Table Ⅰ. Investigators and experimental results in marginal opening of In-Ceram crowns Investigators Marginal fit(μm) Sulaiman, et al. 4) 161±46 Besch

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1 대한치과보철학회지 :Vol. 40, No. 2, 2002 Celay/In-Ceram, Conventional In-Ceram, Empress 2 전부도재관의변연적합도에관한비교연구 서울대학교치과대학치과보철학교실 양재호 여인성 이선형 한중석 이재봉 Ⅰ. 서론심미적보철에대한요구가증가함에따라전부도재관은이제일반적인보철처치의하나가되었다. 그러나그적용은아직까지제한적이며, 여러가지전부도재시스템이개발되었지만많은것은일시적으로사용되다가현재쓰이지않고있다. 금속도재관과비교하여우수한심미성을가지고있는데도불구하고많은전부도재시스템이사용되지못한것은전부도재관제작에잠재적인문제점이있기때문이다. 전부도재관시스템이극복해야할문제는변연적합도, 강도, 기공과정의편리성등으로볼수있다. 변연적합도는금관가공의치학에서매우중요한개념중하나다. 변연적합도가좋지못할경우, 치은열구액, 치태침착, 골소실의증가 1,2) 를보인다. 따라서치주염과이차우식의빈도가증가하게되고, 결국치아상실의가능성이높아진다. 전부도재관의변연적합도에대한많은연구가있었다. 그러나어떤논문에서는결과에대한통계처리가쉽지않음 3,4) 을보여주고있다. Table I에서보는것처럼 In-Ceram crown의변연적합도에대한여러논문의결과를살펴보면그수치가큰차이가있음을알수있다. 다양한실험조건들에대한고려가필요하다하더라도이러한일관성을찾기어려운결과의원인에는각조사자간의서로다른통계학적관점과추론이작용했다고보여진다. 전부도재관의충분한강도와제작의용이성등에 대한요구로현재널리사용되는전부도재시스템으로는 In-Ceram(Vita Zahnfabrik, Bad Säckingen, Germany), IPS-Empress 2(Ivoclar, Schaan, Germany), CAD/CAM(Procera Allceram, Celay) 등이있다. In-Ceram 시스템은 slip casting법을사용한다. In-Ceram core alumina powder slip을내화모형에바른후 10시간동안 furnace에서소결하고, liquid glass를바르고 4시간동안 furnace에서 infiltration하면강한 alumina core가완성되고그위에장석도재를올려치관을제작한다. IPS Empress 2 시스템은 heat-press 기술을이용한다. 모형에 core를 wax-up하여매몰한후 injection방법으로 lithium-disilicate glass core를만든후장석도재를축조하여치관을제작한다. CAD/CAM 시스템은기존의도재관제작과는다른과정인 copy-milling법을사용한다. Procera Allceram (Nobel Biocare, Gö teborg, Sweden) 은형성된치아모형을 Procera reader로읽은단면자료를 Sweden으로모뎀전송하면, 전송된자료를모아 CAD/CAM 작업으로 milling 하여 high purity alumina core를제작한다. 이렇게제작, 관리함으로써균일한품질의수복물을제공할수있으나, 시스템구축의번거로움등이있어국내에서는아직일반화되지않고있다. Celay(Mikrona AG, Spreitenbach, Switzerland) 시스템도 copymilling법으로치관제작을하는데, 특히 Celay/In- Ceram 제작은시간을많이절약할수있는장점이있다. 소결과정이끝난 alumina blank를 milling하여 core를만들고, liquid glass를발라 40분동안 infil- 131

Table Ⅰ. Investigators and experimental results in marginal opening of In-Ceram crowns Investigators Marginal fit(μm) Sulaiman, et al. 4) 161±46 Beschnidt, et al. 5) 52 91 Shearer, et al.

그후장석도재를축조하여치관을완성하기때문에, 기존의 slip casting에서요구하는 14시간 ( 소결 : 10시간, glass infiltration: 4시간 ) 을약 90 분 (milling: 약 50 분, glass infitration: 40분 ) 으로줄일수있다.

