Toughening and Reduction of Shrinkage Polymerization of

Dental Nano Composites

Presented ByErlich Itay - I.D 011189255

&Asaf Faran - I.D 040836066

SupervisorsProf. Hanna Dodiuk, Shenkar CollegeEngineer Kira Lizenboin, BJM Labs.

July 2008

The aim of the study

• Improving Mechanical properties

• Reduction of Polymerization Shrinkage

• Improving Fracture Toughness

Fracture or decay can cause a portion of a tooth to break off, and in some cases, there’s simply not enough tooth left to place a crown.

Fortunately, we can replace the missing portion and save the tooth by building it up with one of the new resin/plastic filling materials.

Once the tooth is built up, we can place a crown.

Polymer Based Dental Restoratives

• The Dental composite is a mixture consists of an organic matrix and inorganic fillers.

• High molecular weight dimethacrylate monomers are used as the matrix phase of dental restorative composites, because of their higher strength and lower polymerization shrinkage.

Base Part Catalyst Part

BisGMA-TEGDMA

Advantages of Polymer Based Restoratives

• Efficient Curing at R.T. in 1-5 min

• Good Handling Properties

• Better Biocompatibility

• Better Esthetics

Disadvantages

• Polymerization Shrinkage

• Shrinkage stress and strain – cause micro defects/cracks Fracture

• High Wear Rates Compared to Amalgam

• Water Sorption

Stress From Shrinkage

Nanocomposites

• Increase Toughness and Strength

• Reduce Polymerization Shrinkage

• Improve Wear Properties

Cyclic compounds possess higher densities than their linear counterparts because they are able to arrange themselves in an orderly and close fit manner in the liquid state.

Shrinkage Reduction by Ring-Opening Polymerization of Cyclic Monomers - according to Bailey's concept

Fracture Toughness measurement

•Not suitable to standard measurements•Impossible to notch•Difficulties in polymerization of big specimens

Shrinkage measurement

•Lack of pre and post – polymerization contraction device•Low viscosity of the unfilled resin•Formation of air bubbles that decreased the accuracy measurement

Measurements Problems

Measurements

• Compressive Strength (ISO 9917)

• Flexural Strength (ISO 4049)

• Impact Strength (ISO 179)

•AFM

Work Process

•Effect on the Unfilled Resin (matrix)

•Effect on the Filled Resin (matrix+filler)

Adding ofNano EpoxyCyclohexyl

POSS

Problems using nano-EpoxyCyclohexyl

•EpoxyCyclohexyl POSS tends to agglomerate at room temperature, in the unfilled resin mixture.

•EpoxyCyclohexyl POSS has low handling properties in lab conditions. Furthermore it does not suit any industrial process.

•The results adding the EpoxyCyclohexyl were inconclusive.

Inconclusive results of mechanical properties (Unfilled Resin)

CS test - EpoxyCyclohexyl POSS

0

50

100

150

200

250

0 0.5 1 3 5

nano POSS content [%]

Str

ess [

MP

a]

Stress at Rupture(mean) [Mpa]

Stress at Max Load(mean) [Mpa]

FS test - EpoxyCyclohexyl

0

50

100

150

200

0 0.5 1 3 5

nano POSS content [%]

Str

ess

[MP

a]

Max Bending Stress atMax Load(mean) [Mpa]

Graph 9.2.1.1, CS Test – EpoxyCyclohexyl POSS/Unfilled Resin

Graph 9.2.1.2, FS Test – EpoxyCyclohexyl POSS/Unfilled Resin

Adding of Nano Glycidyl POSS

to Unfilled Resin

Improving of mechanical properties(Unfilled Resin)

CS test - Glycidyl POSS

0

50

100

150

200

250

300

0 0.5 1 3 5

nano POSS content [%]

Str

ess

[MP

a]Stress at Rupture(mean) [Mpa]

Stress at Max Load(mean) [Mpa]

FS test - Glycidyl POSS

0

50

100

150

200

250

300

0 0.5 1 3 5

nano POSS content

Str

ess

[Mp

a]

Max Bending Stress atMax Load (mean) [Mpa]

Graph 9.1.1.1, CS Test – Glycidyl POSS/Unfilled Resin

Graph 9.1.1.2, FS Test – Glycidyl POSS/Unfilled Resin

Improving of mechanical properties (Unfilled Resin)

Impact test - Glycidyl POSS

0

2

4

6

8

10

12

14

0 0.5 1 3 5

nano PSS content [%]

Re

sil

ien

ce

[K

J/m

^2

]

Resilience (mean)[KJ/m²]

Matrix's Rms Rough Comparison

0

5

10

0.5 1 3 5

Glycidyl nano content [%]

Rq [n

m]

Rms Rough (Rq)

Graph 9.1.1.3.1, Impact Test – Glycidyl POSS/Unfilled Resin

Graphe 9.1.1.4.1, Rms Rough comparison (AFM test),Glycidyl POSS/Unfilled Resin

Adding of Nano Glycidyl POSS

to Filled Resin

Un-improvement of mechanical properties (Filled Resin)

CS test - Glycidyl POSS/Filled Resin

0

50

100

150

200

250

0 1from resin 1from all

nano content [%]

Str

ess

[MP

a]Stresss at Max Load(mean)

Stress at Rupture(mean)

FS test - Glycidyl POSS/Filled Resin

0

50

100

150

200

0 1from resin 1from all

nano content [%]

Str

ess

[MP

a]

Max Bending Stress atMax Load (mean)

Graph 9.1.2.1.1/2, CS Test – Glycidyl POSS/Filled Resin (Matrix+Filler)

Graph 9.1.2.2.1/2, FS Test – Glycidyl POSS/Filled Resin

Conclusion

•EpoxyCyclohexyl POSS tends to agglomerate at room temperature, and has low handling properties in lab conditions. Furthermore it does not suit any industrial process.

