• Journal of Technologic Dentistry
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• v.34 no.3
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• pp.221-226
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• 2012

Purpose: This study was performed to compare mechanical properties for sintering methods of porous Ti implants. Methods: The specimens of Ti implant were fabricated by several sintering methods. One of them is spark plasma sintering(SPS). Another is electro discharge singering(EDS) and the other is high vacuum sintering(HVS). Mechanical properties of porous Ti implants were evaluated by universal testing machine(UTM) and their fracture surface was examined under a sanning electron microscope(SEM). Results: The tensile strength was in a range of 71 to 230 MPa, and Young's modulus was in a range of 11 to 21 Gpa. It matched with range of cortical bone. Conclusion: Mechanical properties of porous Ti implants were similar to human bone. It was shown that sintering methods of spherical powders can efficiently produce porous Ti implants with various porosities. Porous metals will be commonly used in orthopedic and dental application despite of initial focus has been on bioceramics.

• Clinics in Shoulder and Elbow
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• v.25 no.2
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• pp.154-157
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• 2022

Periprosthetic joint infection (PJI) is one of the most devastating complications that can occur after shoulder arthroplasty. Although staged revision arthroplasty is the standard treatment in many cases, surgical intervention with debridement, antibiotics, and implant retention (DAIR) can be an effective option for acute PJI. We report a complex case of infected reverse shoulder arthroplasty (RSA) in a 73-year-old male. The patient had been previously treated for infected nonunion of a proximal humerus fracture caused by methicillin-resistant Staphylococcus epidermidis. He presented with a sinus tract 16 days after the implantation of RSA and was diagnosed with PJI caused by Serratia marcescens. The patient was successfully treated with DAIR and was free of infection at the last follow-up visit at 4 years postoperatively.

• Archives of Plastic Surgery
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• v.35 no.5
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• pp.589-596
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• 2008

Purpose: The nasal bone fracture is most common fracture in facial bone injuries. Regardless of the severity or type of fracture, closed reduction has traditionally been the common method of treatment. However, through detailed pre-operative evaluation, we found out that many patients consider rhinoplasty prior to trauma due to aesthetic desire or nasal deformity with or without septal deviation. In treatment of nasal bone fracture, we focused not only on the fracture management but also on the patients' desire prior to trauma, and we made additional operation according to patients' desire with fracture reduction and gained rewarding outcomes. Methods: From March 2005 to June 2007, total 263 patients were treated for nasal bone fracture. Among these patients, 57 patients (21%) had the additional operation with nasal fracture reduction. The additional operations were categorized in three types: augmentation rhinoplasty with tip plasty (40%), septoplasty only (16%), corrective rhinoplasty (44%). The mean follow-up period was 5.6 months and results were evaluated by scoring. Results: Forty four of 57 patients (77%) were highly satisfied regardless of any additional operation kinds. The complications were one septal perforation, two displacement of implant and four remnant nasal deformities. For the septal perforation, no further management was performed because we lost the contact with the patient. Then 4 of the other complicated patients were revised. Conclusion: In general, many physicians tend to consider nasal fracture as a simple trauma. However through the strict history taking, physical examination and professional counseling, we could catch the patient's cosmetic desire and get the eyes on new concept: the nasal fracture is not only a trauma but a cosmetic and functional field. In the treatment of nasal bone fracture, if additional rhinoplasty is performed, patients will be more satisfied and we also can expect higher profits.

• The Journal of Korean Academy of Prosthodontics
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• v.34 no.2
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• pp.385-402
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• 1996

The purpose of this study was to analyze how the stability of the implant prostheses and the loosening of the fastening screw was affected when the various types of Hex structure provided for the effect of anti-rotation of the single prostheses were given. Three dimensional finite element model was designed with which the implants with the external hex type of 0.75mm, 1.5mm and the implant with the internal hex type of 0.75mm, 1.5mm and the implant with the external hex type of $15^{\circ}$ tapered shape of 0.75mm were supposed to completely osseointegrate to the mandible. After fininshing the finite element model, the preload of 10N at the fastening screw was applied and then the vertical and $30^{\circ}$ lateral load of 200N was applied respectively at the cusp tips of the prostheses. The following results were obtained : 1. In case of displacement, the amount of displacement was increased at the internal hex type(model C, D) than at the external hex type(model A, B, E) when the vertical and lateral load was applied. 2. Less equivalent stress was represented at the model B with increased external hex height than at the model A when the vertical and lateral load was applied. 3. Much stress was represented at the model E with increased hex angle than at the model A in case of the stress happened to the implant body and the fastening screw when the vertical and lateral load was applied. 4. Much equivalent stress was represented at the model D with deepened internal hex height than at the model C when vertical and lateral load was applied. 5. The least stress was taken at the model B and the most stress was taken at the model D in case of the stress happened to the implant when the vertical and lateral load was applied. 6. The least stress was taken at the model C at the vertical load. And the least stress was taken at the model B at lateral load in case of the stress happened to the fastening screw. As a results of this study, the good lateral stability of prostheses and less stress of the component of implant was taken when the external hex height was increased, and the risk of neck fracture of implant and fastening screw was increased when the internal hex height was deepned because of long screw neck portion and thin implant neck portion.

