대한치과보철학회지 :Vol. 37, No. 6, 1999 정밀연삭된지대주와합성수지지대주를이용한보철물의적합도에대한비교연구 조선대학교치과대학치과보철학교실 정선희 마장선 정재헌 Ⅰ. 서론최근임플랜트보철의시술확대와더불어그에따른제반합병증이증가되고있는추세를보이고있는데이러한합병증으

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1 대한치과보철학회지 :Vol. 37, No. 6, 1999 정밀연삭된지대주와합성수지지대주를이용한보철물의적합도에대한비교연구 조선대학교치과대학치과보철학교실 정선희 마장선 정재헌 Ⅰ. 서론최근임플랜트보철의시술확대와더불어그에따른제반합병증이증가되고있는추세를보이고있는데이러한합병증으론 1차및 2차수술단계에서나타나는합병증, 수술후연조직합병증, 보철후발생하는합병증등으로크게대별될수있으며, Dan 등 14) 은보철물과관련된합병증을조사한결과임플랜트고정체의상실, 연조직합병증, 기계적합병증등을볼수있었으며이중연조직합병증이가장많았고그다음이보철후기계적인합병증이라고보고한바있는데이중기계적합병증이발생하는주원인은자연치와임플랜트간의근본적인구조적차이에기인하는것으로써골유착성임플랜트는악골과직접결합되므로써기능시초래되는외력은매식체를통해직접악골에전달되게되므로치주인대에의해둘러싸여있는자연치아에서와같이완압및완충의역할을수행하지못하기때문인것으로보인다 22,23). 따라서생역학적관점에서보면구강내에식립된견고한임플랜트는자연치치근막의성질인탄성적이고, 자기방어적이며, 치주적으로연결되어있는체계를무너뜨릴수있다 21). 이러한기계적인합병증으론과다한응력으로인한임플랜트고정체및상부구성성분의파절이상당한부분을차지하고있는데이는임플랜트의직경이너무작은경우와보철물의적합도가부적당한경우라고보고된바있다 5,6,8,20). 파절현상을부적당하게가해지는과다한응력의 결과로본다면파절의원인이되는과다한응력은실제구강내에서행해지는저작이나연하와같은기능력의과다함보다는임플랜트구성성분과보철물간의부적합에의한것이실제로더흔한이유가된다. 이러한부적합은보철물을제작하는동안임상및기공과정에서당면할수있는인상용핀과고정체의부적합, 인상재료의변형이나부적절한인상채득법, 작업모형과매몰재의팽창, 금속의주조수축등에의하며결국상부보철물을임플랜트고정체에수동적이고정확하게적합시키는데실패하게된다 10,18). Binon 등 6,7) 은임플랜트구성성분의부적합이빈번한나사풀림, 만성적인나사파절뿐아니라치태침착, 불리한연조직반응, 골유착의상실등을가져올수있으므로구성성분의정확한적합이매우중요하다하였고, Jansen 등 17) 은지대주와임플랜트사이에간격의발생은기술적인관점에서피할수없으며이러한간격에대한임상적인중요한인식을임플랜트제조업자나임상가들은대부분이등한시하고있으며이러한간격에박테리아의침투, 서식으로인하여임플랜트주변의연조직에염증반응을야기할수있다하였다. 또한 Carr 등 12,13) 은지대원주와임플랜트간의수동적이고완전한적합을얻는것이역학적으로매우중요하며이때전하중 (preload) 도최대로얻을수있다고하였으며, 국내에서도고등 1) 의유한요소법적분석연구에의하면고정체와상부보철물간의적합이좋지못한경우에응력의발생이심하며특히임플랜트구성성분과보철물간에는수직적인적합성분보다는수평적인적합성분이응력 825

