• The Journal of Advanced Prosthodontics
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• 제2권1호
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• pp.1-3
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• 2010

BACKGROUND. Even though excellent impression materials are now available for making accurate replication for hard and soft tissue, the numerous dentists have faced lots of obstacles in making simultaneous impressions of multiple abutments. CASE DESCRIPTION. This article describes a modified method of tray fabrication using auto-polymerizing acrylic resin and impression technique for multiple prepared teeth in cases with limitations and difficulties in taking dental impressions. CLINICAL IMPLICATION. This segmental tray technique has several advantages, including higher impression quality, fewer impressions, and being more comfortable for the patient and less stressful for the clinician.

• The Journal of Advanced Prosthodontics
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• 제10권1호
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• pp.65-72
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• 2018

PURPOSE. The aim of this in vitro study was to investigate the fracture resistance under chewing simulation of implant-supported posterior restorations (crowns cemented to hybrid-abutments) made of different all-ceramic materials. MATERIALS AND METHODS. Monolithic zirconia (MZr) and monolithic lithium disilicate (MLD) crowns for mandibular first molar were fabricated using computer-aided design/computer-aided manufacturing technology and then cemented to zirconia hybrid-abutments (Ti-based). Each group was divided into two subgroups (n=10): (A) control group, crowns were subjected to single load to fracture; (B) test group, crowns underwent chewing simulation using multiple loads for 1.2 million cycles at 1.2 Hz with simultaneous thermocycling between $5^{\circ}C$ and $55^{\circ}C$. Data was statistically analyzed with one-way ANOVA and a Post-Hoc test. RESULTS. All tested crowns survived chewing simulation resulting in 100% survival rate. However, wear facets were observed on all the crowns at the occlusal contact point. Fracture load of monolithic lithium disilicate crowns was statistically significantly lower than that of monolithic zirconia crowns. Also, fracture load was significantly reduced in both of the all-ceramic materials after exposure to chewing simulation and thermocycling. Crowns of all test groups exhibited cohesive fracture within the monolithic crown structure only, and no abutment fractures or screw loosening were observed. CONCLUSION. When supported by implants, monolithic zirconia restorations cemented to hybrid abutments withstand masticatory forces. Also, fatigue loading accompanied by simultaneous thermocycling significantly reduces the strength of both of the all-ceramic materials. Moreover, further research is needed to define potentials, limits, and long-term serviceability of the materials and hybrid abutments.

• 구강회복응용과학지
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• 제26권3호
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• pp.273-283
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• 2010

이 연구는 다수의 임플란트에 의해 지지되는 보철물과 단일 임플란트 보철물에서 호환 가능한 세 가지 종류의 나사의 풀림토크값을 측정하여 나사 결합부 안정성에 차이가 있는지를 알아보고자 하였다. 이를 위해, 네 개의 외부 육각 임플란트에 직접 연결되는 임플란트 상부구조물을, 아크릴릭 레진을 이용한 연결인상법으로 얻은 총 6개의 실험모형에 20 Ncm의 힘으로 조인 후, 각 나사의 풀림토크값을 총 2회 측정하였다. 사용한 지대주 나사는 토크타이트(TorqTite), 골드타이트(Gold-Tite), 그리고, 티타늄(Titanium) 나사였다. 또한, 단일 임플란트 수복의 경우 를 가정하여 총 5개의 실험모형 상의 2개의 임플란트에, 한 개의 지대주(GoldAdapt Engaging)를 다시 세 종류의 나사로 연결한 후, 각 나사의 풀림토크값을 총 2회 측정하였다. 나사의 풀림토크값의 비교를 위한 통계적 분석을 혼합모형(mixed model)을 이용하여 유의수준 .05에서 실시한 결과, 다수 임플란트 지지 상부구조물의 경우, 나사의 종류에 따른 풀림토크값은 통계적으로 유의성 있는 차이를 보이지 않았다(p>0.05). 그러나 단일 임플란트 지대주의 경우에는 통계적으로 유의성 있는 차이를 보였으며(p=0.0175), 토크타이트 나사(p=0.0462)와 티타늄 나사(p=0.0348)는 각각, 골드타이트 나사보다 유의성 있게 큰 풀림토크값을 보였으나, 두 나사 간에는 유의성 있는 차이가 없었다(p>0.05). 이상의 연구 결과로 보아, 서로 다른 종류의 나사가 나사 결합부의 초기 안정성에 미치는 영향은, 단일 임플란트 보철물의 경우에서와는 달리, 다수의 임플란트에 의해 지지되는 보철물의 경우에는 미미하다고 할 수 있다.

