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THE CHANGE OF THE INITIAL DYNAMIC VISCO-ELASTIC MODULUS OF COMPOSITE RESINS DURING LIGHT POLYMERIZATION

광중합 복합레진의 중합초기 동적 점탄성의 변화

  • Kim, Min-Ho (Department of Conservative Dentistry, School of Dentistry, Seoul National University) ;
  • Lee, In-Bog (Department of Conservative Dentistry, School of Dentistry, Seoul National University)
  • 김민호 (서울대학교 치의학대학원 치과보존학교실) ;
  • 이인복 (서울대학교 치의학대학원 치과보존학교실)
  • Published : 2009.09.30

Abstract

The aim of this study was to measure the initial dynamic modulus changes of light cured composites using a custom made rheometer. The custom made rheometer consisted of 3 parts: (1) a measurement unit of parallel plates made of glass rods, (2) an oscillating shear strain generator with a DC motor and a crank mechanism, (3) a stress measurement device using an electromagnetic torque sensor. This instrument could measure a maximum torque of 2Ncm, and the switch of the light-curing unit was synchronized with the rheometer. Six commercial composite resins [Z-100 (Z1), Z-250 (Z2), Z-350 (Z3), DenFil (DF), Tetric Ceram (TC), and Clearfil AP-X (CF)] were investigated. A dynamic oscillating shear test was undertaken with the rheometer. A certain volume ($14.2\;mm^3$) of composite was loaded between the parallel plates, which were made of glass rods (3 mm in diameter). An oscillating shear strain with a frequency of 6 Hz and amplitude of 0.00579 rad was applied to the specimen and the resultant stress was measured. Data acquisition started simultaneously with light curing, and the changes in visco-elasticity of composites were recorded for 10 seconds. The measurements were repeated 5 times for each composite at $25{\pm}0.5^{\circ}C$. Complex shear modulus G*, storage shear modulus G', loss shear modulus G" were calculated from the measured strain-stress curves. Time to reach the complex modulus G* of 10 MPa was determined. The G* and time to reach the G* of 10 MPa of composites were analyzed with One-way ANOVA and Tukey's test ($\alpha$ = 0.05). The results were as follows. 1. The custom made rheometer in this study reliably measured the initial visco-elastic modulus changes of composites during 10 seconds of light curing. 2. In all composites, the development of complex shear modulus G* had a latent period for $1{\sim}2$ seconds immediately after the start of light curing, and then increased rapidly during 10 seconds. 3. In all composites, the storage shear modulus G" increased steeper than the loss shear modulus G" during 10 seconds of light curing. 4. The complex shear modulus of Z1 was the highest, followed by CF, Z2, Z3, TC and DF the lowest. 5. Z1 was the fastest and DF was the slowest in the time to reach the complex shear modulus of 10 MPa.

본 연구의 목적은 새로 개발한 점탄성 측정기를 사용하여 수종의 광중합 복합레진의 초기 동적 점탄성 변화를측정하는 것이다. 본 연구에 사용된 점탄성 측정기는 세 부분으로 구성되었다. 첫째, 시편이 놓여지는 parallel plates; 둘째, DC 모터와 크랭크로 이루어진 회전진동전단변형 (Oscillatory shear strain)을 발생시키는 부분; 셋째, 전자기적 토크센서를 이용한 응력 측정 부분으로 구성되었다. 본 점탄성 측정기는 최대 2 Ncm의 토크를 측정할 수 있으며, 광중합기의 스위치는 컴퓨터와 연동하여 데이터 획득을 시작할 때 동시에 켜지도록 하였다. 본 연구에서는 시판 중인 6종의 광중합 복합레진 [Z-100 (Z1), Z-250 (Z2), Z-350 (Z3), DenFil (DF), Tetric Ceram (TC), Clearfil AP-X (CF)]을 사용하였다. 점탄성 측정기를 사용하여 동적 회전전단실험을 시행하였다. 직경 3 mm인 유리막대로 구성된 parallel plates 사이에 $14.2\;mm^3$의 복합레진을 적용시켰으며, 6 Hz의 진동수와 0.00579 rad의 진폭으로 변형을 가하고 발생된 응력을 측정하였다. 광중합이 시작됨과 동시에 측정이 시작되었으며, 광중합 후 10초 동안 점탄성의 변화를 관찰하였다. 각 복합레진에 대해 5 회 반복하여 측정하였고, 실험은 $25{\pm}0.5^{\circ}C$에서 진행되었다. 측정된 변형-응력 곡선으로부터 복소전단탄성계수 G*, 저장전단탄성 계수 G', 손실전단탄성 계수 G"를 구하였고 G*가 10 MPa에 이르는 시간을 구하였다. 각 재료의 복소전단탄성계수 G*와 10 MPa에 이르는 시간에 대해 일원분산분석 (One-way ANOVA)과 사후검정 (Tukey 검정)을 시행하였다 (${\alpha}$= 0.05). 결과는 다음과 같다. 1.본 연구를 위해 제작한 점탄성 측정기는 광중합 복합레진의 중합 초기 10초 동안의 동적 점탄성 변화를 신뢰성 있게 측정 할 수 있었다. 2. 모든 복합레진은 광조사 개시 후 $1{\sim}2$초의 불응기를 지난 다음 급격한 전단탄성계수의 증가를 보였다. 3. 모든 복합레진은 광중합 10 초간 손실전단탄성계수보다 저장전단탄성계수의 높은 증가를 보였다. 4. 광중합 초기 10초 후 복소전단탄성계수 값은 $150.3{\sim}563.7\;MPa$로, Z-100이 가장 높았고, 그 다음 Clearfil, Z-250, Z-350, Tetric Ceram, DenFil의 순이었다. 5. 복소전단탄성계수가 10 MPa에 이르는 시간은 Z-100이 2.55초로 가장 빨랐고, DenFil이 4.06초로 가장 느렸다.

