在復形牙科中，光聚合複合樹脂已經被普遍使用。然而，複合樹脂的缺點是在聚合過程中會產生體積收縮。本研究目的是使用光學同調斷層掃描(optical coherence tomography)記錄複合樹脂聚合收縮過程的斷面影像，並以數位影像相關法(digital image correlation)軟體分析複合樹脂聚合收縮模式及填補介面剝離，創立一種全新的觀測方式。
研究方法首先測試光學同調斷層影像是否可以數位影像相關法軟體進行分析。先在磨平的門牙表面製備一窩洞，以流動複合樹Filtek™ Z350 XT Flowable Restorative(Z350F)填補，並以光學同調斷層紀錄二維影像。再分別以虛擬位移(以軟體進行影像平移)和實際位移(在光學同調斷層掃描儀下移動)的影像，進行數位影像相關法軟體分析。其次，為了製造出可供數位影像相關法分析的斑點特徵影像，在流動複合樹脂(Z350F)中加入比例不同(17%, 9%, 4.8 wt. %)的三種不同顆粒(75 µm玻璃微珠、150~212 µm玻璃微珠、75~150 µm氧化鋯粉末)，並以數位影像相關法軟體分析光聚合過程光學同調斷層掃描影像。接著以此觀測方式，分析Filtek™ Z350 XT Flowable (Z350F)、Filtek™ Z350 XT Universal (Z350)、 Filtek™ Bulk Fill Posterior (Bulk Fill) 三種不同樹脂的收縮模式。將這三種複合樹脂填補在門牙表面窩洞中，在有、無黏著的狀態下進行聚合。
第一部分結果顯示，若兩張影像移動不超過132µm，光學同調斷層掃描影像以數位影像相關法所測量出位移誤差小於0.01%。第二部分結果顯示，單純不加顆粒的掃描影像最適合用於分析，因為所加入的玻璃微珠和氧化鋯粉末會在影像上造成假影，干擾數位影像相關法分析。因此第三部分以不加入玻璃微珠及氧化鋯粉末的單純複合樹脂進行收縮模式分析。複合樹脂表面在聚合20秒後向下位移之量測顯示，未黏著組別中，Z350F最大(約22 µm)，Z350(約8 µm)和Bilk Fill(約12 µm)較小；黏著組別中，Z350F最大(約28 µm)，Z350和Bulk Fill相當(約15 µm)；追蹤聚合20秒過程中，未黏著之Z350F和Bulk Fill表面各在4.6、7.4秒時收縮達穩定，Z350反在8.8秒時有一明顯往上位移。於複合樹脂底部，無論何種黏著狀態，三種樹脂聚合20秒後位移變異量皆較表面大，無黏著狀態其向上位移為2-12 µm；黏著狀態下則為3-5 µm，且Z350在聚合約8.8秒，底部同樣有位移往上現象。在微滲漏測量中，無黏著狀態下三種複合樹脂都產生微滲漏，但無發現特定模式；黏著狀態下無發現微滲漏產生。
本研究結合光學同調斷層掃描儀搭配數位影像相關法，結果可成功觀測複合樹脂聚合收縮過程，且不需要額外加入填料增加影像辨識，過程和臨床使用方式相同，因此可成為一不需接觸、非破壞性、可觀察斷面資訊的新觀測方式，同時量測樹脂聚合收縮表現與微滲漏的相關性。

The use of light-cured resin composites has become common in restorative dentistry. However, a drawback of dental composites is their volumetric shrinkage that occurs during the polymerization. The purpose of this study was to investigate the polymerization shrinkage mode and debonding of the composite restorations by combining optical coherence tomography (OCT) and a digital image correlation (DIC) technique.
