레진시멘트의접착내구성에관한연구 레진시멘트의접착내구성에관한연구 조민우 박상혁 김종률 최경규 * 경희대학교대학원치의학과치과보존학교실 ABSTRACT THE BONDING DURABILITY OF RESIN CEMENTS Min-Woo Cho, Sang-Hyuk Park,

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1 조민우 박상혁 김종률 최경규 * 경희대학교대학원치의학과치과보존학교실 ABSTRACT THE BONDING DURABILITY OF RESIN CEMENTS Min-Woo Cho, Sang-Hyuk Park, Jong-Ryul Kim, Kyoung-Kyu Choi* Department of Conservative Dentistry, Division of Dentistry, Graduate of Kyung Hee University The objectives of this study was to evaluate the durability of 4 resin cements by means of microtensile bond strength test combined with thermocycling method and fractographic FE-SEM analysis. Experimental groups were prepared according to thermocycling (0, 1,000, 5,000) and the kind of resin cements, those were Variolink II, Multilink, Panavia F 2.0, Rely X Unicem. Flat dentin surfaces were created on mid-coronal dentin of extracted third molars. Then fresh dentin surface was grounded with 320-grit silicon carbide abrasive papers to create uniform smear layers. Indirect composite block (Tescera, Bisco Inc., Schaumburg, IL, USA) was fabricated ( mm 3 ). It s surface for bonding to tooth was grounded with silicon carbide abrasive papers from 180- to 600-grit serially, then sandblasted with μm alumina oxide. According to each manufacturer s instruction, dentin surface was treated and indirect composite block was luted on it using each resin cement. For Rely X Unicem, dentin surface was not treated. The bonded tooth-resin block were stored in distilled water at 37 for 24 hours. After thermocycling, the bonded tooth-resin block was sectioned occluso-gingivally to 1.0 mm thick serial slabs using an Isomet slow-speed saw (Isomet, Buehler Ltd, Lake Bluff, IL, USA). These sectioned slabs were further sectioned to mm 2 composite-dentin beams. The specimens were tested with universal testing machine (EZ-Test, Shimadzu, Japan) at a crosshead speed of 1.0 mm /min with maximum load of 500 N. The data was analyzed using one-way ANOVA and Duncan s multiple comparison test at p 0.05 level. Within the limited results, we conclude as follows; 1. The bond strength of Variolink II was evaluated the highest among experimental groups and was significantly decreased after 1,000 thermocycling (p < 0.05). 2. The bond strength of Multilink was more affected by thermocycling than the other experimental groups and significantly decreased after 1,000 thermocycling (p < 0.05). 3. Panavia F 2.0 and Rely X Unicem showed the gradually decreased tendency of microtensile bond strength according to thermocycling but there was no significant difference (p > 0.05). * Corresponding Author: Kyoung-Kyu Choi Professor of Division of Dentistry, Graduate school of KyungHee University 1, Hoegi Dong, Dongdaemun Gu, Seoul, Korea, Tel: choikkyu@khu.ac.kr 343