• 한국지진공학회논문집
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• 제8권1호
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• pp.77-86
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• 2004

본 논문은 강교좌장치를 가지고 있는 연속 강교량을 지진으로부터 보호하기 위해서 형상기억합금을 이용한 장치를 제안했다. 예로 사용하고 있는 연속 강교량은 고정단을 가진 교각에 지진하중이 집중하고 상당히 큰 상부구조의 중량으로 인하여 교각에 손상을 입기 쉽고 상판의 교대에 대한 충돌로 교대의 수동변위가 크게 나타날 수 있다. 본 연구에서는 두 가지 종류의 restrainer-damper가 제안되었으며 지진해석을 통해서 효과를 검증하였다. 또한 미주에서 일반적으로 사용되고 있는 강재 케이블의 restraoiner와 성능을 비교하였다.

• 대한치과보철학회지
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• 제33권1호
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• pp.32-47
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• 1995

The purpose of this study was to determine the displacement of prosthesis & abutment and the stress distribution patterns induced in the periodontium by applying force to the fixed prosthesis. Two levels of periodontal support were compared using two-dimensional finite element stress analysis after placement of 3unit or 4 unit fixed partial denture(FPD) in case of missing of the lower first molar. Concentrated vertical load was delivered at the cusp tip of the second bicuspid or the central fossa of the pontic. The following results were obtained : 1. The greater the loss of alveolar bone in abutment teeth area, the greater the displacement of FPD and the stress concentration in alveolar bone around abutment. 2. The amount and direction of displacement and distribution of stress in the 4-unit FPD was better than those in the 3-unit FPD. 3. Multiple abutments reduced the amount of mesial and downward displacement of the weaked abutments and more uniformly distributed the stresses.

• The Journal of Advanced Prosthodontics
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• 제10권5호
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• pp.381-387
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• 2018

PURPOSE. Cement-retained implant prostheses can lack proper retrievability during repair, and residual cement can cause peri-implantitis. The purpose of this in vitro study was to evaluate the influence of abutment height and convergence angle on the retrievability of cement-retained implant prostheses with lingual slots, known as retrievable cement-type slots (RCS). MATERIALS AND METHODS. We fabricated six types of titanium abutments (10 of each type) with two different heights (4 mm and 6 mm), three different convergence angles ($8^{\circ}$, $10^{\circ}$, and $12^{\circ}$), a sloped shoulder margin (0.6 mm depth), a rectangular shape ($6mm{\times}6.5mm$) with rounded edges, and a rectangular ledge ($2mm{\times}1mm$) for the RCS. One monolithic zirconia crown was fabricated for each abutment using a dental computer-aided design/computer-aided manufacturing system. The abutments and crowns were permanently cemented together with dual-curing resin cement, followed by 24 hours in demineralized water at room temperature. Using a custom-made device with a slot driver and torque gauge, we recorded the torque ($N{\cdot}cm$) required to remove the crowns. Statistical analysis was conducted using multiple regression analysis and Mann-Whitney U tests (${\alpha}=.05$). RESULTS. Removal torques significantly decreased as convergence angles increased. Multiple regression analysis showed no significant interaction between the abutment height and the convergence angle (Durbin-Watson ratio: 2.186). CONCLUSION. Within the limitations of this in vitro study, we suggest that the retrievability of cement-retained implant prostheses with RCS can be maintained by adjusting the abutment height and convergence angle, even when they are permanently cemented together.

• 한국강구조학회 논문집
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• 제19권6호
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• pp.587-597
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• 2007

강케이블 변위제어장치는 미국 캘리포니아주에서 프레임 구조 교량의 낙교를 방지하는데 효과적인 것으로 지난 몇 차례의 지진에서 밝혀졌다. 이러한 효과를 바탕으로, 미국 중부의 다경간 단순지지 교량에 강케이블을 적용할려는 시도가 행해지고 있다. 또한, 형상기억합금의 인장거동을 이용한 변위제어장치가 동일한 적용을 위해서 연구되고 있다. 프레임 구조교량에서는 변위제어장치가 교각에 힘을 전달하지만, 다경간 단순지지 교량에서는 교대에 힘을 전달하게 된다. 따라서 이러한 교량에서는 교대의 거동을 동시에 점검해야한다. 본 연구에서는 다경간 단순지지 교량에 대한 세 가지의 변위제어장치의 성능을 비교하였다. 강케이블, 인장거동 형상기억합금 봉 및 휨거동 형상기억합금 봉을 이용한 변위제어장치의 중진 및 강진에 대한 변위제어성능 및 교대에 미치는 영향을 분석하였다. 이를 위해서 형상기억합금 봉의 휨 실험 및 해석모델을 제시하였다. 또한, 비선형 시간이력해석을 수행하여 원래의 교량과 보강된 교량의 거동을 비교하여 변위제어장치의 성능 및 영향을 파악하였다. 인장거동의 형상기억합금 봉은 내부힌지에서 열림의 상대변위를 제어하는데 가장 우수한 성능을 보여주었으나, 교대의 능동변위를 증가시켜 손상을 발생시켰다. 따라서 강진에 대해서는 변위제어장치를 설치하는 경우 교대의 능동거동에 대한 보강이 요구된다.

