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1 J Dent Hyg Sci Vol.13, No.4, 2013, pp RESEARCH ARTICLE 지르코니아코어의표면처리방법에따른도재축성의전단결합강도 신천호 1 ㆍ황성식 2 ㆍ한경순 1,3 1 가천대학교보건대학원보건학과, 2 경동대학교치기공학과, 3 가천대학교보건과학대학치위생학과 Shear Bond Strength of Veneering Ceramic and Zirconia Core according to the Surface Treatments Cheon-Ho Sin 1, Seong-Sig Hwang 2 and Gyeong-Soon Han 1,3 1 Department of Oral Health Science, Graduate School of Public Health, Gachon University, Incheon , 2 Department of Dental Technology, Kyung Dong University, Sokcho , 3 Department of Dental Hygiene, College of Health Science, Gachon University, Incheon , Korea This study aimed to illuminate the correlatives between the surface processing of Zirconia core and the shear bond strength. The specimens were made by precipitating for two minutes in color liquid and drying to produce a colored Zirconia core following the manufacturer s instructions. The specimens were divided into 4 subgroups according to the surface treatment sandblasted+liner treatment, SLT group; sandblasted treatment, ST group; liner treatment, LT group; non treatment (control), NT group. The specimens were put on the device with regard to ISO/TS 11405, then tested the shear bond strength with 1 mm shearing speed per minute using the Instron multi-purpose tester. The collected data was analysed by one way ANOVA and t-test. After applying the liner and sandblast to the Zirconia core, shear bond strength value were SLT (23.19 MPa), ST (21.17 MPa), LT (20.53 MPa) and NT (16.46 MPa) in the order. There was a significant difference in the surface roughness between NT and ST group (p <0.001), and in the compressive shear bond strength between NT and SLT group (p<0.05). Therefore, sandblasted plus liner treatment on pre-sintered substructure increased the bond strength of veneering ceramic, compared with other surface treatments. Key Words: Shear bond strength, Surface treatments, Veneering ceramic, Zirconia core 서론 도재는구강에서저작기능과심미기능개선을위해치과보철물로일찍이개발되어사용되고있다. 최근치과영역에서는 computer-aided design/computer-aided manufacturing (CAD/CAM) 장비활용이보편화되고있는데, 이는지속적인발전으로강도가보강되고있는재료의발전과더불어보철물제작의정밀도와편리성을증가시키고있으므로심미적인수복물로의도재활용도는보다증가할것으로예상된다. 특히, 전부도재치관 (all ceramic crown) 은금속-도재치관 (metal-ceramic crown) 보다우수한심미성, 생체적합성, 화학적안정성, 자연치와유사한열팽창계수등여러가지장점을갖고있어임상영역에서관심이증가하고있다 1). 지르코니아산화세라믹 (zirconia oxide ceramics) 은전부도재치관의한종류로기존의도재보다높은굴곡및파절강도를나타내므로임상영역에서활용도가매우높아졌다. 그러나지르코니아수복물은색상이불투명하고백색을띠어치과임상에서의색조재현이완벽하지못하기때문에최종 Received: November 25, 2013, Revised: December 3, 2013, Accepted: December 3, 2013 ISSN (Print) / ISSN (Online) Correspondence to: Gyeong-Soon Han Department of Dental Hygiene, College of Health Science, Gachon University, 191, Hambangmoe-ro, Yeonsu-gu, Incheon , Korea Tel: , Fax: , gshan@gachon.ac.kr Copyright 2013 by the Korean Society of Dental Hygiene Science This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License ( by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