•Addition of 1% Glycidyl POSS to the unfilled resin improved by 3 times the CS and 1.5 times the FS compared to the neat unfilled resin, as a result of reacting with the matrix.

•Addition of 3%wt. Glycidyl POSS improved by 2 times the Impact strength in comparison to the neat unfilled resin.

•Rms roughness of the unfilled resin increased with the addition of Glycidyl POSS content till 3%wt and decreased above 3%.

•Addition of Glycidyl POSS to the filled resin (matrix and fillers) doesn't improve the mechanical properties and even gives a small decrease in FS. The filler prevents from the nano to react with the matrix.

Conclusion

End

Thank you for listening!

11. Reference[1] B W Darvell. Materials Science for Dentistry. 8th edition, B D Darvell 2006.[2] Shalaby W. Shalaby, Ulrich salz. Polymwrs for Dental and Orthopedic Applications. Chpter 2, pg. 13-66. [3]Mohamad Atai, David C. Watts, Zahra Atai. Shrinkage straun-rates of dental resin-monomer and composite system, Biomaterials 26 (2005) 5015-5020.[4]Asmussen E, Peutzfeldt A. Influence of UEDMA, BisGMA and TEGDMA on selected mechanical properties of experimental resin composites. Dent Mater 6 (1998) 15-51.[5] C. L Davidson and A. J. Feilzer, polymerization shrinkage and polymerization shrinkage stress in polymer-based restoratives. Journal of Dentistry, Vol. 25, pp. 435-440, 1997.[6] Van Noort R. Intruduction to dental materials. 2nd ed. Mosby 2002, chapter 1.6 pag. 33-42.[7] Gustavo Arenas, Sergio Noriega, Claudia Vallo, Ricardo Duchowicz. Polymerization shrinkage of a dental resin composite determined by a fiber optic Fizeau interferometer. Optics Communications Vol. 271, pp 581-586, 2007. [8] Jeffrey W. Stansbury, Marianela Trujillo-Lemon, Hui Lu, Xingzhe Ding, Yan Lin, Junhao Ge. Conversion-dependents shrinkage strass and strain in dental resins and composites. Dental Materials. Vol. 21, pp. 56-67, 2005.[9] Hui Lu, Jeffery W. Stansbury, Christopher N. Bowman. Towards the elucidation of stress development and relaxation in dental composite. Dental Materials, Vol. 20, pp. 979-96, 2004.[10] W.D. Cook, M. Forrest, A.A. Goodwin. A simple method for measurement of polymerization shrinkage in dental composites, Dental Matirial, 15, 1999, 447-449.[11] Magali Dewaele, Delphine Truffier-Boutry, Jacques Devaux, Gaetane Leloup. Volume contraction in photocured dental resus. Dental Materials, Vol. 22, pp. 359-365, 2006.[12] Bergenholtz G. Evidence for bacterial causation of adverse pulpal responses in resin-based dental restorations. Crit Rev Oral Biol Med, Vol. 11, pp. 467-480, 2000.[13] http://plc.cwru.edu/[14] Kenneth J. Anusavice, Science of Dental Materials, 11th edition, by Philips', Chapter 7, Pg. 143-167.[15] Hao Fong, Sabine H. Dickens, Glenn M. Flaim, Evaluation of Dental restorative composites containing polyhedral oligomeric silsesquioxane methacrylate, Dental Matirials, 21, 2005, 520-529.[16] Rees JS, Jacobsen PH. The polymerization shrinkage of composite resins. Dent mater. 1989;5:41-44.[17] de Gee AF, Feilzer AJ, Davidson CL. True linear polymerization shrinkage of unfilled resins and composites determined with a linometer. Dent mater, 1993, 9, 11-14.[18] Watts DC, ash AJ.Determination of polymerization shrinkage kinetics in visible-light-cured materials: methods development. Dent mater,1991,7,281-287.[19] Bandyopadhyay S. study of volumetric setting shrinkage of some dental materials. J Biomed Mater Res, 1982, 16, 135-144. [20] Patel, M.P., Braden M. and Davy K. W. M. Polymerization shrinkage of methacrylate esters. Biomaterials, 1978, 8, 53-56. [21] Pucket, A. D. and Smith, R., Method to measure the polymerization shrinkage of light-cured composites. Journal of Prosthetic Dentistry, 1992, 68. 57-58.[22] Attin, T., Buchalla, W., Kielbassa, A. M. and Helwig, E., Curing shrinkage and volumetric changes of resin-modified glass ionomer restorative materials, Dental Materials, 1995, 11, 359-362.[23] Munksgaard, E. C., Hansen, E. K. and kato, H., Wall to wall polymerization contraction of composite resins versus filler content. Scandinavian Journal of dental research, 1987, 95, 526-531.[24] Grajower, R. and Guelmann, M., Dimensional changes during setting of a glass ionomer filling material. Quintes-sence international, 1989, 20, 505-511.[25] Feilzer, A. J., De Gee, A. J. and Davidson, C. L., Increased wall-to-wall curing contraction in thin bonded resin layers. Journal of Dental Research, 1989, 68, 48-50.[26] Peter J. Schudel, Mochael S. Johnson, Nicholas A. Warrior, Chris D. Rudd, Characterisation of thermoset laminates for cosmetic automotive applications: Part 3 – Shrinkage control via nanoscale reinforcement.[27]M.S. So, A.Yap, and A. Sellinger,Post-gel Polymerization Shrinkage of Novel Low-shrinkage POSS Based Nanocomposites,Dental Materials,V 1, Seq #62. [28] Mohammad Atai and Dvid C. Watts, A new kinetic model for the photopolymerization shrinkage-strain of dental composites and resin-monomers, Dental Materiald, 2006, 22, 785-791.

