대한치과보철학회지 :Vol. 45, No. 5, 2007 타이타늄표면코팅이도재결합에미치는영향 전남대학교치의학전문대학원치과보철학교실 * 전남대학교신소재공학부및기능성표면공학연구소 김연미 김현승 이광민 * 이도재 * 오계정 임현필 서윤정 박상원 Ⅰ. 서론심미성에대한관심이높아

대한치과보철학회지 :Vol. 45, No. 5, 2007 타이타늄표면코팅이도재결합에미치는영향 전남대학교치의학전문대학원치과보철학교실 * 전남대학교신소재공학부및기능성표면공학연구소 김연미 김현승 이광민 * 이도재 * 오계정 임현필 서윤정 박상원 Ⅰ. 서론심미성에대한관심이높아지면서도재수복물이널리이용되고있으며그중금속의견고성과도재의심미성을함께갖춘도재전장금관이가장대표적으로사용되고있다. 1-3 도재용합금에서도많은발전이있었는데그중가장큰성과는순수타이타늄과타이타늄합금의개발이다. 4-5 타이타늄은우수한내식성과생체적합성 (biocompatibility), 높은강도와귀금속합금에비해경제적이라는장점때문에임플랜트뿐만아니라, 최근에는단일금관이나계속가공의치, 금속알러지가있는가철성국소의치환자에서도사용범위가확대되어귀금속의대체금속으로주목받고있다. 6-7 그러나타이타늄은도재와의결합력이통상적인금속-도재결합력보다약하다는문제점이있다. 3-4 이는도재소성온도에서타이타늄의산화와타이타늄주조시표면에형성되는 α-case 층이주요요인이다. α-case 층은타이타늄주조시고온에서매몰재내의산소가타이타늄격자사이로확산되어타이타늄표면에형성되는두꺼운산화층으로연성과피로저항성을감소시켜결국타이타늄-도재결합력을저하시킨다. 6-8 통상적인도재의소결 (sintering) 온도는 950 이상이다. 하지만 950 에서형성된타이타늄산화층 은두껍고기포와내부응력에의해비교적쉽게금이가거나떨어져나가도재와의결합에부적절하다. 7 따라서타이타늄은 660 870 정도의용융온도를갖으며, 타이타늄의열팽창계수와유사하거나약간낮은열팽창계수를갖는전용도재를사용한다. 9-10 도재소성동안과다한타이타늄산화를막기위한방법으로다양한순수금속과도재들을타이타늄표면에코팅하는방법들이연구되어왔다. Wang과 Fung 등 11 은타이타늄위에 Cr 코팅을실시하여타이타늄의낮은산화율을보고하였다. 또다른연구 12-13 에서는 silver 코팅을시행하여타이타늄-도재결합이개선되었음을보여주었다. Wang과 Weltch 등 7 은타이타늄위에 Si3N4 코팅을시행하고 Oshida와 Fung 등 14 은타이타늄위에 TiN 코팅을시행함으로써타이타늄표면의질화 (nitridation) 가고온에서타이타늄산화를제한하여도재와의결합에효과적이었다고보고하였다. 최근 Y2O3-ZrO2 을코팅한타이타늄도도재와의결합을향상시켰다고보고되었다. 15 또한 De rand와 Herψ 16 는주조와가공타이타늄에대한도재와의결합에관한연구에서금결합제가타이타늄-도재의결합에비효과적이었다고보고하였다. Lee 등 6 의연구에서는 Au sputter 코팅을시행한경우타이타늄표면에가장많은도재가부착되었음을보고하였는데, Au 코팅이타이타늄표면과화학적결합을하여타이타늄-도재와의결합에 This study was supported by second stage Brain Korea 21 project for school of dentistry. 601

효과적이라고하였다. 따라서본연구에서는주조타이타늄과가공타이타늄을각각 Au, TiN 코팅과 Al2O3 sandblasting으로표면처리후도재를축성소성하여도재와타이타늄의결합력을 2축굴곡실험을통하여비교하고, 임상적으로적용가능성을평가하고자한다. Ⅱ. 연구재료및방법 분류하였다 (Table I). Au 코팅군은 sputter coater(ps-1200, ParaOne, Korea) 로 40mA, 1000s로코팅하였고, TiN 코팅군은 AIP (Arc Ion Plating) 법 (Hybrid coating system, 아텍시스템, Incheon, Korea) 으로 300 에서 N2 유량 300sccm를유입하여공정압력 7.5mTorr에서바이어스 -30V, 아크전류 65A로약 2시간동안증착하여코팅하였다. 1. 금속시편제작 3. 도재소성 주조타이타늄은 CP-Ti(Grade 2, Kobe still Co., Kobe, Japan) 를 13 13 1mm의아크릴판형을제작한뒤 MgO계매몰재 (Selevest CB, Selec, Japan) 로매몰후원심주조하였다 (n=8). 가공타이타늄은 1mm두께의 CP-Ti(Grade 2, Kobe still Co., Kobe, Japan) 판재를초정밀와이어가공기 (AP450L, Sodic Co, Japan) 를사용하여 13 13 1mm크기로준비하였다 (n=8). Au-Pd-In alloy는비교군으로 13 13 1 mm의납형을제작한뒤인산염계매몰재 (Powercast ; Whipmix, USA) 로매몰하고, Au-Pd-In 합금 (Cast- 3, Alphadent, Seoul, Korea) 를 gas-oxygen torch 로용융시킨후원심주조기로주조하였다 (n=8). 