2 J Dent Hyg Sci Vol. 13, No. 4, 2013 수복물의색상을위해유색지르코니아를사용하고있다 2). 때문에정밀한수복물의완성도와투명도, 자연치와의조화를위해도재의축성이필요하다. 방법으로는 hand-layered powder build-up과 pressed technique이있는데, 두방법중 hand-layered powder build-up이보편적으로이루어지고있다 3). 지르코니아수복물의결정적인단점으로는기능시발생할수있는 chipping, 즉박리현상에의해실패하는경우를들수있다 4). Chipping의원인으로는불충분한코어와도재의결합강도 5), 열팽창계수차이에의한과도한응력 6), 부적절한코어디자인 7), 소성시도재의수축 8) 과코어와도재의두께비 9) 등으로볼수있다. Manicone 등 8) 은지르코니아수복물의가장취약한부분이지르코니아코어와도재사이의계면이라고하였고, Fischer 등 10) 은계면의결합강도에영향을주는요소에대해화학적결합, 코어표면의거칠기에따른기계적인결합, 도재의젖음성 (wettability), 코어와도재간의열팽창계수에따른압축력등이라고보고한바있다. 한편 Saito 등 9) 은지르코니아코어와도재간의결합강도에관여하는서로다른표면처리의효과와기전에대해서는명확히밝혀진바가없다고하였다. 이를배경으로지르코니아코어와도재사이의계면상태, 특히지르코니아코어제작을도재와동일한구조로하였을때코어표면의처리방법이수복물의전단결합강도에영향력이있는지를확인하는것은중요한의미를가진다고볼수있다. 이에본연구에서는도재와동일한구조로코어를제작한후코어표면의거칠기처리와 liner 도포방법을각기다르게하여도재의전단결합강도를측정하고자한다. 이결과를통해확인된지르코니아코어표면처리방법에따른코어와도재와의결합기전은도재수복물의문제점을개선하는데도움을줄수있을것으로기대한다. 연구대상및방법 1. 실험재료및시편제작본연구를위한시편은안정화지르코니아 (Y-TZP, ZIRpremium-DS; Acucera Inc., Namyangju, Korea) 를가운데가뚫려있는원기둥형태의직경 5.0 mm, 높이 15 mm 인반소결되어있는 block 형태의코어였으며, CAD/CAM (CAM Software and Milling Machine; Imes-Icore Co., Berlin, Germany) 을이용하여제작하였다 (Table 1). 가공한코어는전기로에넣고 8.3 o C/min의승온속도로 1,500 o C까지올려 2시간동안유지하여소결하였다. 제작한 40개의시편은불순물을제거한후건조하였다. 건조된시편은유색지 Table 1. Chemical Composition of Zirconia (wt%) Y 2O 3 Al 2O 3 SiO 2 Fe 2O 3 ZrO 2+HfO Ig-loss a Max Max a Organic matter, reduced by the amount of moisture in the temperature. Ig: ignition loss, Max.: maximum. 르코니아코어로만들기위해서제조사의지시에따라 colouring liquid (Zenostar Color Zr; Wieland Dental Co., Pforzheim, Germany) 에 2분간담근후건져내어 1시간건조하였다. 이후전용 furnace (Dekema Austromat sintering furnace; Wieland Lufttechnik Co., Erlangen, Germany) 를이용하여제조사의지시에따라 1,500 o C에서 10시간 1분 35 초동안두번째소결과정을시행하였다. 2. 표면처리제작한 40개의시편은 10개씩 4개의군으로나누었으며, 시편의표면전체에대해군별로각각다른방법으로처리하였다. Non treatment (NT) 군의표면은어떤처리도하지않았으며 (n=10), liner treatment (LT) 군은 liner (IPS e.max Ceram; Ivoclar Vivadent Co., New York, NY, USA) 를도포하였다 (n=10). Sandblasted treatment (ST) 군의표면처리는평균입경 150 μm 알루미나 (Al2O3) 연마제 (Hi-aluminas; Shofu Inc., Kyoto, Japan) 를사용하여 10 mm 떨어진위치에서압력 4기압으로 15초동안분사처리한후증류수에담구어 5분동안초음파세척을하였고이를건조하였다 (n=10). Sandblasted+liner treatment (SLT) 군은 ST군과같은방법으로분사와건조과정을거친후 liner 도포를추가하였다 (n=10). 3. 도재축성대조군을포함한각각의시편도재 (IPS e.max Ceram) 를 silicon jig을이용하여두께 1.5 mm, 높이 3.0 mm로축성하였다. 이후제조사의지시에따라시편을 silicon jig에꽂아 1, 2, 3차에걸친축성및소결과정을거쳤다. 4. 표면조도및전단결합강도, 계면상태측정표면조도 (surface roughness) 는결합강도에대한표면거칠기의영향을파악하고자측정하였다. 표준시편으로조정된측정기 (SJ-400; Mitutoyo Co., Kanagawa, Japan) 를이용하였고, 0.5 mm/s의이동조정된중앙부위에서 4.0 mm 의거리를시편당 3회측정하여각평균값을기록하였다. 전단결합강도는 37 o C 항온수조에증류수를담아 24시간 488

