Function Of Stomatognathic System Research Articles

Effect of Increasing Occlusal Vertical Dimension on Smile Parameters

Introduction: Increasing Occlusal Vertical Dimension (OVD) becomes important aspect of complex prosthodontic treatment for maintaining balance between form of oral structures and function of stomatognathic system. The purpose of this study is to determine the effect of increasing OVD on various smile parameters during posed smile. Methodology: This observational descriptive study included 30 patients, 14 male and 16 females, visiting dental department of National Academy of Medical Sciences (NAMS), Bir Hospital. Four polyvinyl siloxane bite records were fabricated on stone cast mounted on a semi-adjustable articulator increasing OVD by +1 mm, +2 mm, +3 mm and +4 mm taking incisal pin as a reference. Photographs of posed smile were taken at OVD of +0 mm, +1 mm, +2 mm, +3 mm and +4 mm using a DSLR camera mounted on a tripod. Head position was stabilized using a head positioning device of a cephalometric unit during photography. Adobe photoshop CS6 extended was used to calculate the various measurement in pixel which was converted into mm with help of conversion ratio obtained. Data were then processed and analyzed using SPSS software at the 5 % significance level. Result: One-way repeated measures ANOVA found statistically significant differences in interlabial gap height, incisal edge to lower lip distance, smile index and display zone area with increasing OVD. No statistically significant differences were found for intercommisural width and incisal edge to upper lip distance. Conclusion: Within the limitations of this study, the excessive increase of OVD may lead to excessive interlabial gap height, incisal edge to lower lip distance, and display zone area. Also, the increase of OVD may lead to reduced smile index. No change may be expected in the position of the upper lip with increase of OVD. In addition, a change in the intercommisural width of the smile should not be expected with increasing OVD.

Oral changes in patients with psoriasis.

Psoriasis is one of the most frequent skin diseases. The cause of psoriasis is not fully expained as there are many factors (infectious, traumatic, hormonal, and chemical) that may play a role in the manifestation of its symptoms. One of the factors that may contribute to the appearance of psoriatic lesions may be the lesions in the oral cavity. The occurrence of lesions in the oral cavity is defined as rare, what can be explained by their nonspecific clinical image, and also by the possibility of being overlooked. Most characteristic symptoms of psoriasis occurring in the oral cavity are the geographic tongue and fissured tongue. It is also believed that there is a correlation between psoriasis and oral health- the periodontal and teeth condition as well as changes in saliva secretion. The psoriasis arthritis changes can also affect temporomandibular joint and impair the function of stomatognathic system. Because of these reports, cooperation of dermatologists and dentists in psoriasis care seems to be necessary.

Late postoperative complications and dysfunction of the stomatognathic system (SS) in patients after orthognathic surgery

