• The Journal of Korean Academy of Prosthodontics
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• v.59 no.4
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• pp.459-468
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• 2021

In patients with myasthenia gravis, it is difficult to manufacture and maintain dentures because the muscles and nervous system in the oral cavity are not properly adjusted. In addition, excessively extended or thick dentures may cause muscle weakness by stimulating the muscles, so dentures should be manufactured in consideration of this. In this case, a denture was fabricated using the closed mouth technique in a patient with myasthenia gravis with mouth opening limitation. Using the closed mouth technique, the patient's masticatory pressure and muscle movements were reproduced and denture with good retention were manufactured.

• Oral Biology Research
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• v.42 no.4
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• pp.208-215
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• 2018

The purpose of this study was to identify the risk of dysphagia among patients that visited prosthodontics department, and evaluate the difference in risks arising from oral conditions and disease in order to preliminarily intervene the various influencing factors of dysphagia. A questionnaire was given to patients that were aged 65 years or older who visited the prosthodontics department between September to December 2017. The data was collected and analyzed using the t-test, $x^2-test$ and logistic regression analysis. The mean age of the patients was 75 years. Out of 300 patients, 206 patients (68.7%) had a risk of dysphagia. There were statistically significant differences between the -non-risk and risk groups, which included the number of natural teeth, total number of teeth including prosthesis, denture use, denture discomfort, number of tooth brushing, oral dryness, digestive system diseases, and musculoskeletal diseases. Among these, oral dryness was a risk factor while the total number of teeth, including natural teeth and prostheses, served as a protective factor. More than half of the elderly patients were at risk of dysphagia. Oral dryness is influenced by many factors and it should continuously be managed. Patients should fully recover their masticatory function by preserving the remaining teeth and compensating for the missing teeth. A dental practitioner should be fully aware of the risk of dysphagia in elderly patients and be able to intervene and offer proper patient health care in advance through treatment guidelines and education.

• The Journal of Korean Academy of Prosthodontics
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• v.59 no.1
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• pp.107-115
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• 2021

Excessive pathological attrition over the entire dentition can cause decreased masticatory function, and pathological problems of the temporomandibular joint and the muscular nervous system. In this case, 71 year-old male patient with severe attrition and fracture across the entire tooth was treated by full mouth rehabilitation for regaining space of restoration. In order to determine the appropriate vertical dimension of the patient's occlusion, facial appearance, aesthetics, restoration space were evaluated, and provisional restoration of the raised vertical dimension was made. After 4 months of evaluation, the entire restoration of monolithic zirconia crown using CAD-CAM was completed. Through the above process, satisfactory aesthetic and functional results were obtained.

• The korean journal of orthodontics
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• v.27 no.1
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• pp.35-44
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• 1997

mastication is basically regulated by central pattern regulalor(CPG) of brain system, target organ output from CPG is modulated by oral sensory feedback, anterior cross bite pattern infuluence the feedback mechanism and change muscle activity and jaw movement. The purpose of this study was to investigate differnce anterior cross bite group from normal group, the selected sample groups were 30 normal patient, 30 anterior cross bite patient. EMG and EGN of Biopak system were used for this study The following results were obtained 1 In resting slate of mandible, anterior cross-bite showed the higher muscle activities in all the muscle.(exception:left digastric muscle) than normal group. 2. In clenching state, No significant difference in muscle activities of normal group and anterior cross bite group was noticed 3. In swallowing state Normal group showed the higher muscle activities in left and right masseter muscle, right posterior temporal muscle. 4. In maximum opening and closing velocity, normal group showed the higher value than anterior cross-bite. 5. In the mean value of the maximum opening,the maximum anterior posterior movemenl from centric-occlusion, the lateral deviation from centric occclusion, normal group showed the higher value than anterior cross-bite group.

• The Journal of Korean Academy of Prosthodontics
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• v.59 no.1
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• pp.97-106
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• 2021

Dental implants should be placed at ideal sites for implant-supported restorations. For a patient with insufficient residual ridge, mouth preparation including surgical intervention can be indicated to establish a soft and hard tissue environment favorable for a definitive prosthesis. Prosthodontic design based on computer-guided surgery and computer-aided design-computer-aided manufacturing (CAD-CAM) provides a visual blueprint allowing a clinician to assess the necessity of such a surgical intervention beforehand. In this case, a definitive restoration was planned and made via a CAD-CAM system according to the patient's oral status before treatment, simulated surgical interventions and serial provisional restorations. Based on the planning, a guided template was made and the implants were installed with bone augmentation using the template. Customized abutments, the first and the second provisional restorations were designed and fabricated by CAD-CAM. The definitive restorations were digitally made following the shape of the second provisional prostheses, which were confirmed in the patient's mouth. The patient was satisfied with the masticatory, phonetic and aesthetic functions of these definitive prostheses.