2 에더많은영향을미치는것으로보고한바있다. 또한 Carr 등 12) 은 screw 유지임플랜트보철은 premade gold 또는 plastic pattern 을이용하여일반적인보철물제작시에이용되는 lost wax casting technique으로제작하는데합금주조시의온도력과취급과정및여러 의형태에따른임상적인결과에관한차이의자세한보고가없음을지적한바있다. 따라서본연구에서는단일치아임플랜트보철수복시상부지대주로서정밀연삭된지대주와합성수지지대주의사용에따른보철물주조후지대주와고정체간의적합성을비교평가해보고자, Steri- Oss 시스템의고정체에정밀연삭된 gold 지대주 (premade or premachined gold ) 와합성수지지대주 (plastic 또는 gold/plastic ) 를각각이용하여주조후, 고정체에직접연결하여간극을주사전자현미경을이용하여측정한결과, 다소의지견을얻었기에이에보고하는바이다. Ⅱ. 연구재료및방법 1. 연구재료 Table 1. Kinds of abutment using in the study implant system kinds of UCLA abutment plastic plastic (lapped) Steri-Oss gold/plastic gold Steri-Oss;Steri-Oss, Yorba Linda, CA, U.S.A.; 한경우에는주조후, 주조과정에서발생된 abutment의고정체와접촉하는부위의불규칙한면을제거하기위해서 lapping tool(diamonded Coated Lapping Tool Kit, Steri-Oss Inc., Yorba Linda, CA) 을이용하여연마한경우와연마하지않은경우로구분하여전체적으론 Table 1에서보는바와같이 4 경우의상부지대주를이용한보철물을제작하였다. 2. 연구방법 1) 임플랜트고정체와주조된상부지대주의연결임플랜트고정체와주조된상부지대주간의간극을비교하기위하여 3i system의 torque wrench를사용해 10N cm의균일한조임력으로각각의경우에따른지대주를고정체에각각연결하였다. 1) 고정체임플랜트하부고정체로는현재임상에서널리사용되고있는 Steri-Oss system의직경 3.8mm thread type으로서상부는 0.75mm 높이의 external hex 구조를갖는 pure titanium fixture를기본고정체로선택하였다. 2) 상부지대주의제작하부고정체에직접연결되는지대주 (UCLA type abutment) 로 Steri-Oss system에서단일치아수복시임상에서널리사용되는 HL-Hexed abutment를이용하였는데, 그형태로는 plastic, gold/plastic, premade gold 를각각선택 (Table 1) 하여제1소구치형태의납형을제작한후, Type Ⅲ 금합금 (We Dong Myung Dental Alloy, Co. LTD.,Korea) 으로각각 3개씩통법에의하여주조하였고매몰재의제거는통상적으로기공실에서일반적으로사용해오고있는 sandblasting 방법으로서시행하였다. 단, plastic 를이용 2) 임플랜트고정체와주조된상부지대주의간극측정연결체의간극측정은 JEOL JSM-840A 주사전자현미경을이용하였으며 (Fig. 2), 각각의연결시편을 sample plate에고정시킨뒤 (Fig. 3), 주사전자현미경으로관찰하기위해시편을건조시킨후 30kV의전압과 10mV의전류로 Ni-filterd CuK αradiation 을이용하여 5 50 (2θ) 까지주사하였다. 이때주사속도 1 /min 이었다. 기본고정체에각지대주종류별로 3개씩연결하여연결부의외면의간극을측정하였다. 먼저연결부분의전체구조를저배율로관찰한후, 1,000배율에서연결부분의임의의 2군데에서사진을촬영하여그각각의사진에서 5군데의간극을측정함으로서하나의고정체와주조된한지대주간의연결부에서 10개의측정치를얻으므로서각경우별로 30개의측정치를얻어이를평균내었으며, 간극의통계적유의성비교는 ANOVA test를적용하였다. 826

Fig.1. Kinds of UCLA abutment(a; plastic, b; gold/plastic, c;gold ). Fig. 2.

The mounting state of fixture-abutment assembly on sample plate for SEM. Table 2.

81 (Lapped) Gold/plastic 9.80±1.68 Gold 5.47±2.43 Ⅲ. 연구성적주사전자현미경을이용하여각시편의간극을관찰, 측정한결과 Steri-Oss 고정체에 plastic 를이용하여주조한지대주를연결한경우에는 9.67 ±1.

