• The Journal of Korean Academy of Prosthodontics
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• v.50 no.4
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• pp.243-248
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• 2012

Purpose: The purpose of this study is to compare the removal torque between prefabricated and customized implant abutment screw. Materials and methods: Three types of implant system (Osstem, Astra, Zimmer) were used. For each system, prefabricated abutment screw (control group) and customized abutment screw (test group) were used to connect the fixture and the abutment (n = 6). Digital torque gauze was used to control the tightening torque and the screws were tightened under each manufacturer's recommendation. 10 minutes after the connection the same tightening torque was applied, and 5 minutes after the second connection, the removal torque was measured. This procedure was repeated 10 times. In the cyclic loading test, 10 minutes after the first connection to the 6 groups (n = 3), the same tightening torque was applied, and a total of 1,000,000 time loading was applied at 30 degree angle to long axis with 50 N load. Repeated measures of ANOVA test (${\alpha}$=.05) was used as statistics to evaluate the effect of repeated loading number on the removal torque. Independent t-test was used to evaluate the difference in removal torque after cyclic loading. Results: The removal torque significantly decreased as the number of loading repetition increased (P<.05). In the 10 time repetition test, there was no significant difference between the prefabricated and customized implant abutment screw of the 3 implant system (P<.05). Also in the cyclic loading test, there was no significant difference between the prefabricated and customized implant abutment screw of the 3 implant system (P<.05). Conclusion: Within the limitation of this study, there was no significant difference in the removal torque between the prefabricated abutment screw and customized abutment screws.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.486-491
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• 2004

A comparative study on the implant screw loosening under the initial clamping force and cyclic loads was conducted. The experiments were performed to evaluate the screw loosening behavior of the internal and external implant systems. It was found that the screw loosening torques of implant systems were significantly affected by the way how the abutment and fixture were connected due to the difference in the load transfer mechanism between abutment and fixture.

• The Journal of the Korean dental association
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• v.47 no.12
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• pp.798-803
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• 2009

지르코니아는 물리적 성질이 금속과 가장 가까운 세라믹이며, 색상이 치아와 비슷하여 치과분야에서 사용빈도가 증가하고 있는 재료이다. 지르코니아는 zirconium dioxide 결정체로서, 1975년 Garvie가 'ceramic steer' 이라고 명명하였듯이 기존의 세라믹과 비교하여 뛰어난 물성을 지니고 있다. 즉, 높은 내열성과 낮은 열전도도, 산성에서 알카리성까지 이르는 내화학 안정성, 낮은 열팽창성, 높은 강도 및 경도, 내마모성을 가지고 있기 때문에 이전부터 공업용 재료로 넓게 시용되어 왔다. 지르코니아의 상변 이를 이용한 toughening방법이 Garvie에 의해 제시됨으로서 세라믹의 최대 단점인 취성은 어느 정도 극복할 수 있게 되었고 이를 계기로 금관 및 계속가공 의치, 임플란트 지대주, 인레이, 온레이 등 치과의 여러 분야에 지르코니아를 적용할 수 있게 되었다. 최근에는 임플란트 매식체에 있어서도 그 적용을 시도함으로서 심미치과치료에 있어서 중요한 부분으로 자리 잡고 있다. 현재 지르코니아는 치과용 세라믹 중에서 가장 높은 기계적 물성을 보이기 때문에 구치부 에서의 사용 가능성이 시도되고 있으며, 코어의 두께를 감소시킴으로써 보철 술식에서 필요한 강도 및 심미성 두 마리 토끼를 잡을 수 있도록 많은 연구가 이루어지고 있다. 이에 지르코니아의 역사 및 이론적 배경에 대하여 알아보고자 한다.

• The Journal of Korean Academy of Prosthodontics
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• v.54 no.2
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• pp.103-109
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• 2016

Purpose: This study is to evaluate the clinical significance of implantation with simultaneous bone graft by comparing the marginal bone loss around maxillary anterior implants with or without bone graft. Materials and methods: Patients treated with implant-retained restorations on maxillary anterior region at Implant Center, Dental Hospital, Wonkwang University between June 2011 and May 2014 were included in this study. Date of implant placement, implant diameter, implant length, implant-abutment connection type and whether the bone graft was done were investigated. The patient's periapical radiographs taken immediately after implantation and at the most recent visit were compared. Marginal bone loss was measured using Emago advanced v5.6 program (Oral diagnostic systems, Amsterdam, Netherlands). Statistical analysis was done in independent t-test by using SPSS 22.0 program. Results: As a result of observing on 83 implants (without bone graft: 44, with bone graft: 39) of 52 patients for 6 - 45 months (average: 18.4 months), implants without bone graft showed $1.42{\pm}0.42mm$, implants with bone graft showed $1.28{\pm}0.45mm$ of marginal bone loss. Conclusion: In limitations of this study, implants with simultaneous bone graft had significantly less marginal bone loss than implants without bone graft.

• The Journal of Korean Academy of Prosthodontics
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• v.60 no.1
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• pp.127-134
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• 2022

Among many contributing factors of implant failure, excessive loading and inflammation contribute mainly to increasing implant failure rate. Especially, poor oral hygiene around implants is one of the most common reasons for implant failure. When implant prosthesis fails to function, the clinician should re-diagnose and plan treatment using the remaining implants. Additional implantation may be needed to make a new type of prosthesis or either implant-assisted RPD and implant overdenture treatment may be performed using the remaining implants. In this article, a patient whose fixed implant prosthesis in the maxilla had failed of poor oral hygiene maintenance was reported to be recovered with removable implant overdenture by using remaining implant abutments and a milled bar with additional retentive elements. Through this treatment, the clinical results were satisfactory in terms of esthetics, masticatory function recovery and oral hygiene management.