2. 표면처리금속시편의종류와표면처리방법에따라군을 각시편에서도재가소성될표면은 dental air abrasion unit(denture Sand Blaster, Hanjin Dental, Seoul, Korea) 에서 50μm Al2O3 particle(korox, Bego, Germany) 로 air abrasion되었다. Air abrasion을위한기압은 0.6MPa (6bar) 에서유지되었고, 표면과 nozzle사이의거리는약 5mm를유지한후약 30초동안 sandblasting하였다. 타이타늄시편의경우초저용융도재 (Vita Titankeramik, Vident, Germany) 를표본의중심에 6mm직경의원형이되게 porcelain bonder를바르고한층의 opaue porcealin과두층의 dentin porcelain을타이타늄전용도재로 (Tikrom, Orotig, Italy) 에서제조회사의추천사이클대로소성하였다 (Table II). 두번째 dentin porcelain 소성후도재의높이를 1.1mm가되게 SiC abrasive paper로연마하였다. 초음파세척기로 5분간세척후건조시키고최종 glaze firing을시행하였다 (Fig. 1). Table I. Experimental groups of specimens used in study Groups Descriptions 1 Cast-titanium, gold coating 2 Cast-titanium, TiN coating 3 Al2O3 blasted cast-titanium 4 Wrought titanium, gold coating 5 Wrought titanium, TiN coating 6 Al2O3 blasted wrought titanium 7 Au-Pd-In alloy 13 mm 6 mm 13 mm 1.1 mm Porcelain 1.0 mm Metal Fig. 1. Dimensions of metal-ceramic specimen. 602

Au-Pd-In 합금시편에서는일반도재 (Creation, Klema, Austria) 를이용하여타이타늄시편에서와동일하게표본의중심에 6mm직경의원형으로 1.1mm높이가되게통상적인도재로 (Austromat 300, Dekema, Germany) 에서제작하였다. 4. 2축굴곡실험 (Biaxial Flexure Test) 실험은특별한 die와 plunger(fig. 2) 를 Load Cell Type의만능재료시험기 (LLOYD-LR50K, LLOYD instrument LTD, UK) 에장착하여금속에서도재가탈락될때까지 0.25mm /min의 cross head speed로압축강도를가하였다. 실험후타이타늄-도재시편상의느슨한도재조각들은 nylon bristle brush로제거된후 10분동안 deionized water에서초음파세척되었다. 락후를검사하였다. 실험후각시편의부착도재면적분율 (AFAP ; Area Fraction of Adherent Porcelain) 이다음과같이계산되었다. Sid - Sit AFAP(%) = 100 Sip - Sit Sip : 도재의첫번째층소성후 Si의원자분율 Sid : 도재탈락후 Si의원자분율 Sit : 도재소성전 Si의원자분율 6. 통계분석 통계처리는 one way ANOVA와 Student-Newman Kuels test (SPSS 10.0 for Windows) 로 95% 유의수준에서통계처리되었다. 5. 표면분석 시편의표면은 EDS(Energy-Dispersive X-ray Spectrometer, Noran, USA) 가있는주사전자현미경 (SEM ; scanning electron microscope, JSM 5400, JEOL, Japan) 으로시편의중심원내의 3.7 2.7mm사각형내에서 Si 함량을조사하였고도재부착의시표로서이용하였다. Si의원자분율 (atomic percentage) 은 50μm Al2O3 sandblasting과초음파세척후, 도재첫번째층소성후, 시편에서도재탈 Plunger Specimen Die Fig. 2. Schematic diagram of a special die and plunger. Table II. Settings of the porcelain furnace used for fusing of the Ultra-Low-Fusing dental porcelain in the present Study Porcelain Layer Porcelain Furnace Setting Paste bonder Heat from 400 to 800 at 60 /min in vacuum, hold at 800 in vaccum for 1 min Opaque