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Materials Science » Composite Materials » "Metal, Ceramic and Polymeric Composites for Various Uses", book edited by John Cuppoletti, ISBN 978-953-307-353-8, Published: July 20, 2011 under CC BY-NC-SA 3.0 license. © The Author(s).

Chapter 21

Effects of Filler Content on Mechanical and Optical Properties of Dental Composite Resin

By Seyed Mostafa Mousavinasab
DOI: 10.5772/21405

Article top

Effects of Filler Content on Mechanical and Optical Properties of Dental Composite Resins

Seyed Mostafa Mousavinasab1

1. Introduction

Filler –matrix coupling determines, to a large extent, the mechanical strength and clinical longevity of dental composites. Incorporation of filler into resin matrix greatly influences and improves material properties provided that filler particles are bonded to polymer matrix or otherwise it may actually weaken the resin.

Benefits of filler content presence are increased hardness, strength, radiopacity and decrease in polymerization shrinkage, thermal expansion and contraction, water sorption, softening, staining and finally improved workability.

Formulation of the monomer and filler, shear rate and temperature greatly influence characteristics of resin composite.(1)

There are significant differences in number of filler particles, size and area occupied for the fine particle composite resins of different brands.(2)

2. Physical and mechanical properties

There is a correlation between physical and mechanical properties and filler content weight and size in composite resins. Following increasing filler particle size an increase in stress concentration and decrease in flexural strength is observed.( 3)

In addition to correlation existed between elastic moduli and filler content fraction of composite resin, the shape and size seem to be fine-tuning factors for young’s modulus.(4-7)

Flexural strength and modulus, hardness as well as fracture toughness are influenced by both filler morphology and filler loading.(8)

flexural strength and modulus of elasticity values are different among different universal hybrid composites whereasthe microfine composite resins present lowest filler weight and mechanical properties compared to universal hybrid and the nanofilled resins present intermediary results.( 9)

Mechanical properties of microfilled composite resins as well as polyacid- modified resin composites are dependent on the inorganic filler content and properties of matrix resin and whether matrix resin is hydriphilic or hydriphobic.(10-12)

Significant exponential relations are found between filler content of the resins and their flexural moduli and flexural strength.(13)Although some studies demonstrate that there is no correlation between fracture toughness and filler content by volume of flowable compositesbut hardness and fracture toughness tend to be linearly proportional to filler content in the composite resin and resin composites demonstrate a range of fracture toughness values.(14-16)

There is a linear relationship between elastic module and filler loading but correlation of fracture strength and fatigue data to filler fraction could not be proved, therefore materials providing high initial strengths don’t obviously reveal the best fatigue resistance.(17)

Condensable composite and hybrid composite resins with similar concentration of inorganic particles may show different flexural strength.(18)

Presence of spherically- shaped filler particles affect the microfracture mechanisms of dental resin composites and increase the bending strength and fracture toughness with a much higher rate for elastic modulus.(19-20)

Percent of submicron silica level in hybrid resin composites has direct effect on physical strength.(21)

The particle size of the filler appear to have a moderate influence on the properties of resin composite.(22)

Presence of nano-filler particles in resin -based restorative materials produce superior performance compared to micro-particles.(23)It also greatly influences grindability of composite resin adhesives.(24)

The flexural strength of metal –resin composite restorative materials containing 4-META treated particles is mainly affected by filler content and immersion time(25)and is increased by the particle size and content of Ag-Sn and Ag-In alloy particles as filler and 4-META as coupling agent.(26-30)

An experimentally prepared metal –resin composite using Ag-Cu particles as filler in which metal particles are involved in the polymerization initiation system has the potential to be used as a dental restorative material,(31)

The bending properties: such as maximum stress and bending modulus, increase with filler content.(32)

Uncontrolled aggregation of amorphous calcium phosphate particulate fillers and their uneven distribution within polymer matrices can have adverse effects on the properties of composite containing this kind of fillers.(33)

