ISSN eissn Original Article Comparison of flexural strength and modulus of elastici

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1 ISSN eissn Original Article Comparison of flexural strength and modulus of elasticity in several resinous teeth splinting materials Je-In Yoo, Soo-Yeon Kim, Bayarchimeg Batbayar, Jin-Woo Kim, Se-Hee Park, Kyung-Mo Cho* 1 Department of Conservative Dentistry, College of Dentistry, Gangneung-Wonju National University School of Dentistry, Gangneung, Republic of Korea 2 Mongolian National University of Medical Sciences, Ulaanbaatar, Mongolia Purpose: Direct splinting material should have high flexural strength to withstand force during mastication and low modulus of elasticity to provide some movement while force applied for relief of stress. The purpose of this study was to compare flexural strength and modulus of elasticity of several resinous splinting materials. Materials and Methods: Four materials; Super-Bond C&B, G-FIX, G-aenial Universal Flo, FiltekTM Z350 XT; were used in this study. Fifteen rectangular bar specimens of each material were prepared. Three-point bending test were performed to determine physical properties. Maximum load at fracture was recorded and flexural strength and modulus of elasticity were calculated. One-way analysis of variance (ANOVA) and Scheffe s tests at a 0.05 level of significance were conducted on all test results. Results: Statistical analysis reveals that Super-Bond C&B had significant low mean value for flexible strength and the other three materials showed no significant difference. For modulus of elasticity, Super-Bond C&B exhibited statistically lower modulus of elasticity. G-FIX presented intermediate result, showing statistically higher modulus of elasticity than Super-Bond C&B but lower than G-aenial Universal Flo and FiltekTM Z350 XT. There was no significant difference on modulus of elasticity between G-aenial Universal Flo and FiltekTM Z350 XT. Conclusion: Using a G-FIX, the newly commercially available splinting material, which shows higher fracture resistance properties comparable to flowable and restorative composite resin and a relatively flexible nature might be a beneficial for stabilizing teeth mobility. (J Dent Rehabil Appl Sci 2016;32(3):169-75) Key words: tooth mobility; splint; flexural strength; modulus of elasticity; 3 point bending test 서론 치아의비생리적인동요는치아의외상, 치주질환, 외상성교합등에의해생기게된다. 임상에서심한동요를보이는치아는발거하게되는경우가많으나다양한이유들로인해치아의유지가결정된경우치아의고정술식이행해질수있다. 치아고정은증가된치아의동요를제한하고고정하기위하여두개또는그이상의치아를연결하는것을의미한다. 이는환자의불편감을해소하 고교합관계와저작기능을회복시키며, 1 저작등의기능중생기는하중을여러치아와넓은면적으로분산시키고해로운측방하중을수직적인방향으로바꿔줌으로써동요치의치주적예후를개선시키는것을목표로한다. 2 치아고정재료를포함한구강내의수복물은온습한환경에서장기간저작압에노출되며스트레스를받으며이는재료자체의파절또는치아와수복재의계면의부착실패를일으킨다. 3 그러므로불리한구강내환경에서파절되지않고견디기위한높은강도와법랑질에의믿을 *Correspondence to: Kyung-Mo Cho Professor, Department of Conservative Dentistry, College of Dentistry, Gangneung-Wonju National University, 7, Jukheon-gil, Gangneung, 25457, Republic of Korea Tel: , Fax: , drbozon@gwnu.ac.kr Received: May 31, 2016/Last Revision: July 19, 2016/Accepted: August 8, 2016 Copyright 2016 The Korean Academy of Stomatognathic Function and Occlusion. cc It is identical to Creative Commons Non-Commercial License. 169

