• 대한치과보철학회지
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• 제43권3호
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• pp.338-351
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• 2005

Statement of problem. Accurate fit between the implant components is important because the misfit of the implant components results in frequent screw loosening, irreversible screw fracture, plaque accumulation, poor soft tissue reaction, and destruction of osseointegration. Purpose. This study is to evaluate the machining accuracy and consistency of the implant fixture/ abutment/screw interfaces of the internal connection system by using a Stereoscopic Zoom microscope and FE-SEM(field emission scanning electron microscope) Materials and methods. The implant systems selected in this study were internal connection type implants from AVANA(Osstem^{\circledR}), Bioplant(Cowell-Medi^{\circledR}), Dio(DIO^{\circledR}), Neoplant(Neobiotech 􀋓), Implantium(Dentium􀋓)systems. Each group was acquired 2 fixtures at random. Two piece type abutment and one piece type abutment for use with each implant system were acquired. Screw were respectively used to hold a two piece type abutment to a implant fixture. The implant fixtures were perpendiculary mounted in acrylic resin block. Each two piece abutment was secured to the implant fixture by screw and one piece abutment also secured to the implant fixture. Abutment/fixture assembly were mounted in liquid unsaturated polyester. All samples were cross-sectioned with grinder-polisher unit. Finally all specimens were analysed the fit between implant fixture/abutment/screw interfaces Results and conclusions. 1. Implant fixture/abutment/screw connection interfaces of internal connection systems made in Korea were in good condition. 2. The results of the above study showed that materials and mechanical properties and quality of milling differed depending on their manufacturing companies.

• 한국기계가공학회지
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• 제10권1호
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• pp.80-86
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• 2011

This study compared and analyzed manual tapping and automatic tapping regarding tapping process characteristics of titanium hard-to-cut-material. Tapping process characteristics of titanium hard-to-cut-material are evaluated as the quality of a screw, wear of a tap, economic analysis, and cycle time etc. The type of screw threads after manual tapping is formed as an irregular type of screw threads, and perfect screw threads are created after automatic tapping. In addition, the chip type after manual tapping process is formed as the discontinuous chip due to work hardening, and the powder type of chip after automatic tapping process is created. In terms of cycle time, an automatic tapping process is shortened by 70% compared to manual tapping process. Insert tip wear of an automatic tapping shown in the process of 5-hole tapping is not found, but hand tap wear for finish cutting is most severe.

• 대한치과교정학회지
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• 제37권2호
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• pp.89-97
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• 2007

교정용 스크류의 적절한 식립 토오크는 스크류와 골과의 경계에 적절히 작용하여 실패를 최소화 할 수 있는데, 너무 낮은 식립 토오크는 안정성이 없으며 반면에 너무 강한 식립 토오크는 열, 기계적 손상으로 골 괴사를 야기할 수도 있다. 본 연구에는 임상적으로 스크류의 길이와 직경 및 형태 등을 달리하여 식립 토오크를 측정해서 스크류의 각 부분에 대한 세분화된 토오크의 변화를 분석하고자 하였다. 연구결과 1.5 mm 두께의 인공피질골 블록에서 cylindrical type 스크류와 taper type 스크류 두 형태 모두에서 스크류 길이가 길수록 최대 식립 토오크 값도 함께 증가하였다. 특히 cylindrical type 스크류에서 길이에 따른 토오크 변화에 대해 통계적으로 유의한 차이가 관찰되었다 (p<0.05). 미니스크류의 연속적인 식립 토오크 분석 결과 cylindrical type 스크류는 연속적인 그래프 형태를 보이면서 불완전 나사부에서 식립 토오크가 크게 증가하였으며, taper type 스크류는 나사선의 마지막 경사진 부분에서 식립 토오크가 크게 증가하였다. 외경이 커질수록 최대 식립 토오크 값은 증가하였는데, 통계적으로 유의한 차이를 보였다 (p<0.05). 형태와 외경, 길이는 모두 토오크 값에 유의한 영향을 미치는데, 식립 토오크에 가장 큰 영향을 미치는 것은 외경, 형태, 길이 순서였다. 본 연구 결과 스크류의 식립 토오크에 가장 큰 영향을 미치는 것은 스크류의 외경이며 각각의 해부학적 구조물에 대한 피질골의 두께를 고려하여 적합한 스크류의 두께 및 나사산의 형태를 선택하는 것이 스크류의 초기 고정력을 얻는데 유리하다고 판단된다.