Adding apatite and titanium nanotubes to resin based cements will increase the fracture toughness, flexural and compressive strength, hardness and modulus without changing radiopacity and biocompatibility.(34-35)

Beside degree of cure other factors like filler content and monomer type affect the color stability, hardness, compressive strength, stiffness and flexural strength of composites.(36-37)

Coefficient of linear thermal expansion and water absorption of glass-fiber reinforced resins depends on the inorganic filler content or glass-fiber content.(38)

There is an underlying relationship among the composition, component stability and post polymerization properties of flowable composites.(39)

Discrepancy between filler and matrix, filler content, particle size and the ability of the polishing systems to abrade filler may contribute to polished surface characteristics of resin composite.(40)

Decrease in filler particle size to less than 1 micrometer and a lower filler loading permit the clinical development and maintenance of smooth surface with microfilled compared to conventional composite restorative resins.(41)

Fluoride release from filled resins containing CaF2 particles as filler in the range of 9.09 mass% concentration is independent of PH solution and may help to reduce the occurrence of both secondary caries and restoration fracture.(42-44)

3. Wear resistanceand polymerization shrinkage

Wear resistance is a major concern about composite resins. In general it is suggested that composite resins with smaller particles wear less and filler components characterize the wear patterns especially in the occlusal contact area. (45-47)

Wear resistance of composite resins is enhanced due to presence of higher filler volume and functional silane treated microfiller particles. (48)

The abrasion resistance of heat curing composites is also controlled by the filler size and filler content.(49)

The effect of filler content on toothbrush wear resistance may vary with different resin matrices.(50)

Increasing the filler content offers characteristics like bulk curing with less polymerization shrinkage, decreased wear and packability to the composite resin.(51)

Polymerization shrinkage:

Filler loading reducespolymerization contraction and reaction inhibition under atmospheric oxygen at the composite resin surface. (52)

Low shrinkage composites including Ormocers and cationic ring –opening systems despite their higher filler mass show no difference regarding mechanical properties compared to highly filled methacrylate-based materials.(53)

There is an inverse linear relationship between filler content and polymerization shrinkage (54)

Higher inorganic content is associated with lower polymerization stress values which is in direct relation with reduced shrinkage.(55)

Increased filler content in packable composite resins assures of improved wear-resistance, strength, longevity, postoperative sensitivity and esthetics.(56)

Compositional interactions between the filler and matrix influence viscosity and flow characteristics of resin composite.(57)

Higher filler loaded flowable composites are preferred to flowable composites with lower filler content when incremental technique is used in conjunction with conventional hybrid composites for 2-mm deep cavities to achieve better marginal integrity.(58)

Marginal adaptation is significantly related to the amount of inorganic component and also to the volume of the prepolymerized inorganic filler content.(59)

Both organic and inorganic composition of the composite resin influence its rate of cure.The rate of polymerization is increased with the level of HEMA and TEDDMA in the monomer composition.(60-61)

Substitution of Bis-GMA, UDMA and TTEGDMA with alternative monomers results in increased flexural strength. Increased hygroscopic expansion and reduced shrinkage are achieved using a very hydrophilic monomer.(62)

Optical properties:

One interesting aspect of filler content effect is on optical properties of the resin. When a ray of light interacts with composite surface, some of the light may be partly reflected and some partly refracted. The density of the filler determines how strongly the light is scattered within the material. The low filler proportion regions show lower scattering than denser filler regions. With the addition of filler to unfilled resin matrices (UDMA and TEGDMA based composite resins) a significantly higher transmitance value will be seen and there is a linear correlation between percentage of Bis-GMA in the resin matrix and the total and diffuse translucency.