A cavity was prepared on a flatten incisor surface, and filled with Filtek™ Z350 XT Flowable Restorative (Z350F). The 2D cross-section images of composite polymerization was recorded by optical coherence tomography (OCT). To examine the feasibility of OCT images for DIC analysis, the OCT images from either virtually moved by software, or the specimen actually moved under the OCT scanning were used for DIC analysis. Secondly, 75 µm glass beads, 150~212 µm glass beads and 75~150 µm zirconia powders were added in Z350F in three weight ratios (17%, 9%, 4.8%) to create the speckle pattern for DIC analysis. The OCT images during polymerization of all groups were used for DIC analysis. Finally, three kinds of composites were filled with/without bonding agent:1) Filtek™ Z350 XT Flowable (Z350F), 2) Filtek™ Z350 XT Universal (Z350), 3) Filtek™ Bulk Fill Posterior (Bulk Fill). Their polymerization shrinkage modes were analyzed by the combined analysis
Firstly, the results showed that movements of OCT images could be precisely (the errors < 0.01%) measured with a limit of 132 µm. Secondly, the blank Z350F presented the most favorable results of DIC analysis compared other composites with particles, since the addition of glass bead and zirconia caused artifacts in OCT images to interfere the analysis of DIC. As a result, three kinds of composite were used to investigate shrinkage without additional particles. In top surface measurement at curing for 20 seconds, Z350F, Z350 and Bulk Fill showed 22 µm (the most), 8 µm and 12 µm downward displacement respectively in nonbonded condition and 28 µm (the most), 15µm and 15 µm respectively in bonded condition. In the top surface displacements measurement during the polymerization process, Z350F and Bulk Fill reached 95 % of maximum displacement at 4.6 second and 7.4 second respectively. However, Z350 changed to upward displacement apparently at 8.8 second. All of the composites showed more variations of displacement in bottom than top surface. In the bottom, there were 2-12 µm upward displacement in nonbonded condition and 3-5 µm upward displacement in bonded condition. Z350 had an apparent upward displacement at 8.8 second as well. No microleakage was measured in bonded condition of three composites and three composites had microleakage in nonbonded condition. However, no specific mode was found in microleakage measurement.
The polymerization process of composites was investigated successfully by combining OCT and DIC. A novel method without contact and destruction was established to investigate the shrinkage mode by real-time cross-section images.

[1] M. Braem, W. Finger, V. Van Doren, P. Lambrechts, G. Vanherle, Mechanical properties and filler fraction of dental composites, Dental Materials 5(5) (1989) 346-349.
[2] S.B. Berger, A.R.M. Palialol, V. Cavalli, M. Giannini, Characterization of water sorption, solubility and filler particles of light-cured composite resins, Brazilian dental journal 20(4) (2009) 314-318.
[3] A. Feilzer, B. Dauvillier, Effect of TEGDMA/BisGMA ratio on stress development and viscoelastic properties of experimental two-paste composites, Journal of dental research 82(10) (2003) 824-828.
[4] A. Ellakwa, N. Cho, I.B. Lee, The effect of resin matrix composition on the polymerization shrinkage and rheological properties of experimental dental composites, Dental Materials 23(10) (2007) 1229-1235.
[5] K. Baroudi, A.M. Saleh, N. Silikas, D.C. Watts, Shrinkage behaviour of flowable resin-composites related to conversion and filler-fraction, journal of dentistry 35(8) (2007) 651-655.
[6] M. Helvatjoglu-Antoniades, Y. Papadogiannis, R. Lakes, P. Dionysopoulos, D. Papadogiannis, Dynamic and static elastic moduli of packable and flowable composite resins and their development after initial photo curing, Dental Materials 22(5) (2006) 450-459.
[7] G.A. Laughlin, J.L. Williams, J.D. Eick, The influence of system compliance and sample geometry on composite polymerization shrinkage stress, Journal of Biomedical Materials Research Part A 63(5) (2002) 671-678.
[8] R. Labella, P. Lambrechts, B. Van Meerbeek, G. Vanherle, Polymerization shrinkage and elasticity of flowable composites and filled adhesives, Dental materials 15(2) (1999) 128-137.
[9] N. Ilie, R. Hickel, Investigations on mechanical behaviour of dental composites, Clinical oral investigations 13(4) (2009) 427.
[10] C.J. Kleverlaan, A.J. Feilzer, Polymerization shrinkage and contraction stress of dental resin composites, Dental Materials 21(12) (2005) 1150-1157.
[11] L.F.J. Schneider, L.M. Cavalcante, N. Silikas, Shrinkage stresses generated during resin-composite applications: a review, Journal of dental biomechanics 2010 (2010).
[12] W. Cook, Spectral distributions of dental photopolymerization sources, Journal of dental research 61(12) (1982) 1436-1438.
[13] J.L. Ferracane, Developing a more complete understanding of stresses produced in dental composites during polymerization, Dental Materials 21(1) (2005) 36-42.
[14] M. Atai, D.C. Watts, A new kinetic model for the photopolymerization shrinkage-strain of dental composites and resin-monomers, Dental Materials 22(8) (2006) 785-791.
[15] J.G. Leprince, W.M. Palin, M.A. Hadis, J. Devaux, G. Leloup, Progress in dimethacrylate-based dental composite technology and curing efficiency, Dental Materials 29(2) (2013) 139-156.
[16] M. Milosevic, Polymerization mechanics of dental composites–advantages and disadvantages, Procedia Engineering 149 (2016) 313-320.
[17] A. Feilzer, A. De Gee, C. Davidson, Setting stress in composite resin in relation to configuration of the restoration, Journal of Dental Research 66(11) (1987) 1636-1639.