2 대한치과보존학회지 : Vol. 32, No. 4, Adhesive based-resin cements showed lower bond strength with or without thermocycling than composite based-resin cements. 5. Variolink II & Multilink showed high bond strength and mixed failure, which was occurred with a thin layer of luting resin cement before thermocycling and gradually increased adhesive failure along the dentin surface after thermocycling. The bonding performance of resin cement can be affected by application procedure and chemical composition. Composite based-resin cement showed higher bond strength and durability than adhesive based-resin cement. [J Kor Acad Cons Dent 32(4): , 2007] Key words: Bonding Durability, Resin Cement, Variolink II, Multilink, Panavia F 2.0, Rely X Unicem - Received , revised , accepted Ⅰ. 서론 최근임상에서간접레진수복은심미적인요구가커짐에따라점차그수요가증가하는추세이다. 이러한술식은직접수복에비해수축응력이작기때문에술후민감성을감소시킬수있다. 간접레진수복을위해서는레진시멘트를사용해야하며치아와수복물간에직접붙는성질때문에 inlay, onlay, crown, post, veneer 등치과용수복물전반으로점차그사용범위가확대되고있다 1-5). 레진시멘트는상아질접착과정을기본으로하며, 치아에전처리없이사용하는자가접착형레진시멘트를제외하고전체산부식형또는자가부식형상아질접착제를필요로한다 6). 레진시멘트는상아질접착제의접착과정에따른방법과레진시멘트의중합방식에따른방법그리고접착기능성단량체의유무와시멘트의조성에따른방법으로분류한다. 레진시멘트의중합방식에따른방법으로자가중합, 이중중합, 광중합형레진시멘트로분류한다 7). 광중합형레진시멘트는색상, 조성등이다양하여심미적이고충분한작업시간을가지며광조사를통해빠른경화를가능하게하는장점을가지지만빛이투과하지못하는곳에서는사용할수없다. 이중중합레진시멘트는자가중합형과광중합형의특징을동시에가지게되지만대부분광중합이먼저선행되지않으면결합강도가저하되는경향이있다 8,9). 자가중합레진시멘트는고정된작업시간및경화시간을가지고빛이투과할수없는곳에사용한다. 접착기능성단량체의유무에따라서복합레진형레진시멘트 (composite based-resin cement) 와접착형레진시멘트 (adhesive based-resin cement) 로분류할수있다 7). 접착형레진시멘트는자가접착능력을지니며, 치질표면에대해스스로간단한부식과정을하거나또는직접적용할수있는레진시멘트이다. 이는접착기능성단량체 (4- META, 10-MDP, Phenyl P, 4-MET 등 ) 를포함하고있기때문이다. 반면에복합레진형레진시멘트는스스로접착할수있는능력이없어상아질접착제를적용한후이용하며그성분이복합레진과유사하기때문에심미성이좋고강도가우수하다. 레진시멘트의결합내구성은많은부분상아질내레진침투층 (resin infiltrated layer) 의영향을받게되며일상적인저작이나구강내온도변화, 이갈이, 기계적인 stress 등많은요소들이영향을끼치게된다. 인산을사용하여상아질을산부식한후접착레진을침투시키는방식인전체산부식형상아질접착제는상아질의탈회된교원질구조를따라접착레진이탈회된깊이만큼침투하지못할수도있다 10,11). 즉시간이경과하면서노출된교원섬유가가수분해되어상아질과접착제계면에서접착레진의결합강도가저하될수있다 12). 이에반해자가부식형접착제는부식및침투능력은제한되지만상아질의탈회와접착레진의침투가동시에이루어져탈회와침투의깊이차이가없으며교원섬유의노출가능성또한낮아산부식형상아질접착제에비하여상대적으로결합이안정적일수있다 13). 결합의내구성을평가하는보편적인방법은 37 수중보관으로이루어지는시효처리 (aging by storage in water) 이다. 고분자기질내로수분이침투하여고분자사슬의마찰력이감소되고기질이팽창 (swelling) 되어물리적성질이저하되며미중합레진단량체가용출되어서시간의경과에따라상아질접착제는변성되거나가수분해되어레진 - 상 344