2 Table Ⅰ. Investigators and experimental results in marginal opening of In-Ceram crowns Investigators Marginal fit(μm) Sulaiman, et al. 4) 161±46 Beschnidt, et al. 5) Shearer, et al. 6) 1 63 Pera, et al. 7) Grey, et al. 8) 123±30 Rinke, et al. 9) tration 과정을거쳐 core를완성한다. 그후장석도재를축조하여치관을완성하기때문에, 기존의 slip casting에서요구하는 14시간 ( 소결 : 10시간, glass infiltration: 4시간 ) 을약 90 분 (milling: 약 50 분, glass infitration: 40분 ) 으로줄일수있다. 그리고 mass product인 alumina blank를사용하기때문에균일한강도의 core를얻을수있다. Hwang 등 10) 은 mass product의 alumina blank를사용할경우약 12% 정도더강한강도를얻을수있다고했다. 여러임상 가들이 copy-milling에대해 technique-sensitive 하고변연적합도가떨어진다고생각한다. 그러나 Groten 등 11) 에의하면 Celay/In-Ceram 치관의변연적합도는매우우수한것으로평가되었다. 현재 Celay는국내에비교적널리보급되어있는 copymilling 시스템이다. 본연구의목적은국내에서사용되고있는전부도재관시스템 (In-Ceram, IPS Empress 2, Celay/In- Ceram) 의변연적합도를비교하고, 실험방법과통계적처리등에대해고찰하는것이다. Ⅱ. 연구재료및방법발치한한개의상악중절치를아크릴릭레진에포매한다. High speed handpiece를사용하여개략적인치아형성을하였다. Milling machine(f2, Degussa Korea, Seoul, Korea) 으로치아형성을마무리하여최종적으로 6 taper, 1mm shoulder 변연을갖는치아형태가되도록하였다 (Fig. 1). A B About 7mm 6 taper 1mm shoulder Fig. 1. The prepared tooth which (the maxillary central incisor) was cleaned and embedded in an self-curing resin block. The long axis of the tooth was perpendicular to the block. A, Labial view. B, Incisal view. C, Schematic diagram of tooth preparation. C 132

개인용 tray 제작을위해예비인상을알지네이트 (Aroma fine, GC Inc, Tokyo, Japan) 로채득하고 plaster model을제작하였다 (Fig. 2, A). Baseplate wax 두장두께로 plaster model을 relief 한후 (Fig.

3, A) 을채득하여 40개의주모형 (Rhombrock, Mitsubishi, Tokyo, Japan) 을제작하였다 (Fig. 3, B).

technique을적용한 IPS Empress 2 치관 10개를제작하였다. 각군의치관은숙련된기공사에의해제조사의지시에따라제작하였다 (Fig. 4). 변연적합도는형성된치아의변연한계점과수복물변연사이의간격으로정의하였다.

3 개인용 tray 제작을위해예비인상을알지네이트 (Aroma fine, GC Inc, Tokyo, Japan) 로채득하고 plaster model을제작하였다 (Fig. 2, A). Baseplate wax 두장두께로 plaster model을 relief 한후 (Fig. 2, B), tray resin(quicky, Nissin Dental Products Inc, Kyoto, Japan) 으로 40개의개인용 tray 를만들었다 (Fig. 2, C). Addition type의 silicon 인상재 (Examix, GC Inc, Tokyo, Japan) 로최종인상 (Fig. 3, A) 을채득하여 40개의주모형 (Rhombrock, Mitsubishi, Tokyo, Japan) 을제작하였다 (Fig. 3, B). 각군당 10개씩, 총 40개의치관을제작 대조군으로 metal 변연의 PFM(Rexillium III, JENER- IC/PENTRON Inc, Wallingford, USA) 치관 10 개, 실험군으로 Celay/In-Ceram alumina 치관 10개, slip casting In-Ceram alumina 치관 10개, layering technique을적용한 IPS Empress 2 치관 10개를제작하였다. 각군의치관은숙련된기공사에의해제조사의지시에따라제작하였다 (Fig. 4). 변연적합도는형성된치아의변연한계점과수복물변연사이의간격으로정의하였다. 측정은 Optical dimensional metrology center(accura 2000, INTEK PLUS, Daejeon, Korea) 로하였다 (Fig. 5). 본측정장치로변연적합도를 240배확대된상에서 0.1μm 의감도로측정하였다. Computer 출력화 A B C Fig. 2. A. The plaster model for individual trays. B. The plaster model that was relieved by 2 sheets of baseplate wax. C. The custom-made tray for final impression. A B Fig. 3. A. The final impression by polyvinyl siloxane using the individual tray. B. The master die for final impression. 133

