demonstrated that E2 (100 nM) treatment enhanced the excitability of isolated trigeminal ganglion (TG) neurons in OVX and OVX EOI rats, and EOI increased the functional expression of transient receptor potential vanilloid-1 (TRPV1). In addition, E2 replacement upregulated the protein expression of TRPV1 in EOI-treated OVX rats. Importantly, intraganglionic administration of the TRPV1 antagonist AMG-9810 strongly attenuated the facilitatory effect of E2 on EOI-induced masseter mechanical sensitivity. These results demonstrate that E2 exacerbated EOI-induced chronic masseter mechanical hyperalgesia by increasing TG neuronal excitability and TRPV1 function. Our study helps to elucidate the E2 actions in chronic myogenic TMD pain and may provide new therapeutic targets for relieving estrogen-sensitive pain.

Genistein reverses the effect of 17β-estradiol on exacerbating experimental occlusal interference-induced chronic masseter hyperalgesia in ovariectomised rats.

Oro-facial pain is more prevalent in women than in men, and oestrogen may underlie this sex difference. Genistein reversed the potentiation of 17β-estradiol (E2) on glutamate-induced acute masseter nociceptive behaviour, but its role in dental experimental occlusal interference (EOI)-induced chronic masseter hyperalgesia remains unclear. This study aimed to investigate sex differences, and to explore the role and underlying mechanisms of genistein in E2-potentiated EOI-induced chronic masseter hyperalgesia in rats. Female and male rats were prepared to compare the sex differences of masseter hyperalgesia induced by EOI using a 0.4-mm-thick metal crown. Female rats were ovariectomised (OVX) and treated with E2 and genistein, followed by EOI. The head withdrawal threshold (HWT) was examined to assess masseter sensitivity. The protein expression of transient receptor potential vanilloid-1 (TRPV1) in the trigeminal ganglion (TG) was detected using western blotting. Immunofluorescence staining was used to reveal the colocalisation of oestrogen receptors (ERs) with TRPV1 and the percentage of TRPV1-positive neurons in the TG. To some extent, female rats displayed enhanced sensitivity to EOI-induced chronic masseter hyperalgesia compared with males. Female rats showed the lowest HWT in the pro-oestrus phase. Pre-treatment with genistein antagonised E2 potentiation in EOI-induced masseter hyperalgesia and blocked the effect of E2 by downregulating TRPV1 protein expression and the percentage of TRPV1-positive neurons in the TG. Female rats showed greater masseter hyperalgesia than males under EOI. Genistein antagonised the facilitation of EOI-induced chronic masseter hyperalgesia by E2 probably through inhibiting TRPV1 in the TG.

Characteristics of orofacial operant test for orofacial pain sensitivity caused by occlusal interference in rats

To compare the orofacial pain sensitivity with operant test and mechanical hyperalgesia with von Frey filaments of two orofacial pain models (EOI: experimental occlusal interference; pIONX: partial infraorbital nerve transection). To investigate the operant and evoked characteristics of EOI-rats. The orofacial operant behaviors were tested by Ugo Basile Orofacial Stimulation Test System. The mechanical thresholds of vibrissal pads were tested by von Frey filaments. Male Sprague-Dawley rats were randomly divided into eight groups: von Frey group: sham-EOI, EOI, sham-pIONX, pIONX (sham: sham-operated group); operant test group: sham-EOI, EOI, sham-pIONX, pIONX (sham: sham-operated group). The mechanical thresholds and orofacial operant behaviors were tested on pre-operation and post-operation days l, 3, 7, 10, 14 and 21. In pIONX of von Frey group, the mechanical withdrawal threshold decreased from days 1 to 21 (P<0.05), peaking from days 7 to 10, and lasted until the end of the experiment. There was no significant difference between the bilateral sides. In pIONX of operant test group, the total contact time decreased from days 10 to 21 (P<0.05), peaking from days 10 to 14, and lasted until the end of the experiment. In EOI of von Frey group, the mechanical withdrawal threshold decreased from days 3 to 21 (P<0.05), peaking on day 7, and lasted until the end of the experiment. There was no significant difference between the bilateral sides. In EOI of operant test group, the total contact time decreased from days 1 to 21 (P<0.05), peaking from days 7 to 10, and lasting until the end of experiment. Orofacial operant test is a stable method to evaluate orofacial pain behaviors, which could discriminate the feature of neuropathic and EOI orofacial pain. In these two animal models, both of the operant behaviors and the mechanical hyperalgesia exhibited different time courses. Orofacial operant test provides a novel method for evaluating the orofacial pain sensitivity and studying the orofacial pain mechanism thoroughly.