Higher transmittance of Bis–GMA compared to UDMA and TEGDMA with the addition of filler positively influence translucency of composite resin. (63)

Improvement of surface treatment material of filler and composition of filler makes it harder toabsorb the microwave energy which is dependent on the size of filler.(64)

There is a linear relation between optical scattering and filler concentration of resin composite and also efficiency of optical scattering is related to size and shape of the filler.(65)

Higher translucency is achieved by decontamination of the added fillers to the matrix of composite resins.(66)

Filler type influences the color difference values and translucency of composite resin artificial teeth.(67) The pigments are usually metal oxides.Certain fluorescent agents are added to resin composite in order to give the materials a natural –looking, tooth like structure. Metal oxides such as titanium oxide are added to composite to produce opaque composite. The volume fraction of the filler and matrix in composite resins influence scattering and absorption as a result the color of composite resin.(68)

Adding fillers such as TIO2 particles to resin matrix will lead to increasing opallescence of resin composite, decrease in translucency parameter but no effect on fluorescency.Presence of TIO2 nanoparticles produce human enamel like appearance.(69)

The orientation of fillers affects the absorption and scattering coefficient differences in fiber reinforced composite resins.(70)

Some of particulate filled composite resins that can be fabricated into metal-free crowns are stable in both translucency and color during storage period in a media such as water.(71)

Darker shades of resin composite contain darker pigments that absorb more light. Refraction index of resin composite is an important factor in attaining a color matching between composite and dental tissues. To prevent light scattering at the resin-filler interface, the refractive indices of the different components (filler-matrix-coupling agent) shouldn’t vary too much, otherwise resulting in a material that looks opaque with reduced transparency for light.

Opalescence parameter varies by the size and amount of filler and translucency parameter decreases as the amount of same filler size increases.(72)

Refractive index match between resin/filler linearly rises with the conversion of composite resin and increase in light transmission during conversion is greater for increasing filler levels.(73)

It has been shown by researchers; light scattering is related to fillerparticle size in the resin composite, that is maximized when the filler Particle size is one half the wavelength of activation light, resulting in a lower transmission coefficient and smaller depth of cure. Transmission Coefficient is influenced by the wavelength of light, refractive indices of the resin and fillers, and type and amount of filler particles.

The depth of cure of a composite resin is affected by the amount of light that reaches the photo initiator.

Light intensity decreases as it passes through the material. Fillers and pigments strongly influence the intensity of the incident light, limiting the depth of cure. Both intensity of the light source and attenuating power of the material influence the degree of conversion. Filler/resin refractive index has significant interaction on cure depth and color matching of composite resin (74)