• 대한치과의사협회지
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• 제54권3호
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• pp.191-197
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• 2016

In the past, restoration of implant crown, ready-made abutment produced by implant manufacturer could only be used. Using straight, angled abutment, there was a limit in adaptation multiple implants. Recently, with the development of implant and CAD/CAM technology, CAD/CAM customized abutment use has become possible which is different from the past when restoration was possible with only prefabricated abutment. Not only it makes emergence profile possible which is similar to natural teeth, but also it makes insertion path possible on CAD in multiple implant restorations. However, on anterior teeth which dental esthetics is very important, another restorations which are formed with natural colored gingiva area could be required. Titanium-based zirconia prostheses which have titanium connection and zirconia structure from 1mm above fixture platform are alternative. Therefore, the purpose of this review is to analyze the characteristics, advantages and disadvantages of the abutment which is used in multiple implant restorations, and to choose right abutment when clinical trials.

• 대한치과기공학회지
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• 제39권1호
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• pp.35-42
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• 2017

Purpose: The purpose of this paper was to evaluate the occurrence of errors regarding adaptation by conducting a three-dimensional assessment comparing the bridge type dental restoration after the cutting process, which has multiple abutments, with a single type dental restoration. Methods: By using ten identical files obtained by scanning the master model, thirty designs were created consisting of ten maxillary right first premolars and ten maxillary right first molars with single crown abutments, along with ten bridge designs with the identical abutment. A 5-axis milling machine was used to produce the design file. The produced denture prostheses were scanned using a silicone replica for a STL file. An evaluation was conducted using 3D analysis software on the master model and each of the thirty data files. Results: The RMS value of the pre-molar (14) was $38.4{\pm}4{\mu}m$ for single and $54.7{\pm}6{\mu}m$ for bridge abutment; therefore, a statistically significant difference was observed for single and bridge designs although both shared the same abutment form (P<.05). Also, the RMS value of the molar (16) was $47.6{\pm}2{\mu}m$ and $56.6{\pm}5{\mu}m$ for the single and bridge designs, respectively, thereby presenting a statistically significant difference (P<.05). Conclusion: As a result, dental prosthesis fabricated using the single method presented better internal adaptation outcomes.

• The Journal of Advanced Prosthodontics
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• 제7권3호
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• pp.183-190
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• 2015

PURPOSE. This study evaluated the fracture load of customized zirconia abutments with titanium insert according to preparation depths, with or without 5-year artificial aging. MATERIALS AND METHODS. Thirty-six identical lithium disilicate crowns (IPS e.max press) were fabricated to replace a maxillary right central incisor and cemented to the customized zirconia abutment with titanium insert on a $4.5{\times}10$ mm titanium fixture. Abutments were fabricated with 3 preparation depths (0.5 mm, 0.7 mm, and 0.9 mm). Half of the samples were then processed using thermocycling (temperature: $5-55^{\circ}C$, dwelling time: 120s) and chewing simulation (1,200,000 cycles, 49 N load). All specimens were classified into 6 groups depending on the preparation depth and artificial aging (non-artificial aging groups: N5, N7, N9; artificial aging groups: A5, A7, A9). Static load was applied at 135 degrees to the implant axis in a universal testing machine. Statistical analyses of the results were performed using 1-way ANOVA, 2-way ANOVA, independent t-test and multiple linear regression. RESULTS. The fracture loads were $539.28{\pm}63.11$ N (N5), $406.56{\pm}28.94$ N (N7), $366.66{\pm}30.19$ N (N9), $392.61{\pm}50.57$ N (A5), $317.94{\pm}30.05$ N (A7), and $292.74{\pm}37.15$ N (A9). The fracture load of group N5 was significantly higher than those of group N7 and N9 (P<.017). Consequently, the fracture load of group A5 was also significantly higher than those of group A7 and A9 (P<.05). After artificial aging, the fracture load was significantly decreased in all groups with various preparation depths (P<.05). CONCLUSION. The fracture load of a single anterior implant restored with lithium disilicate crown on zirconia abutment with titanium insert differed depending on the preparation depths. After 5-year artificial aging, the fracture loads of all preparation groups decreased significantly.