• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.12 no.1
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• pp.21-26
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• 1982

A radiologic study of 139 dentigerous cysts (128 patients) indicated the followings: 1. There was higher incidence in males (62.99%) than in females (37.01%). The most common age group was 11-20 years and the average age was 23.6 years. 2. The most common clinical symptoms was swelling of the jaws (49 cases, 33.09%), and no symptoms was presented in 26 cases (18.71%). 3. Dentigerous cysts were found to be slightly more common in the maxilla (53.24%) than in the mandible (46.76%) and there was almost no difference in occurance between right and left side. The maxillary supernumerary tooth was the most frequent site of the dentigerous cyst and no dentigerous cyst was found to be related to a deciduous tooth. 4. The most common radiographic findings was root resorption of the adjacent teeth (33.09%), and the central dentigerous cysts were 78 cases (56.12%), the lateral dentigerous cysts were 61 cases (43.88%). 5. The increased radiolucency at the crown portion of the tooth in a cystic cavity was seen in 44 cases (31.65%), and a case of dentigerous cyst was found in a edentulous patient, and 16 cases of multiple dentigerous cysts were found in 5 patients. 6. The ameloblastic changes in 8 cases, the keratinization of the cyst wall in 2 cases, and a case of epidermoid carcinoma were confirmed microscopically.

• Imaging Science in Dentistry
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• v.46 no.1
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• pp.39-45
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• 2016

The incidental finding of an enlarged mastoid foramen on the right posterior mastoid region of temporal bone is reported, together with a discussion of its clinical significance. A 67-year-old female underwent the pre-implant assessment of a maxillary left edentulous region. A cone-beam computed tomographic (CBCT) image was acquired and referred for consultation. Axial CBCT slices revealed a unilateral, well-defined, noncorticated, low-attenuation, transosseous defect posterior to the mastoid air cells in the right temporal bone. The borders of the osseous defect were smooth and continuous. No other radiographic signs suggestive of erosion or sclerosis were noted in the vicinity. The density within the defect was homogenous and consistent with a foramen and/or soft tissue. The patient's history and physical examination revealed no significant medical issues, and she was referred to a neuroradiologist for a second opinion. The diagnosis of an enlarged mastoid foramen was made and the patient was reassured.

• Journal of Periodontal and Implant Science
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• v.38 no.3
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• pp.445-452
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• 2008

Purpose: The purpose of this study was comparison of survival rate of implant as two sinus elevation techniques and when window opening procedure had done it was comparison of survival rate of implant between the procedure of implantation after 6 month of sinus elevation to allow healing period and that of implantation with sinus elevation simultaneously. Material and Methods: All 79 of patients treated at DanKook University Dental Hospital Dept. of Periodontics for 164 implantation of maxillary posterior edentulous area with sinus elevation. Sinus elevation technique was divided of the technique : Osteotome technique and window opening technique. Result: 14 implants among 96 implants was failed implants of using osteotome for sinus elevation whereas one implant of 68 implants was failed of using window opening technique. Conclusion: Window opening technique had higher survival rate than osteotome technique. In case of window opening, there was no significant difference of immediate implantation and delayed implantation.

• Journal of Technologic Dentistry
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• v.42 no.1
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• pp.27-33
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• 2020

Purpose: This study is to compare and analyze the precision of glass fiber resin dentures. Methods: A lower edentulous model was prepared. Ten study models were produced using Type IV stone. Ten wax lower resin dentures containing artificial teeth were prepared. The lower wax denture was buried with plaster and deflasking was performed to remove the wax. Five conventional lower resin dentures and five glass fiber lower resin dentures were produced. The scanning spray was coated on the impression surface and then scanned. Independent sample t-test were performed using statistical software. Results: In the color different map, which is a qualitative evaluation, the green area of the precision of the conventional lower resin denture occupied the whole. The glass fiber conventional resin dentures had many negative and positive area. In quantitative evaluation, the RMS of conventional lower resin was 89.83 ㎛ and that of fiberglass resin was 224.92 ㎛. The two groups showed statistically significant differences (p<0.05). Conclusion: Conventional lower resin dentures were superior in precision, and glass fiber resin dentures would have to improve the process.

• The Journal of Korean Academy of Prosthodontics
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• v.34 no.3
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• pp.611-619
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• 1996

The purpose of this study was to evaluate the fitness of 4 kinds of resin record base materials. The record base materials used on the edentulous cast in this study were Triad VLC resin (Dentsply International Inc., U.S.A.), custom tray resin (Kerr Ltd., U.S.A.), heat-cure resin (Dentimex Co., Holland), and self-cure resin (Dentimex Co., Holland). The gap width between record base and cast were measured in the ridge crest and midpalatal area with microhardness tester. The results obtained were as follows : 1. Among the 4 kinds of record base, heat-cure Vertex fitted best on the cast. Triad and Fomatray fitted better than self-cure Vertex. Self-cure Vertex had the poorest fit. 2. The quality of the fit of the record base varied at different locations on the cast. The record base fit better in the ridge crest than midpalatal area. 3. In the midpalatal area, there's no significant difference in the fit of Fomatray, Triad and heat-cure Vertex. They all fit better than self-cure Vertex. 4. In the ridge crest, heat-cure Vertex fit better than any other record base.