1 - Lee JH, Um CM, Lee IB. Rheological properties of resin composites according to variations in monomer and filler composition. Dent Mater. 2006 Jun;22 6 51526 .
2 - Jaarda MJ, Lang BR, Wang RF, Edwards CA. Measurement of composite resin filler particles by using scanning electron microscopy and digital imaging. J Prosthet Dent. 1993 Apr;69 4 41624 .
3 - Y. Tanimoto, T. Kitagawa, M. Aida, N. Nishiyama, Experimental, approach. computational, evaluating. for, mechanical. the, of. characteristics, composite. dental, with. resins, filler. various, sizes, Acta Biomater. 2006 Nov;2 6 6339 .
4 - K. Masouras, N. Silikas, D. C. Watts, Correlation of filler content and elastic properties of resin-composites. Dent Mater. 2008 Jul;24 7 9329 .
5 - K. Masouras, R. Akhtar, D. C. Watts, N. Silikas, Effect of filler size and shape on local nanoindentation modulus of resin-composites. J Mater Sci Mater Med. 2008 Dec;19 12 35616 .
6 - M. Kawaguchi, T. Fukushima, T. Horibe, T.[. Watanabe, of. Effect, system. filler, the. on, properties. mechanical, light-cured. of, resins. I. composite, II. Mechanical properties of visible light-cured composite resins with binary filler system]. Shika Zairyo Kikai. 1989 Mar;8 2 1804 .
7 - M. Kawaguchi, T. Fukushima, T. Horibe, T. Watanabe, Effect of filler system on the mechanical properties of light-cured composite resins. I. Effect of various types of silica fillers on the mechanical properties of the composite resins]. Shika Zairyo Kikai. 1989 Mar;8 2 1749 .
8 - Kim KH, Ong JL, Okuno O.The effect of filler loading and morphology on the mechanical properties of contemporary composites.J Prosthet Dent. 2002 Jun;87 6 6429 .
9 - Rodrigues Junior SA, Zanchi CH, Carvalho RV, Demarco FF.Flexural strength and modulus of elasticity of different types of resin-based composites.Braz Oral Res. 2007 Jan-Mar;21 1 1621 .
10 - T. Hirasawa, S. Hirano, S. Hirabayashi, I. Harashima, I. Nasu, T. [. Kurosawa, [Mechanical properties of microfilled composite resins (author’s transl)].Shika Rikogaku Zasshi. 1981 Apr;22 59 18795 .
11 - Raptis CN, Fan PL, Powers JM.Properties of microfilled and visible light-cured composite resins.J Am Dent Assoc. 1979 Oct;99 4 6313 .
12 - Schulze KA, Zaman AA, Söderholm KJ.Effect of filler fraction on strength, viscosity and porosity of experimental compomer materials. J Dent. 2003 Aug;31 6 37382 .
13 - M. Inoue, W. J. Finger, M. Mueller, of. Effect, content. filler, restorative. of, on. resins, strength. retentive, acid-conditioned. to, enamel, Am J Dent. 1994 Jun;7 3 1616 .
14 - T. Yamaga, Y. Sato, Y. Akagawa, M. Taira, K. Wakasa, M. Yamaki, Hardness, toughness. fracture, four. of, visible. commercial, composite. light-cured, veneering. resin, materials, J Oral Rehabil. 1995 Dec;22 12 85763 .
15 - E. D. Bonilla, G. Mardirossian, A. A. Caputo, toughness. Fracture, posterior. of, composites. resin, Int. Quintessence, 2001 Mar;32 3 20610 .
16 - E. D. Bonilla, M. Yashar, A. A. Caputo, toughness. Fracture, nine. of, resin. flowable, J. composites, Dent. Prosthet, 2003 Mar;89 3 2617 .
17 - U. Lohbauer, R. Frankenberger, N. Krämer, A. Petschelt, Strength, performance. fatigue, filler. versus, of. fraction, types. different, direct. of, restoratives. J. dental, Mater. Biomed, B. Res, Biomater. Appl, 2006 Jan;76 1 11420 .
18 - Adabo GL, dos Santos Cruz CA, Fonseca RG, Vaz LG.The volumetric fraction of inorganic particles and the flexural strength of composites for posterior teeth. J Dent. 2003 Jul;31 5 3539 .