3 아질간의결합이실패하게된다 14,15). 결합의내구성을평가하는다른방법에는열순환방법이있으며이는가장널리사용되는인공시효처리방법이다열순환방법은 5 55 의수중에서반복적으로침지순환을하는것으로수중보관시효처리보다효율적으로접착내구성을평가할수있다 15-17). 열순환기를이용한인공시효처리는다음의두가지과정을통해이루어진다. (1) 첫째, 온수가접착계면의노출된교원섬유의가수분해를촉진시키고미중합레진단량체들을용출시킨다 18,19). (2) 두번째는치질과수복물간열팽창계수의차이로수축과팽창이반복되어계면에균열이생기고이를통해온수가소통하게되며이는더욱균열이확장되는것을촉진하게된다 (percolation). Krejci 와 Lutz 20) 는열순환후에법랑질결합강도는변하지않았으나, 상아질결합강도는영향을받아감소하였으며, 상아질과레진사이의누출이존재하였다고보고하였다. 본연구는 4 종의레진시멘트를통해접착한상아질과간접레진수복물간의인장결합강도를측정하고, 열순환시 효처리여부에따른결합강도를비교하고, 주사전자현미경관찰을통하여각레진시멘트의접착내구성을평가하고자시행되었다. 1. 실험재료 Ⅱ. 실험재료및방법 우식이없는건전한 48 개의제 3 대구치를발치하여 Tymol 용액에보관한후미세인장결합강도측정및전계방출형주사전자현미경 (FE-SEM) 관찰에사용하였다. 본연구에서사용한레진시멘트는 Variolink II (Ivoclar Vivadent, Schaan, Lichtenstein), Multilink (Ivoclar Vivadent, Schaan, Lichtenstein), Panavia F 2.0 (Kuraray Medical Inc, Osaka, Japan), Rely X Unicem (3M ESPE, Seefeld, Germany) 이다. 이들의각구성성분과분류는 Table 1 과같으며각레진시멘트에사용되는상아질접착제와그분류는 Table 2 와같다. Table 1. Resin cements used in this study Resin cements Type Curing mode Composition Lot Number Variolink II (Ivoclar Vivadent Base Paste : BisGMA, UDMA, TEGDMA, DMA, J03646 Schaan, Composite Dual barium sulfate, Ba-Al-F-Si glass, ytterbium trifluoride J01609 Lichtenstein) Catalyst Paste : benzoylperoxide Multilink (Ivoclar Vivadent Self dimethacrylate, HEMA, barium glass filler, ytterbium H33577 Schaan, trifluoride, silica filler, catalyst, stabilizer Lichtenstein) A Paste : 10-MDP, bisphenol A polyethoxy dimethacrylate, hydrophobic dimethacrylate, hydrophilic dimethacrylate, 00176A Panavia F 2.0 benzoyl peroxide, silianated silica, colloidal silica, D,L-CQ (Kuraray, Adhesive Dual B Paste : bisphenol A polyethoxy dimethacrylate, hydrophobic Osaka Japan) dimethacrylate, hydrophilic dimethacrylate, N,N -diethanol- P-toluidine, sodium 2,4,6-trisopropyl benzene sulffinate, 00025B silanated barium glass, silanated titanium oxide, sodium fluoride, colloidal silica Rely X Unicem Powder : glass powder, silica, calcium hydroxide, pigment, (3M ESPE, Dual substituted pyrimidine, peroxy compound, initiator Seefeld Liquid : methacrylated phosphoric ester, dimethacrylate, Germany) acetate, stabilizer, initiator 345

4 대한치과보존학회지 : Vol. 32, No. 4, 실험방법 A. 실험군의분류 4 가지레진시멘트를이용하여복합레진 block 을상아질표면에결합시킨후, 각각 0, 1,000, 5,000 번열순환회수에따라 12 개의실험군으로분류하였다. B. 시편의제작 48 개의건전한제 3 대구치의교합면법랑질을제거한후저속 diamond saw (Isomet, Buehler Ltd, Lake Bluff, IL, USA) 로연마하여건전한상아질표면을노출시킨후표면을 #320 SiC paper 를이용하여연마하고표준도말층을형성하였다. 복합레진 block 을 Tescera (Bisco Inc., Schaumburg, IL, USA) 를사용하여 mm 3 의크기로제작하였다. 제작된복합레진 block 을순차적으로 #180, #320, #600 SiC paper 를이용하여연마하고 μm산화알루미늄으로 10 초간표면처리 (sandblast) 하여접착면을형성하였다. 