• Journal of Dental Rehabilitation and Applied Science
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• v.21 no.1
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• pp.1-14
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• 2005

The purpose of this study was to assess the loading distributing characteristics of implant prosthesis of internal connection system(ITI system) according to position and direction of load, under vertical and inclined loading using finite element analysis (FEA). The finite element model of a synOcta implant and a solid abutment with $8^{\circ}$ internal conical joint used by the ITI implant was constructed. The gold crown for mandibular first molar was made on solid abutment. Each three-dimensional finite element model was created with the physical properties of the implant and surrounding bone. This study simulated loads of 200N at the central fossa in a vertical direction (loading condition A), 200N at the outside point of the central fossa with resin filling into screw hole in a vertical direction (loading condition B), 200N at the centric cusp in a $15^{\circ}$ inward oblique direction (loading condition C), 200N at the in a $30^{\circ}$ inward oblique direction (loading condition D) or 200N at the centric cusp in a $30^{\circ}$ outward oblique direction (loading condition E) individually. Von Mises stresses were recorded and compared in the supporting bone, fixture, and abutment. The following results have been made based on this study: 1. Stresses were concentrated mainly at the ridge crest around implant under both vertical and oblique loading but stresses in the cancellous bone were low under both vertical and oblique loading. 2. Bending moments resulting from non-axial loading of dental implants caused stress concentrations on cortical bone. The magnitude of the stress was greater with the oblique loading than with the vertical loading. 3. An offset of the vertical occlusal force in the buccolingual direction relative to the implant axis gave rise to increased bending of the implant. So, the relative positions of the resultant line of force from occlusal contact and the center of rotation seems to be more important. 4. In this internal conical joint, vertical and oblique loads were resisted mainly by the implant-abutment joint at the screw level and by the implant collar. Conclusively, It seems to be more important that how long the distance is from center of rotation of the implant itself to the resultant line of force from occlusal contact (leverage). In a morse taper implant, vertical and oblique loads are resisted mainly by the implant-abutment joint at the screw level and by the implant collar. This type of implant-abutment connection can also distribute forces deeper within the implant and shield the retention screw from excessive loading. Lateral forces are transmitted directly to the walls of the implant and the implant abutment mating bevels, providing greater resistance to interface opening.

• 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.58 no.3
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• pp.257-267
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• 2020

The goal of suction denture is to enhance retention of dentures by the formation of negative pressure between the denture base and the underlying tissue and sealing around the denture by the mucosa. This patient has been converted to a completely edentulous state after the extraction of residual teeth. Fabrication of suction denture was planned because it was estimated that the conventional compete would be hard to achieve retention due to the absorption of residual ridge and lack of sublingual fold. Through appropriate clinical and laboratory technique such as preliminary impression on the mandibular rest position, provisional vertical dimension determination with Centric Tray^® (Ivoclar Vivadent AG, Schaan, Liechtenstein), closed mouth definitive impression and jaw relation record using individual tray with Gnathometer M^® (Ivoclar Vivadent AG, Schaan, Liechtenstein), artificial teeth arrangement considering stability of the denture, and proper polymerization technique that minimizes polymerization shrinkage, restoring the patient with suction denture resulted in satisfaction throughout the function and asesthetics.

• Journal of Dental Rehabilitation and Applied Science
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• v.19 no.3
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• pp.169-183
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• 2003

According to our recent investigation that the increase in the occlusal vertical dimension made the appendage muscle strength got higher, the occlusal appliances were made by increasing the occlusal vertical dimension "from the centric relation" position of the mandible. In this experiment, the authors tried to study the change in the appendage muscle strength due to increase in occlusal vertical dimension from intercuspal position(ICP) of mandible with the same subjects and manner as the former experiment. For this study, ten male athletes in a mean age of 23 year who were joined the former study were selected. All the subjects had a complete or almost complete set of natural teeth and reported no subjective symptoms of temporomandibular disorders. Upper and lower casts were mounted on the semi-adjustable articulator at the intercuspal position and a point was marked on the attached gingival area between the right canine and the right 1st. premolar in each upper and lower cast. From the points, the occlusal vertical dimension was increased by 2mm, 3.5mm and 5mm, and then each 10 maxillary type occlusal splint at each 3-increased position were fabricated with heat curing clear acrylic resin. Including the intercuspal position, the 3 kinds of occlusal splints were placed on the subjects individually, and then isokinetic muscle strength on 7 parts of the human appendage which are shoulder, knee, ankle, wrist, forearm, elbow and hip was measured with the CYBEX 6000 SYSTEM (Lumex, NewYork, USA). The results were as follows: The highest mean value in muscular strength was shown at the position of 2mm-increased vertical dimension. The muscle strength during internal/external rotation of shoulder and knee, plantarflexion of ankle, flexion of elbow, and flexion and extension of hip at the increased occlusal vertical dimension position were significantly higher than them at the intercuspal position (p<0.05). Only in view of the increase in the appendage muscle strength, regardless of the way of making the occlusal splints by elevating the occlusal vertical dimension from the centric relation position or intercuspal position, the occlusal splints had an effect on the increase of isokinetic muscle strength at the occlusal vertical dimension which increased within the proper range on the habitual arc of closure.