19 - Kim KH, Park JH, Imai Y, Kishi T.Fracture behavior of dental composite resins.Biomed Mater Eng. 1991;1(1):45-57.
20 - K. H. Kim, J. H. Park, Y. Imai, T. Kishi, Microfracture mechanisms of dental resin composites containing spherically-shaped filler particles. J Dent Res. 1994 Feb;73 2 499504 .
21 - B. I. Suh, C. Ferber, R. Baez, of. Optimization, composite. hybrid, properties, J Esthet Dent. 1990 Mar-Apr;2 2 448 .
22 - Y. Li, M. L. Swartz, R. W. Phillips, B. K. Moore, T. A. Roberts, Effect of filler content and size on properties of composites. J Dent Res. 1985 Dec;64 12 1396401 .
23 - S. Rüttermann, C. Wandrey, W. H. Raab, R. Janda, nano-particles. Novel, as for. fillers, experimental. an, restorative. resin-based, material, Acta Biomater. 2008 Nov;4 6 184653 .
24 - M. Iijima, T. Muguruma, W. A. Brantley, T. Yuasa, J. Uechi, I. Mizoguchi, Effect of mechanical properties of fillers on the grindability of composite resin adhesives.
25 - J. Am, Dentofacial. Orthod, Orthop, 2010 Oct;138 4 4206 .
26 - S. Urapepon, H. Ogura, Metal-resin composite restorative material using powder-liquid system.Dent Mater 1999 1999 Sep;18 3 27894
27 - K. Kakuta, S. Urapepon, Y. Miyagawa, H. Ogura, C. Suchatlampong, A. Rittapai, Development of metal-resin composite restorative materia. Part 1. Experimental composite using silver-tin alloy as filler and 4 as coupling agent. Dent Mater J. 1999 Mar;18 1 110 .
28 - S. Urapepon, K. Kakuta, Y. Miyagawa, H. Ogura, C. Suchatlampong, A. Rittapai, of. Development, composite. metal-resin, material. restorative, Part 2. Effects of acid and heat treatments of silver-tin filler particles on flexural properties of metal-resin composite.Dent Mater 1999 1999 Jun;18 2 14454 .
29 - S. Urapepon, K. Kakuta, H. Ogura, C. Suchatlampong, A. Rittapai, Development of metal-resin composite restorative material. Part 3. Flexural properties and condensability of metal-resin composite using Ag-Sn irregular particles.Dent Mater 2000 2000 Jun;19 2 18695 .
30 - K. Kakuta, S. Urapepon, Y. Miyagawa, H. Ogura, M. Yamanaka, C. Suchatlampong, A. Rittapai, of. Development, composite. metal-resin, material. restorative, Part 4. Flexural strength and flexural modulus of metal-resin composite using Ag-In alloy particles as filler. Dent Mater 2002 2002 Jun;21 2 18190
31 - S. Urapepon, K. Kakuta, H. Ogura, of. Development, composite. metal-resin, material. restorative, Part 5: Evaluation of the bonding between Ag-Sn particle and 4 coupling agent of the metal-resin composite.Dent Mater J. 2003 Jun;22 2 13745 .
32 - H. Soma, Y. Miyagawa, H. Ogura, Setting, properties. flexural, metal-resin. of, using. composite, particles. Ag-Cu, as filler, accelerator. chemical, Dent Mater 2003 2003 Dec;22 4 54355 .
33 - Y. Tanimoto, T. Nishiwaki, K. Nemoto, G. Ben, of. Effect, content. filler, bending. on, of. properties, composites. dental, simulation. numerical, the. with, of. use, finite-element. the, method, J Biomed Mater Res B Appl Biomater. 2004Oc Oct 15;71 1 18895 .
34 - Antonucci JM, Liu DW, Skrtic D.Amorphous Calcium Phosphate Based Composites: Effect of Surfactants and Poly(ethylene oxide) on Filler and Composite Properties. J Dispers Sci Technol. 5 28 819824 2007
35 - M. Okazaki, H. Ohmae, Mechanical and biological properties of apatite composite resins.Biomaterials. 1988 Jul;9 4 3458 .