2 Yoo JI, Kim SY, Batbayar B, Kim JW, Par SH, Cho KM 만한접착강도가요구된다. 또한치아고정재료는치아의생리적인움직임을허용할수있도록낮은탄성계수를지녀야한다. 많은연구에서생리적치아동요를허용하는연성치아고정의이점이보고되고있다. 4-7 생리적인치아의움직임은치아주위조직에기능적인자극을줌으로써치주인대섬유의재배열과치근유착의방지, 재혈관화과정에긍정적인영향을준다고알려져있다. 4,6,8 또한복합레진을포함한취성재료의파절은인장응력이생기는부위에서균열이진전되어일어나게되는데, 유연한성질을지닌치아고정재료는그렇지않은것에비하여어느정도의변형에도파절되지않고더잘견디는반면, 과도하게단단한치아고정재료는중합수축동안소성변형이적게일어나기때문에응력을완화하지못하며적은응력내구성을지녀점진적인약화가진행되기쉽다. 2 현재까지 titanium trauma splint (TTS), cap splint, 강선복합레진고정, 복합레진고정, 봉합고정등을이용한다양한치아고정방법이문헌에소개되어왔다. 9,10 여러방법중, 인접치의법랑질에직접재료를접착시켜고정을도모하는레진치아고정은치아삭제가거의필요하지않아보존적이고임상에서적용이간편하고술식시간이빠르며심미적으로우수하다는장점을지닌다. 또한비교적구강위생을방해하지않으며추가적인진단과치료를허용할수있다. 이러한장점들로인해레진치 아고정은동요치고정을위한고정방법중널리사용되고있는방법중하나로최근에는레진치아고정을위한전용제품도개발되어출시되어사용되고있는실정이다. 현재다양한치아고정종류에따른여러기계적성질또는그예후에관한많은연구가있으나, 2,5,11-13 레진을이용한동요치고정에사용되는여러재료들의물리적성질에대한연구는매우부족하며특히최근새롭게시판되었거나개발중인제품에관한연구는거의없었다. 이에본연구에서는동요치고정에사용될수있는레진계치아고정재료의굴곡강도와탄성계수를평가하고비교함으로써임상에서의유용성을평가하고임상가들에게있어재료의선택에도움이되고자하였다. 연구재료및방법실험재료 실험군으로 4종의레진을사용하였다. 자가중합레진시멘트인 Super-Bond C&B (Sun Medical Co Ltd, Shiga, Japan), 광중합스플린트재료인 G-FIX (GC Co., Tokyo, Japan), 유동성복합레진인 G-aenial Universal Flo A2 (GC Co.), 수복용복합레진인 Filtek TM Z350 XT A2B (3M ESPE, St. Paul, MN, USA) 를사용하였다. 각재료의구성성분은 Table 1에나타내었다. Table 1. Composition of materials used in this study Material Manufactures Composition G-aenial Universal Flo GC Matrix (31% wt.): UDMA, Bis-MEPP, TEGDMA Filler (69% wt., 50% vol.): Silicon dioxide (16 nm) strontium glass (200 nm) pigment Initiator: Photo initiator Super-Bond C&B Sun Medical Catalyst V: Tri-n-butylborane, hydrocarbon Monomer: MMA, 4-META Polymer: PMMA, metal oxides Filtek TM Z350 XT 3M ESPE Matrix: Bis-GMA, UDMA, TEGDMA, Bis-EMA Filler (78.5% wt., 59.5% vol.) : Aggregated zirconia/silica cluster with primary particle size (5-20 nm) : Nonagglomerated silica (20 nm) Data from manufacturers websites and/or product catalogs. Data of G-FIX was not revealed by its manufacturer. UDMA, Urethane dimethacrylate; Bis-MEPP, 2,2-Bis(4-methacryloxypolyethoxyphenyl)propane; TEGDMA, Triethyleneglycol dimethacrylate; MMA, Methyl methacrylate; 4-META, 4-methacryloxyethyltrimellitic acid anhydride; Bis-EMA, Bisphenol-A-ethoxylated dimethacrylate; PMMA, Polymethyl methacrylate; Bis-GMA, Bisphnol-A-glycidylmethacrylate. 170 J Dent Rehabil Appl Sci 2016;32(3):169-75

Comparison of flexural strength and modulus of elasticity in several resinous teeth splinting materials 시편제작 2 mm 25 mm 각재료의굴곡강도와탄성계수의평가를위해가로 25 mm, 세로 2 mm, 높이 2 mm의테플론주형 (Fig.