Metallic crown-induced occlusal trauma as a protocol to evaluate inflammatory response in temporomandibular joint and periodontal tissues of rats.

The goal of this study is to propose a standard protocol of experimental occlusal trauma to evaluate the inflammatory hyperalgesia induced by metallic crowns on orofacial tissues of rats. Thirty animals were randomly divided into six groups (n = 5 per group). Detailed methodology on the manufacturing of metallic crowns is described. The inflammatory hyperalgesia induced by occlusal interference was evaluated by intra-articular injection of a low dose of 0.5% formalin (30μl) or vehicle (saline) into temporomandibular joint, 21 or 28days after metallic crown cementation. Posteriorly, pro-inflammatory cytokines were evaluated by enzyme-linked immunosorbent assay to assess the effect of occlusal interference on periodontium. The cementation of metallic crowns with dental anatomy on the lower molar of rats does not show signs of stress and lack of feeding. Metallic crown-induced occlusal trauma results in a temporomandibular joint inflammatory hyperalgesia (P < 0.05: ANOVA, Tukey's test). Otherwise, it was observed that occlusal trauma results in the increase of protein level of pro-inflammatory cytokines TNF-alpha and IL-1beta in the gingival tissues (P < 0.05). This study demonstrates in detail a methodology of occlusal trauma resulting from the cementation of metallic crowns in the lower molars of rats, mimicking occlusal interferences commonly evaluated in the dental clinic. This methodology makes new studies to better understand the mechanisms involved in the occlusal trauma of orofacial tissues possible. The standardization of an experimental occlusal interference model will allow us to understand the deleterious effect and mechanisms that affect the orofacial tissues.

Association of occlusal interference-induced masseter muscle hyperalgesia and P2X3 receptors in the trigeminal subnucleus caudalis and midbrain periaqueductal gray.

P2X3 receptor plays a role in nociception transmission of orofacial pain in temporomandibular disorder patients. A previous study found that P2X3 receptors in masseter muscle afferent neurons and the trigeminal ganglia were involved in masseter muscle pain induced by inflammation caused by chemical agents or eccentric muscle contraction. In this study, we attempted to investigate changes in P2X3 receptors in the trigeminal subnucleus caudalis (Vc) and midbrain periaqueductal gray (PAG) in relation to the hyperalgesia of masseter muscles induced by occlusal interference. Experimental occlusal interference by crown application was established in 30 rats and another 30 rats were treated as sham controls. On days 1, 3, 7, 14, and 28 after crown application, the mechanical pain threshold was examined by von-Frey filaments. The expression of the P2X3 receptor in Vc and PAG was investigated by immunohistochemistry and quantitative PCR. We found that mechanical pain threshold of bilateral masseter muscles decreased significantly after occlusal interference, which remained for the entire experimental period. The mRNA expression of the P2X3 receptor increased significantly and the number of P2X3R-positive neurons increased markedly in Vc and PAG accordingly. These results indicate that the upregulated expression of P2X3 receptors in Vc and PAG may contribute toward the development of orofacial pain induced by occlusal interference and P2X3 receptors in the PAG may play a key role in the supraspinal antiociception effect.