Introduction: Patients with maxillofacial and intraoral defects require orthognathic surgery to improve the appearance of the face and correct the occlusion. The number of orthognathic surgeries has been increasing in recent years. The motivation to undergo these surgeries is the possibility for patients to improve stomatognathic system functions i.e. chewing, swallowing and pronunciation, as well as aesthetic and psychosocial factors. Aim: The aim of the paper was to assess the occurrence of late postoperative complications and dysfunction of the stomatognathic system in patients after orthognathic surgeries such as Maxillary Lefort 1 Osteotomy and Bilateral Sagittal Split Osteotomy (BIMAX). Additionally, the paper emphasizes the necessity of quick activation of the stomatognathic system structures in patients after orthognathic surgeries in order to reduce the incidence of complications.Material and methods: The research was conducted with the help of the users of internet groups: "Progenia, mandibular prognathism, photos BEFORE and AFTER the operation :)" (in Polish: „Progenia, wysunięta szczęka, zdjęcia PRZED i PO operacji :)”) and "Suffering from progenia" („Progenicy”) as well as users of the Jawsurgeryforums.com online forum who have given their informed consent to participate in the survey. The analysis was carried out on a group of 92 people who underwent orthognathic surgery of Maxillary Lefort 1 Osteotomy and Bilateral Sagittal Split Osteotomy (BIMAX) type in the years 2004-2019. To assess the opinions of patients, a diagnostic questionnaire method was used, based on a proprietary electronic questionnaire, which consisted of three parts. The first part is metric, i.e.: age, gender and questions concerning the number of orthognathic surgeries performed, time of wearing intermaxillary traction wiring or splints, postoperative rehabilitation. The second part of the questionnaire consisted of 15 close-ended questions assessing the occurrence of symptoms of SS system disorders and functioning. The third part of the questionnaire consists of 20 questions concerning postoperative complications after 3 and 6 months from surgery and functioning of the dental system after surgery. The fourth part of the questionnaire consists of 5 close-ended questions concerning the evaluation of the overall impression after surgery and the most important effects of it. The test results were statistically analyzed using the correlation coefficient and Pearson's chi-squared test (p ≤ 0.05).Results: 92 people, of which 86 women (93.5%) and 6 men (6.5%), participated in the study. The most common ailments before the surgery—affecting more than half of the patients—were chewing impairment, speech defect, breathing problems and headaches. 3 months after the operation, facial neurosensory disturbances and facial swelling were the most frequent of the ailments reported by the patients (more than 70% of the respondents), limited jaw mobility, joint pains and chewing impairment were also frequent (more than 40%). 6 months after the surgery, the most frequent persisting ailments were facial neurosensory disturbances (> 60%), facial swelling and acoustic problems (> 30%), as well as pains of masticatory and mandibular muscles, headaches and limited joint mobility (> 20%). More than half of the patients (n=48) were satisfied with the surgery, the second largest group were patients delighted with the result (n=25). 4 people were dissatisfied and 3 very dissatisfied. 12 patients had difficulties in determining their satisfaction with the results of the surgery. 19 people (20.7%) did not report disturbances of somatosensory system in any of the facial areas, and among the patients experiencing ailments, 40 people (43.5%) reported problems in two areas, 27 people (29.3%) in one, 5 people (5.4%) in four and 1 person (1.1%) in three areas. In the 3rd month after the surgery it was observed that people who did not use physiotherapeutic treatment were 11.5% more likely to suffer from bone inflammation [X2(1)=4.359; p=0.037]. Two statistical tendencies were observed, suggesting that people using physiotherapy slightly less often showed limitations in mandibular mobility [by 17.6%; X2(1)=3.599; p=0.065] and by 4.7% less often experienced bone inflammation [X2(1)=1.238; p=0.076]. Conclusions: The most common postoperative complication is somatosensory system disturbance of the lower facial muscles. Orthognathic surgery contributes to the reduction of stomatognathic system ailments. Persons using physiotherapy suffer less frequently from bone inflammation and enjoy greater mobility of the temporomandibular joint.

Class III Reversion with Immediate Complete Denture and Immediate Implant-Retained Overdenture: Case Report

With the increased life expectancy, complete dentures have been used in the treatment of edentulism progressively. It restores stomatognathic system functions, providing improvements in chewing, aesthetics, and phonetics. The aim was to report an oral rehabilitation of a patient with severe aesthetic and functional impairment, with Angle’s class III malocclusion. The patient sought the extension project of the School of Dentistry of the Federal University of Minas Gerais with aesthetic complaints. After clinical and radiographic evaluation, the proposed planning was immediate complete denture maxilla and immediate implant-retained overdenture in mandible. During clinical evaluation it was observed that the patient was Angle’s III. The rehabilitation was performed as proposed and at the end of the treatment, it was possible to revert the class III occlusal pattern to Angle’s I. The excellent maxillomandibular relationship was achieved, which ensured optimal facial aesthetics and functional condition. It was concluded that the immediate complete dentures and immediate implant-retained overdenture might be beneficial for restoring the aesthetics and function of patients with Angle’s class III malocclusion.