4 A B C Fig. 4. Forty crowns were fabricated; A, PFM crowns (n=10) with metal margin. B, Copy-milled In-Ceram crowns (n=10) by Celay technology. C, In-Ceram alumina crowns (n=10) by slip casting technique. D, IPS Empress 2 crowns (n=10) by layering technique. D Fig. 5. The optical dimensional metrology center. Fig. 6. The schematic diagram showing the measurement method of marginal gap. 134

5 Table Ⅱ. The means and standard deviations of marginal fits in each 4 groups (μm) PFM Celay/In-Ceram Conventional In-Ceram Empress Mean Standard deviation Table Ⅲ. Kruskal-Wallis test statistics N Mean Rank PFM Celay/In-Ceram Conventional In-Ceram Empress Total 40 Asymp. Sig Table Ⅳ. Mann-Whitney test statistics Sig. PFM-Celay/In-Ceram PFM-Conventional In-Ceram PFM-Empress * Celay/In-Ceram-Conventional In-Ceram Celay/In-Ceram-Empress * Conventional In-Ceram-Empress * (* shows statistically different marginal accuracy) 면에잡힌확대상에서, 변연간격은치아변연에서얻은최소자승선과치관변연의한점사이의최소거리로측정되었다 (Fig. 6). 한치관의임의로선택된 50곳에서변연간격을측정하여구한평균값을그치관의변연적합도로표시하였다. 통계처리는비모수적방법을사용하였다. 평균값과표준편차를구하고, Kruskall-Wallis 검정을사용하여각군의평균값을비교, 평가하였다. Ⅲ. 결과각군의변연오차의평균값및표준편차는 Table Ⅱ와같다. Table Ⅲ는 Kruskal-Wallis 검정결과를보여주고있다. P<0.05 수준에서근사유의확률이 P=0.001이므로각군간의평균값이같지않다고할수있다. 비모수통계는사후검정법이따로없기때문에, 두군씩짝을지어 Mann-Whitney 검정을시행하였다 (Table Ⅳ). Table Ⅳ에서알수있듯이, Empress 2는통계적으로유의성있게우수한변연적합도를보였으나, 다른세군의변연적합도의차이는통계적유의성이없었다. Ⅳ. 총괄및고안수종전부도재관의변연적합도를정확히비교하려면, 각전부도재관제작시스템을제외한다른모든조건이동일해야한다. 따라서비교할모든수복물시편은한개의형성된치아로부터제작되는것이바람직하다. 그러나, 이러한실험설계하에서는수복물과치아를접착한상태에서변연적합도를측정할수없다. 동일한조건으로영구접착후, 변연오차를측정하기위해서는제작된치관시편수와같은수의치아가필요하다. 영구접착하기전과후의수복물의변연적합도는통계적으로유의성이있는차이를보인다. 12) 또한, cement의종류에따라, 변연적합도의차이가각기다른결과를나타낸다. 13) 따라 135