3 Fig.1. Kinds of UCLA abutment(a; plastic, b; gold/plastic, c;gold ). Fig. 2. Kinds of samples(a; non lapped casting made from plastic, b; lapped casting made from plastic, c; casting made from gold/plastic, d; casting made from gold ) Fig. 3. The mounting state of fixture-abutment assembly on sample plate for SEM. Table 2. The mean value of gap between Steri- Oss fixture and each UCLA abutment(unit : μm) kind fixture-abutment gap of abutment Plastic 9.67±1.50 Plastic 3.01±2.81 (Lapped) Gold/plastic 9.80±1.68 Gold 5.47±2.43 Ⅲ. 연구성적주사전자현미경을이용하여각시편의간극을관찰, 측정한결과 Steri-Oss 고정체에 plastic 를이용하여주조한지대주를연결한경우에는 9.67 ±1.50μm 의간극을보였고, plastic 를이용하여주조한지대주를연마 (lapped) 하여연결한경우에는 3.01±2.81μm 로가장적은간극을보였다. Steri-Oss 고정체에 gold/plastic 을이용하여주조한지대주를연결한경우의간극을관찰한결과 9.80±1.68μm 로가장큰간극을보였고, premade gold 을이용하여주조한지대주를연 결한경우에는 5.47±2.43μm 의간극을보였다 (Table 2). 각경우간의평균치를비교하였을경우 gold/ plastic, plastic, premade gold, plastic 를주조후연마한경우의순으로간극의크기가감소를보였는데 ANOVA test를적용한결과, plastic 의경우와 gold/plastic 의경우간에는통계적유의성을나타내지않았고, 그외에의다른경우간에는통계적유의성을나타내었다 (Table 3). 827

(ANOVA-test) kind of abutment Plastic Plastic Gold/plastic Gold kind of

* * * *; The mean difference is significant at the.05 level FIg. 4a.

External interface of plastic abutment mating with implant fixture. Fig.

4 Table 3.The statistic comparison of gap according to kinds of abutment (ANOVA-test) kind of abutment Plastic Plastic Gold/plastic Gold kind of abutment (lapped) Plastic * * Plastic (lapped) * * * Gold/plastic * * Gold * * * *; The mean difference is significant at the.05 level FIg. 4a. Interface between implant fixture-abutment by use of plastic. Fig. 4b. External interface of plastic abutment mating with implant fixture. Fig. 5a. Interface between implant fixture-abutment by use of plastic (lapped). Fig. 5b. External interface of plastic (lapped) abutment mating with implant fixture. 828

Fig. 6a. Interface between implant fixture-abutment by use of gold/plastic. Fig. 6b.

Interface between implant fixture-abutment by use of gold. Fig. 7b.

총괄및고찰임플랜트를이용한보철수복시각각의구성성분이수동적으로완벽하게적합되므로서나사로인한압축및인장력이임플랜트에굽힘을야기하는것을피할수있다.

만약어떠한이유로인하여상부보철물과임플랜트구성성분간에부적합이존재하는경우, 이러한보철물에기능하중이가해지면그결과로서나사결합체 (screw joint)

5 Fig. 6a. Interface between implant fixture-abutment by use of gold/plastic. Fig. 6b. External interface of gold/ plastic abutment mating with implant fixture. Fig. 7a. Interface between implant fixture-abutment by use of gold. Fig. 7b. External interface of gold abutment mating with implant fixture. Ⅳ. 총괄및고찰임플랜트를이용한보철수복시각각의구성성분이수동적으로완벽하게적합되므로서나사로인한압축및인장력이임플랜트에굽힘을야기하는것을피할수있다. 즉, 나사를조임으로써전하중 (preload) 을적용시키기전에, 보철물의기저부와모든지대치상면간의적합의질을최대한높여주어야한다. 만약어떠한이유로인하여상부보철물과임플랜트구성성분간에부적합이존재하는경우, 이러한보철물에기능하중이가해지면그결과로서나사결합체 (screw joint) 내에미세운동이나이동이발생되어임플랜트와지대치사이에부가적인운동을허용함으로써더욱불안정한나사결합체를야기하는 것은물론수복물의불량한계면적합, 나사의파절등을초래할수있다 9,25). 또한적절한적합이일어나지않을경우즉, 나사를조이기전에보철물과임플랜트구성성분간의양면이어떠한응력도존재하지않는수동적인접촉을이루지못하고있는상태에서는보철물시적후나사를조임으로써발생하는전하중이지대나사에전체적으로하중을가하게되며, 이러한하중은부분적으로만접촉되어있던임플랜트구성성분들을완전히접촉시키기위해상부구조물을당겨결국구조물들의굽힘과변형을야기시키게된다 25-27). 또부적합의정도및양상에따라임플랜트의장축과일치하지않는정상적인치관의해부학적형태를벗어나게되므로임플랜트파절에대해직접적인요소로관여하게된다. 829