porcelain Heat from 400 to 790 at 110 /min in vacuum, hold at 790 in vaccum for 1 min First-layer dentin Heat from 400 to 770 at 50 /min in vacuum, porcelain hold at 770 in vaccum for 1 min Second-layer dentin Heat from 400 to 770 at 50 /min in vacuum, porcelain hold at 770 in vaccum for 1 min Glaze Heat from 400 to 790 at 60 /min in vacuum, hold at 790 in vaccum for 1 min 603

Ⅲ. 결과 Fig. 3은타이타늄의코팅전과후그리고 Au- Pd-In 합금의 SEM사진으로타이타늄시편에서각코팅은주조타이타늄과가공타이타늄에서유사한코팅양상을보였다. Fig. 4는 2축굴곡실험후금속표면을 30배율로촬영한 SEM사진이다. Fig. 4의외견은 3부분으로구분되어지는데백색부분은잔존하는 dentin porcelain, 밝은회색부분은 bonding porcelain이나 opaque porcelain이며검은부분은타이타늄이다. 비교군인 7군이잔존하는도재가가장많고, 3군이가장적으며나머지 1군, 2군, 4군, 5군, 6군은비슷한정도이다. Table III은도재탈락후 Si 성분 (weight concentraion) 을비교한결과이다. 주조타이타늄과가공타이타늄에 Au 코팅과 TiN 코팅을시행한 1군, 2군, 4 군, 5군과가공타이타늄에 Al2O3 sandblasting만을시행한 6군은 Si 함량이약 14~17wt.% 나타내었다. 반면, 주조타이타늄에 Al2O3 sandblasting을시행한 3군은 Si 함량이 7wt.% 를나타내었다. Table IV는 Si 성분의원자분율을나타내었다. 본연구에서도재의첫번째층소성후와도재파절후의 EDS 분석에서 Si 함량을비교해보면, 모든군에서도재의첫번째층소성후가더높은 Si 함량을보인다. 이는도재내파절보다는금속과도재의계면사이파절이일어났음을의미한다 (Table IV). 귀금속이사용된 7군에서도동일한결과를얻은것으로보아, 코팅방법이임상에서사용시일반금속-도재간의결합력과코팅처리된타이타늄-도재간의결합력의차이가크지않을것으로사료된다. 주조와가공타이타늄에대한도재와의결합력을비교해보면, 주조타이타늄에서 Al2O3 sandblasting 한군은 29.88%, 가공타이타늄에서 Al2O3 sandblasting한군은 56.51% 로유의한차이를보였다 (p<.05). 이는주조타이타늄표면에형성된 α-case 층이도재와의결합을방해하여가공타이타늄이도재와의결합력이더우수한것으로사료된다. 하지만본연구에서 110 μm Al2O3 입자로 sandblasting했던것을de rand 등 7 의문헌보고에서처럼주조타이타늄에서 250 μm Al2O3 입자로철저히 sandblasting했다면가공타이타늄에서 Al2O3 sandblasting한군뿐만아니라코팅처리한군들과도유의한차이가없을것으로예상되어이러한점에서앞으로의연구가 Table III. EDS Analyses results (wt.%) on titanium surfaces before & after the porcelain debonding Group Method Ti Au N Al Si 1 Gold coated on C-Ti 4(0) 96(0) 0 0 0 Debonded 43(5) 17(4) 0 3(0) 16(4) 2 TiN coated on C-Ti 96(0) 0 5(0) 0(0) 0 Debonded 57(4) 0 0 2(0) 16(2) 3 Al2O3 blasted on C-Ti 89(1) 0 0 2(0) 0 Debonded 83(3) 0 0 2(0) 6(1) 4 Gold coated on W-Ti 3(1) 97(1) 0 0 0 Debonded 40(4) 20(3) 0 3(0) 16(4) 5 TiN coated on W-Ti 95(0) 0 5(0) 0 0 Debonded 56(4) 0 0 3(0) 17(2) 6 Al2O3 blasted on W-Ti 89(0) 0 0 2(0) 0 Debonded 64(5) 0 0 4(0) 14(2) 7 Au-Pd-In alloy 0 99(0) 0 0 0(0) Debonded 1(0) 79(5) 0 2 (0) 7(1) Entries are mean values. Standard deviations are in parentheses. Data were based on analysis of eight specimens. C-Ti : Cast titanium, W-Ti : Wrought titanium. 604