• The Journal of Korean Academy of Prosthodontics
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• v.32 no.4
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• pp.484-514
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• 1994

Cantilever bridge is widely used by mny clinicians, but its worst mechanical character, so called Class I lever system, makes dentists hesitate to restore the missing tooth with it. Therefore it is important to study stress of the cantilever bridge. In this study, two models of cantilever bridges that restores the missing mandibular second molar with two abutment teeth were constructed. One model was a type of cantilever bridge supported by a normal alveolar bone, the other one was supported by an alveolar bone resorbed to its 1/3 of root length. Maximum bite force(550N) and funtional maximum bite force(300N) were vertically applied to the distal end of the pontic, distal 1/3, and distal half of the pontic. And each force was also applied to centric occlusal contacts as a distributed force. Total 16 loading cases were compared and analyzed with 3-dimensional finite element method. The results were as follows: 1. The stress was concentrated on the joint of the pontic and the retainer, grooves, and distal cervical margin of the posterior retainer. 2. In case of maximum bite force(550N) at the end of the pontic, the risk of fracture at the joint of the pontic and the retainer was high. 3. In case of distributed force in centric occlusion and functional maximum bite force(300N), the stresses were less than the yield strength of the type VI gold for any loading cases. 4. In case of alveolar bone resorption, the occlusal force to the cantilever pontic caused more stress on the root apex and less stress on the alveolar crest region of the distal surface of the posterior abutment. 5. In case of alveolar bone resorption, the displacement was larger than that of normal alveolar bone in all loading cases.

• Journal of Dental Rehabilitation and Applied Science
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• v.38 no.4
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• pp.242-248
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• 2022

Recently, through the development of CAD/CAM technology, it is also being used for fabricating dentures. Compared to conventional methods, when digital dentures are fabricated, the fabrication process is facilitated, and the number of visits to hospitals is reduced and errors are reduced. In this case, the vertical dimension was increased using a CAD program in a patient who needed vertical dimension recovery due to the use of old dentures, and the final denture was fabricated using a monolithic disc through the milling method. The centric relation was recorded using existing dentures, and using the information from the intraoral scan and the existing denture model scan, a trial denture was fabricated and delivered to the patient to evaluate the midline and occlusion. Based on the evaluation of the trial denture, the final denture was fabricated using a milling method and a monolithic disc, and the final denture showed satisfactory results functionally and aesthetically.

• The Journal of Korean Academy of Prosthodontics
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• v.52 no.4
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• pp.346-351
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• 2014

Suction dentures enhance retention and support by forming negative pressure temporarily at the internal surface of denture base at times of swallowing and chewing because the areas surrounding the denture flanges are sealed by mobile mucosa. In this case, an 81-year-old male visited for new dentures. Considering the high expectations for retention and masticatory efficiency of dentures, fabricating complete dentures with suction dentures was planned. Preliminary impression was taken without applying pressure on retromolar pad area and diagnostic cast was fabricated. Afterwards, individual tray was made and final impression was taken, at the same time, gothic arch tracing was done to acquire centric relation and vertical dimension. Then, anatomic teeth were placed on maxilla and non-anatomic teeth were placed on mandible forming lingualized occlusion. Consequently, restoring a complete edentulous patient with complete dentures using mandibular suction denture resulted in recovering satisfying retention and function.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.21 no.2
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• pp.353-365
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• 1991