6 서, 영구접착후변연적합도비교측정에있어같은조건을부여하려면, cementing medium이같아야하지만, 여기서도고려할점은각수복물제작시스템차이외에 cement 자체의점주도, film thickness 등이변수로개재된다는것이다. 이런면들을고려하여, 본실험에서는 cementation을하지않은상태에서변연적합도를측정하도록하였다. 본실험설계에서변연적합도에영향을주는인자는두가지이다. 하나는제작시스템이고다른하나는제작하는기공사의기술적차이다. 기공사의테크닉은많은주관적인요소가복합되어있는것으로이를고려하게되면일관성있는통계적추론을하기매우어려워진다. 따라서그시스템을사용하여치관을제작하는기공사간에기술적인차이가없다는가정이필요하다. 본실험에서는이가정을적용하기위해, 그시스템에대해충분한경험이있는기공사를각시스템당일인씩선정하여제작을의뢰하였다. 기공사간의테크닉의차이가없을때, 제작된치관의변연적합도를측정하여얻은평균과표준편차는각기특정한의미를갖게된다. 평균값은시스템자체가내재적으로가지고있는정확도를의미하고, 표준편차는 technique sensitivity로해석할수있다. 본실험결과에의하면, copy-milling method 인 Celay/In-Ceram 시스템은다른군과비교하였을때, technique sensitive하지않았다. 즉적절히훈련될경우 copy-milling 방법은비교적균일한변연적합도의치관수복물을제작할수있었다. 이러한결과의신뢰도를높이려면, 시편수의크기를어느정도로설정하는가가중요한문제가된다. 통계적추론의신뢰도는일반적으로모수통계분석이비모수분석보다높다. 모수통계분석이가능하다면, 비모수통계는사용하지말아야한다. 14) 모수적방법을사용하려면, 추출한표본의모집단이정규분포를이루어야한다는가정이필요하다. 이 가정을성립시키기위해적절한시편수의크기가요구된다. 비교군의수가 3개이상이될때평균값비교를위한모수통계로일원배치분산분석 (oneway ANOVA) 을사용한다. 치관수복물의변연적합도측정연구논문의다수는통계처리로일원배치분산분석을적용하였다. 모수적방법을적용한논문에서각군당추출한시편수의크기는대개 10개정도였다 ) 본연구의결과처럼변연적합도의평균값과표준편차를비교해보면산포도가큰것이일반적이다. 이런경우 10개정도의시편수로모집단의정규성을가정할수는없다. 정규성의가정이성립하지않으면모수적통계방법을사용해서는안된다. 비록모수통계분석이비모수적방법보다높은신뢰도를보이나, 이때에는비모수통계추론 (Kruskal-Wallis) 이보다정확한분석이된다. 비모수통계처리는신뢰도가좀떨어지는단점은있으나, 적은시편수로손쉽게분석할수있는장점이있다. 다만위에서언급한것처럼비모수처리는모수적방법에서사용하는사후분석이없기때문에각각두군씩짝지어비교해야한다는불편함이있다. 치관수복물의변연적합도연구에있어서, 모수적통계분석을사용하려면, 각군당추출한표본시편수의크기는 30 이상이되어야한다. 표본수를 30 으로조절하면, 모집단의정규성을가정할수있다. 또한이경우표준편차 (technique-sensitivity) 에대한해석의신뢰도도높아진다. 한시편의변연적합도를구할때, 본실험에서제작된한치관의 50 곳에서측정한변연오차는 Table Ⅴ와같다. 임의로선택된 50 points의평균값은 90.8μm 이다. Table Ⅴ에서네점을선택 여러논문에서사용한방법 3,4,19) 하여평균값을구하면 90.8μm 과상당한차이를보이는결과를발견할수있었다. 예를들어 Table Ⅴ의처음네수치의평균을구하면 115.4μm 이다. 따라서, 한시편의변연적 Table Ⅴ. 50 measurements of marginal opening in one crown sample(μm)