• Journal of the korean academy of Pediatric Dentistry
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• v.31 no.2
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• pp.228-235
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• 2004

The development and proliferation of the mandibular condyle can be altered by changes in the biomechanical environment of the temporomandibular joint. The biomechanical loads were varied by feeding diets of different consistencies. The purpose of the present study was to determine whether changes of masticatory forces by feeding a soft diet can alter the trabecular bone morphology of the growing mouse mandibular condyle, by means of micro-computed tomography. Thirty-six female, 21 days old, C57BL/6 mice were randomly divided into two groups. Mice in the hard-diet control group were fed standard hard rodent pellets for 8 weeks. The soft-diet group mice were given soft ground diets for 8 weeks and their lower incisors were shortened by cutting with a wire cutter twice a week to reduce incision. After 8 weeks all animals were killed after they were weighed. Following sacrifice, the right mandibular condyle was removed. High spatial resolution tomography was done with a Skyscan Micro-CT 1072. Cross-sections were scanned and three-dimensional images were reconstructed from 2D sections. Morphometric and nonmetric parameters such as bone volume(BV), bone surface(BS), total volume(TV), bone volume fraction(BV/TV), surface to volume ratio(BS/BV), trabecular thickness(Tb. Th.), structure model index(SMI) and degree of anisotropy(DA) were directly determined by means of the software package at the micro-CT system. From directly determined indices the trabecular number(Tb. N.) and trabecular separation(Tb. Sp.) were calculated according to parallel plate model of Parfitt et al.. After micro-tomographic imaging, the samples were decalcified, dehydrated, embedded and sectioned for histological observation. The results were as follow: 1. The bone volume fraction, trabecular thickness(Tb. Th.) and trabecular number(Tb. N.) were significantly decreased in the soft-diet group compared with that of the control group (p<0.05). 2. The trabecular separation(Tb. Sp.) was significantly increased in the soft-diet group(p<0.05). 3. There was no significant differences in the surface to volume ratio(BS/BV), structure model index(SMI) and degree of anisotropy(DA) between the soft-diet group and hard-diet control group (p>0.05). 4. Histological sections showed that the thickness of the proliferative layer and total cartilage thickness were significantly reduced in the soft-diet group.

• Journal of Oral Medicine and Pain
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• v.24 no.4
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• pp.421-437
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• 1999

This study was performed to investigate the electromyographic(EMG) activity, firing time and sequence of the mandibular elevator muscle on gum chewing. For this study, 28 patients with temporomandibular disorders(TMD), especially internal derangement of TM joint, and 16 dental students without any signs and symptoms in the masticatory system were selected as the patients group and as the normal group, respectively. The patients group was composed of 14 right and 14 left side affected patients. For recording of EMG activity(${\mu}V$) of the anterior temporalis(TA) and the masseter muscle(MM), and measuring of firing time(millisecond) from the start of mandibular opening movement to the firing of the muscles, BioEMG, BioEGN, and Combo program integrated in the Biopak system(Bioresearch Inc., Milwaukee, USA) were used. Gum chewing stroke was performed in both right and left side for several times, and the first and the second chewing strokes were analysed and compared with regard to EMG activity, firing time, firing sequence, correlation between EMG activity and firing time. The data obtained were analysed by SPSS windows program and the results of this study were as follows : 1. In the patients group, chewing on the affected side showed higher EMG activities in the masseter of the side than those of the contralateral side, but chewing on the unaffected side showed higher EMG activity in the masseter and in the anterior temporalis of the side than those of the contralateral side. 2. There were no difference of firing time between both sides on chewing on the affected side, but firing time in the chewing side were earlier than that of contralateral side on chewing on the unaffected side in patients group. 3. In the normal group, EMG activities in the masseter and in the anterior temporalis in the chewing side were always higher than those of the contralateral side, and there were no difference of firing time between the two sides. 4. In general, firing sequence of four muscles of both sides were ipsilateral TA, ipsilateral MM, contralateral TA, and contralateral MM in earlier order of time in both groups. Correlation coefficients between EMG activity and firing time were negative value, and more significant correlation were appeared in the normal group than in the patients group.