제조사의지시에따라상아질접착제를적용한후, 치아표면에각레진시멘트를적용하고복합레진 block 을접착시켰다 (Table 3). Rely X Unicem 은치면처리를하지않고직접시멘트를적용하였다. 각시멘트를사용하여 12 개의치아에접착시킨후광조사가필요한 Variolink II, Panavia F 2.0, Rely X Unicem 에서는 LED 광중합기 (Elipar FreeLight 2, 3M ESPE, St. Paul, MN, USA) 를사용하여 40 초간중합시켰다 (Table 3). C. 시편의열순환제작된 12 개실험군의시편을 37 증류수에 24 시간동안보관한후, 열순환을시행하지않은즉시군 (T = 0), 1,000 회군 (T = 1000), 5,000 회군 (T = 5000) 으로나누어열순환기 ( 항온수조기, TaeWon Tech, Sihung, Korea) 에서열순환을시행하였다. 본실험의열순환기는 5 및 55 의항온수조로구성되며, 시편이수조에머무르는시간은각각 15 초이며이동시간은 6 초가소요되었다. 모든열순환과정은프로그램에의하여자동으로제어되도록하였다 (Figure 1). D. 미세인장결합강도측정접착된 12 개실험군의시편을저속 diamond saw (Buehler, USA) 를이용하여치아의장축을따라 1 mm의두께로절단하고, 이를다시수직절단하여단면적이약 1 mm 2 가되도록막대형시편을제작하였다 (Figure 2). 절단된시편을미세인장결합강도측정을위한 jig 에 Zapit (Palladium, USA) 을이용하여부착한후 universal testing machine (EZ Tester, Shimadzu, Japan) 을이용하여 1 mm /min 의속도로인장응력을가하여미세인장결합강도를측정하였다. 유의수준 0.05 level 에서 one-way ANOVA / Duncan s test 로통계분석하였다. Table 2. Bonding system of resin cements used in this study Resin cements Bonding Type Bonding system Composition Lot Number Variolink II (Ivoclar Vivadent Total etching Excite DSC : Etchant : 37% phosphoric acid gel J03640 Schaan, Adhesive : BisGMA, HEMA, ethanol, water, filler, CQ Lichtenstein) Multilink Primer A : water, initiator J04346 (Ivoclar Vivadent Self etching Primer B : phosphoric acid acrylate, HEMA, methacrylate Schaan, Lichtenstein) modified polyacrylic acid stabilizer J03234 ED Primer II A : 2-hydroxyethyl methacrylate, 10-MDP, Panavia F 2.0 N-methacryloyl 5-aminosalicylic acid, N,N - diethanol-p B (Kuraray Self etching toluidine, water Medical Inc, ED Primer II B : 2-hydroxyethyl methacrylate, sodium Osaka Japan) bezen sulfinate, N-methacryloyl 5-aminosalicylic acid, 00100A N,N -diethanol-p-toluidine, water, Rely X Unicem (3M ESPE, Seefeld Auto adhesive none Germany) 346

5 Table 3. Bonding procedure of resin cements used in this study Resin cement Bonding Procedure 1. etch for 15s, wash and blot dry Variolink II 2. apply Excite DSC for 10s, light cure for 10s 3. mix equal volume of base & catalyst 4. lute and light cure for 40s 1. mix Primer A & B 1:1 2. apply for 15s and wait 15s Multilink 3. dry with water & oil free air 4. mix Multilink paste 5. lute and wait 5 minutes 1. mix ED primer II A & B 1:1 2. apply and wait 30s Panavia F gently air dry 4. mix equal volume of paste A & B 5. lute and light cure for 40s 1. mix Applicap capsule by Rotomix for 10s Rely X Unicem 2. lute and light cure for 40s Thermocycling method : dwelled for 15s at each bath and interval for 6s : 0, 1000, 5000 cycles Figure 1. Schematic presentation of thermocycling method. Figure 2. Schematic presentation of μtbs testing. E. 