3 Comparison of flexural strength and modulus of elasticity in several resinous teeth splinting materials 시편제작 2 mm 25 mm 각재료의굴곡강도와탄성계수의평가를위해가로 25 mm, 세로 2 mm, 높이 2 mm의테플론주형 (Fig. 1) 을이용하여각실험군당 15개씩총 60개의시편이제작되었다. Glass mixing slab 위에주형을위치시킨후주형에각재료를유입시켰다. 혼합이필요한 Super-Bond C&B 는제조사의지시대로혼합하여주형에유입시켰다. 각재료로채워진주형위에 celluloid matrix를압접한상태에서압력을주어여분을제거하여균일한두께가되도록한뒤중합하였다. G-FIX, G-aenial Universal Flo, Filtek TM Z350 XT 는 LED 광중합기 (G-Light, GC Co.) 를이용하여 20초씩다른위치에서 3회중합하였다. 3회의중합위치는서로중첩되게하여미중합되는부위가없도록하였다. Super-Bond C&B는압력을가한상태로경화될때까지움직이지않고유지하였다. 중합을완료한후시편은주형에서제거하여 37 C, 상대습도 100% 를유지하는항온기 (SIB-1, Seo-kwanng Sience Co., Seoul, Korea) 에서 24시간동안보관하였다. 3점굽힘시험시행전에 0.01 mm 단위까지측정할수있는디지털캘리퍼 (CD-15CP, Mitutoyo, Kawasaki, Japan) 를이용하여각각의시편의두께와높이를측정하여기록하였다. 굴곡강도와탄성계수측정만능시험기 (RB-306, R&B Inc., Daejeon, Korea) 를이용하여최대하중 800 kg의조건에서분당 1.0 mm의 cross-head speed로시편이파절되는시점까지하중을주었다. 시편에가해진최대힘 (N) 이측정되고기록되었으며굴곡강도와탄성계수는다음공식에따라계산되었다. 2 mm Fig. 1. Schematic drawing of the mold used for specimen fabrication. 굴곡강도 F = 3P f L/2BH 2 (MPa) P f 는시편이파괴되는시점의최대힘 (N) 이고, L 은지 지대사이의간격 (10 mm), B 와 H 는 3 점굽힘시험전에 측정된시편의폭과두께 (mm 단위 ) 를뜻한다. 탄성계수 E = δ f /δ y L 3 /4BH 3 (GPa) δ f /δ y 는단위변형률 (δ y ) 에대한응력의변화율 (δ f ) 이고 L 은지지대사이의간격 (10 mm), B 와 H 는 3 점굽힘시 험전에측정된시편의폭과두께 (mm 단위 ) 를뜻한다. 통계분석 SPSS Ver 21.0 (SPSS Inc., Chicago, USA) 를사용하 여측정된굴곡강도와탄성계수에대한정규분포검정을 시행한후 One-way ANOVA test 로분석하였다. 이후 95% 유의수준에서 Scheffe s test 로사후검정하였다. 결과 각실험재료의굴곡강도와탄성계수의평균과표준편 차는각각 Table 2, 3 에나타내었다. 이를바탕으로 One- Table 2. Flexural strength of materials tested [Mean (MPa) and standard deviation] Group Mean (MPa) ± standard deviation Super-Bond C&B ± 8.8 a G-FIX ± 18.9 b G-aenial Universal Flo ± 30.4 b Filtek TM Z350 XT ± 36.0 b a,b,c means followed by different alphabet letters are significant difference (P <.05) in each mechanical properties. Table 3. Modulus of elasticity of materials tested [Mean (GPa) and standard deviation] Group Mean (MPa) ± standard deviation Super-Bond C&B 16.2 ± 4.5 a G-FIX 24.9 ± 2.5 b G-aenial Universal Flo 60.4 ± 5.5 c Filtek TM Z350 XT 64.0 ± 5.1 c a,b,c means followed by different alphabet letters are significant difference (P <.05) in each mechanical properties. J Dent Rehabil Appl Sci 2016;32(3):

4 Yoo JI, Kim SY, Batbayar B, Kim JW, Par SH, Cho KM Table 4. Result of One-way ANOVA test on flexural strength Sum of squares df Mean square F Sig. Intergroup <.001 Intragroup Sum df, degree of freedom; Sig., significance. Table 5. Result of One-way ANOVA test on modulus of elasticity Sum of squares df Mean square F Sig. Intergroup <.001 Intragroup Sum df, degree of freedom; Sig., significance. way ANOVA test와 Scheffe s test를시행하여그룹내, 그룹간의통계적유의성을살펴본결과를 Table 4, 5에나타내었다. 