Effect of Short-Term Forward Head Posture Correction for Masseter Muscle Activity and Temporomandibular Joint Function for People with Upper Cross Syndrome

Background. In 1996, meta-analysis of studies was performed and it showed the connections between head posture changes and temporomandibular joint (TMJ) dysfunctions (Harrison et al., 1996), but the abnormalities of the mandibular usually were treated as the only pathology leading to poor clinical effect (Lee et al., 2017). Supposedly, occlusion problems are related not only to the position of the jaw and skull, but also to the shoulder and spine, which act as a biomechanical chain (Moreno, Aranza, 2013; Shousha et al., 2018). There is a lack of evidence how head posture correction changes stomatognathic system functions, that is why our study aimed to determine if a short-term head posture correction affects the system. Research aim. Determine the effect of short-term forward head posture correction for temporomandibular joint (TMJ) function. Research methods. Evaluation of posture, TMJ range of motion, jaw opening stereotype. Research results. After a short-term head posture correction, head inclination angle alteration was as follows: ScapularR = 5.65°, ScapularL = 3.9°. Jaw opening alteration was ScapularR 15.09 mm, ScapularL 15.58 mm. The difference between mandibular deviations decreased to ScapularR 0.32 mm; ScapularL 1.60 mm. Deviation during jaw opening reduced ScapularR 2.06 mm; ScapularL 2.38 mm. Conclusion. Short-term head posture correction signifcantly reduced head inclination angle, mandibular opening movement amplitude and deviation from the centre line in individuals with upper cross syndrome and asymmetric scapular position.Keywords: temporomandibular joint, head posture, upper cross syndrome.

Customized Microstomia Prevention Appliance Therapy: A Case Report

Microstomia is a condition with abnormally small oral aperture which is associated with compromised aesthetics and function of stomatognathic system. In young children, the leading cause of microstomia is oral electrical or chemical burns. Management of microstomia requires multidisciplinary approach including surgery, physiotherapy and appliance therapy. Appliance therapy in form of microstomia prevention appliance plays a pivotal role in prevention of contraction of tissue during healing. Numerous appliances have been described in literature to prevent microstomia. However, decision to use a particular appliance require meticulous planning considering the efficacy and effectiveness of the appliances and various patient factors like age, dentition status and compliance. This paper presents an unusual clinical condition where a unique customized microstomia prevention appliance therapy was instituted to prevent microstomia in 2 year old female patient following lip surgery. This appliance was constructed easily and inexpensively, could be adjusted so that it was almost painlessly inserted, and was progressively adapted. It was convenient for use in young child with minimal compliance offering improved mouth opening and consequently functional outcomes.

Preventive orthodontic approach for functional mandibular shift in early mixed dentition: A case report

The case reported here highlights the importance of examination of functional occlusion along with static occlusion. Any undetected malocclusion during early mixed dentition has potency to alter the growth and function of stomatognathic system. Premature contacts in primary canine region is the most prevalent cause of functional mandibular shift and can lead to TMJ problems for the prevalence of self correction of such malocclusion is very low if not intervened. A case of functional mandibular shift due to faulty canine guidance because of premature contacts is discussed here. Selective grinding of premature contacts and myofunctional exercise resulted in well balanced centric occlusion coinciding with centric relation.