전계방출형주사전자현미경 (FE-SEM) 관찰미세인장결합강도실험전에열순환을하지않은즉시군 (T = 0) 의시편의접착계면을수직절단하여노출된접착면을 #1500, #2000 SiC paper 와 ZnO 분말을이용하여연마하고산부식 3 초, NaOCl 에 3 분처리한후 gold sputtering (SC 502 sputter coater, VG Microtech, England) 하였고, 미세인장결합강도실험후의상아질측파단면을 gold sputtering 하여 FE-SEM (Leo Supra 55, Carl Zeiss, Germany; Genesis 2000, Edax, USA) 을이용하여관찰하였다. 347

6 대한치과보존학회지 : Vol. 32, No. 4, 미세인장결합강도 Ⅲ. 실험성적 Table 4 는 4 종류의레진시멘트의열순환전후의미세인장결합강도를나타내고있다. Variolink II 의경우, 2 단계전체산부식형상아질접착제 를사용하는복합레진형레진시멘트로서즉시군 (T = 0) 에서높은결합강도를보여주고있으며 1,000 회열순환이후에통계적으로유의성있는결합강도의감소가관찰되었으나 (p < 0.05), 5,000 회이후에는유의차가없었다 (Figure 3). Multilink 는 1 단계자가부식형상아질접착제를사용하며 1,000 회열순환이후에결합강도가유의성있게감소되 Table 4. Microtensile bond strengths(mpa, mean strength ± SD) of 12 experimental groups T = 0 T = 1000 T = 5000 Variolink II ± a ± b ± b Multilink ± b ± 9.21 c ± cd Panavia F ± cd ± cd ± 8.55 cd Rely X Unicem ± 6.94 cd ± 7.41 d ± 4.62 d * Groups with the same superscripts are not statistically significant. Figure 3. Microtensile bond strength of Variolink II. Figure 4. Microtensile bond strength of Multilink. Figure 5. Microtensile bond strength of Panavia F 2.0. Figure 6. Microtensile bond strength of Rely X Unicem. 348

7 Figure 7. Comparison of μtbs for each experimental group. 었고 (p < 0.05), 5,000 회이후에는유의차가없었다 (Figure 4). Panavia F 2.0 은자가부식형상아질프라이머를사용하는접착형레진시멘트로서복합레진형 (Variolink II) 보다즉시군에서결합강도가많이낮게나타났다. 열순환후점진적으로결합강도가감소되는양상을보여주고는있지만, 통계적으로유의성은없었다 (p > 0.05)(Figure 5). Rely X Unicem 은상아질접착과정을거치지않는자가접착형레진시멘트이며 4 가지레진시멘트중가장낮은결합강도를보여주었다. 그러나열순환이후에통계적으로유의성있는차이를보여주지않았다 (p > 0.05)(Figure 6). a b c d Figure 8. FE-SEM photograph illustrating the resin/dentin interface ( 1000). a. Cross-sectioned image of Variolink II. The thickness of resin cement was approximately 30 μm, hybrid layer was 10 μm, and the adhesive layer was likely thick. Uniform resin tags could be noticed. b. Cross-sectioned image of Multilink. The short and uncertain resin tags were formed. Hybrid layer was not certain. The thickness of resin cement was approximately 50 μm. c. Cross-sectioned image of Pavavia F 2.0. The thickness of resin cement was approximately 30 μm, slender resin tags were formed and hybrid layer was not certain. d. Cross-sectioned image of Rely X Unicem. The thickness of resin cement was approximately 15 μm and hybrid layer and resin tag were not formed. Notice slightly detached interface between resin cement and dentin. (RC : Resin cement, AD : Adhesive layer, HL : Hybrid layer, RT : Resin tag, D : Dentin, R : Tescera composite resin) 349