Role of TRPV1 and ASIC3 channels in experimental occlusal interference-induced hyperalgesia in rat masseter muscle.

Masticatory muscle pain may occur following immediate occlusal alteration by dental treatment. The underlying mechanisms are poorly understood. Transient receptor potential vanilloid-1 (TRPV1) and acid-sensing ion channel-3 (ASIC3) mediate muscle hyperalgesia under various pathologic conditions. We have developed a rat model of experimental occlusal interference (EOI) that consistently induces mechanical hyperalgesia in jaw muscles. Whether TRPV1 and ASIC3 mediate this EOI-induced hyperalgesia is unknown. Rat model of EOI-induced masseter hyperalgesia was established. Real-time polymerase chain reaction, Western blot and retrograde labelling combined with immunofluorescence were performed to evaluate the modulation of TRPV1 and ASIC3 expression in trigeminal ganglia (TGs) and masseter afferents of rats after EOI. The effects of intramuscular administration of TRPV1 and ASIC3 antagonists on the EOI-induced hyperalgesia in masseter muscle were examined. After EOI, gene expressions and protein levels of TRPV1 and ASIC3 in bilateral TGs were up-regulated. The percentage of ASIC3- (but not TRPV1-) positive neurons in masseter afferents increased after EOI. More small-sized and small to medium-sized masseter afferents expressed TRPV1 and ASIC3 separately following EOI. These changes peaked at day 7 and then returned to original status within 10days after EOI. Intramuscular administration of the TRPV1 antagonist AMG-9810 partially reversed this mechanical hyperalgesia in masseter muscle. No improvement was exhibited after administration of the ASIC3 antagonist APETx2. Co-injection of AMG-9810 and APETx2 enhanced the effect of AMG-9810 administration alone. Peripheral TRPV1 and ASIC3 contribute to the development of the EOI-induced mechanical hyperalgesia in masseter muscle.

Effects of experimental occlusal interference on body posture: an optoelectronic stereophotogrammetric analysis

In recent years, there has been increasing interest in the relationship between dental occlusion and body posture both among people and in scientific literature. The aim of the present longitudinal study is to investigate the effects of an experimental occlusal interference on body posture by means of a force platform and an optoelectronic stereophotogrammetric analysis. An occlusal interference of a 0- to 2-mm-thick glass composite was prepared to disturb the intercuspal position while not creating interference during lateral or protrusive mandibular excursions. Frontal and sagittal kinematic parameters, dynamic gait measurements and superficial electromyographic (SEMG) activity of head and neck muscles were performed on 12 healthy subjects. Measurements were taken 10 days before the application of the occlusal interference, and then immediately before the application, the day after it, and at a distance of 7 and 14 days under four different exteroceptive conditions. The outcomes of this study show that an occlusal interference does not modify significantly over time static and dynamic parameters of body posture under different exteroceptive conditions. It has a minimal influence only on the frontal kinematic parameters related to mandibular position, and it induces a transient increase of the activity of masticatory muscles. In this study, the experimental occlusal interference did not significantly influence the body posture during a 14-day follow-up period.

Evaluation of psychological effect of prosthetic treatment using Emotion Spectrum Analysis Method (ESAM)

An experimental occlusal interference tended to increase mental stress and decrease relaxation.

Experimental occlusal interference induces long-term masticatory muscle hyperalgesia in rats