[18] M.-R. Lee, B.-H. Cho, H.-H. Son, C.-M. Um, I.-B. Lee, Influence of cavity dimension and restoration methods on the cusp deflection of premolars in composite restoration, Dental materials 23(3) (2007) 288-295.
[19] S.-F. Chuang, C.-H. Chang, T.Y.-F. Chen, Contraction behaviors of dental composite restorations—finite element investigation with DIC validation, Journal of the mechanical behavior of biomedical materials 4(8) (2011) 2138-2149.
[20] B.-S. Lim, J. Ferracane, R. Sakaguchi, J. Condon, Reduction of polymerization contraction stress for dental composites by two-step light-activation, Dental Materials 18(6) (2002) 436-444.
[21] I.-B. Lee, B.-H. Cho, H.-H. Son, C.-M. Um, B.-S. Lim, The effect of consistency, specimen geometry and adhesion on the axial polymerization shrinkage measurement of light cured composites, dental materials 22(11) (2006) 1071-1079.
[22] D. Watts, A. Marouf, Optimal specimen geometry in bonded-disk shrinkage-strain measurements on light-cured biomaterials, Dental Materials 16(6) (2000) 447-451.
[23] X. Liu, H. Li, J. Li, P. Lu, A.S.-L. Fok, An acoustic emission study on interfacial debonding in composite restorations, dental materials 27(9) (2011) 934-941.
[24] J. Park, J. Chang, J. Ferracane, I.B. Lee, How should composite be layered to reduce shrinkage stress: incremental or bulk filling?, Dental Materials 24(11) (2008) 1501-1505.
[25] F. Rueggeberg, W.F. Caughman, J. Curtis, Effect of light intensity and exposure duration on cure of resin composite, Operative dentistry 19 (1994) 26-26.
[26] J. Chesterman, A. Jowett, A. Gallacher, P. Nixon, Bulk-fill resin-based composite restorative materials: a review, British dental journal 222(5) (2017) 337.
[27] N. Ilie, S. Bucuta, M. Draenert, Bulk-fill resin-based composites: an in vitro assessment of their mechanical performance, Operative Dentistry 38(6) (2013) 618-625.
[28] H. El-Damanhoury, J. Platt, Polymerization shrinkage stress kinetics and related properties of bulk-fill resin composites, Operative dentistry 39(4) (2014) 374-382.
[29] A.A. Kumar, V. Hariharavel, A. Narayanan, S. Murali, Effect of protective coating on marginal integrity of nanohybrid composite during bleaching with carbamide peroxide: A microleakage study, Indian Journal of Dental Research 26(2) (2015) 167.
[30] J.L. Ferracane, Placing dental composites—a stressful experience, Operative Dentistry 33(3) (2008) 247-257.
[31] J.B. Novaes, E. Talma, E.B. Las Casas, W. Aregawi, L.W. Kolstad, S. Mantell, Y. Wang, A. Fok, Can pulpal floor debonding be detected from occlusal surface displacement in composite restorations?, Dental Materials 34(1) (2018) 161-169.
[32] Y.-C. Chiang, P. Rösch, A. Dabanoglu, C.-P. Lin, R. Hickel, K.-H. Kunzelmann, Polymerization composite shrinkage evaluation with 3D deformation analysis from μCT images, dental materials 26(3) (2010) 223-231.
[33] J.-y. Li, A. Lau, A.S. Fok, Application of digital image correlation to full-field measurement of shrinkage strain of dental composites, Journal of Zhejiang University SCIENCE A 14(1) (2013) 1-10.
[34] Y.-S. Hsieh, Y.-C. Ho, S.-Y. Lee, C.-C. Chuang, J.-c. Tsai, K.-F. Lin, C.-W. Sun, Dental optical coherence tomography, Sensors 13(7) (2013) 8928-8949.
[35] H. Schneider, K.-J. Park, M. Häfer, C. Rüger, G. Schmalz, F. Krause, J. Schmidt, D. Ziebolz, R. Haak, Dental applications of optical coherence tomography (OCT) in cariology, Applied Sciences 7(5) (2017) 472.
[36] A. Sadr, Y. Shimada, J.R. Mayoral, I. Hariri, T.A. Bakhsh, Y. Sumi, J. Tagami, Swept source optical coherence tomography for quantitative and qualitative assessment of dental composite restorations, Lasers in Dentistry XVII, International Society for Optics and Photonics, 2011, p. 78840C.
[37] E.A. Swanson, J.G. Fujimoto, The ecosystem that powered the translation of OCT from fundamental research to clinical and commercial impact, Biomedical optics express 8(3) (2017) 1638-1664.