• The Journal of Korean Academy of Prosthodontics
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• v.58 no.4
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• pp.356-362
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• 2020

All the faculties at the prosthodontic department in Kyung Hee University Dental Hospital at Gangdong, have been implementing the Top-Down concept of treatment approach since 2006 in which the outcomes of the last prosthetic treatment are predicted in advance during the treatment planning stage of patients with dental tissue defects. Based on the Top-Down concept, this report is also an example of how the final prosthetic treatment was performed in advance before going into implant surgery for the missing teeth. Among the various methods of connecting implant fixture and restoration, the cement-retained method is relatively simple to manufacture restoration without being constrained by the angle of the implants placed, but difficult to remove remaining subgingival excess cement completely, and to detach it being when necessary. In the report, SB-locking method will be introduced which enables an aesthetic implant restoration without either a screw hole or residual excess cement.

• Journal of Dental Rehabilitation and Applied Science
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• v.34 no.1
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• pp.46-55
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• 2018

Oral rehabilitation of a patient having severe periodontitis with alveolar bone resorption and periodontal inflammation presents a challenge to clinicians. However, if appropriate implant placement according to the bone shape is selected, unnecessary bone grafting or soft tissue surgery can be minimized. In recent years, using cone beam CT and software, it has become possible to operate the planned position with the surgical guide made with 3D printing technology. This case was a 70 years old female patient who required total extraction of teeth due to severe periodontitis and performed a full-mouth rehabilitation with an implant - supported fixed prosthesis. During the surgery, the implant was placed in a flapless manner through a surgical guide. Immediate loading of the temporary prosthesis made by CAD/CAM method before surgery was done. Since then, we have produced customized abutments and zirconia prostheses, and have reported satisfactory aesthetic and functional recovery.

• The Journal of Korean Academy of Prosthodontics
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• v.53 no.2
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• pp.105-110
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• 2015

Purpose: The purpose of this study was to evaluate the 3 dimensional accuracy of impression taking on the newly developed healing abutment and impression coping combined system comparing conventional pick-up type impression. Materials and methods: For 10 patients who had a single missing tooth on molar area, dental implants (SuperLine; Dentium, Seoul, Korea) were placed and healing abutment (MyHealing; Raphabio Co., Seoul, Korea) abutments were connected. After 3 months, transfer type impression with MyHealing and pick-up type impression with impression coping were performed twice in the same patients, and master models were fabricated. Customized prosthetic abutments (Myplant; Raphabio Co., Seoul, Korea) were milled and connected to the master casts. Through a dental scanner (Scanner S600; Zirkonzahn, South Tyrol, Italy), the master casts were converted into virtual casts. The length and angulation differences between casts were measured using 3 dimentional analysis program (Geomagic Qualify 12; Geomagic, Morrisville, NC, USA). Statistical significance was calculated using Kruskal Wallis test and Mann-Whitney U test (${\alpha}$=.05). Results: The length differences between the two systems were 0.032 mm in sagittal plane, and 0.029 in coronal plane, and 0.023 mm in horizontal plane. The angulation differences were $0.755^{\circ}$ in sagittal plane, and $1.275^{\circ}$ in coronal plane, and $0.420^{\circ}$ in horizontal plane. Conclusion: The accuracy of newly developed healing abutment system is similar to that of conventional pick-up impression. The new system can reduces chair time by not using separate impression coping.

• The Journal of Korean Academy of Prosthodontics
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• v.54 no.4
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• pp.458-467
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• 2016

Cement-retained implant prosthesis has several advantages in the esthetic and occlusal aspects. However, the difficulty of the retrievability and the possibility of peri-implantitis induced by the cement excess would be a threatening factor to the implant prognosis. Peri-implantitis resulting from the remaining cement could occur later on to the patients with periodontitis history. Retention can be controlled by selecting the right cement type. Retention of the cement was the strongest in the resin cement, followed by resin modified glass ionomer cement, poIycarboxylate cement, zinc phosphate cement and glass ionomer cement. Retention of the provisional cement weakened after thermocycling. Other factors such as the abutment number, abutment alignment, height and taper of the abutment can also affect the total retention. To the success of the cement-retained prosthesis, it's important to select the right cement for the clinical purpose. The prosthesis should be fabricated in accordance with the biomechanical requirements. The prosthesis should be cemented with the techniques to reduce the excess cement as much as possible. In addition, the excess cement should be identified using the radiography and carefully removed.

• The Journal of Korean Academy of Prosthodontics
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• v.60 no.4
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• pp.431-441
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• 2022

The digital facebow device records the trajectory of the mandibular movement where it is then reflected on the computer-aided design software, leading to an improvement on treatment outcomes of prosthetic restorations. In this clinical case, using a digital technology, an implant placement and prosthetic restoration were done in a patient who has lost maxillary and mandibular molars. Following an intraoral scan, a surgical stent for implant surgery was fabricated based on digital diagnostic wax-up, and implants were installed. After six months of sufficient osseointegration, customized abutments and the first temporary prostheses were delivered. Then two months later, at an abutment level, an intraoral scan and digital facebow transfer device were used to mount the intraoral scan data on a virtual articulator, and record the mandibular movements. Once the second temporary prostheses were fabricated and delivered on a basis of the mandibular movement, the definitive zirconia prostheses were designed and delivered based on a stabilized occlusion that was duplicated via double scan technique.