Current Evidence for the Possible Interactions of Nutritional Behavior with the Development and Formulation of the Stomatognathic System within the Craniofacial Complex

Current Evidence for the Possible Interactions of Nutritional Behavior with the Development and Formulation of the Stomatognathic System within the Craniofacial Complex Introduction: From time to time, various studies support the association between nutritional habits and development of the stomatognathic system (SS). Purpose: The investigation of the impact of nutritional behavior on the craniofacial morphology, the masticatory function and dentition, as well as the research for possible correlation between body mass index (BMI) and harmonic function of stomatognathic system. Methods: A comprehensive review of the dental and medical literature, using appropriate keywords. Results: Several studies support the hypothesis according to which nutritional behavior has an impact on the development and formulation of the stomatognathic system, but also teeth wear. It is also supported that there is negative relationship between masticatory performance and BMI. Furthermore, the factors which affect the masticatory performance are referred, such as age, gender, height, physical activity, smoking, face shape, sleep bruxism, oral health, number, position and dentition. Conclusions: SS is highly reliant on nutritional behavior, therefore the collaboration between oral health doctors and nutritionists is considered essential for the methodical prevention programs training, in order to eliminate the disorders of stomatognathic system and for the general health but also to eliminate deviations from ideal weight and improve the quality of life in general.

Fiber reinforced composite bridge as a replacement for missing upper permanent lateral incisor – a case report

Abstract Hypodontia of upper lateral incisors is significant aesthetic problem in young people. Ideal solution to this problem would be an implant placement, but there is a problem of unfinished growth and development. It is therefore necessary to have a temporary solution in order to maintain normal stomatognathic system functions and solve aesthetic problems until the final restoration is placed. The aim of this study was to show the possibility of treating hypodontia of permanent upper lateral incisors by creating adhesive bridge in one visit. A 15-year-old patient was referred to the Department for Prosthodontics, School of Dental Medicine in Belgrade with hypodontia of permanent upper lateral incisors. The patient had braces until 14 years of age after which she was rehabilitated with partial denture that was neither aesthetically nor functionally acceptable solution for her and significantly affected her emotional security. The adhesive bridge was made using GC composite fibers and a set of GC composite materials for the purpose of temporary replacement of missing teeth. This treatment provided good functional and aesthetic results. The space for the placement of two endosseous implants is preserved and a period of adaptation positively influenced the patient’s social development in sensitive adolescent age.

Comparative evaluation of custom and standard boil and bite (self-adapted) mouthguards and their effect on the functioning of the oral cavity.

Mouthguards provide an effective preventive method against the effects of injuries sustained during sports activities, in particular cycling, football, basketball, skiing or hockey. However, when placed in the oral cavity, they can induce disorders in basic physiological functions. The objective of this clinical study was to compare the effects of various custom mouthguards with generally available standard boil and bite mouthguards on the functions of the oral cavity. A total of a 168 mouthguards (five custom and three standard boil and bite mouthguards) were assessed in a questionnaire-based survey. Their negative effects on the integrity of mucosa, speech, breathing, salivary flow and taste as well as in terms of inducing gag reflex, tooth clenching and temporomandibular joint complaints were compared. Porida mouthguard was reported to have the most adverse effects on oral functions. In the majority of the respondents, the remaining mouthguards did not have any adverse effects on the stomatognathic system functions. Mouthguards do not significantly disturb basic functions of the stomatognathic system. Standard Porida mouthguards were shown to have the most unfavourable effect on oral functions.

Temporomandibular disorder in children at deciduous and mixed denture

The temporomandibular joint (TMJ) plays an important role in the function of stomatognathic system. The acronym TMD – Temporomandibular disorder – is a general term for a series of signs and symptoms involving the masticatory muscles, TMJ, and associated structures. TMDs have a multifactorial etiology despite that many controversies still exist on this subject. Structural factors as trauma, malocclusion, systemic hypermobility, oral parafunctions, and emotional conditions (stress, anxiety, and depression) may trigger TMDs appearance. Objective: This study aimed to evaluate the signs and clinical symptoms of TMDs in patients treated at the School of Dentistry of the Institute of Science and Technology of São José dos Campos – UNESP - SP. Material and Methods: Fifty patients, both genders, aged between five and thirteen years were examined through muscle palpation and auscultation. Intra and extraoral examinations were performed, observing occlusion interference, denture type, protrusion or retrusion of the mandible, open bite or crossbite, edge-to-edge bite relation, midline shifts, limitation of mouth opening, and mandible shift during mouth opening and closing. Anamnesis comprised questions on the child’s habits and symptoms noticeable by the parents or legal guardians, information on the child’s personality and mood. Results: The obtained data were analyzed through percentage and qualitative analysis. Conclusion: It can be concluded that children exhibited signs and symptoms of TMDs, but TMDs presence cannot be affirmed in the studied sample; stress or altered behavior influenced on the presence of the signs and symptoms in the TMJ area Keywords Temporomandibular joint; Mixed dentition; Primary dentition; Temporomandibular joint dysfunction syndrome.