8 대한치과보존학회지 : Vol. 32, No. 4, 전계방출형주사전자현미경 (FE-SEM) 관찰 접착계면에대한 FE-SEM 관찰에서 2 단계전체산부식형상아질접착제를사용하는복합레진형레진시멘트인 Variolink II 에서두꺼운접착레진층과함께균질의혼성층이형성되어있고레진 tag 가잘형성되어있었다 (Figure 8a). 1 단계자가부식형상아질접착제를사용하는 Multilink 에서는혼성층이불분명하였고레진 tag 는약 5 μm정도로짧게형성되어있었다 (Figure 8b). 자가부식형상아질프라이머를사용하는 Panavia F 2.0 에서는마찬가지로혼성층이레진시멘트층과혼재되어불분명하였으며레진 tag 는가늘고길게형성되었다 (Figure 8c). 상아질접착과정을거치지않는 Rely X Unicem 은혼성층과레진 tag 는관찰되지않았다 (Figure 8d). 파단면의관찰에서 Variolink II 의열순환하기전시편에서혼합형파괴양상이관찰되었으며, 이후열순환에의해접착성파괴양상이증가하는경향을나타내었다 (Figure 9, 13). Multilink 의경우, 열순환하기전시편에서는혼합형파괴양상이관찰되었으며, 열순환이후접착성파괴양상을보여주었다 (Figure 10, 14). Panavia F 2.0 의경우열순환전후접착성파괴양상을보여주었다 (Figure 11). Rely X Unicem 의경우에는접착층이없으며열순환전비균일한레진시멘트의파괴가관찰되었으나, 열순환후점차균일한파괴양상이관찰되었다 (Figure 12). a b a : mixed failure without thermocycling b : adhesive failure with thermocycling of 5,000 cycle Figure 9. Debonded interface of Variolink II ( 100). A : adhesive, D : dentin a b a : mixed failure without thermocycling b : adhesive failure with thermocycling of 5,000 cycle Figure 10. Debonded interface of Multilink ( 100). A : adhesive 350

9 a b a : adhesive failure without thermocycling b : adhesive failure with thermocycling of 5,000 cycle Figure 11. Debonded interface of Panavia F 2.0 ( 100). A : adhesive a b a : failure without thermocycling b : failure with thermocycling of 5,000 cycle Figure 12. Debonded interface of Rely X Unicem ( 100). Figure 13. Debonded interface of Variolink II without thermocycling ( 1000). Failure mode was mixed failure and dentinal tuble was observed. Figure 14. Debonded interface of Multilink without thermocycling ( 2000). Failure mode was mixed failure and small dentinal tubule was observed. 351

10 대한치과보존학회지 : Vol. 32, No. 4, 2007 Ⅳ. 총괄및고안 접착치과학은괄목할만한성장을이루었으며이는상아질접착기술의발전이근간을이루고있다. 최근의상아질접착시스템에는상아질과의결합을향상시키기위하여친수성을지닌레진단량체가포함되어있다 21). 친수성레진단량체가포함된프라이머를사용하는전체산부식형접착제는상아질내교원질을탈회시키고친수성단량체가그공간및상아세관내로침투할수있게해준다 22). 반면에자가부식형접착제는충분한산도를가지고도말층을없애지않고용해변형시켜상아질과접착한다 23). 본연구는상아질접착방식및성분에따라레진시멘트를구분하고열순환전후의결합강도를비교하여임상적으로내구성파악에도움을주고자하였다. 본연구에사용된레진시멘트는상아질접착방식에따라전체산부식형혹은자가부식형상아질접착제를사용하는레진시멘트, 상아질접착제를사용하지않는레진시멘트로분류할수있다. 또한접착능력을가지는기능성단량체의유무에따라복합레진형레진시멘트 (composite based-resin cement) 와접착형레진시멘트 (adhesive based-resin cement) 로분류할수있다. 2 단계전체산부식형접착제를사용하는 Variolink II 의경우는복합레진형레진시멘트이다. 실험결과에서다른레진시멘트보다월등히높은미세인장결합강도를보여주었는데, 이는산부식과상아질접착제의도포를통해다른자가부식형접착제와는달리두꺼운혼성층과굵고깊은레진 tag 가형성되었기때문으로생각된다 (Figure 8a). 더욱이복합레진형레진시멘트로서다른접착형레진시멘트보다성분이복합레진에가깝기때문에물리적성질이우수했기때문으로볼수있다. 