6 이러한상부지대주와고정체간의적합도를임상적으로평가하는데는구강내에서직접눈으로관찰하거나타진, 일상적인방사선촬영등이이용되고있으나이는제한된방법으로서적합도에관한연구를위해서는대부분의실험이모형이나컴퓨터시뮬레이션을이용해시행되고있다 1,2). 따라서본연구에서는단일치아임플랜트보철수복시상부지대주로서정밀연삭된지대주와주조지대주의사용에따른보철물주조후지대주와고정체간의적합성을비교평가해보고자, Steri-Oss 시스템의고정체에정밀연삭된 gold 지대주 (premachined or premade gold ) 와 plastic pattern 지대주 (plastic 또는 gold/plastic ) 를각각이용하여주조후, 고정체에연결하여간극을주사전자현미경을이용하여측정하였다. 이때 plastic 를이용한경우에는주조후, 주조과정에서발생된 abutment 의고정체와접촉하는부위의불규칙한면을제거하기위해서 lapping tool을이용하여연마한경우와연마하지않은경우로구분하였다. 임플랜트의적합에관한많은보고들 3,4,15,19,24,27) 은주로임플랜트고정체와상부보철물간의수동적이고완벽한적합의여부를관찰하였으며이때발생된오차들은연결체에하중을가하게되면구조체에변형이일어나면서결합이이루어지게됨으로써마치적합을이루는것처럼보이며또한지나치게큰조임으로인한회전력은과도한 preload를생성하여고정체와지대주의수동적인결합을방해할수있다하였다. 따라서본연구에서는임플랜트고정체와상부보철물간의수동적인상태에서의적합도를평가하고자각각의지대주를고정체에교차연결하여 3i system의 10N torque wrench를사용하여 10N cm의회전력 3) 을균일하게적용하여고정체와지대주의간극을측정하였다. 본연구에서 Steri-Oss 시스템의고정체와각지대주를연결하여주사전자현미경을이용하여각시편의간극을관찰, 측정한결과, Table 2에서보는바와같이 Steri-Oss 고정체에 plastic 를이용하여주조한지대주를연결한경우에는 9.67±1.50μm 의간극을보였고, plastic 를이용하여주조한지대주를연마 (lapped) 하여연결한경우에는 3.01±2.81μm 로가장적은간극을보였다. Steri-Oss 고정체에 gold/plastic 을이용하여주조한지 대주를연결한경우의간극을관찰한결과 9.80± 1.68μm 로가장큰간극을보였고, premade gold 을이용하여주조한지대주를연결한경우에는 5.47±2.43μm 의간극을보이므로서 gold/ plastic, plastic, premade gold, plastic 를주조후연마한경우의순으로간극의크기가감소됨을보였다. plastic 의경우와 gold/plastic 의경우간에는통계적유의성 (ANOVA test) 을나타내지않았고, 그외에의다른경우간에는통계적유의성을나타내었다 (Table 3). 임플랜트고정체와지대주간의간극을측정한연구로 Binon 등 6,7) 은 Steri-Oss 시스템의고정체와지대주를연결하여주사전자현미경을이용하여관찰한결과 μm 의간극을보였다하였는데본연구에서는대체로 Binon 등의연구결과보다간극이다소높게나타났다. 이와같은결과는본연구에서는지대주와고정체간의수동적인결합을얻고자 10N cm의조임력으로연결한반면 Binon 등은 30N cm의조임력으로고정체와지대주를연결한결과라고사료되며김등 2) 의연구에서는 Steri-Oss 시스템의고정체와 HL Hexed abutment를연결시간극이 3.96±1.15μm 를보여주었는데이는 10N cm의조임력은같으나주조하지않은상태로그대로의연결에의해주조에따른변형을줄여줄수있어, 본실험에서 premade gold 를이용하여주조한경우의간극인 5.47±2.43μm 보다적게나온것으로사료된다. Carr 등 12,13) 은기존의 gold 와 plastic 를사용한보철물에서의 preload에관한실험을하였는데 gold screw, gold, abutment joint 에서의결과가되는 preload는주조과정, type의선택, 주조합금, 매몰, 임플랜트 의마무리및연마술식등에의해영향을받을수있다하였고, plastic pattern을사용하여주조하는경우에는임플랜트 의마무리및연마를시행한경우가이를시행하지않은경우보다 preload가증가된다는실험결과를보여주었다. 또한 premade metal 를사용함으로서 preload의크기와정확도에서 plastic pattern보다더큰장점을제공한다하였다. Hurson 16) 은 plastic burnout pattern은적절히과정을시행한 premade gold 를따를수 830