Efetividade da fonoterapia em pacientes com paralisia facial pós-parotidectomia

O objetivo deste estudo foi verificar a efetividade da fonoterapia em pacientes com paralisia facial decorrente da manipulação do VII nervo encefálico realizada durante o tratamento cirúrgico para neoplasia de glândula parótida, assim como, identificar e promover intervenção fonoaudiológica das alterações de sucção, mastigação e deglutição. Trata-se de uma pesquisa qualitativa com análise descritiva. A avaliação constou da análise da face em repouso e em movimento, documentação fotográfica, uso do Paquímetro Digital para quantificação da paralisia facial, além da avaliação das funções estomatognáticas. A fonoterapia foi definida com base nos achados da avaliação e seguiu a necessidade de cada indivíduo. Nos resultados da avaliação pós-fonoterapia em repouso houve melhora em todos os aspectos avaliados nos quatro pacientes. Na avaliação em movimento três pacientes apresentaram movimentação mais clara da pele com aumento do número e profundidade das rugas. No registro fotográfico todos os pacientes obtiveram melhora significante nos movimentos avaliados, sendo possível observar um aumento nas linhas de expressões e maior simetria entre as hemifaces. Os valores da incompetência dos movimentos, mensurados pós-fonoterapia, demonstraram melhora significante em todos os pontos medidos. A fonoterapia proposta para os casos de paralisia facial pós-parotidectomia foi eficiente na melhora da mímica facial, sobretudo para as alterações das funções estomatognáticas. É importante salientar a necessidade de novas pesquisas envolvendo um número maior de participantes para garantir a fidedignidade dos achados.

Peran dan fungsi prostesis dalam fungsi sistem stomatognatik Role and function of prosthesis in the stomatognathics system function

Do literary study of the role and function of the prosthesis in overcoming or restoring function stomatognathicsystem cannot function optimally. There is a variety of lost body parts due to illness or accident requiringabnormalities restoration or rehabilitation with artificial materials. To overcome this thing, there are a variety ofprosthesis, the dental prosthesis, maxillofacial prosthesis, and supporting prosthesis (ancillary prosthesis). Theanalysis focused on overcoming tooth loss causes shortening jaw arch and various maxillofacial abnormalitiesusing compatible materials, a variety of complications and their consequences. Data showed that the loss of thesystem's structure can disrupt stomatognathic masticatory function, esthetics, phonetics, swallowing and breathing.Installation of a removable prosthesis, partial or full will improve the efficiency of mastication and chewing ability,a greater increase in fixed prostheses and implants. Esthetic and satisfaction very disturbed due to missing fronttooth with a large variation of subjectivity for the age group, social, cultural, regional and state. Generally, patientsare less affected by the phonetic compared to mastication. Although not fully, function prosthesis can replacemissing teeth and the surrounding tissue, and keep tissue health of the stomatognathic system. It was concluded thatprosthesis can help, restore and maintain function of stomatognathic system, namely the mastication, esthetics,phonetics, swallowing and breathing.