Keywords

References

  1. Dauvillier BS, Feilzer AJ, De Gee AJ, Davison CL. Visco-elastic parameters of dental restorative materials during setting. J Dent Res 79(3):818-823, 2000 https://doi.org/10.1177/00220345000790030601
  2. Guggenberger R, Weinmann W. Exploring beyond methacrylates. Am J Dent 13:82-84, 2000
  3. Ellakwa A, Cho N, Lee IB. The effect of resin matrix composition on the polymerization shrinkage and rheological properties of experimental dental composites. Dent Mater 23:1229-1235, 2007 https://doi.org/10.1016/j.dental.2006.11.004
  4. Labella R, Lambrechts P, Van Meerbeek B, Vanherle G. Polymerization shrinkage and elasticity of flowable composites and filled adhesives. Dent Mater 15:128- 137, 1999 https://doi.org/10.1016/S0109-5641(99)00022-6
  5. Braga RR, Ferracane JL. Contraction stress related to degree of conversion and reaction kinetics. J Dent Res 81:114-118, 2002 https://doi.org/10.1177/154405910208100206
  6. Kleverlaan CJ, Feilzer AJ. Polymerization shrinkage and contraction stress of dental resin composites. Dent Mater 21:1150-1157, 2005 https://doi.org/10.1016/j.dental.2005.02.004
  7. Feilzer AJ, De Gee AJ, Davison CL. Setting stress in composite resin in relation to configuration of the restoration. J Dent Res 66:1636-1369, 1987 https://doi.org/10.1177/00220345870660110601
  8. Charton C, Colon P, Pla F. Shrinkage stress in lightcured composite resins: Influence of material and photoactivation mode. Dent Mater 23:911-920, 2007 https://doi.org/10.1016/j.dental.2006.06.034
  9. Odian G. Principles of polymerization. 3rd Ed, p. 216- 226, John Wiley & Sons, Inc., New York, 1991
  10. Sakaguchi RL, Shah NC, Lim BS, Ferracane JL, Borgersen SE. Dynamic mechanical analysis of storage modulus development in light-activated polymer matrix composites. Dent Mater 18:197-202, 2002 https://doi.org/10.1016/S0109-5641(01)00082-3
  11. Mesquita RV, Axmann D, Geis-Gerstorfer J. Dynamic visco-elastic properties of dental composite resins. Dent Mater 22:258-267, 2006 https://doi.org/10.1016/j.dental.2005.04.019
  12. Helvatjoglu-Antoniades M, Papadogiannis Y, Lakes RS, Dionysopoulos P, Papadogiannis D. Dynamic and static elastic moduli of packable and flowable composite resins and their development after initial photo curing. Dent Mater 22:450-459, 2006 https://doi.org/10.1016/j.dental.2005.04.038
  13. Nakayama WT, Hall DR, Grenoble DE, Katz JL. Elastic properties of dental resin restorative materials. J Dent Res 53:1121-1126, 1974 https://doi.org/10.1177/00220345740530050901
  14. Braem M, Lambrechts P, Van Doren V, Vanherle G. The impact of composite structure on its elastic response. J Dent Res 65:648-653, 1986 https://doi.org/10.1177/00220345860650050301
  15. Lee IB, Son HH, Um CM. Rheologic properties of flowable, conventional hybrid, and condensable composite resins. Dent Mater 19:298-307, 2003 https://doi.org/10.1016/S0109-5641(02)00058-1
  16. Lee IB, Cho BH, Son HH, Um CM. Rheological characterization of composites using a vertical oscillation rheometer. Dent Mater 23:425-432, 2007 https://doi.org/10.1016/j.dental.2006.02.013
  17. 서희연, 이인복. 치과용 복합레진의 중합 전 slumping resistance와 점탄성. 대한치과보존학회지 33:235-245, 2008
  18. Braem M, Lambrechts P, Vanherle G, Davidson CL. Stiffness increase during the setting of dental compos ite resins. J Dent Res 66(12):1713-1716, 1987 https://doi.org/10.1177/00220345870660120301
  19. Sakaguchi RL, Wiltbank BD, Murchison CF. Prediction of composite elastic modulus and polymerization shrinkage by computational micromechanics. Dent Mater 20:397-401, 2004 https://doi.org/10.1016/j.dental.2003.11.003
  20. Lee JH, Um CM, Lee IB. Rheological properties of resin composites according to variations in monomer and filler composition. Dent Mater 22:515-526, 2006 https://doi.org/10.1016/j.dental.2005.05.008
  21. Tanimoto Y, Nishiwaki T, Nemoto K. Dynamic viscoelastic behavior of dental composites measured by split Hopkinson pressure bar. Dent Mater J 25(2):234-240, 2006 https://doi.org/10.4012/dmj.25.234
  22. Ferracane JL. Developing a more complete understanding of stresses produced in dental composites during polymerization. Dent Mater 21:36-42, 2005 https://doi.org/10.1016/j.dental.2004.10.004
  23. 서덕규, 민선홍, 이인복. 측정장치의 compliance 유무가 복합레진의 중함수축응력의 측정에 미치는 영향. 대한치과보존학회지 34:146-152, 2009
  24. 박준규, 임범순, 이인복. 5급 와동의 복합레진 수복 시 발생되 는 교두굴곡에 관한 연구. 대한치과보존학회지 33:83-89, 2008