Temporomandibular joint or related masticatory muscle pain represents the most common chronic orofacial pain condition. Patients frequently report this kind of pain after dental alterations in occlusion. However, lack of understanding of the mechanisms of occlusion-related temporomandibular joint and muscle pain prevents treating this problem successfully. To explore the relationship between improper occlusion (occlusal interference) and masticatory muscle pain, we created an occlusal interference animal model by directly bonding a crown to a maxillary molar to raise the masticating surface of the tooth in rats. We raised the occlusal surface to three different heights (0.2, 0.4, and 0.6 mm), and for one month we quantitatively measured mechanical nociceptive thresholds of the temporal and masseter muscles on both sides. Results showed a stimulus–response relationship between the height of occlusal interference and muscle hyperalgesia. Removal of the crown 6 days after occlusal interference showed that the removal at this time could not terminate the 1 month duration of mechanical hyperalgesia in the masticatory muscles. Lastly, we systemically administered NMDA antagonist MK801 (0.2, 0.1, and 0.05 mg/kg) to the treated rats and found that MK801 dose dependently attenuated the occlusal interference-induced hyperalgesia. These findings suggest that occlusal interference is directly related to masticatory muscle pain, and that central sensitization mechanisms are involved in the maintenance of the occlusal interference-induced mechanical hyperalgesia.

The effect of change of oral sensory input accordance with the experimental occlusal interference on electroencephalogram

The aim of this study is to clarify the effect of the change of oral sensory input on brain function and to confirm whether it can be detected electroencephalographically.Eight healthy dentate dental students were selected as subjects, and asked to wear the experimental occlusal interference on the right second molar for 1 week. Simultaneous recordings were made with electromyograms (EMG) and electroencephalogram (EEG) before and after maximum clenching. Evaluation by visual analogue scale (VAS) questionnaires was also done. Twelve‐session experiments were carried out over a period of 12 days. Daily changes of EMG activity of masticatory muscle, six comfort parameters (VAS), and EEG caused by premature contact were analysed statistically applying repeated measured anova and Tukey–Kramer analysis.The discomfort which was described by VAS did not disappear during the interference period. Just after applying the interference, EMG activity during clenching was decreased significantly (P &lt; 0·01) compared with control. Significant change in EEGs between before and after clenching were observed, that is, the percentage power fraction of β wave (%β) tends to increase. On the contrary, %α in EEGs after clenching decreased significantly (P &lt; 0·01) compared with before clenching during the interference period, as verified by VAS evaluation.In conclusion, it is suggested that the decrease of %α in EEGs after clenching may be caused by premature contact influence on the masticatory system, reflected in the presence of discomfort during occlusion, and somatosensor information from the occlusal sensation might be recognized in the higher centre of the brain, and the possibility of detecting change might be indicated electroencephalographically.

Influence of mastication on the amount of hemoglobin in human brain tissue

The purpose of this study was to investigate the influence of mastication on the amount of hemoglobin in human brain tissue. Nine healthy volunteers (6 males and 3 females) participated in this study. They underwent two tasks: 1) at rest, 2) gum-chewing. In seven of the nine (4 males and 3 females), experimental occlusal interference was applied to the first molar of the mandibule on the habitual masticatory side. They underwent the gum-chewing task. To evaluate the amount of hemoglobin, both the hemoglobin oxygenation state and blood volume during gum-chewing were measured in the frontal region, using near-infrared spectroscopy. The amount of total-hemoglobin (blood volume) and oxyhemoglobin of subjects significantly increased during gum-chewing (p < 0.01). When the subjects finished gum-chewing, both levels returned to the original levels. When experimental occlusal interference was imposed on the subject, the amount of them significantly decreased compared with subjects without experimental occlusal interference (p < 0.05). The results suggested that increases of cerebral blood flow in the frontal region were not due to the mandibular movement, and that human brain activity caused by mastication was not only in the cortical masticatory area but also in the frontal region.