열순환이후에결합강도가감소하였고 5,000 회열순환이후에는즉시군 (T = 0) 보다약 22% 가감소되는결과를보여주었다 (Table 4). 또한 FE- SEM 을통한파단면관찰을통해열순환을할수록접착성파괴가일어남을알수있었다 (Figure 9). 전체산부식형접착제를적용할때, 탈회된상아질의교원질구조내로완전히침투가되지않는층 (hybridoid layer) 이발생하고, 용매가모두제거되지않으면친수성단량체가다량존재하기때문에불안정한혼성층이형성될수있다. 따라서열순환시행후가수분해가일어나결합강도의저하또는변연누출등이일어나기쉽다 24). Armstrong 등 25) 은상아질접착후수중에서 15 개월보관하고미세인장결합강도를측정한결과, 2 단계전체산부식형접착제의결합강도는 3 단계또는 2 단계자가부식형접착제에비하여시간경과에따라결합강도가감소한다고하였으며, 파괴양상은 2 단계전체산부식형접착제에서시간경과에따라접착성파괴가증가하였다고보고하였다. 즉 Variolink II 의경우결합강도의감소는열순환후접착층의내구성이약화되었기때문으로사료된다. Multilink 는자가부식형레진시멘트로서 6 세대상아질접착제를사용한다. 구성성분상 HEMA 를포함하기때문에접착형레진시멘트의일종으로볼수있지만접착력의대부분을상아질접착제가담당하게된다 (Table 1). HEMA 를제외하고는복합레진성분과유사하고다른접착형레진시멘트보다즉시군 (T = 0) 에서결합강도가높게나타났다. 결합강도는 1,000 회열순환이후유의성있게감소되었으며 (p < 0.05), 5,000 회이후에는즉시군보다약 44% 가감소되는결과를보여주었다 (Table 4). 6 세대자가부식형상아질접착제는시술과정의단순화및편의성이라는장점을가지는반면접착신뢰성과내구성에는아직까지문제가있음을지적받고있다 26). Amstrong 등 26) 은 6 세대자가부식형상아질접착제가와동형태와수중시효처리에매우민감하다고하였다. 6 세대자가부식형접착제의내구성은 5 세대접착제에비하여낮은것으로보고되고있으며, 이는임상적접착력평가에주로이용되는 5 급와동에대한연구에서입증되었다 27,28). Multilink 의열순환이후급격한결합강도감소는자가부식능력의제한으로접착레진의불완전한침투가원인으로추정된다 (Figure 8b). FE-SEM 을통한파단면관찰에서초기열순환전에는혼합형파괴양상을보이나열순환이후접착성파괴양상을보여이설명에부합한다할수있을것이다 (Figure 10). Panavia F 2.0 은자가부식형프라이머를사용하며접착기능성단량체인 10-MDP 를포함하고있는접착형레진시멘트이다. 즉시군 (T = 0) 의결합강도는복합레진형레진시멘트와비교하여낮은값을보여주고있으며, 열순환이후에점진적인감소양상을보여주고는있지만통계적인유의차는없었다 (p > 0.05)(Table 4, Figure 5). Panavia F 2.0 은상아질접착제의적용과정이일반적인레진시멘트와는다른방식이다. ED primer II 는 2 bottle 로구성되어있고혼합하여도포하는방식이다. 즉 ED primer II 를도포하고접착레진의도포없이시멘트를적용하는것으로이는시멘트내의기능성단량체가직접상아질에작용하도록설계된것이다. 동일회사의 5 세대자가부식형상아질접착제인 Clearfil SE bond 의경우 primer 와 adhesive 로구성되어있으며이제품의 primer 는 Panavia F 2.0 에포함된 ED primer II 와그성분이유사하다. SE bond 의 adhesive 는접착레진으로접착기능성단량체 (10-MDP) 와레진기질, 미세필러를함유하고있다. Panavia F 2.0 의경우열순환후결합강도가별로감소되지않았는데, 이것은 5 세대자가부식형상아질접착제가열순환에영향을적게받는다는연구에서그원인을찾을 352

11 수있을것이다 29-31). Panavia F 2.0 은 ED primer II 를통한상아질전처리후에접착형시멘트를직접적용하기때문에 2 단계자가부식형상아질접착제인 Clearfil SE bond 와유사한방식으로접착되는것이다. 파단면관찰을통해서 Panavia F 2.0 은열순환을하지않았을때접착성파괴가일어나는것을알수있는데 (Figure 11), 이것은이시멘트의낮은결합강도와자가부식형상아질접착제의특성으로혼성층상방에서분리되었기때문으로사료된다. Rely X Unicem 은상아질접착제를사용하지않는자가접착형레진시멘트로서기능성단량체로 methacrylated phosphoric ester 를함유하고있으며산부식과동시에레진기질로작용을한다 (Table 1). 하지만 FE-SEM 관찰에서다른레진시멘트와는달리혼성층이나레진 tag 가형성되지않았다 (Figure 8d). 이는선학들의연구와같은양상을보여주고있다 32.33). Rely X Unicem 은다이아몬드버등의삭제로형성된거칠고불규칙한상아질표면을미약하게탈회시키고기계적인접합층을형성한다 32). 이에따라낮은결합강도가보고되었고본실험에서도확인되었다. 하지만열순환이후결합강도의감소가적게나타났으며 (Table 4), 이는접착층이거의존재하지않는이레진시멘트의특성으로이해할수있을것이다. 본연구에서산부식과정을거치고상아질접착제를적용하는복합레진형레진시멘트로 Variolink II 를사용하였다. 레진시멘트를적용할때상아질접착제의접착력에의존하게되는복합레진형레진시멘트는현재까지발전된상아질접착기술에의해서그결합강도가매우우수하며본실험에서도또한확인되었다. Multilink 의경우 HEMA 를포함하고있어완전한복합레진형으로분류할수는없지만접착력의상당부분이상아질접착제에의한것으로생각된다. 