To Determine the Influence of the Complete Denture Prosthesis on Masticatory Muscle Activity in Elderly Patients: An in vivo Study

ABSTRACT Introduction Mastication is a highly coordinated neuromuscular function involving fast effective movements of the jaw and continuous modulation of force. In older subjects these mechanisms act with marked differences. They have a reduced capacity in various functions of stomatognathic system. Objectives To evaluate the elevator and depressor muscle activity with and without complete denture prosthesis. Materials and methods For the purpose of the study 12 patients between the age of 40 and 70 years were selected. Surface electrodes from the electromyographic unit were placed in the region of right and left anterior temporal muscles, Masseter muscle and depressor muscle at the region of anterior belly of digastric and the electromyographic activity was recorded. Results and discussion The obtained values were subjected to statistical analysis. A paired t- test was performed to determine the difference between the subjects with and without denture prosthesis. Conclusion The elevator muscles showed higher activity in subjects wearing the denture prosthesis when compared to those without denture prosthesis. No significant change in muscle activity was seen on maximal opening of the depressor muscle between the subjects with and without denture prosthesis.

Adaptações do sistema estomatognático em indivíduos com desproporções maxilo-mandibulares: revisão da literatura

Esta pesquisa procurou identificar as adaptações do sistema estomatognático em indivíduos com desproporções maxilomandibulares. A revisão bibliográfica se fez por meio das bases de dados nacionais e internacionais, abordando as adaptações do sistema estomatognático em indivíduos com desproporção maxilo-mandibular submetidos a tratamento ortodôntico-cirúrgico (cirurgia ortognática) associado à intervenção fonoaudiológica. Observou-se que sujeitos com prognatismo e retrognatismo apresentam adaptações em todas as funções realizadas pelo sistema motor oral, no período pré-cirurgia ortognática. No prognatismo mandibular, a função mais adaptada é a mastigação, caracterizando-se em movimentos verticalizados com utilização do dorso da língua para amassamento do alimento e pouca utilização dos músculos mastigatórios. No retrognatismo mandibular, estudos mostram que a deglutição apresenta-se bastante adaptada, com presença de deslize mandibular anterior somado ao movimento póstero-anterior de língua e com participação da musculatura perioral. Após a cirurgia ortognática, alguns casos podem apresentar adequação das funções do sistema estomatognático, porém em outros persistem as alterações, sendo necessário o conhecimento do fonoaudiólogo sobre as adaptações pré-existentes para traçar o melhor plano de reabilitação.

Principle of Treatment on the Removable Prosthodontics

The principle of dental treatment focuses on to achieve a good balance between “maintaining the residual tissues in healthy condition” and “the functional recoveries”. At first, the two major prerequisite for the residual tissues maintenance are bacterial control and mechanical loading force control, through pre-operative microbial test, and examinations and diagnostics of residual tissues such as temporomandibular joint, muscular groups, existing teeth, periodontal tissues, and residual ridges. Secondly, the functional recoveries are to increase the rate to the utmost of various functions of stomatognathic system as mastication, swallowing, respiration pronunciation and sensation, including aesthetics.

Evaluation of the treatment changes of functional posterior crossbite in the mixed dentition

Functional posterior crossbite (FPXB) malocclusion is frequently seen in the deciduous or mixed dentition. It is often accompanied by lateral mandibular shift and mandibular midline deviation because of the reduction in the width of the maxillary dental arch. The aims of this prospective study were to examine in detail the morphologic, skeletal, dental, and functional effects of FPXB, and the effects of maxillary expansion treatment with quad-helix appliance. The experimental group consisted of 35 FPXB patients (20 girls, 15 boys) having a mean age of 10.6 +/- 1.4 years; the control group consisted of 31 normocclusive subjects (18 girls, 13 boys) with a mean age of 9.8 +/- 1.6 years. Lateral, posteroanterior, and submentovertex cephalograms, transcranial temporomandibular joint radiographs, joint vibration analysis, and electromyographic recordings were obtained from every patient before and after maxillary expansion. Magnetic resonance images were taken before treatment for diagnostic purposes. These data were collected at 1 time point in the controls. The pretreatment posteroanterior, submentovertex, and transcranial temporomandibular joint radiographs showed mandibular asymmetry relative to the cranial base and condylar malpositioning in the glenoid fossa. Joint vibration analysis findings showed different vibrations between the crossbite and noncrossbite sides, and imbalanced electromyographic findings in the experimental group. After treatment, the asymmetric morphology and position of the mandible and condyles were eliminated, and the stomatognathic system functions were normalized. Early orthodontic treatment of FPXB creates optimum conditions for normal growth of the craniofacial skeleton and normal function of the stomatognathic system.