• The Journal of Korean Academy of Prosthodontics
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• v.52 no.3
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• pp.239-245
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• 2014

Complete denture prosthodontics includes replacement of natural teeth and associated maxillary and mandibular structures for full edentulous patients. The final objectives of prosthodontic treatment include esthetic and functional rehabilitation. Because the esthetic demand of senior patients has increased esthetic requirement should not be overlooked in denture treatment. In complete denture treatment, attempts have been made to reproduce tooth wear, arrangement, recession of cervical gingiva, staining, improved gingival shade and so on. This 61 year old female patient came to the Department of Prosthodontics with the chief complaint that dentures made 5 years ago in a local clinic were broken and did not fit well. The patient put more emphasis on fabrication of natural and esthetic dentures than recovery of masticatory function. Remake of maxillary complete denture and mandibular implant retained overdenture was planned. In order to create esthetic and natural contour, Aesthetic Color Set Easy system$^{(R)}$ (Candulor dental GmbH, Wangen, Germany) was used to make complete dentures reproducing various gingival shades. Patient's esthetic satisfaction was high. When complete denture prosthodontics treatment involves appropriate expression of individual characteristics in addition to proper selection of esthetic materials, treatment will give satisfaction to both dentist and patient.

• Journal of Oral Medicine and Pain
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• v.35 no.2
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• pp.155-163
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• 2010

Dermatomyositis (DM) is an idiopathic inflammatory connective tissue disorder and a systemic autonomic immune disease which shows a progressive muscle weakness and characteristic rash. It is identified by a characteristic rash accompanying, or more often preceding muscle weakness. Pathognomonic skin lesions are a blue-purple discoloration on the upper eyelids with edema (heliotropic rash), a flat red rash on the face and upper trunk, and erythema of the knuckles with a raised violaceous scaly eruption (Gottron's papule). The myopathy represents inflammatory and degenerative changes primarily affecting proximal muscles. DM often involves GI tract and respiratory system with as risk of 15-25% internal malignancy. It's managed with sun protection since muscle weakness as well as a rash could be aggravated by sun exposure. Systemic corticosteroid is an initial therapy and other immunosuppressive agent has been used as alternatives. Facial muscles are unaffected and masticatory muscles are rarely affected in DM. We present trismus close to muscle contracture in a patient with DM. Therefore, it needs continuous mouth-opening exercise to prevent progressive muscle contracture and to ensure normal mouth opening.

• The Journal of Korean Academy of Prosthodontics
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• v.36 no.2
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• pp.203-244
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• 1998

The human mandible is always under the condition of loading by the various forces extorted by the attached muscles. The loading is an important condition of the stomatognathic system. This condition is composed of the direction and amount of forces of the masticatory muscles, which are controlled by the neuromuscular system, and always influenced by the movement of both opening and closing. Mandible is a strong foundation for the teeth or various prostheses, nevetheless it is a elastic body which accompanies deformation by the external forces on it. The elastic properties of the mandible is influenced by the various procedures such as conventional restorative treatments, osseointegrated implant treatments, reconstructive surgical procedures and so forth. Among the treatments the osseointegrated implant has no periodontal ligaments, which exist around the natural teeth to allow physiologic mobility in the alveolar socket. And so around the osseointegrated implant, there is almost no damping effect during the transmission of occlusal stress and displacements. If the osseointegrated implants are connected by the superstructure for the stabilization and effective distribution of occlusal stresses, the elastic properties of mandible is restricted according to the extent of 'splinting' by the superstructure and implants. To investigate the change of elastic behaviour of the mandible which has osseointegrated implant prosthesis of various numbers of implant installment and span of superstructre, a three dimensional finite element model was developed and analyzed with conditions mentioned above. The conclusions are as follows : 1. The displacements are primarily developed at the area of muscle attachment and distributed all around the mandible according to the various properties of bone. 2. The segmentation in the superstructure has few influence on the distribution of stress and displacement. 3. In the load case of ICP, the concentration of tensional stress was observed at the anterior portion of the ramus($9.22E+6N/m^2$) and at the lingual portion of the symphysis menti($8.36E+6N/m^2$). 4. In the load case of INC, the concentration of tensional stress was observed at the anterior portion of the ramus($9.90E+6N/m^2$) and the concentration of tensional stress was observed at the lingual portion of the symphysis menti($2.38E+6N/m^2$)). 5. In the load case of UTCP, the relatively high concentration of tensional stress($3.66E+7N/m^2$) was observed at the internal surface of the condylar neck.