신천호외 : 지르코니아코어의표면처리에따른도재의전단결합강도 Fig. 1. Photograph of push shear bonding test of zirconia core/ porcelain. Table 2. Roughness Values Experimental Groups (μm) Group Mean SD t p-value a NT 19.52 0.62 2.

Effect of Shear Bond Strength according to Zirconia Core Surface Treatments Group Mean SD F p-value a NT 16.46 6.42 1.744 0.175 LT 20.53 5.41 ST 21.17 7.40 SLT 23.19 7.57 Total 20.34 6.

3 신천호외 : 지르코니아코어의표면처리에따른도재의전단결합강도 Fig. 1. Photograph of push shear bonding test of zirconia core/ porcelain. Table 2. Roughness Values Experimental Groups (μm) Group Mean SD t p-value a NT <0.001 ST a p-values by t-test. NT: non treatment, ST: sandblasting treatment, SD: standard deviation. Table 3. Effect of Shear Bond Strength according to Zirconia Core Surface Treatments Group Mean SD F p-value a NT LT ST SLT Total a p-values by one way ANOVA. NT: non treatment, LT: liner treatment, ST: sandblasted treatment, sandblasted+liner treatment, SD: standard deviation. aging을한후 ISO/TS (Dental Materials-Testing of adhesive to tooth structure) 에따른장치에옮기고인스트론만능시험기 (Intron 8871; Instron Co., Canton, OH, USA) 를이용하여분당 1 mm의전단속도로전단결합강도시험을진행하였다 (Fig. 1). 전단결합강도를구하기위해서원주상에띠상의결합계면을갖는경우작용력을결합부의단면적으로나누어서다음의공식을이용하여전단결합강도 ( ) 를계산하였다. P: 작용력 (N) d: 시편의직경 h: 시편의높이 파절된계면의상태는전단결합강도를측정한후시편에서파절된부위를백금코팅처리하여 scanning electron Table 4. Effect of Compressive Shear Bond Strength according to NT or SLT Group Mean SD t p-value a NT SLT a p-values by t-test. NT: non treatment, SLT: sandblasted+liner treatment, SD: standard deviation. microscope (SEM, JSM-6510; Jeol Resonance Inc., Tokyo, Japan) 를이용하여관찰하였다. 5. 통계분석지르코니아표면처리에따른표면조도와전단및압축결합강도의분석은 IBM SPSS Statistics version 20.0 (IBM Co., Armonk, NY, USA) 을이용하여 one way ANOVA와 t-test를실시하였다. 통계적유의성판정은 p<0.05에서실시하였으나, 유의수준은낮지만향후연구에서충분한고려를위해 0.2 이하인경우도경향성을주요하게검토하였다. 결과 1. 표면조도지르코니아코어의표면거칠기처리후표면조도측정결과는 Table 2와같다. 표면조도는 ST군이 μm, NT군은 μm로통계적으로유의한차이를나타냈다 (p<0.001). 2. 전단결합강도전단결합강도는 Table 3, 4와같다. 4개군의평균전단결합강도차이를파악하기위해 one way ANOVA를시행하였다. SLT군이 MPa로가장높았고, ST군은 MPa였으며, LT군은 MPa였고, NT군이 MPa 으로가장낮은값을나타냈다 (p=0.175). SLT군을 NT군과 489