実験的早期接触によるそしゃく系ならびに精神生理学的応答とその脳波学的検討

目的: 実験的咬合干渉を1週間付与し, Visual Analogue Scale (VAS) による感覚的評価, 咀嚼筋筋電図から末梢フィードバックへの影響を評価し, あわせて咀嚼前後の脳波を経日的に解析した.方法: 正常有歯顎者8名に実験的に早期接触型咬合干渉装置を1週間にわたって付与し, VASによる感覚的評価, 咀嚼筋筋電図による末梢フィードバックへの影響, 咀嚼前後の脳波を同時記録した. 観察期日は干渉装置装着前をコントロールとし, 装着直後, 同1～7日後, 除去直後, 除去1～2日後の連日12回とし, 早期接触によって誘起される咀嚼筋活動と情動, および脳波の経日的変化を検討した.結果: 咀嚼筋筋電図から求めた群化放電図では中枢性の制御傾向を認めたが, 装置装着1日後には回復した. 一方, 両側性協調パターンは作業側咬筋優勢パターンの崩壊傾向を認め, 装置除去2日後でも回復しなかった. 咀嚼前の脳波には経日的変化を認めなかったが, 咀嚼後のα波含有率は, コントロールと比較して装置装着中は有意に減少し, 装置装着中では消失しなかった違和感, 不快感といったVASによる感覚的評価の変動と一致した.結論: α 波含有率は口腔感覚由来の情動変化を反映し, 咀嚼系の障害感を検出しうる可能性が示唆された.

実験的こう合障害がラット前頭皮質ドーパミン放出に及ぼす影響

It is very interesting to determine whether disturbance of mastication following occlusal dysfunction has an effect on mental stress. Therefore, an experimental occlusal interference was attached, and the effect on dopamine release from the rat prefrontal cortex was examined.The extracellular fluid dopamine volume of the prefrontal cortex was measured by the brain microdialysis method.1. Though experimental occlusal interference during nonfunctional periods was intraoral, it. was found that the metabolism of the prefrontal cortex dopamine did not change.2. Experimental occlusal interference during functional periods, that is, feeding periods with cubed food under occlusal interference increased the prefrontal cortex dopamine volume. It was clarified that experimental occlusal interference strongly impacts the affect of the rat by changing the metabolism of dopamine in the prefrontal cortex.3. Cubed food and powdered food increased the prefrontal cortex dopamine volume in the same way. It was found that there was no difference in transition of the increase in the prefrontal cortex dopamine volume from the difference in the texture of the food.Experimental occlusal interference related to feeding behavior affected dopamine metabolism in the rat prefrontal cortex, and it was clarified that a strong stress reaction was induced by experimental occlusal interference.

こう合力負荷時の歯の変形

The purpose of this study was to evaluate the relationship between tooth deformation and functional occlusal loading. Vertical length of buccal tooth surface was measured with a newly-developed submicron transform detector. Deformations of upper canines and first premolars of 13 adult volunteers were evaluated under different occlusal conditions. Buccal tooth surface was contracted with buccal cusp loading and expanded with palatal cusp loading. The median of the first premolar deformation was-171 nm/mm/ 100 N with buccal cusp loading and 34 nm/mm/100 N with palatal cusp loading.Maximum clenching at eccentric occlusion exhibited significantly larger tooth deformation than that of intercuspal occlusion. The experimental occlusal interference exhibited relatively large tooth deformation, while insignificant deformation was seen with mastication. The results suggested that tooth structure may receive more harmful influence from occlusal imbalance and bruxism, and that tooth deformation analysis may have potential to a evaluate a clinically ideal occlusion.

Sixty-eight years of experimental occlusal interference studies: What have we learned?

Statement Of Problem. Understanding is needed regarding the effect that occlusal interferences have on the teeth, periodontium, and especially on jaw function. Purpose. This article summarizes research in which experimental occlusal interferences have been placed on the teeth of animals and human volunteers. Material And Methods. Data from 18 human and 10 animals studies were reviewed. Experimental occlusal interferences were grouped into those that alter intercuspal position and those contacting on lateral jaw movement only. The outcome of these interferences were analyzed according to their local pulpal-periodontal, jaw function, or bruxism effects. Results. Experimental occlusal interferences in maximum intercuspation had a deleterious effect on periodontal and pulpal tissues of the affected tooth; sometimes this produces a disruption of smooth jaw function and occasionally jaw muscle pain and clicking. Experimental occlusal interferences that contact only in a lateral jaw movement are infrequently harmful to jaw function. Furthermore, no reliable evidence demonstrates that occlusal interferences can cause nocturnal bruxism, or stop it. Conclusion. Transient local tooth pain, loosening of the tooth, a slight change in postural muscle tension levels, chewing stroke patterns, and sometimes a clicking joint can be induced by an experimental occlusal interference. Because such findings are present in relatively asymptomatic patients, these data do not prove that occlusal interferences are causally related to a chronic jaw muscle pain or temporomandibular joint dysfunction problems. (J Prosthet Dent 1999;82:704-13.)