36 - Khaled SM, Miron RJ, Hamilton DW, Charpentier PA, Rizkalla AS.Reinforcement of resin based cement with titania nanotubes.. Dent Mater. 2010 Feb;26 2 16978 .
37 - Germain. H. St, M. L. Swartz, R. W. Phillips, B. K. Moore, T. A. Roberts, of. Properties, composite. microfilled, as influenced. resins, filler. by, content, J Dent Res. 1985 Feb;64 2 15560 .
38 - Braga RR, Cesar PF, Gonzaga CC. Mechanical properties of resin cements with different activation modes. J Oral Rehabil. 2002 Mar;29 3 25762 .
39 - K. Fujii, H. Arikawa, T. Kanie, T. Hamano, Y. Nishi, E. Nagaoka, viscoelastic. Dynamic, of. properties, glass-fibre. commercial, resin. reinforced, for. used, crowns, J. bridges, Rehabil. Oral, 2002 Sep;29 9 82734
40 - N. Tanoue, A. Mikami, M. Atsuta, H. Matsumura, of. Effects, composition. monomer, filler. original, on. content, loading. filler, the. in, centrifuged. resulting, Dent. composites, Mater, 2007 2007 Jul;26 4 5015 .
41 - Yap AU, Lye KW, Sau CW. Surface characteristics of tooth-colored restoratives polished utilizing different polishing systems.Oper Dent. 1997 Nov-Dec;22 6 2605 .
42 - H. H. Xu, J. L. Moreau, L. Sun, L. C. Chow, Strength and fluoride release characteristics of a calcium fluoride based dental nanocomposite. Biomaterials. 2008 Nov;29 32 42617 .
43 - Anusavice KJ, Zhang NZ, Shen C..Effect 2 CaF2 content on rate of fluoride release from filled resins.. J Dent Res. 2005 May;84 5 4404
44 - H. H. Xu, J. L. Moreau, L. Sun, L. C. Chow, Ca Novel, 2 nanocomposite with high strength and fluoride ion release. J Dent Res. 2010 Jul;89 7 73945 .
45 - A. Okamoto, K. Sekiya, M. Fukushima, M. Iwaku, vivo. In, pattern. wear, experimental. of, hybrid. light-cured, resins. composite, Dent Mater 1993 1993 Dec;12 2 22532 .
46 - B. R. Lang, M. Jaarda, R. F. Wang, Filler particle size and composite resin classification systems. J Oral Rehabil. 1992 Nov;19 6 56984 .
47 - K. Sekiya, A. Okamoto, M. Fukushima, M. Iwaku, vivo. In, pattern. wear, experimental. of, resins. composite, different. containing, components. filler, Dent Mater 1994 1994 Jun;13 1 3646
48 - Lim BS, Ferracane JL, Condon JR, Adey JD.Effect of filler fraction and filler surface treatment on wear of microfilled composites. Dent Mater. 2002 Jan;18 1 111 .
49 - S. Yuasa, Influences of composition on brush wear of composite resins. Influences of particle size and content of filler. Shika Zairyo Kikai. 1990 Jul;9 4 65978
50 - Frazier KB, Rueggeberg FA, Mettenburg DJ. J Esthet Comparison of wear-resistance of Class V restorative materials.Dent. 1998;10(6):309-14.
51 - Munoz-Viveros CA. An advance in condensable composites. Compend Contin Educ Dent Suppl. 35 1999
52 - Nunes TG, Pereira SG, Kalachandra S.Effect of treated filler loading on the photopolymerization inhibition and shrinkage of a dimethacrylate matrix. J Mater Sci Mater Med. 2008 May;19 5 18819 .
53 - J. Leprince, W. M. Palin, T. Mullier, J. Devaux, J. Vreven, G. Leloup, Investigating filler morphology and mechanical properties of new low-shrinkage resin composite types.J Oral Rehabil. 2010Ma May
54 - Razak AA, Harrison A.The effect of filler content and processing variables on dimensional accuracy of experimental composite inlay material. J Prosthet Dent. 1997 Apr;77 4 3538 .
55 - F. Gonçalves, Y. Kawano, R. R. Braga, stress. Contraction, to. related, inorganic. composite, Dent. content, Mater, 2010 Jul;26 7 7049 .
56 - Poss SD. Using a new condensable composite for posterior restorations.Compend Contin Educ Dent Suppl. 148 1999