본연구의결과굴곡강도에서는 Super-Bond C&B 는다른재료들과비교시유의하게낮은평균굴곡강도를보였다 (P < 0.05). 이와비교하여 G-FIX, G-aenial Universal Flo, Filtek TM Z350 XT는비슷하게높은굴곡강도를나타내었으며이들사이에통계적으로유의한차이는없었다 (P > 0.05). 탄성계수의경우 Super-Bond C&B가가장낮은값을보였고 (P < 0.05) G-FIX는 Super-Bond C&B보다는높지만 G-aenial Universal Flo와 Filtek TM Z350 XT보다는낮은탄성계수를보였으며 G-aenial Universal Flo와 Filtek TM Z350 XT는유의하게높은탄성계수를보였다. G-aenial Universal Flo와 Filtek TM Z350 XT는통계적으로유의한차이는없었다 (P > 0.05). 고찰 본실험에서사용된 Super-Bond C&B는 4-META/ MMA-TBB를포함하는자가중합형레진시멘트로다른재료들에비해유의하게낮은굴곡강도와탄성계수를보였다. 굴곡강도와탄성계수와같은레진의기계적성질은사용된모노머의종류와양, 무기질필러의종류와입자크기, 커플링제의종류및개시제의양등에의해 영향을받는다. 14 레진기질에포함되어있는필러입자들은기질그자체보다훨씬강한기계적성질을나타내기때문에무기질필러의함량이높을수록높은굴곡강도와탄성계수를갖게된다. 14,15 이는무기질필러를포함하지않는 Super-Bond C&B가다른복합레진들에비해현저히낮은기계적성질을보이는이유에대한설명중하나가될수있을것이다. 또한 Super-Bond C&B는사용전액체와분말을혼합하는과정을거치게되며혼합과정중불가피하게공기가유입되어구조를약하게하는기포를생성하게되며산소의유입은중합과정을방해한다. 16 이는시편간의오차를야기하며낮은굴곡강도와탄성계수에영향을미쳤을가능성이있다. 기존에치아고정재료로많이사용되던 Super-Bond C&B는앞에서설명한것과같이낮은물성및조작의차이가물성에큰영향을미친다는단점이외에도광중합복합레진과비교시작업시간을조절할수없고경화시간이길어임상에서사용하기에불리한점이있다. 실험에사용된 3 종류의광중합복합레진 (G-FIX, G-aenial Universal Flo, Filtek TM Z350 XT) 은서로비슷하게높은굴곡강도를보였으며, G-FIX는 Super-Bond C&B보다는높으나다른광중합복합레진들보다는유의하게낮은탄성계수를보였다. 제조사에서제시하는구성성분과함량을확인해보았을때 G-aenial Universal Flo와 Filtek TM Z350 XT는많은양의필러를함유할 172 J Dent Rehabil Appl Sci 2016;32(3):169-75

5 Comparison of flexural strength and modulus of elasticity in several resinous teeth splinting materials 수있고이는뛰어난기계적성질을보이는이유로생각해볼수있다. 두복합레진의필러함유량을비교시 G-aenial Universal Flo는 69% wt., 50% vol., Filtek TM Z350 XT는 78.5% wt., 59.5% vol. 의필러를함유하고있었으며필러함량이많은Filtek TM Z350 XT에서높은굴곡강도와탄성계수를보일것을기대하였으나이번연구에서는유의한차이를확인하지못하였다. 또한두재료는공통으로포함된 UDMA, TEGDMA에더하여 G-aenial Universal Flo는 Bis-MEPP를, Filtek TM Z350 XT는 Bis-GMA와 Bis-EMA를포함한다. 모노머는광중합레진의물리적성질에영향을미치는요인중하나로여겨지며기존연구에서건조한환경에서 Bis-MEPP 를포함한레진은 Bis-GMA를포함한레진보다높은굴곡강도와낮은탄성계수를보인다고보고된바있으나 17 역시이번연구에서는확인하지못하였다. 이는모노머와필러및커플링제의종류, 각구성성분의함량등에의한영향이복합적으로작용하여실험결과에나타났기때문으로생각된다. G-FIX의경우높은굴곡강도와상대적으로낮은탄성계수를보이며이를설명하기위하여구성성분과함량을알아보려하였으나제조사에서자세한정보를제공하지않고이에대한연구도아직미미하기때문에설명하기에어려움이있다. 제조사에서설명하는바에따르면 G-FIX는새로개발한고인성모노머 (elastic crosslinking monomer) 를채택하여사용함으로써동요치고정에적합한유연성과점인성을부여하였다고했으며이를설명하기위해서는추가적인정보와연구가필요할것이다. 굽힘시험에사용되는시편의제작은국제표준규격 (ISO) 4049에의한방법이널리사용되고있다 본연구에서도이에따라 mm의시편이제작되었으며 2 mm의시편두께는광중합시에균일하고효과적인중합이가능한두께이다. 21 그러나굽힘시험에사용된시편의길이 (25 mm) 는구강내수복물에사용되는직경과비교시에차이가크며이러한시편의길이는굽힘성질에영향을미칠수있으므로임상적으로보다현실적인길이의시편을이용한굽힘시험이필요하다고이전의연구에서언급된바있다. 22 본연구에서도치아고정재료가치간의협소한공간에적용됨을고려했을때구강내의임상적인상황과실험환경의편차가있을것이라고유추할수있다. 또한시편의길이 (25 mm) 는 3가지광중합복합레진의중합에사용된광조사기의출력창의직경보다길기 때문에미중합되는부위가없도록다른위치에서 3회광중합하였으며이과정에서중합이중첩된부위가생긴다. 이러한중첩된중합이복합레진의굽힘성질에미치는영향에대해언급한기존연구에의하면중첩된중합이이루어진부위는인접한다른부위에비해증가된빛에너지의밀도를받으며이는시편의비균일한중합을야기한다고하였으며, 22 이는실험결과의오차로작용할가능성이있다. 동요치고정을목적으로개발된 G-FIX는유동성복합레진과수복용복합레진과비등한굴곡강도를보이면서도상대적으로낮은탄성계수를보여이러한측면에서동요치고정에유리한재료라고사료된다. 