7 없으며가장좋은적합을얻기위해서는 gold abutment를우선적으로추천하였고, Byren 등 11) 도 plastic pattern을이용하여주조한경우가 premade gold 를이용하는경우보다고정체와지대치적합에서더큰수직변위를보여준다는실험결과를보여주었는데, 본연구의결과에서도 premade gold 를이용한경우가 plastic pattern 의 를이용한경우보다고정체와의적합도에서보다유리하였다. 주조후매몰재를제거하는가장일반적인방법은 sandblasting으로서이러한경우에해당면을손상시킬수있으므로산을이용하여화학적으로매몰재를제거하는방법을추천하기도하였으나 16), 본연구에서는통상적으로기공실에서일반적으로사용해오고있는 sandblasting으로서매몰재를제거하는경우로하였으나, 가능하면 abutment의고정체와접촉하는부위 (apical portion) 는 sandblasting을하지않는것이추천되고있다. 이때 plastic 를이용한경우에는주조후, 주조과정에서발생된 abutment의고정체와접촉하는부위의불규칙한면을제거하기위해서 lapping tool을이용하여연마한경우와연마하지않은경우로구분하였는데, diamonded coated lapping tool을이용하는경우에는 abutment에상대적으로평평한면을만들어낼수있다고보고한바와같이 16) 본연구에서도 plastic 를주조후연마하지않은경우에비해서연마한경우가훨씬간극의크기의감소를보여주므로서 plastic 가사용될때는고정체와접합하는 의해당부위를연마함으로써보다좋은적합도를얻을수있었다. 그외에도 Byren 등 11), Carr 등 12) 은 premade gold 나 plastic 를이용하는모든경우에서합금을이용한주조과정이나세라믹의소성시에온도변화에따른변형의가능성을제시하면서이에관한자세한임상적보고가미약함을지적한바있는데앞으로도계속해서 gold/plastic, premade gold 와새로운주조합금과의결합, 부식및변형등에관한추가적인연구가진행되어야하리라고사료된다. Ⅴ. 결론하부고정체에직접연결되는지대주로 UCLA type abutment 종류인 plastic, plastic (lapped), gold/plastic, premade gold 의 4종류 을각각선택주조하여 Steri-Oss 시스템의고정체에 10N cm 의조임력으로연결하고주사전자현미경을이용, 그간극을측정하여그적합도를평가해본결과다음과같은결론을얻었다. 1. Plastic 을이용하여주조된지대주를연결한경우 9.67±1.50μm 의간극을보였다. 2. Plastic 을이용하여주조후연마한지대주을연결한경우 3.01±2.81μm 의간극을보였다. 3. Gold/plastic 을이용하여주조된지대주을연결한경우 9.80±1.68μm 의간극을보였다. 4. Gold 을이용하여주조된지대주을연결한경우 5.47±2.43μm 의간극을보였다. 5. Gold/plastic, plastic, gold, plastic (lapped) 의경우순으로간극이점차로적어짐을보였다.(plastic 와 gold/plastic 의경우간에서만통계적으로유의한차이가없었고, 다른경우간에는통계적으로유의한차이를보였다.) 이연구의결과로서 premade gold 를이용한경우가 plastic pattern의 를이용한경우보다고정체와의적합도에서보다유리하였고, plastic 가사용될때는고정체와접합하는 의해당부위를연마함으로써보다좋은적합도를얻을수있었다. 참고문헌 1. 고용석, 손승기, 정재헌, 상부구조물적합도에따른골유착성임플랜트보철물의유한요소법적응력분석. 대한악기능교합학회지 1996 ; 12 : 김미정, 정재헌, 상호호환성있는임플랜트지대주와고정체간의적합도에관한연구. 조선대학교석사학위논문, Adell R, Eriksson B, Lekhorm U et al., A long 831