• Journal of Technologic Dentistry
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• v.8 no.1
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• pp.85-90
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• 1986

The effect of splinting on aqbutment tooth distal movement was performed in vitro study. An acrylic resin mandibular model with missing 2nd premolars, molars and a removable partial denture framework were constructed. The roots of the canines, 1st premolars and edentulous ridges were coated with silicone rubber. A modified Ney Surveyor was used for vertical load appkication, and abutment tooth distal movement were measured with a dial gauge with four conditions of splinting methods were tested by applying unilateral vertical loadings. The results are follows; 1. The magnitude of abutment tooth distal movement on the non-load side was less 40$\sim$69% than that occurred on the load side. 2. On the load side, reducing effect of splinting on abutment tooth movement in the condition of load side double abutment(30%), non-load side double abutment(10%), double abutments of both sides(40%) was compared with single abutments of both sides. 3. On the non-load side, reducing effect of splinting on abutment tooth movement in the condition of load side double abutment(5%), non-load side double abutment(22%), double abutments of both sides(59%) was compared with single abutments of both sides. 4. The magnitude of abutment tooth distal movement in the condition of double abutments of both sides was less 40$\sim$59% than that in the condition of single abutments of both sides.

• Journal of Technologic Dentistry
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• v.43 no.3
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• pp.84-92
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• 2021

Purpose: The purpose of this study was to compare the dimension safety evaluation between a general ultrasonic cleaner and an ultrasonic cleaner equipped with UV-C (ultraviolet-C). Methods: An edentulous model was prepared. A denture base and an occlusal rim were fabricated, and scanning was performed. After scanning, a denture base and full arch artificial teeth were designed. The full arch artificial teeth were printed using a three-dimensional printer (n=10). The residual resin was washed with alcohol and then scanned (reference data). The printed specimens were classified and cleaned using a general ultrasonic cleaner (GU group) and an ultrasonic cleaner equipped with UV-C (UC group). After each washing, a rescan was performed (scan data). Reference data and scan data were superimposed using overlapping software. Data were statistically analyzed using the Mann-Whitney test (α=0.05). Results: In the deviation values of full arch artificial teeth, the GU group showed a high deviation of 18.02 ㎛ and the UC group showed a low deviation of 15.02 ㎛. The two groups demonstrated a statistically significant difference (p<0.05). Conclusion: Full arch artificial teeth prepared using photopolymerized resin were deformed according to the temperature of water generated in the ultrasonic cleaner. It is judged that there is no deformation according to the UV-C ultrasonic cleaner.

• The Journal of Advanced Prosthodontics
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• v.11 no.2
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• pp.112-119
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• 2019

PURPOSE. Zirconia materials have been used for implant-retained restorations, but the stress distribution of zirconia is not entirely clear. The aim of this study is to evaluate the stress distribution and risky areas caused by the different design of zirconia restorations on the atrophic bone of the posterior maxilla. MATERIALS AND METHODS. An edentulous D4-type bone model was prepared from radiography of an atrophic posterior maxilla. Monolithic zirconia and zirconia-fused porcelain implant-retained restorations were designed as splinted or non-splinted. 300-N occlusal forces were applied obliquely. Stress analyses were performed using a 3D FEA program. RESULTS. According to stress analysis, the bone between the 1) molar implant and the 2) premolar in the non-splinted monolithic zirconia restoration model was stated as the riskiest area. Similarly, the maximum von Mises stress value was detected on the bone of the non-splinted monolithic zirconia models. CONCLUSION. Splinting of implant-retained restorations can be more critical for monolithic zirconia than zirconia fused to porcelain for the longevity of the bone.

• The Journal of Korean Academy of Prosthodontics
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• v.59 no.1
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• pp.36-42
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• 2021

Even though implant overdentures are preferentially recommended to mandibular edentulous patients, many patients may select conventional complete dentures due to cost and general condition. Proper retention and stability of conventional complete dentures in patients with severe alveolar bone resorption is difficult to achieve. To overcome the limitations, mandibular suction dentures with the closed mouth impression technique have been used. However, the previous technique requires the Frame cut back tray, the Centric tray, and the Gnathometer M. This article introduces a technique for fabricating a mandibular suction denture with common dental materials.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.12
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• pp.105-112
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• 2020

The increase in the edentulous jaw which occurs in the aged population has led to personal dental health concerns. In the case of dental implant surgery, the duration of a patient's recovery depends on the surgical plan and their physicical ability. A device may be required to assist a physician in controlling vibration reduction of free-hand drilling and prescribing a good treatment plan that is suitable for the patient's condition. In this work, an artificial tooth-root implant assistant manipulator was studied. The structure and the vibration analysis of the dynamic restraint manipulator that is for drilling the alveolar bone in the mandible bone were performed, and the structural stability was analyzed. Further, a virtual prototype of an artificial tooth-root implant assisted manipulator was fabricated and tested. Hence, the state of the Remote Center of Motion (RCM) point and the driving state of the manipulator were confirmed. Furthermore, the drilling experiments were performed by using materials similar to a human jawbone in order to evaluate the performance of the drilling process that is operated using the assistant manipulator.