57 - D. F. Taylor, S. Kalachandra, M. Sankarapandian, J. E. Mc Grath, between. Relationship, filler, resin. matrix, characteristics, properties. the, uncured. of, pastes. composite, Biomaterials, 1998 Jan-Feb;19(1-3):197-204.
58 - 2009I. Ikeda, M. Otsuki, A. Sadr, T. Nomura, R. Kishikawa, J. Tagami, Effect of filler content of flowable composites on resin-cavity interface. Dent Mater J. 2009 Nov;28 6 67985 .
59 - W. Yukitani, T. Hasegawa, K. Itoh, H. Hisamitsu, S. Wakumoto, adaptation. Marginal, dental. of, containing. composites, filler. prepolymerized, Dent. Oper, 1997 Nov-Dec;22 6 2428 .
60 - A. Ellakwa, N. Cho, I. B. Lee, effect. The, resin. of, composition. matrix, the. on, shrinkage. polymerization, properties. rheological, experimental. of, composites. dental, Dent Mater. 2007 Oct;23 10 122935 .
61 - E. Asmussen, A. Peutzfeldt, of. Influence, on. composition, of. rate, contraction. polymerization, light-curing. of, composites. resin, Acta Odontol Scand. 2002 Jun;60 3 14650 .
62 - S. Rüttermann, I. Dluzhevskaya, C. Grosssteinbeck, W. H. Raab, R. Janda, of. Impact, Bis. replacing-G, M. A. , T. E. G. D. M. A. by, commercially. other, monomers. available, the. on, of. properties, composites. resin-based, Dent Mater. 2010 Apr;26 4 3539 .
63 - N. Azzopardi, K. Moharamzadeh, D. J. Wood, N. Martin, R. van Noort, Effect of resin matrix composition on the translucency of experimental dental composite resins. Dent Mater. 2009 Dec;25 12 15648 .
64 - H. Urabe, Y. Nomura, K. Shirai, M. Yoshioka, H. Shintani, of. Effect, content. filler, to. size, of. properties, resins. composite, microwave. on, curing, J Mater Sci Mater Med. 1999 Jun;10 6 3758 .
65 - Campbell PM, Johnston WM, O’Brien WJ Light scattering and gloss of an experimental quartz-filled composite. J Dent Res. 1986 Jun;65 6 8924
66 - Y. Yoshida, K. Shirai, H. Shintani, M. Okazaki, K. Suzuki, B. Van Meerbeek, Effect of presilanization filler decontamination on aesthetics and degradation resistance of resin composites. Dent Mater 2002 2002 Dec;21 4 38395
67 - S. Imamura, H. Takahashi, I. Hayakawa, P. G. Loyaga-Rendon, S. Minakuchi, Effect of filler type and polishing on the discoloration of composite resin artificial teeth. Dent Mater 2008 2008 Nov;27 6 8028 .
68 - Lee YK. Influence of scattering/absorption characteristics on the color of resin composites. Dent Mater. 2007 Jan;23 1 12431 .
69 - B. Yu, J. S. Ahn, J. I. Lim, Y. K. Lee, Influence, 2 TiO2 nanoparticles on the optical properties of resin composites. Dent Mater. 2009 Sep;25 9 11427
70 - Chirdon WM, O’Brien WJ, Robertson RE. Diffuse reflectance of short-fiber-reinforced composites aligned by an electric field. Dent Mater. 2006 Jan;22 1 5762 .
71 - T. Nakamura, O. Saito, M. Mizuno, H. Tanaka, Changes in translucency and color of particulate filler composite resins. Int J Prosthodont. 2002 Sep-Oct;15 5 4949 .
72 - Lee YK. Influence of filler on the difference between the transmitted and reflected colors of experimental resin composites. Dent Mater. 2008 Sep;24 9 12437 .
73 - B. Howard, N. D. Wilson, S. M. Newman, C. S. Pfeifer, J. W. Stansbury, between. Relationships, temperature. conversion, properties. optical, composite. during, photopolymerization, Acta Biomater.2010 Jun;6 6 20539 .
74 - A. C. Shortall, W. M. Palin, P. Burtscher, Refractive index mismatch and monomer reactivity influence composite curing depth. J Dent Res. 2008 Jan;87 1 848 .