(a) (d) (b) (e) (c) (f) (g) Fig. 3. SEM photomicrographs of surface treated specimens( 500). (a) cast titanium (b) gold coated cast titanium (c) TiN coated cast titanium (d) wrought titanium (e) gold coated wrought titanium (f) TiN coated wrought titanium (g) Au-Pd-In alloy 605

(a) (d) (b) (e) (c) (f) (g) Fig. 4. SEM photomicrographs specimens after porcelain debonding( 30). (a) Group 1, (b) Group 2, (c) Group 3, (d) Group 4, (e) Group 5, (f) Group 6, (g) Group 7. 606

Table IV. Silicon atomic percentage at each step during determination of AFAP Group After firing of first layer of After debonding of porcelain porcealin 1 29.58(3.20) 19.98(3.50) 2 27.54(1.57) 18.43(1.30) 3 28.15(2.09) 8.33(1.31) 4 32.75(1.49) 20.74(3.30) 5 29.34(2.34) 18.82(1.36) 6 29.20(2.72) 16.62(2.15) 7 24.76(0.52) 19.17(1.43) Entries are mean values. Standard deviations are in parentheses. Data were based on analysis of eight specimens. Table V. Area Fraction of Adherent Porcelain(AFAP%) of all groups Group AFAP 1 66.00(10.84) 2 67.38( 5.68) 3 29.88( 6.16) 4 63.47(10.61) 5 64.67( 8.67) 6 50.51( 7.47) 7 76.53( 7.01) Entries are mean values. Standard deviations are in parentheses. Data were based on analysis of eight specimens. 더필요하리라사료된다. 또한주조타이타늄에서 TiN 코팅한군 (67.38%) 이 Au 코팅한군 (66.0%) 보다약간더높은 AFAP 값을보여주었고 (p>.05), 가공타이타늄에서도 TiN 코팅한군 (64.67%) 이 Au 코팅한군 (63.47%) 보다약간더높은 AFAP value 를보여주었는데 (p>.05) 이는 TiN이치과용도재와유사한성분이기때문인것으로여겨진다. 따라서타이타늄표면의코팅처리가타이타늄의산화를제한하여도재와의결합력을높인다는것을뒷받침해주며, 또한주조타이타늄에서타이타늄표면의코팅처리가기계적처리보다는도재와의결합력을증진시킴을보여준다. Student-Newman Kuels test결과주조타이타늄 에서 Al2O3 sandblasting을시행한 3군은나머지군들과통계학적으로유의한차이를보였고 (p<.05), 1군, 2군, 4군, 5군, 6군간에는통계학적인유의한차이가없었다 (p>.05). Ⅳ. 고찰이러한결과를종합해보면, 주조타이타늄에서 Al2O3 sandblasting만을시행한군의낮은 AFAP 값은타이타늄주조시형성되는두꺼운산화층인 α- case 층때문에나머지군들과현저히낮은 AFAP 값을보인것으로생각된다 (p<.05). 반면, 주조타이타늄과가공타이타늄에서산화층조절을위해코팅처리한경우에 Au 코팅은도재소성시타이타늄의산화층과새로운화합물인 Au2Ti 를형성하는화학반응을일으켜도재와의결합력을증진시켰으며, TiN 코팅은도재소성시산소확산의방어막으로작용하여도재와의결합력을증진시켰다. 또한, 코팅처리한군들은비교군인 Au-Pd-In 합금의 AFAP 값과유의한차이가없었다 (p>.05). 따라서실제임상에서도도재전장금관수복시 Au나 TiN 코팅된타이타늄이사용된다면증진된결합력으로귀금속을대체하여경제적인효과를얻을수있을것이다. 하지만타이타늄코팅방법이상용화되지못해널리사용되기는어려운실정이므로앞으로치과에서손쉽게사용할수있는코팅방법에대해지속적인연구가필요할것으로사료된다. 607