Photographs of specimen before push shear

NT: non treatment, LT: liner treatment, ST:

Scanning electron microscope micrograph of

100). sandblasted+ liner treatment. Fig. 6.

zirconia core-veneering porcelain after push

sandblasted+liner treatment, Zr: Zirconia,

microscope/electron deflection system (SEM/

전단결합강도 시험 후 계면상태는 NT 군에서는 완전히 박리된 상태를 보였으나

4 J Dent Hyg Sci Vol. 13, No. 4, 2013 Fig. 2. Photographs of specimen before push shear bonding test ( 100). NT: non treatment, LT: liner treatment, ST: sandblasted treatment, SLT: sandblasted+liner treatment. Fig. 5. Photographs of specimen after push shear bonding test. ( 45). NT: non treatment, LT: liner treatment, ST: sandblasted treatment, SLT: sandblasted+liner treatment. Fig. 3. Scanning electron microscope micrograph of specimen after push shear strength test ( 100). NT: non treatment, LT: liner treatment, ST: sandblasted treatment, SLT: sandblasted+ liner treatment. Fig. 6. SEM/EDS analysis of the interface between zirconia core-veneering porcelain after push shear bond strength test ( 2,000). NT: non treatment, LT: liner treatment, ST: sandblasted treatment, SLT: sandblasted+liner treatment, Zr: Zirconia, O: Oxygen, Al: Alumina, Si: Silica, Ca: Calcium. 비교하기 위해 t-test를 시행한 결과 2개 군의 차이는 통계적 으로 유의하였다(p 0.05). 3. 계면상태 Fig. 4. Scanning electron microscope micrograph of specimen after push shear bonding test ( 500). NT: non treatment, LT: liner treatment, ST: sandblasted treatment, SLT: sandblasted+ liner treatment. 490 지르코니아 코어와 도재 시편의 계면상태를 scanning electron microscope/electron deflection system (SEM/ EDS)로 분석하였다. 전단결합강도 시험 후 계면상태는 NT 군에서는 완전히 박리된 상태를 보였으나 LT군에서는 박리 되지 않았고, ST군에서는 응집효과가 나타났으며, SLT군 에서는 보다 더 응집된 상태를 나타냈다(Fig. 2 5). 수복물 의 핵심 역할을 하고 있는 코어는 결합기전과는 관련이 없 음을 알 수 있었다(Fig. 6).