• 대한치과보철학회지
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• 제47권4호
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• pp.365-375
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• 2009

연구목적: 임플란트 보철물의 유지형태 중 나사 및 시멘트 혼합 유지형의 경우 나사 풀림력 등에 영향을 주는 임플란트 구성 성분의 응력에 관한 연구가 부족하였다. 임플란트 상부 보철물의 유지형태, 즉, 시멘트 유지와 나사 유지, 그리고 이 두 가지 유지형태가 서로 연결된 혼합형의 임플란트 보철물의 응력분산의 특징들을 3차원 유한요소분석법을 이용하여 비교하고자 하였다. 연구재료 및 방법: 하악골에서 제1소구치 부위와 제1대구치 부위에 2개의 임플란트 (SS II, Osstem Co. Ltd., Seoul, Korea)를 식립한 가상의 3본 계속가공의치를 모델화하였다. 지대주 종류와 그 위치에 따라, 4가지 모형 군으로 나누어 실험하였다. 모형 1은제1대구치와 제1소구치 각각의 고정체에 모두 동일한 시멘트 유지형 지대주인 Comocta abutment (Osstem Co. Ltd) 를 장착하여 3본 계속가공의치를 합착시킨 경우이고, 모형 2는 제1대구치와 제1소구치 각각의 고정체에 모두 나사 유지형 지대주인 Octa abutment (Osstem Co. Ltd) 를 장착하여 3본 계속가공의치를 나사로 고정시킨 경우이며, 모형 3은 제1대구치의 고정체에는 시멘트 유지형 지대주인 Comocta abutment를 장착하고, 제1소구치에는 나사 유지형 지대주인 Octa abutment를 장착한 후 3본 계속가공의치를 각각 시멘트 합착 및 나사로 고정시킨 경우이다. 그리고 모형 4는 모형 3에서 각각 제1대구치 및 제1소구치의 지대주를 맞바꾼 후 3본 계속가공의치를 나사 및 시멘트로 고정시킨 경우로 나누었다. 평균저작압인 하중을 대구치 565 N과 소구치 288 N의 힘으로 설정하고 수직방향으로 중심와와 협측 교두정에, 그리고 $30^{\circ}$ 경사 하중을 협측 교두정 부위에 준 다음 골, 고정체, 지대주, 그리고 지대주 나사 등에 나타나는 von-Mises stress 양상을 평가하였다. 결과: 네 가지 모형 중 나사 유지형 지대주인 Octa abutment를 제1대구치와 제1소구치 부위에 사용한 모형 2가 전반적으로 가장 낮은 안정적인 응력 분포를 보였다. 네 가지 모형 모두 피질골 및 고정체에 미치는 응력 크기 및 분포는 거의 유사하며, 치조골에 작용하는 응력은 하중의 종류와 상관없이 주로 피질골에 집중되었다. 지대주, 지대주 나사, 그리고 보철물 나사 등에 미치는 응력 크기나 분포는 모형에 관계없이 나사 유지형인 경우가 시멘트 유지형인 경우에 비해 낮은 안정적인 값을 보였다. 제1대구치와 제1소구치의 상부 구조물의 차이에 의한 교호작용 (reciprocal action)은 상대적으로 약하였다. 모든 부위에서 중앙 수 직하중, 교두정 수직하중, 그리고 교두정 경사하중의 순으로 응력값이 증가하였다. 결론: 본 유한 요소실험의 한계내에서 나사 및 시멘트 혼합 유지형의 임플란트 보철물은 시멘트 유지형만 사용하는 경우와 비교하여 주위에 더 큰 응력을 나타내지는 않았다. 이상적인 passive fit의 가정하에서 나사 유지형의 임플란트 보철물이 본체와 주위에 가장 작은 응력을 나타내었다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1993년도 추계학술대회 논문집
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• pp.181-186
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• 1993

Thermal expansion of ball screw in the semi-closed loop type CNC LATHE introduces positioning errors directly along the travelling the axis. In this paper the thermal displacements of the ball screw were estimated by using macro variable. The estimated displacements of the ball screw were given to the ball screw of the CNC LATHE under the constant driving conditions were measured to examine the effectiveness of the compensation method. The results showed that thermal displacements of the ball screw could be maintained less then 6 .mu.m positioning accaracy while using this compensation.