Ⅴ. 결론본연구는타이타늄-도재결합시주조타이타늄과가공타이타늄에서 Au 코팅과 TiN 코팅으로표면처리후타이타늄과도재와의결합강도가증진되는지를알아보고자타이타늄표면에 Au 코팅, TiN 코팅, Al2O3 sandblasting을시행하고, Au-Pd-In 합금과비교하여다음과같은결과를얻었다. 1. 주조타이타늄의 AFAP 값은 TiN 코팅을시행한 2군, Au 코팅을시행한 1군, Al2O3 sandblasting을시행한 3군의순서였고, 1, 2군과 3 군간에는통계학적인유의한차이가있었다 (p<.05). 2. 가공타이타늄의 AFAP 값은 TiN 코팅을시행한 5군, Au 코팅을시행한 4군, Al2O3 sandblasting을시행한 6군의순서였지만, 이군들간에는통계학적인유의한차이가없었다 (p>.05). 3. 주조타이타늄과가공타이타늄의 AFAP 값은비슷하였지만 (p>.05), 주조타이타늄에서 Al2O3 sandblasting한군만은통계학적으로유의하게낮은수치를보였다 (p<.05). 4. Au-Pd-In 합금을사용한 7군이가장높은 AFAP 값을보였다. 사용된도재가달라단순비교는곤란하지만타이타늄군들은모두낮은수치를보였다. 참고문헌 1. Bagby M, Marshall SJ, Marshall GW. Metal ceramic compatibility: A review of the literature. J Prosthet Dent 1990; 63:21-25. 2. Dent RJ, Preston JD, Moffa JP. Effect of oxidation on ceramometal bond strength. J Prosthet Dent 1982;47:59-62. 3. Park SY, Jeon YC, Jeong CM. Comparison of the bond strength of ceramics fused to titanium and Ni-Cr alloy. J Korean Acad Prosthodont 2003;41:89-98. 4. Cai Z, Bunce N, Nunn ME, Okabe T. Porcelain adherence to dental cast CP titanium : effects of surface modifications. Biomaterials 2001;22:979-986 (2001). 5. Sadeq A, Cai Z, Woody RD, Miller W. Effects of interfacial variables on ceramic adherence to cast and machined commercially pure titanium. J Prosthet Dent 2003;90:10-17. 6. Lee KM. Cai Z, Griggs JA, Guiatas L, Lee DJ, Okabe T. SEM/EDS Evaluation of Porcelain Adherence to Gold-Coated Cast Titanium. J Biomed Mater Res Part B: Appl Biomater 2004;68B:165-173. 7. Wang R, Welsch G, Monterio O. Silicon nitride coating on titanium to enable titaniumceramic bonding. J Biomed Mater Res 1999;46:262-270. 8. Pang IC, Gilbert JL, Chai J, Lautenschlager EP. Bonding characteristics of low-fusing porcelain bonded to pure titanium and palladium-copper alloy. J Prosthet Dent 1995;73:17-75. 9. Togaya T, Suzuki M, Tsutsumi A, Ida K. An application of pure titanium to metal porcelain system. Dent Mater J 1983;2:210-219. 10. Kimura H, Horning CJ, Okazaki M, Takahashi J. Thermal compatibiltiy of titanium-porcelain system. J Osaka Uni Dent Sch 1990;30:43-52. 11. Wang RR, Fung KK. Oxidation behavior of surface-modified titanium for titanium-ceramic restorations. J Prosthet Dent 1997; 77:423-434. 12. Könönen M, Varpaveara P, Kivilahti J. Bonding of low-fusing dental porcelain to silver-coated titanium. J Dent Res 1999;78:127(Abst.73). 13. Varpaveara P, Kivilahti J, Könönen M. Comparison of a novel titanium-ceramic system with the commercial systems. J Dent 608