Surface electromyography of facial muscles during natural and artificial feeding of infants

To measure and compare the activity of the masseter, temporalis and buccinator muscles in different infant feeding methods. Cross-sectional study of 60 full-term infants with no intercurrent diseases, aged between two and three months, classified into the following groups: 1) exclusive breastfeeding; 2) breastfeeding plus bottle-feeding; and 3) exclusive breastfeeding plus cup feeding. Surface electromyography was performed during infant feeding. The Krushal-Wallis test was used, complemented by multiple paired comparisons of the groups. A 5% significance level was chosen for the tests. Statistically higher results were verified in the breastfeeding group in relation to the bottle-feeding one, both in the range of movement and the mean contraction of the masseter. With regard to the temporalis muscle, statistically higher results were found in the breastfeeding group comparatively to the bottle-feeding one. As to the buccinator muscle, statistically higher results were observed in the breastfeeding group in relation to the bottle-feeding one, although in this case, the difference concerned only the range of contraction. The similarities between the muscle activity in the breastfeeding and in the cup-feeding groups suggests that cup-feeding can be used as an alternative infant feeding method, being better than bottle-feeding, due to the hyperactivity of the buccinator muscle, which could result in changes to the structural growth and development of the stomatognathic system functions.

顎顔面形態がこう合力とそしゃく筋筋放電活動に及ぼす影響について ＩＩＩ‐３． Ｎｏｒｍａｌ ｆａｃｅ群におけるクレンチング方向の変化がこう合力値とその方向，筋放電活動に及ぼす影響について

In this study, dentulous subjects in the normal face group were selected had been engaged in vertical and anterior clenching to measure the magnitude and direction of bite force as well as the EMG activity of masticatory muscles. The influence of changing direction between vertical and anterior clenching on the functions of stomatognathic system were analyzed.The results were as follows:1. The magnitude of bite force in anterior clenching was smaller than that of in vertical clenching at 25-100%MC.2. According to the increase of bite force, the direction of bite force (θ) in vertical and anterior clenching was increasing.The dircetion of bite force (θ) in anterior clenching was smaller than that in vertical clenching 25-100%MC.3. The EMG activity per 1kgf of temporalis in anterior clenching was smaller than that in vertical clenching at 50-100%MC.The EMG activity per 1kgf of lateral and medial pterygoid muscle in anterior clenching was larger than that in vertical clenching at 25-100%MC.

顎顔面形態がこう合力とそしゃく筋筋放電活動に及ぼす影響について ＩＩＩ‐１． Ｎｏｒｍａｌ ｆａｃｅ群の垂直方向クレンチング

To analyze the influence of craniofacial morphology on the functions of stomatognathic system, dentulous subjects in the normal face group were selected and had been engaged in vertical clenching to measure the magnitude and direction of bite force as well as the EMG activity of masticatory muscles. The correlation was studied among them.The results were as follows:1. The correlation curve of temporal muscle was hyperbolic. The correlation curves of masseter muscle and medial pterygoid muscle were linear.2. The ratio of the EMG activity of the increasing part was equal to or higher than that of the holding part at 25-100%MC.3. A significant correlation was observed between θ' and 4 angle measurements. The correlation of 13 items of the craniofacial measurements and direction of bite force was investigated with the EMG activity per 1kgf. A significant correlation was observed between the EMG activity per 1kgf and several items of craniofacial measurements.