[38] M. Mandurah, A. Sadr, Y. Shimada, Y. Kitasako, S. Nakashima, T.A. Bakhsh, J. Tagami, Y. Sumi, Monitoring remineralization of enamel subsurface lesions by optical coherence tomography, Journal of biomedical optics 18(4) (2013) 046006.
[39] Y. Shimada, A. Sadr, Y. Sumi, J. Tagami, Application of optical coherence tomography (OCT) for diagnosis of caries, cracks, and defects of restorations, Current oral health reports 2(2) (2015) 73-80.
[40] W. Drexler, M. Liu, A. Kumar, T. Kamali, A. Unterhuber, R.A. Leitgeb, Optical coherence tomography today: speed, contrast, and multimodality, Journal of biomedical optics 19(7) (2014) 071412.
[41] J. Hayashi, Y. Shimada, J. Tagami, Y. Sumi, A. Sadr, Real-Time Imaging of Gap Progress during and after Composite Polymerization, Journal of dental research 96(9) (2017) 992-998.
[42] B.W. Colston, U.S. Sathyam, L.B. DaSilva, M.J. Everett, P. Stroeve, L. Otis, Dental oct, Optics express 3(6) (1998) 230-238.
[43] F.I. Feldchtein, G. Gelikonov, V. Gelikonov, R. Iksanov, R. Kuranov, A.M. Sergeev, N. Gladkova, M. Ourutina, J. Warren, D. Reitze, In vivo OCT imaging of hard and soft tissue of the oral cavity, Optics express 3(6) (1998) 239-250.
[44] T. Tabata, Y. Shimada, A. Sadr, J. Tagami, Y. Sumi, Assessment of enamel cracks at adhesive cavosurface margin using three-dimensional swept-source optical coherence tomography, Journal of dentistry 61 (2017) 28-32.
[45] Y. Zhou, Y. Shimada, K. Matin, A. Sadr, Y. Sumi, J. Tagami, Assessment of bacterial demineralization around composite restorations using swept-source optical coherence tomography (SS-OCT), Dental Materials 32(9) (2016) 1177-1188.
[46] K. Horie, Y. Shimada, K. Matin, M. Ikeda, A. Sadr, Y. Sumi, J. Tagami, Monitoring of cariogenic demineralization at the enamel–composite interface using swept-source optical coherence tomography, Dental Materials 32(9) (2016) 1103-1112.
[47] I. Hariri, A. Sadr, Y. Shimada, J. Tagami, Y. Sumi, Effects of structural orientation of enamel and dentine on light attenuation and local refractive index: an optical coherence tomography study, J Dent 40(5) (2012) 387-96.
[48] S.-F. Chuang, C.-H. Chang, T.Y.-F. Chen, Spatially resolved assessments of composite shrinkage in MOD restorations using a digital-image-correlation technique, Dental materials 27(2) (2011) 134-143.
[49] K. FUJITA, N. NISHIYAMA, K. NEMOTO, T. OKADA, T. IKEMI, Effect of base monomer's refractive index on curing depth and polymerization conversion of photo-cured resin composites, Dental materials journal 24(3) (2005) 403-408.
[50] J. Lehtinen, T. Laurila, L.V. Lassila, P.K. Vallittu, J. Räty, R. Hernberg, Optical characterization of bisphenol-A-glycidyldimethacrylate–triethyleneglycoldimethacrylate (BisGMA/TEGDMA) monomers and copolymer, dental materials 24(10) (2008) 1324-1328.
[51] R.J.-Y. Kim, Y.-J. Kim, N.-S. Choi, I.-B. Lee, Polymerization shrinkage, modulus, and shrinkage stress related to tooth-restoration interfacial debonding in bulk-fill composites, Journal of dentistry 43(4) (2015) 430-439.
[52] R. Wang, M. Zhang, F. Liu, S. Bao, T. Wu, X. Jiang, Q. Zhang, M. Zhu, Investigation on the physical–mechanical properties of dental resin composites reinforced with novel bimodal silica nanostructures, Materials Science and Engineering: C 50 (2015) 266-273.
[53] Y. Kwon, J. Ferracane, I.-B. Lee, Effect of layering methods, composite type, and flowable liner on the polymerization shrinkage stress of light cured composites, Dental Materials 28(7) (2012) 801-809.
[54] T. Melo-Silva, C. Melo-Silva, C. Carvalho, A. Teixeira, J. Lins, J. Gouvêa, Evaluation of Mechanical Properties of Composite Materials Used in Dentistry Varying the Inorganic Composition, Materials Science Forum, Trans Tech Publ, 2015, pp. 320-324.