The author analyzed and compared tomographs with lateral oblique transcranial radiographs of 60 temporomandibular joints from 30 asymptomatic young adults. The results were as follows: 1. The mean height & width of condylar head were 6.82±1.99㎜, 11.98±1.28㎜ in tomographs and 5.41±0.79㎜, 10.67±1.28㎜ in transcranial radiographs. The mean height of articular fossa was 10.19±1.60㎜ in tomographs and 8.44±1.65㎜ in transcranial radiographs. 2. The mean width of articular fossa was 20.71 ±2.98㎜ in tomographs and 17.47±2.58㎜ in transcranial radiographs. There were significant differences in both the height and the width of articular fossa between two radiographic techniques (P<0.01). 3. In centric occlusion, the superior joint spaces were 4.28±1.09㎜, 4.18±1.28㎜, the anterior joint spaces were 2.84±1.02㎜, 2.53±0.72㎜, the posterior joint spaces were 3.11±1.19㎜, 2.66±0.89㎜ in tomographs and transcranial radiographs respectively. There were significant differences in right posterior joint spaces (P<0.05), and posterior joint spaces (P<0.05) between two radiographic techniques. 4. The condylar position in articular fossa was displaced posteroinferiorly (-0.35±4.40㎜ posteriorly, -1.55±1.24㎜ inferiorly) in tomographs and anteroinferiorly (0.45±3.77㎜ anteriorly, -1.29±1.26㎜ inferiorly) in transcranial radiographs with 1 inch opening. In maximum opening, it was displaced anteroinferiorly (5.39±3.63㎜ anteriorly, -1.22±1.67㎜ inferiorly) in tomographs and anteroinferiorly (6.35±4.00㎜ anteriorly, -0.55 ±1.98㎜ inferiorly) in transcranial radiographs. There was significant difference in superoinferior positions of both condyles with maximum opening between two radiographic techniques (P<0.05).

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.22 no.2
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• pp.351-364
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• 1992

Internal derangement of the temporomandibular joint can be defined an abnormal relationships of the meniscus relative to the mandibular condyle, articuar fossa and eminence. This may cause variable mandibular dysfunctions and pain. For diagnosis, arthrography, computed tomography and magnetic resonance imaging are used. In this study, the author reviewed 98 TMJs of 88 patients who were diagnosed as internal derangement througth inferior joint space arthrography at the department of Oral & Maxillofacial Radiology, Dental Hospita, Dankook university through 1986 to 1992. 98 TMJs consisting of 30 disc displcement with reduction, 48 disc displcement without reduction and 20 perforation were studied about clinical and radiological findings. The results were as follows: 1. Internal derangement was found most frequently in the 2nd 3rd decades and the average age of perforation was higher than that of disc displcement with higher than that of disc displcement with reduction. The sexual predilection was 2 times hiher in females. 2. The most frequent chief complaints were TMJ sound in disc displcement with reduction, pain and limitation of mouth opening in disc displcement without reduction and pain in perforation. The duration of the chief complaints was longer in disc displcement with reduction with than in preforation and disc displcement without reduction. 3. Reciprocal click was the most frequently TMJ sound in disc displcement with reduction. History of joint sound in disc displcement without reduction an crepitus in perforation was the most frequent one. 4. The average maximum opening was 45.4㎜ in disc displcement with reduction, 31.4㎜ in disc displcement without reduction and 33.8㎜ in perforation. 5. In the centric occlusion, posterior condylar position was the most frequent in disc displcement with reduction. posterior and concentric condylar position was frequent in disc displcement without reduction, concentric and anterior condylar position in perforation. At 1 inch opening, the same position to articular eminence was most frequently found in disc displcement with reduction, posterior position in disc disp1cement without reduction, posterior and nterior position in perforation was frequently found. 6. Bony changes, especially sclerosis and flattening, was most frequently found in perforation.

• The Journal of Korean Academy of Prosthodontics
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• v.54 no.3
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• pp.291-297
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• 2016

Patients with $Sj{\ddot{o}}gren^{\prime}s$ syndrome usually suffer from teeth discoloration and attrition due to xerostomia. If the anterior teeth are badly worn, problems such as loss of anterior guidance, occlusal disharmony, and limited space for restoration may occur. However, ideal occlusion is obtained in both centric and eccentric relation by regaining the disocclusion of the posterior teeth through the anterior and lateral guidance using twin-stage method. In this case, rehabilitation was performed for a $Sj{\ddot{o}}gren^{\prime}s$ syndrome patient with maxillary and mandibular incisor's severe attrition and teeth discoloration by using twin-stage method.