5 신천호외 : 지르코니아코어의표면처리에따른도재의전단결합강도 고찰 심미적인수복물로의도재활용도는앞으로보다증가할것으로예상된다. 그러나도재의결정적인문제점은기능시발생할수있는박리현상으로지르코니아코어와도재사이의계면이가장취약한부위로알려져있다. 따라서지르코니아강화도재수복물의성공은지르코니아코어와도재사이의안정적인결합형성에따라달라질것으로예상된다. 본연구는지르코니아코어와도재간의전단결합강도에대한코어표면거칠기의차이와 liner 적용의상호작용을알아보기위한목적으로진행하였다. 지르코니아코어의표면조도 (surface roughness) 는 ST군이 μm로 NT군의 μm보다높아통계적으로유의한차이를나타냈다 (p<0.001). Kirmali 등 11) 도표면처리를하지않거나레이저만을이용하여표면을처리하였을때에는표면조도효과가없었으나, 연마제분사를병행한경우거친표면을확인하였다고하여본연구와유사하였다. 그러나 Kirmali 등 12) 은지르코니아코어표면을연마제분사와레이저, liner를이용하여표면을다르게처리한후소결과정을거쳤을때표면조도에는차이가없었다고하였다. 따라서표면처리방법에따른표면조도의차이에대해추후검토할필요성이있을것으로생각된다. 지르코니아코어와도재의결합강도실패양상에대해 Aboushelib 등 6) 과 Saito 등 9), Ozkurt 등 13) 은 air-borne particle abrasion 또는 liner의사용에영향을받는다고하였다. Guazzato 등 14) 은 air borne particle abrasion이코어의표면을거칠게하여기계적결합력을증가시킨다고하였고, Fischer 등 10) 은 air borne particle abrasion이결합강도를증가시키는데영향력이없었다고하였다. Liner의적용에대해 Aboushelib 등 6) 은코어를차폐 (masking) 하기위해사용하는것으로도재의젖음성 (wettability) 을증가시키고결합강도를강하게한다고하였고, Tinschert 등 15) 과 Fischer 등 10) 은 liner의적용이오히려결합강도를약화시킨다고보고한바있다. 따라서본연구에서는연마제분사를이용한표면거칠기처리와 liner 적용을각기다르게적용한 4개군시편의지르코니아코어의전단결합강도를분석하였다. 결과는 SLT군이 MPa로가장높은전단결합강도를나타냈고, 다음으로 ST군이 MPa였으며, LT군은 MPa였고, NT군은 MPa으로가장낮은값을나타내 (p=0.176) 통계적유의수준은낮았으나표면처리방법에따라전단결합강도의차이를나타낼가능성을확인하였다. 이후가장높은값을나타낸 SLT군과 NT군의두개군을선택하여전단결합강도의통계적유의수준을분석한결과에 서는유의한차이가있음을확인하였다 (p<0.05). 이결과를통해표면거칠기처리나 liner를단일하게적용하는것으로는전단결합강도를높이는데큰영향을미칠수없지만표면거칠기처리와 liner를함께적용하는경우에는전단결합강도가매우높아짐을알수있다. 따라서전단결합강도를높이기위해서는지르코니아표면처리과정이매우중요하며특히표면거칠기처리와 liner를함께적용하는것은지르코니아코어와도재의결합여부에효과적인요인으로작용하고있음을본연구방법에서확인하였다. 지르코니아코어와도재시편의결합강도시험후계면상태를 SEM/EDS로분석한결과결합계면의파절양상은표면을처리하지않은군에서는완전히박리된상태를보였으나, liner를적용한군에서는박리되지않았고, 표면거칠기를적용한군에서는응집효과가나타났으며, 표면거칠기와 liner를도포한군에서는보다더응집된상태를나타냈다. 또한수복물의핵심역할을하고있는코어는결합기전과는관련이없음을알수있었다. Lee 등 16) 도지르코니아와도재의결합계면상태를관찰한결과화학반응된층은발견할수없었으며, 도재가지르코니아의결정및결정립에침투하여결합하고있는것을볼수있었다고하여본연구와유사한결과를보고한바있다. 이러한결과는지르코니아와도재가화학적결합보다는물리적결합에의존하고있음을나타내는것으로표면거칠기처리는지르코니아코어와도재의결합강도를높이는의미있는과정임을확인할수있는중요한결과라고생각된다. 본연구는구강내환경을그대로재현하지못한상태에서진행하였다는점에서한계점을가지고있으므로일반화하는데신중을기할필요가있다. 그러나지르코니아코어표면처리방법에따른코어와도재와의결합강도를확인하여도재수복물의문제점개선시도에도움을줄수있다는점에서연구의의미를찾을수있다. 향후구강환경재현과피로강도측정을병행한연구를통해코어표면처리과정과전단결합강도의관련성에대한확신을더할필요성이있을것이다. 요약 본연구는지르코니아코어표면처리방법에따른코어와도재와의결합기전을파악하여도재수복물의문제점을개선하고자도재와동일한구조의코어를제작한후코어표면의거칠기처리와 liner 적용방법을각각달리한 4개군의전단결합강도의차이를분석한바다음과같은결론을얻었다. 491