• The Journal of Korean Academy of Prosthodontics
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• v.40 no.5
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• pp.507-524
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• 2002

Load transfer of implant overdenture varies depending on anchorage systems that are the design of the superstructure and substructure and the choice of attachment. Overload by using improper anchorage system not only will cause fracture of the framework or screw but also may cause failure of osseointegration. Choosing anchorage system in making prosthesis, therefore, can be considered to be one of the most important factors that affect long-term success of implant treatment. In this study, in order to determine the effect of anchorage systems on load transfer in mandibular implant overdenture in which 4 implants were placed in the interforaminal region, patterns of stress distribution in implant supporting bone in case of unilateral vertical loading on mandibular left first molar were compared each other according to various types of anchorage system using three-dimensional photoelastic stress analysis. The five photoelastic overdenture models utilizing Hader bar without cantilever using clips(type 1), cantilevered Hader bar using clips(type 2), cantilevered Hader bar with milled surface using clips(type 3), cantilevered milled-bar using swivel-latchs and frictional pins(type 4), and Hader bar using clip and ERA attachments(type 5), and one cantilevered fixed-detachable prosthesis(type 6) model as control were fabricated. The following conclusions were drawn within the limitations of this study, 1. In all experimental models. the highest stress was concentrated on the most distal implant supporting bone on loaded side. 2. Maximum fringe orders on ipsilateral distal implant supporting bone in a ascending order is as follows: type 5, type 1, type 4, type 2 and type 3, and type 6. 3. Regardless of anchorage systems. more or less stresses were generated on the residual ridge under distal extension base of all overdenture models. To summarize the above mentioned results, in case of the patients with unfavorable biomechanical conditions such as not sufficient number of supporting implants, short length of the implant and unfavorable antero-posterior spread. selecting resilient type attachment or minimizing distal cantilever bar is considered to be appropriate methods to prevent overloading on implants by reducing cantilever effect and gaining more support from the distal residual ridge.

• Journal of Dental Rehabilitation and Applied Science
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• v.25 no.4
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• pp.349-360
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• 2009

Purpose: As the esthetic demands of dental implant patients are increased, the demands of zirconia as implant abutment material are also increased. It has non-metalic color, good biocompatibility, high strength and high toughness. Even thought the advatage of zirconia abutment, there are a few studies about mechanical properties of zirconia abutment. This study evaluated the mecanical strength with compressive bending strength and endurance limit of implant-zirconia abutment assembly. Materials and Methods: Static and cyclic loading of implant-Zirconia abutment assembly were simulated under worst case condition according to ISO. Test groups were implants of external butt joint with straight regular diameter and angled regular diameter zirconia abutment, implant of external butt joint with narrow straight diameter zirconia abutment and implant of internal conical joint with straight narrow diameter zirconia abutment. All test group were evaluated the mecanical strength with compressive bending strength and endurance limit. After fatique testing, fracture surface were examined by SEM. Results: The compressive bending strengths exceed 927N. Regular diameter zirconia abutment were stronger than narrow diameter zirconia abutment(P<.05). The endurance limits ranged from 503N to 868N. Conclusion: Within the limitation of this study, zirconia implant abutment exceeded the estabilished values for maximum incisal biting forces reported in the literature.