이것은열순환이후에결합강도가유의성있게감소되었고, 이는 6 세대자가부식형상아질접착제들에서나타나는내구성이약화된다는보고와일치하기때문이다. 이를종합할때복합레진형레진시멘트는적절한상아질접착제를함께사용할경우높은내구성과결합강도를가질것으로생각된다. Panavia F 2.0 에서는상아질전처리로 ED primer II 를사용하였다. Carvalho 등 6) 은 Panavia F 를사용할때부가적으로레진층을도포하면결합강도가증가됨을보고하였다. 본실험과유사한방식으로진행되었던선행연구에서김등 34) 은 Panavia F 와 Clearfil SE bond 를사용하였을경우, 미세인장결합강도가약 35.7 MPa 까지증가한다고보고하였다. 따라서 Panavia F 2.0 을적용할때에는부가적인접착레진의도포가결합강도와내구성을증가시킬수 있을것으로사료되며이는제조사에서참고할수있을것이다. Rely X Unicem 은레진시멘트가나아가야할다른방향을제시하고있는선행재료라할수있다. 본연구의열순환이최대 5,000 회이므로이를임상에적용하거나일반화된실험방법으로평가하기는어려울것이다. 하지만전처리또는접착과정이없는새로운개념의레진시멘트는초기결합강도는다른레진시멘트에비하여현저히낮지만안정성에서는유리한측면이있어앞으로이에대한논의와연구가더필요할것으로생각된다. 본연구는열순환으로최대 5,000 회를시행하였고교합압이작용하는환경은고려치않았다는점에서임상적으로적용시키는데에한계가있다. 열순환횟수를더증가시켰을경우, 결합강도의감소양상은본연구결과와상이할수도있을것이다. 하지만본실험결과에국한하여볼때, 적절한상아질전처리와접착과정을행한다면복합레진형레진시멘트는접착형레진시멘트보다결합강도와내구성이우수하다고할수있을것이다. 앞으로이에대한지속적인연구가진행되어야할것으로생각한다. Ⅴ. 결론 서로다른접착과정을갖는 4 가지레진시멘트를이용하여상아질에간접레진으로수복을하였고이시편의열순환 0 회, 1,000 회, 5,000 회시효처리후의미세인장결합강도를측정하였다. 접착계면과파단면을 FE-SEM 을통하여관찰한결과다음의결론을얻었다. 1. Variolink II 의결합강도는다른실험군보다높게나타났으며, 1,000 회열순환후유의성있게감소되었다 (p < 0.05). 2. Multilink 의결합강도는열순환에가장많은영향을받았으며 1,000 회열순환이후유의성있게감소되었다 (p < 0.05). 3. Panavia F 2.0 과 Rely X Unicem 의결합강도는열순환에의하여감소되지않았다 (p > 0.05). 4. 접착형레진시멘트는복합레진형레진시멘트에비해서열처리전후모두낮은결합강도를보여주었다. 5. 결합강도가높은 Variolink II 와 Multilink 에서는혼합형파괴양상을보였고, 결합강도가낮은 Panavia F 2.0 에서는접착성파괴양상을나타내었다. 접착성간접수복물의결합강도와내구성은레진시멘트의접착과정과종류, 형태에의해영향을받기때문에이들의적절한선택과올바른사용이성공적인수복을위해중요하다. 353

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13 국문초록 조민우 박상혁 김종률 최경규 * 경희대학교대학원치의학과치과보존학교실 4 종의레진시멘트를통한상아질과간접레진수복물간의인장결합강도를열순환시효처리여부에따라측정하여비교하고, 주사전자현미경관찰을통하여각레진시멘트의접착내구성을평가하고자시행하였다. 48 개의건전한제 3 대구치의상아질표면을평탄하게노출시키고 #320 grit Sic Paper 로연마하였다. 복합레진블록을제작하여 #600 grit Sic Paper 로연마한후에접착면을 Sandblast 로처리하였다. 각각의레진시멘트로제조사지침에따라적용하여복합레진블록을상아질표면에접착하였다. 이후제작된시편을열순환시키지않거나, 1,000 회, 5,000 회열순환시킨후 (5-55 ) 미세인장결합강도를측정하였다. 열순환전시편의접착계면 ( 수직절단면 ) 과파절된시편의상아질파단면을전자현미경관찰하여다음과같은결론을얻었다. 1. Variolink II 의결합강도는다른실험군보다높은결합강도를보여주었으며, 1,000 회열순환후유의성있게결합강도가감소되었다 (p < 0.05). 2. Multilink 의결합강도는열순환에가장많은영향을받았으며 1,000 회열순환이후유의성있게감소되었다 (p < 0.05). 3. Panavia F 2.0 과 Rely X Unicem 의결합강도는열순환에의하여감소되지않았다 (p > 0.05). 4. 접착형레진시멘트는복합레진형레진시멘트에비해서열처리전후모두낮은결합강도를보여주었다. 5. 결합강도가높은 Variolink II 와 Multilink 에서는혼합형파괴양상을보였고, 결합강도가낮은 Panavia F 2.0 에서는접착성파괴양상을나타내었다. 이상의연구결과를토대로적절한전처리와접착제를도포한다면복합레진형레진시멘트는접착형레진시멘트보다결합강도와그내구성이우수하다고할수있을것이다. 접착성간접수복물의초기결합강도와내구성은레진시멘트의접착과정과종류, 형태에의해영향을받기때문에이들의적절한선택과올바른사용이성공적인수복을위해중요하다. 주요어 : 접착내구성, 레진시멘트, Variolink II, Multilink, Panavia F 2.0, Rely X Unicem 355