7 합도를나타내는대표값을구하려면, 적절한측정회수가필요하다는것을알수있다. Groten 등 20) 은50 회이상측정하게되면, 측정위치를임의로선택하나, 전략적으로선정하는가에관계없이유사한값을갖게된다고하였다. 즉한치관시편의변연적합도를계산하기위해서는최소 50points 이상에서변연측정이필요하다. 그러므로, 본연구에서는한시편에서변연적합도를측정하기위해 50개의위치를임의로선정하여측정하였다. 임상적으로전부도재관이성공적으로수복되기위해요구되는변연적합도의한계는명확히규명되어있지않다. Sorensen 등 1) 은변연오차로인해발생하는골소실등을억제하기위해서는변연적합도가 50 μm 이하이어야한다고하였다. 그러나, 대부분의학자들은전부도재관의변연적합도에관한연구에서그이상의변연오차를보고하고있고그러면서도훌륭히임상에서성공한증례를발표하고있다. 수복인공치관의적절한변연적합도에관해고찰한내용들을살펴보면, 아직까지명확한근거를찾지못하고있으나, 다수는 μm 정도면임상적으로받아들일만한것으로보고있는것같다 ) 이를토대로본연구결과를검토하면, 대조군을포함한모든전부도재관시스템은단일치관수복물에서임상적으로적절한변연적합도를보인다고하겠다. 그러나보다명확한변연적합도규격에관한계속적연구가필요할것으로사료된다. Ⅴ. 결론 본연구결과다음과같은결론을얻을수있었다. 1. 각시스템으로제작된단일수복치관의변연적합도는 PFM 치관이 98.2±40.6μm, Celay/In- Ceram 치관이 83.5±18.7μm, conventional In-Ceram 치관이 104.9±44.1μm, IPS Empress 2 layering 치관이 45.5±11.5μm 이었다. 비모수통계분석결과 IPS Empress 2 시스템이다른시스템보다유의성있게우수한변연적합도를보였고, 다른세군의변연적합도는통계적으로유의성이없었다 (P<0.05). 2. 임상적으로받아들일수있는적절한변연적합도의한계를 μm 라고할때, 대조군과세전부도재관시스템은모두임상적으로사용가능 한변연오차를보였다. 3. 본연구와같이, 변수를 수복치관제작시스템 만으로조절한경우, 평균값은각시스템으로제작한수복치관의변연적합도, 표준편차는각시스템이가지고있는 technique-sensitivity로해석할수있다. 4. 각군의표준편차를비교한결과, copy-milling 방법은다른제작법보다 technique-sensitivity가높지않았다. 5. 평균값과표준편차에대한해석의신뢰도를높이려면비모수적방법보다모수통계추론을사용하는것이바람직한데, 모수적방법을사용하기위해서는각군당표본수의크기를 30 이상으로조절하여야한다. 임상적으로받아들일수있는변연간격에대한명확한결과와근거는아직마련되어있지않으며이에대한보다많은연구가필요하다. REFERENCES 1. Sorensen SE, Larsen IB, Jo/rgensen KD. Gingival and alveolar bone reaction to marginal fit of subgingival crown margins. Scand J Dent Res 1986;94: Sorensen JA. A rationale for comparison of plaque-retaining properties of crown systems. J Prosthet Dent 1989;62: Leong D, Chai J, Lautenschlager E, Gilbert J. Marginal fit of machine-milled titanium and cast titanium single crowns. Int J Prosthodont 1994;7: Sulaiman F, Chai J, Jameson LM, Wozniak WT. A comparison of the marginal fit of In- Ceram, IPS Empress, and Procera Crowns. Int J Prosthodont 1997;10: Beschnidt SM, Strub JR. Evaluation of the marginal accuracy of different all-ceramic crown systems after simulation in the artificial mouth. J Oral Rehabil 1999;26: Shearer B, Gough MB, Setchell DJ. 137

8 Influence of marginal configuration and porcelain addition on the fit of In-Ceram crowns. Biomaterials 1996;17: Pera P, Gilodi S, Bassi F, Carossa S. In vitro marginal adaptation of alumina porcelain ceramic crowns. J Prosthet Dent 1994;72: Grey NJ, Piddock V, Wilson MA. In vitro comparison of conventional crowns and a new all-ceramic system. J Dent 1993;21: Rinke S, Huls A, Jahn L. Marginal accuracy and fracture strength of conventional and copy-milled all-ceramic crowns. Int J Prosthodont 1995;8: Hwang JW, Yang JH. Fracture strength of copy-milled and conventional In-Ceram crowns. J Oral Rehabil 2001;28: Groten M, Girthofer S, Probster L. Marginal fit consistency of copy-milled all-ceramic crowns during fabrication by light and scanning electron microscopic analysis in vitro. J Oral Rehabil 1997;24: Hung SH, Hung KS, Eick JD, Chappell RP. Marginal fit of porcelain-fused-to-metal and two types of ceramic crown. J Prosthet Dent 1990;63: Kern M, Schaller HG, Strub JR. Marginal fit of restorations before and after cementation in vivo. Int J Prosthodont 1993;6: Chao LL. Statistics: methods and analyses. Tokyo:McGraw-Hill Inc Richter-Snapp K, Aquilino SA, Svare CW, Turner KA. Change in marginal fit as related to marginal design, alloy type and porcelain proximity in porcelainfused-to-metal restorations. J Prosthet Dent 1988;60: May KB, Russell MM, Razzoog ME, Lang BR. Precision of fit: The Procera AllCeram crown. J Prosthet Dent 1998;80: Cooney JP, Richter WA, MacEntee MI. Evaluation of ceramic margins for metalceramic restorations. J Prosthet Dent 1985;54: Blackman R, Baez R, Barghi N. Marginal accuracy and geometry of cast titanium copings. J Prosthet Dent 1992;67: Schaerer P, Tomohiko S, Wohlwend A. A comparison of the marginal fit of three cast ceramic crown systems. J Prosthet Dent 1988;59: Groten M, Axmann D, Pröbster L, Weber H. Determination of the minimum number of marginal gap measurements required for practical in vitro testing. J Prosthet Dent 2000;83: Björn AL, Björn H, Grkovic B. Marginal fit of restorations and its relation to periodontal bone level. II. Crowns. Odontol Revy 1970;21: Christensen GJ. Marginal fit of gold inlay castings. J Prosthet Dent 1966;16: McLean JW, von Fraunhofer JA. The estimation of cement film thickness by an in vivo technique. Br Dent J 1971;131: Reprint request to: Jae-Ho Yang, D.D.S., M.S.D., Ph.D. Department of Prosthodontics, College of Dentistry, Seoul National University 28-1, Yeongun-Dong, Chongno-Gu, Seoul, , Korea Tel jhoyang@snu.ac.kr 138