• The Journal of Korean Academy of Prosthodontics
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• v.49 no.4
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• pp.283-290
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• 2011

Purpose: This study compared the marginal bone loss around dental implant that were placed in the canine areas of the mandibles and finded the survival rate of implants, marginal bone loss around implants and prosthetic complications in 10 patients treated with overdentures retained with Locator attachments. Materials and methods: Ten patients who had received implant retained overdentures in the mandibules using two implants and Locator attachments at Daegu Catholic University Medical Center from 2004 to 2010 were included in this study. Evaluations of the survival rate of implants, marginal bone loss and prosthetic complications were performed. Results: Implants placed in this study showed a 100% survival rate and the average annual bone loss was 1.03 mm ${\pm}$ 0.20 mm in the first year. The patients have verbally indicated that they are comfortable and that their overdentures function well. But, implant retained overdentures had various prosthetic complications such as male change, relining, rebasing and denture fracture. Conclusion: Implant retained overdentures using two implant and Locator attachments in the fully edentulous mandibles is considered as a stable way for long terms because of minimal invasive operation, simple prosthetic process and easy repair.

• Journal of Dental Rehabilitation and Applied Science
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• v.27 no.2
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• pp.185-195
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• 2011

In this study, titanium abutments and zirconia abutments were connected to each implant in external type implants. After that they were loaded 10000 times with 20Kg as occlusal force. The surface changes of external hexgon part and platform were observed in FESEM image. Viker's hardness of an implant, a titanium abutment and a zirconia abutment were measured respectively. 1. Viker's hardness of an implants, a titanium abutment and a zirconia abutment was $309.80{\pm}11.78$ HV, $318.40{\pm}11.82$ HV, and $1495.30{\pm}16.21$ HV respectively. There was no statistical significance between an implant and a titanium abutment (P>0.05, Anova). However, there was statistical significance between an implant and a zirconia abutment(P<0.05, Anova). 2. The wear was observed at the joint of implant and abutment in both a titanium abutment group and a zirconia abutment group after loading 10,000 times. The zirconia abutment showed more remarkable wear than the titanium one. In conclusion, the wear of external hexagon and platform was much more notable in a zirconia abutment group than a titanium one. It was suggested that it could result from the difference of surface hardness between titanium and zirconia. The wear of junction between an implant and a zirconia abutment becomes more severe, the connection of an implant and an abutment is much more unfit. This is likely to cause loosening and fracture of the abutment screw. so it is considered that the possibility of implant supra-structure failure can be increased.

• Journal of Dental Rehabilitation and Applied Science
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• v.37 no.3
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• pp.147-156
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• 2021

There are various treatment options such as conventional complete denture, hybrid prosthesis and implant-supported fixed prosthesis for fully edentulous patients. In case of implant-supported fixed prosthesis, compared to removable prosthesis, it is difficult to place the implant in the correct position considering the anatomical contours of the final prosthesis. In this case, a full mouth rehabilitation with implant-supported fixed prosthesis was performed for a patient who required extraction of all remaining teeth due to dental caries and chronic periodontitis. In the implant placement stage, the implant was placed in the desired position using a surgical guide fabricated considering the anatomical contours of the final prosthesis, and the function and esthetics were evaluated through correction and re-fabrication of the fixed provisional restoration. A final restoration of porcelain fused to gold prosthesis was delivered to the patient based on the provisional restoration. To cope with complications such as loosening of screws and fracture of porcelain, a screw-retained type prosthesis was fabricated for the posterior part and a screw-cement-retained type prosthesis for the anterior part. As a result, the patient showed an improved prognosis in terms of functional and esthetics after the final prosthesis was delivered.

• Journal of the Ergonomics Society of Korea
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• v.27 no.2
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• pp.83-89
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• 2008

Study was developed the metallic plate for fixation in the femur fracture and plates has a firm place in fracture treatment. This plates can be stabilized for fracture fixation as well as biological and dynamical device. The device's designation and sizing has a optimization with bending structural stiffness and strength, known meaning that is reliable regardless of the plate by the short type and long type. The bending strength of the curved metallic long plate has to evaluate a 11,000N and the bending strength of the curved metallic short plate has to evaluate a 6,525N. This see the X-ray image of bending angle made certain of 15$^{\circ}$ at number 2 and same 82.87$^{\circ}$ at number 2, 4, 5, 7, 8, 9, 10 by outside angle, and confirmed 25.26$^{\circ}$ at number 3, 3.68$^{\circ}$ at number 6, 15.64$^{\circ}$ at number 9 by inside angle. This study shows that keep up the metallic plate for fixation in the femur fracture through X-ray Image and the device can be used to support Revision case of Hip Implant and to use a case of Hip screw compression of Hip Neck Fracture. Short plate have a wrapping of femur and long plate have to preserve a pole of femur.