8 term follow up study of osseointegrated implants in the treatment of totally edentulous jaws. Int J Oral Maxillofac Implants 1998 ; 4 : Baishi T, Preventing and resolving complications with osseointegrated implants. Dent Clin North Am 1989 ; 33 : Beaty K, The role of screw in implant systems. Int J Oral Maxillofac Implants 1994 ; 9(special suppl): Binon PP, Evaluation of maching Accuracy and Consistency of Selected Implant, Standard Abutments and Laboratory Analog. Int J Prosthodont 1995 ; 8 : Binon PP, Evaluation of three slip fit Hexagonal Implants. Implant Dent 1996 ; 5 : Breeding LC, Dixon DL, Nelson EW et al, Torque required to loosen single-tooth implant abutment screw before and after simulated function. Int J Prosthodont 1993 ;6(5): Brunski JE, Hipp JE, In the forces on endosteal implant ; A measurement system and biomechanical consideration. J Prosthet Dent 1984 ; 51 : Burguete RL, Johns RB, King T et al, Tightening characteristics for screw joints in osseointegrated dental implants. J Prosthet Dent 1994; 71 : Byren D, Houston F, Cleary R et al, The fit of cast and premachined implant abutments. J Prosthet Dent 1998; 80 : Carr AB, Brunski JB, Hurley E, Effect of Fabrication, Finishing, and Polishing Procedures on Preload in Prostheses using Conventional Gold and Pastic Cylinders. Int J Oral Maxillofac Implants 1996; 11: Carr AB, Larsen E, Papazolou E et al, Reverse torque of various screw design Implants in Baboons. J Dent Res 1994; 73(IADR abstract) : Dan ET, William RL, Tissue- integrated prostheses complication. Int J Oral Maxillofac Implants 1992; 7 : Hobo S, Ichida E, In Osseointegration and Occlusal Rahabilitation. Quintessence Publ Co 1989; Hurson S, Laboratory techniques to prevent screw loosening on dental implants. J Dent Technol April, Jansen VK, Conrads G, Richter EJ, Microbial leakage and marginal fit of the Implant- Abutment Interface. Int J Oral Maxillofac Implants 1997; 12: Lambert JS, Quon SJ, Adhesive abutment luting. J Prosthet Dent 1993; 69: Lekholm U, Adell R, Brnemark PI, Possible complications :Osseointegration in Clinical Dentistry. Chicago : Quintessence Publ Co 1985; Morgan J, James D, Pilliar M, Fractures of the fixture component of an osseointegrated implants. Int J Oral Maxillofac Implants 1993; 8 : Richer EJ, Basic Biomechanics of dental Implants in Prosthetis dentistry. J Prosthet Dent 1989; 61: Skalak R, Aspect of biomechanical consideration, in Branemark PI, Zarb GA, Albrecksson, T: Tissue integration prosthesis, chicago, Quintessence. publ. co 1985; Skalak R, Biomechanical consideration in osseointegrated prosthesis. J Prosthet Dent 1983; 49 : Sones A, Advanced problem solving: Complications with osseointegrated implants. 53rd Annual Scientific Meeting, Pacific Coast Society of Prosthodontists, Sun River, Ore, Sones AD, Complication with osseointegrated implants. J Prosthet Dent 1989; 62 : 832

9 Sutter F, The role of screw in implant system. Int J Oral Maxillofac Implants 1994; 9(special suppl) : Worthingyon P, Bolender CL, Taylor TD, The Swedish system of osseointegrated implants : Problems and complications encountered during a 4-year trial period. Int J Oral Maxillofac Implants 1987; 2 :

10 ABSTRACT A COMPARATIVE STUDY ON THE FIT IN PROSTHESES USING PREMADE GOLD CYLINDER AND PLASTIC CYLINDER Seon-Hee Jung, D.D.S., Jang-Seon Ma, D.D.S., M.S.D., Chae-Heon Chung, D.D.S., M.S.D., Ph.D. Department. of Prosthodontics, College of Dentistry, Chosun University Recently, various implant s were supplied, especially received gold s, cast s produced from premade gold and plastic s and plastic s. This study measured and compared precise fit produced when using conventional gold and plastic s. The comparative fit of lapped and non-lapped castings made from plastic pattern was examined. The implant/abutment interface fit was evaluated by scanning electron microscopy(sem) for each of four s. The following results were obtained: 1. The case of plastic showed 9.67±1.50μm gap when Steri-Oss fixture was connected. 2. The case of lapped casting made from plastic showed 3.01±2.81μm gap when Steri-Oss fixture was connected. 3. The case of gold/plastic showed 9.80±1.68μm gap when Steri-Oss fixture was connected. 4. The case of gold showed 5.47±2.43μm gap when Steri-Oss fixture was connected. 5. In case of each which was connected with Steri-Oss fixture, the size of gap was showed less in the order of the case of gold/plastic, the case of plastic, the case of gold and the case of lapped casting made from plastic. As results of this study, the use of premade gold offers an advantage over plastic patterns in precise fit. When plastic patterns are used, polishing of implant components should provide precise fit. Key words : Premade gold, Plastic, Gold/ plstic, Lapping, Fit 834

7-2È£

7-2È£ original article OA A comparative study on accuracy of the implant torque devices for screw tightening Hi-Chan Jung 1, Chang-Mo Jeong 2 1 Graduate student, DDS,MSD Dept of Prosthodontic Dentistry, College