9 ABSTRACT MARGINAL FIT OF CELAY/IN-CERAM, CONVENTIONAL IN-CERAM AND EMPRESS 2 ALL-CERAMIC SINGLE CROWNS Jae-Ho Yang, D.D.S., M.S.D., Ph.D., In-Sung Yeo, D.D.S., M.S.D., Sun-Hyung Lee, D.D.S., M.S.D., Ph.D., Jung-Suk Han, D.D.S., M.S., Ph.D., Jai-Bong Lee, D.D.S., M.S.D., Ph.D. Department of Prosthodontics, College of Dentistry, Seoul National University. There have been many studies about marginal discrepancy of single restorations made by various systems and materials. But many of statistical inferences are not definite because of sample size, measurement number, measuring instruments, etc. The purpose of this study was to compare the marginal adaptations of the anterior single restorations made by different systems and to consider more desirable statistical methods in analysing the marginal fit. The in vitro marginal discrepancies of three different all-ceramic crown systems (Celay In-Ceram, Conventional In-Ceram, IPS Empress 2 layering technique) and one control group (PFM) were evaluated and compared. The crowns were made from one extracted maxillary central incisor prepared with a 1mm shoulder margin and 6 taper walls by milling machine. 10 crowns per each system were fabricated. Measurements of a crown were recorded at 50 points that were randomly selected for marginal gap evaluation. Non-parametric statistical analysis was performed for the results. Within the limits of this study, the following conclusions were drawn: 1. Mean gap dimensions and standard deviations at the marginal opening for the maxillary incisor crowns were 98.2±40.6μm for PFM, 83.5±18.7μm for Celay In-Ceram, 104.9±44.1μm for conventional In-Ceram, and 45.5±11.5μm for IPS Empress 2 layering technique. The IPS Empress 2 system showed the smallest marginal gap (P<0.05). The marginal openings of the other three groups were not significantly different (P<0.05). 2. The marginal discrepancies found in this study were all within clinically acceptable standards ( μm). 3. When the variable is so controlled that the system may be the only one, mean value is interpreted to be the marginal discrepancy of a restoration which is made by each system and standard deviation is to be technique-sensitivity of each one. 4. From the standard deviations, the copy-milling technique (Celay/In-Ceram) was not considered to be technique-sensitive in comparison with other methods. 5. Parametric analysis is more reliable than non-parametric one in interpretation of the mean and standard deviation. The sample size of each group has to be more than 30 to use parametric statistics. The level of clinically acceptable marginal fit has not been established. Further studies are needed. Key words : Marginal fit, Marginal gap, Celay In-Ceram, In-Ceram, Empress 2 139

1997-35-3

1997-35-3 - 대한 치과 보철학회지 Vol. 35 No. 3, 1997 - In-Ceram Alumina Bridge Restoration의 단기예후에 관한 임상적 연구 대구파티마병원치과 및 치과보철학교실 조병완ㆍ박재범ㆍ안재진 Ⅰ. 서 론 치아결손에 의한 보철수복은 일상의 임상에서 자 주 접하게 되며, 전치부는 주로 Porcelain Fused to Metal Crown(이하