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ABSTRACT EFFECTS OF TITANIUM SURFACE COATING ON CERAMIC ADHESION Yeon-Mi Kim, D.D.S., Hyun-Seung Kim, Ph.D., Kwang-Min Lee, Ph.D.*, Doh-Jae Lee, Ph.D.*, Gye-Jeong Oh, B.S., Hyun-Pil Lim, D.D.S., Yoon-Jung Seo, B.S. Sang-Won Park, D.D.S., Ph.D. Department of Prosthodontics, College of Dentistry, Chonnam University *Division of Materials Science and Engineering, Research Institute for Functional Surface, Chonnam National University Statement of problem: The adhesion between titanium and ceramic is less optimal than conventional metal-ceramic bonding, due to reaction layer form on cast titanium surface during porcelain firing. Purpose: This study characterized the effect of titanium-ceramic adhesion after gold and TiN coating on cast and wrought titanium substrates. Material and method: Six groups of ASTM grade Ⅱ commercially pure titanium and cast titanium specimens(13mm 13mm 1mm) were prepared(n=8). The conventional Au- Pd-In alloy served as the control. All specimens were sandblasted with 110μm Al2O3 particles and ultrasonically cleaned for 5min in deionized water, and dried in air before porcelain firing. An ultra-low-fusing dental porcelain(vita Titankeramik) was fused on titanium surfaces. Porcelain was debonded by a biaxial flexure test at a cross head speed of 0.25mm/min. The excellent titanium-ceramic adherence was exhibited by the presence of a dentin porcelain layer on the specimen surface after the biaxial flexure test. Area fraction of adherent porcelain(afap) was determined by SEM/EDS. Numerical results were statistically analyzed by one-way ANOVA and Student- Newman-Keuls test at α=0.05. Results: The AFAP value of cast titanium was greatest in the group 2 with TiN coating, followed by group 1 with Au coating and the group 3 with Al2O3 sandblasting. Significant statistical difference was found between the group 1, 2 and the group 3 (p<.05). The AFAP value of wrought titanium was greatest in the group 5 with TiN coating, followed by the group 4 with Au coating and the group 6 with Al2O3 sandblasting. Conclusion: No significant difference was observed among the three groups (p>.05). The AFAP values of the cast titanium and the wrought titanium were similar. However the group treated with Al2O3 sandblasting showed significantly lower value (p<.05). Key words : Titanium, Au and TiN Coating, Titanium-Ceramic Adhesion 610