顎口腔系の状態と全身状態との関連に関する研究 実験的こう合干渉が自律神経機能に及ぼす影響

As part of a study to clarify the effects of changes in the stomatognathic system on autonomic functions, experimental occlusal interference was applied to the mandibular molar on the primary mastication side in 10 healthy subjects with natural teeth. Then examination was carried out on daily changes in the heights of digital plethysmograms and the R-R intervals on the electrocardiogram as well as their coefficients of variation. The results were as follows:1. The heights of digital plethysmograms had decreased 24 hours after the interference was applied but increased daily after its removal, returning nearly to the pre-interference value after another 48 hours. The coefficient of variation had increased 24 hours after the interference was applied but decreased daily after its removal, nearly recovering the pre-interference value after 48 hours.2. The R-R interval on the electrocardiogram had decreased 24 hours after the interference was applied but had nearly recovered its pre-interference value 24 hours after the interference was removed. The coefficient of variation had decreased 24 hours after the interference was applied but recovered daily after its removal, nearly recovering the pre-interference value after 48 hours.3. These results suggest that abnormalities such as occlusal interference in the stomatognathic system induce functional abnormalities and that these affect both sympathetic and parasympathetic functions in the autonomic nervous system. One week after the removal of interference, each parameter had nearly recovered its pre-interference value. This suggests that normalization of the stomatognathic system is involved in the normalization of the autonomic function.

こう合と全身の機能との関係

In order to verify the relation between the body function and occlusion, the gravity function, electronystagmography, and auditory brainstem response of TMD patients, edentulous patients and healthy subjects with 500 μm thick experimental occlusal interference were analyzed, and it was confirmed that occlusal problems impede the auditory system, body's posture adjusting system and vestibule system. Further, when the relation between the occlusal contact and the bodily motor function were compared between healthy subjects and patients whose occlusion had been treated, it was confirmed that there was close relation between the two.Furthermore, from the analysis of human body phenomena of healthy subjects with 100 μm thick experimental occlusal interference, it was confirmed that occlusal problems induced bruxism or continuously aggravated the problem and eventually entailed TMD, as well as changed the function of the autonomic nervous system and provoked emotional stress and sleep disorders.From these results, it was verified that occlusal problems affected the function of the middle ear transmission system, equilibrium sense, auditory brainstem response, function of autonomic nervous system, emotion and sleep and that the occlusal function was closely related to the bodily motor function.

顎口腔系の状態と全身状態との関連に関する研究 歯科における指尖容積脈波の応用

A series of studies on the relationship between the condition of the stomatognathic system and the systemic condition has been conducted, it has been found that they both influence the somatic nervous system. In this series, the usefulness of the digital plethysmogram, which is simple, noninvasive, quick, and quantitative among autonomic function tests, was evaluated. Experimental occlusal interference was applied to the lower first molar teeth on the primary mastication side in 5 healthy subjects with natural teeth, and changes in the height of the digital plethysmogram were examined after interference. The following conclusions were drawn concerning the usefulness of the test.1. The height of the digital plethysmogram was reduced 24 hours after occlusal interference, and its base line was unstable in many subjects. It tended to return to the level before interference one week after discontinuation of interference.2. These findings suggest that plethysmography is useful for evaluation of the effect of occlusal interference as an abnormality of the stomatognathic system on autonomic activity.