그러나어느정도의탄성계수를가지는치아고정재료가임상적으로유리할것인지에대한추가적인연구가필요할것이다. 또한이번연구에서조사한굴곡강도와탄성계수는치아고정재료의선택시고려되는성질중일부분일뿐이며, 성공적인치아고정을위해서는이외에도법랑질과의접착강도, 중합수축, 용해도, 생체적합성, 조작성, 심미성등다양한요소가복합적으로고려되어야만한다. 결론 동요치의고정에사용될수있는여러레진계치아고정재료의굴곡강도와탄성계수를 3점굽힘시험을통해알아보았으며 G-FIX는동요치고정을위해기존에많이이용되던 Super-Bond C&B 보다크고 G-aenial Universal Flo 및 Filtek TM Z350 XT와유사한굴곡강도를가져잘파절되지않으면서도상대적으로유연한성질을보여동요치고정에유리할것으로생각된다. Acknowledgements 이논문은 2015년도강릉원주대학교학술연구조성비지원에의하여수행되었다. ORCID Je-In Yoo Soo-Yeon Kim Bayarchimeg Batbayar Jin-Woo Kim J Dent Rehabil Appl Sci 2016;32(3):

6 Yoo JI, Kim SY, Batbayar B, Kim JW, Par SH, Cho KM Se-Hee Park Kyung-Mo Cho References 1. Bernal G, Carvajal JC, Muñoz-Viveros CA. A review of the clinical management of mobile teeth. J Contemp Dent Pract 2002;3: Mazzoleni S, Meschia G, Cortesi R, Bressan E, Tomasi C, Ferro R, Stellini E. In vitro comparison of the flexibility of different splint systems used in dental traumatology. Dent Traumatol 2010;26: Wood M, Kern M, Thompson VP, Romberg E. Ten-year clinical and microscopic evaluation of resin-bonded restorations. Quintessence Int 1996;27: Burcak Cengiz S, Stephan Atac A, Cehreli ZC. Biomechanical effects of splint types on traumatized tooth: a photoelastic stress analysis. Dent Traumatol 2006;22: Andreasen JO, Andreasen FM, Mejàre I, Cvek M. Healing of 400 intra-alveolar root fractures. 2. Effect of treatment factors such as treatment delay, repositioning, splinting type and period and antibiotics. Dent Traumatol 2004;20: Andreasen JO, Andreasen FM, Andersson L. Textbook and color atlas of traumatic injuries to the teeth. 4th ed. Oxford; Blackwell Munksgaard; p von Arx T. Splinting of traumatized teeth with focus on adhesive techniques. J Calif Dent Assoc 2005;33: Bauss O, Schwestka-Polly R, Schilke R, Kiliaridis S. Effect of different splinting methods and fixation periods on root development of autotransplanted immature third molars. J Oral Maxillofac Surg 2005;63: von Arx T, Filippi A, Lussi A. Comparison of a new dental trauma splint device (TTS) with three commonly used splinting techniques. Dent Traumatol 2001;17: Filippi A, von Arx T, Lussi A. Comfort and discomfort of dental trauma splints - a comparison of a new device (TTS) with three commonly used splinting techniques. Dent Traumatol 2002;18: Prévost J, Granjon Y. An in vitro study of the passivity of splints in dental trauma. J Dent 1998;26: Prévost J, Nivoit M, Granjon Y. Management of dental trauma: development of a 2D data acquisition system to evaluate passivity of dental splints. Med Biol Eng Comput 1997;35: Menendez ME, Thornton E, Kent S, Kalajian T, Ring D. A prospective randomized clinical trial of