• 대한치과보철학회지
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• 제35권4호
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• pp.767-780
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• 1997

One of the most common problems of implant prosthesis is the screw loosening of abutment screws. This brings on discomfort in mastication, inflammation in the peri-implant tissue due to poor oral hygiene and fracture of prosthesis or loss of osseointegration. To prevent screw loosening, appropriate implantation to direct the occlusal force to the long axis of the implant, accurate design of the superstructure, decrease of the occlusal table, and adequate torque on the abutment screw are necessary. In this study the screw loosening torque was evaluated in implants with dimples or flutes in the internal surface of abutment screw holes. The abutments were fastened with slot type and hexagonal type abutment screws and were sealed with vinyl poly siloxane impression and bite registration material respectively. The screw loosening torque was evaluated after 1,800 and 12,600 times loading under a loading machine. The results were as follows. 1. The flute form group showed significantly higher loosening torque compared to the dimple form group and the group with no inner surface treatment (p<0.05). 2. There was no statistical difference in loosening torque according to the sealing materials. 3. The loosening torque according to the types of abutment screw showed no significant difference. 4. The loosening torque was significantly higher after 1800 times loading compared to 12600 times loading(p<0.05). From the above results. it is thought that formation of a flute in the internal surface of the screw hole decreases the chance of screw loosening, but the sealing materials and types of abutment screw did not show significant difference in prevention of screw loosening.

• The Journal of Advanced Prosthodontics
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• 제10권2호
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• pp.155-162
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• 2018

PURPOSE. The aim of this study was to compare the fracture of implant component behavior of external and internal type of implants to suggest directions for successful implant treatment. MATERIALS AND METHODS. Data were collected from the clinical records of all patients who received WARANTEC implants at Seoul National University Dental Hospital from February 2002 to January 2014 for 12 years. Total number of implants was 1,289 and an average of 3.2 implants was installed per patient. Information about abutment connection type, implant locations, platform sizes was collected with presence of implant component fractures and their managements. SPSS statistics software (version 24.0, IBM) was used for the statistical analysis. RESULTS. Overall fracture was significantly more frequent in internal type. The most frequently fractured component was abutment in internal type implants, and screw fracture occurred most frequently in external type. Analyzing by fractured components, screw fracture was the most frequent in the maxillary anterior region and the most abutment fracture occurred in the maxillary posterior region and screw fractures occurred more frequently in NP (narrow platform) and abutment fractures occurred more frequently in RP (regular platform). CONCLUSION. In external type, screw fracture occurred most frequently, especially in the maxillary anterior region, and in internal type, abutment fracture occurred frequently in the posterior region. placement of an external type implant rather than an internal type is recommended for the posterior region where abutment fractures frequently occur.

• 대한치과기공학회지
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• 제35권3호
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• pp.201-207
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• 2013

Purpose: In this study, the loosening torque test was conducted with three implant products that are produced, approved and sold in Korea, which are manufactured in different fixture and abutment tightening methods (internal submerged type, internal morse taper type, and external type) to examine the loosening torque of the screw according to the method of tightening the implant fixture and abutment. Methods: In the loosening torque test, the three types of fixtures and abutments with different tightening methods were tightened by rotating them clockwise with a $30N{\cdot}cm$ force using a driver equipped with an electric torque meter. The results of the test are as follows. Results: The loosening torque values of the internal submerged type, internal morse taper type and external type implants were $24.10{\pm}0.742N{\cdot}cm$, $29.10{\pm}1.710N{\cdot}cm$, and $26.60{\times}1.636N{\cdot}cm$, respectively. Conclusion: The screw loosening torque values of the three fixture and abutment tightening methods were analyzed via Kruskal Wallis test layout, and they were significantly different (p<0.05).

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2005년도 춘계학술대회 논문집
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• pp.132-137
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• 2005

This research presents a modeling and a manufacturing method of screw type flow meter. This paper introduces the efficient design and manufacturing method of screw type flow meter using reverse engineering and test technology. The methods introduced this paper utilize the reverse engineering that is increasing accuracy of modeling and manufacturing of reverse model. And then it can be used in performance test with hydraulic test equipment. Hence this can be used in the basic document for development of the quite accurate flow meter.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집D
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• pp.337-342
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• 2001

A numerical study of three-dimensional fluid flow and heat transfer in the metering section of a single screw extruder has been performed. The mathematical model for the screw channel is simplified by unwound channel and fixing the coordinate system to the screw. The pressure boundary and the prescribed mass flow rate conditions are imposed on the inlet and outlet, respectively. The commercial code STAR-CD based on the finite volume method is used to obtain the results of the present work. The computation of the reverse flow, which cannot be computed by the marching-type 3-D model, is performed in the present study.