6 J Dent Hyg Sci Vol. 13, No. 4, 코어의표면거칠기처리여부는표면조도에영향을주었다 (p<0.001). 2. 지르코니아코어표면을표면거칠기와 liner를도포한군 (SLT군) 이 MPa로가장높았고, 표면거칠기만적용한군 (ST군) 이 MPa였으며, liner만적용한군 (LT 군 ) 은 MPa였고, 표면비처리군 (NT군) 이 MPa 으로가장낮은값을나타내 (p=0.176) 표면처리에따른전단결합강도에차이가있을가능성을나타냈다. 또한표면거칠기와 liner를도포한군 (SLT군) 과표면비처리군 (NT군) 에서두군간의차이는통계적으로유의하였다 (p<0.05). 3. 계면상태는 SLT군이 ST군과 LT군, NT군에비해도재결합의응집된상태를나타냈다. 코어의표면처리특히거칠기처리는지르코니아코어와도재의물리적결합즉, 전단결합강도를높일수있는의미있는과정임을확인하였다. References 1. Scherrer SS, Kelly JR, Quinn GD, Xu K: Fracture toughness (KIc) of a dental porcelain determined by fractographic analysis. Dent Mater 15: , Ardlin BI: Transformation-toughened zirconia for dental inlays, crowns and bridges: chemical stability and effect of low-temperature aging on flexural strength and surface structure. Dent Mater 18: , Beuer F, Naumann M, Gernet W, Sorensen JA: Precision of fit: zirconia three-unit fixed dental prostheses. Clin Oral Investig 13: , Della Bona A, Mecholsky JJ Jr, Anusavice KJ: Fracture behavior of lithia disilicate- and leucite-based ceramics. Dent Mater 20: , De Jager N, de Kler M, van der Zel JM: The influence of different core material on the FEA-determined stress distribution in dental crowns. Dent Mater 22: , Aboushelib MN, de Jager N, Kleverlaan CJ, Feilzer AJ: Microtensile bond strength of different components of core veneered all-ceramic restorations. Dent Mater 21: , Sailer I, Fehér A, Filser F, et al.: Prospective clinical study of zirconia posterior fixed partial dentures: 3-year follow-up. Quintessence Int 37: , Manicone PF, Rossi Iommetti P, Raffaelli L: An overview of zirconia ceramics: basic properties and clinical applications. J Dent 35: , Saito A, Komine F, Blatz MB, Matsumura H: A comparison of bond strength of layered veneering porcelains to zirconia and metal. J Prosthet Dent 104: , Fischer J, Stawarczyk B, Hämmerle CH: Flexural strength of veneering ceramics for zirconia. J Dent 36: , Kirmali O, Akin H, Kapdan A: Evaluation of the surface roughness of zirconia ceramics after different surface treatments. Acta Odontol Scand Nov 21, [Epub ahead of print] 12. Kirmali O, Akin H, Ozdemir AK: Shear bond strength of veneering ceramic to zirconia core after different surface treatments. Photomed Laser Surg 31: Ozkurt Z, Işeri U, Kazazoğlu E: Zirconia ceramic post systems: a literature review and a case report. Dent Mater J 29: , Guazzato M, Quach L, Albakry M, Swain MV: Influence of surface and heat treatments on the flexural strength of Y-TZP dental ceramic. J Dent 33: 9-18, Tinschert J, Natt G, Mautsch W, Spiekermann H, Anusavice KJ: Marginal fit of alumina-and zirconia-based fixed partial dentures produced by a CAD/CAM system. Oper Dent 26: , Lee SS, Lee SH, Ahn JS, Kim MH: A comparative study on the fracture behavior of zirconia, glass infiltrated alumina and PFM full crown system. J Korean Acad Prosthodont 50: ,

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