prescription of full-time versus as-desired splint wear for de Quervain tendinopathy. Int Orthop 2015;39: Monteiro GQ, Montes MA. Evaluation of linear polymerization shrinkage, flexural strength and modulus of elasticity of dental composites. Mater Res 2010;13: Hofmann N, Papsthart G, Hugo B, Klaiber B. Comparison of photo-activation versus chemical or dual-curing of resin-based luting cements regarding flexural strength, modulus and surface hardness. J Oral Rehabil 2001;28: Anusavice KJ, Phillips RW. Phillips' science of dental materials. 11th ed. St. Louis; Saunders; p Kawaguchi M, Fukushima T, Horibe T. Effect of monomer structure on the mechanical properties of light-cured unfilled resins. Dent Mater J 1988;7: Chang M, Dennison J, Yaman P. Physical property evaluation of four composite materials. Oper Dent 2013;38:E Azillah MA, Anstice HM, Pearson GJ. Long-term flexural strength of three direct aesthetic restorative materials. J Dent 1998;26: Attar N, Tam LE, McComb D. Flow, strength, stiffness and radiopacity of flowable resin composites. J Can Dent Assoc 2003;69: Yap AU. Effectiveness of polymerization in composite restoratives claiming bulk placement: impact of cavity depth and exposure time. Oper Dent 2000;25: Yap AU, Teoh SH. Comparison of flexural properties of composite restoratives using the ISO and mini-flexural tests. J Oral Rehabil 2003;30: J Dent Rehabil Appl Sci 2016;32(3):169-75

7 Original Article 여러레진계치아고정재료의굴곡강도및탄성계수비교 유제인 1, 김수연 1, Batbayar Bayarchimeg 2, 김진우 1, 박세희 1, 조경모 1 * 1 강릉원주대학교치과대학치과보존학교실 2 몽골국립의과학대학교치과대학 목적 : 본연구의목적은수종의레진계치아고정재료의굴곡강도와탄성계수를비교분석하는것이다. 연구재료및방법 : 레진계치아고정재료로 Super-Bond C&B (SB), G-FIX (GF), G-aenial Universal Flo (GU), Filtek Z350 XT (FZ) 를이용하여각군당 15개씩총 60개의시편을제작하였다. 3점굽힘시험으로측정된값에따라굴곡강도와탄성계수를계산하였다. 실험값은 One-way ANOVA test로분석하고, Scheffe s test로사후검정하였다. 결과 : 본연구의결과 SB는다른재료들과비교시가장낮은굴곡강도를보였으며 GF, GU, FZ는비슷하게높은굴곡강도를보였다. 탄성계수의경우 SB가가장낮은값을보였고 GF는 SB보다는높지만 GU와 FZ보다는낮은탄성계수를보였으며 GU와 FZ는유의하게높은탄성계수를보였다. 결론 : 동요치고정을목적으로새로개발된 GU (G-FIX) 는유동성복합레진과수복용복합레진과같이높은강도를보이며잘파절되지않으면서도상대적으로유연한성질을보여동요치고정에유리할것으로사료된다. ( 구강회복응용과학지 2016;32(3):169-75) 주요어 : 치아동요 ; 고정 ; 굴곡강도 ; 탄성계수 ; 3 점굽힘시험 * 교신저자 : 조경모 (25457) 강원도강릉시죽헌길 7 강릉원주대학교치과대학치과보존학교실 Tel: Fax: drbozon@gwnu.ac.kr 접수일 : 2016 년 5 월 31 일 수정일 : 2016 년 7 월 19 일 채택일 : 2016 년 8 월 8 일 175

ISSN eissn Original Article Influence of water absorption on flexural strength and ela

ISSN eissn Original Article Influence of water absorption on flexural strength and ela https://doi.org/10.14368/jdras.2018.34.2.72 ISSN 2384-4353 eissn 2384-4272 Original Article Influence of water absorption on flexural strength and elastic modulus in several resinous teeth splinting materials