[29] Hargreaves AS. The prevalence of fractured dentures: a survey. Br Dent J 1969;126:451–5.[30] K.S. Chan, Y.-D. Lee , D.P. Nicolella , B.R. Furman , S. Wellinghoff, R. Rawls. Improving fracture toughness of dental nanocomposites by interface engineering and micromechanics. Engineering Fracture Mechanics 74 (2007) 1857–1871.[31] Faber KT, Evans AG. Crack deflection processes – theory. Acta Metall 1983;31:565–76.[32] Suresh S. Fatigue crack deflection and fracture surface contact: micromechanical models. Metall Trans A 1985;16A:249 60.[33] Venkateswara Rao KT, Soboyejo WO, Ritchie RO. Ductile-phase toughening and fatigue-crack growth in nb-reinforced molybdenum disilicide intermetallic composites. Metall Trans A 1992;23A:2249–57.[34] Bower AF, Ortiz M. A Three-dimensional analysis of crack trapping and bridging by tough particles. J Mech Phys Solids1991;39:815–58.[35] B. B. Johansen, A.J. Kinloch, R.D. Mohammed, A. C. Taylor, S. Sprenger. Toughening mechanisms of nanoparticle-modified epoxy polymers. Polymer 48 (2007) 530-541.[36] Paul Franklin*, David J. Wood, Nigel L. Bubb. Reinforcement of poly(methyl methacrylate)denture base with glass flake. Dental Materials (2005) 21, 365–370.[37] Hill RG, Bates JF, Lewis TT, Rees N. Fracture toughness ofacrylic denture base. Biomaterials 1983;4:112–20.[38] Tamer A. Hamza, BDS, MS, Stephen F. Rosenstile, BDS, MSD, Mohamed M. Ibraheem, BDS, MS, PhD, J Prosthet Dent 2004, 91, 258-264.[39] D.E. Ruddell, M.M. Maloney, J.Y. Thompson, Effect of novel particles on the mechanical and wear properties of dental composites, Dental materials, 2002, 18, 72-80.[40] Chantikul P, Anstis GR, Lawn BR, Marshall DB. A critical evaluation of indentation technique for measuring fracture toughness: 2. Strength method. J Amer.[41] Nano-structured Dental Composite Restorative Materials, published by MIDCR, 2004.[42] Liqun Xu, L. James Lee, Effect of nanoclay on shrinkage control of low profile unsaturated polyester resin cured at room temperature, Polymer Journal 45, 2004, 7325-7334.[43] Kristen S. Wilson, Joseph M. Antonucci, Interphase structure-property relationships in thermoset dimethacrylate nanocomposites, Dental Materials, 22, 2006, 995-1001.[44] B. Akbari, R. Bagheri, “Deformation mechanism of epoxy/clay nanocomposite”, European Polymer Journal 43 (2007) 782–788.[45] A.J. Brunner, A. Necola, M. Rees, Ph. Gasser, X. Kornmann, R. Thomann, M. Barbezat, “The influence of silicate-based nano-filler on the fracture tougheness of epoxy resin”, Engineering Fracture Mechanics, 73 (2006) 2336–2345.[46] A.J. Kinloch, B.B Johnsen, R.D Mohammed, A.C Taylor and S. Sprenger “Toughening mechanisms of nanoparticle-modified epoxy polymer”, proceedings of the adhesion society.inc, issn 1086-9506,2007, 340-342. [47] Xiaohua Zhang, Weijian Xu, Xinnian Xia, Zhenghua Zhang, Renqi Yu, “Toughenning of cycloaliphatic epoxy resin by nanosize silicon dioxide”, Materials Letters 60 (2006) 3319–3323.[48] Lei Wang, Ke Wang, Ling Chen, Yongwei Zhang, Chaobin He, “Preparatio, morphology and thermal/mechanical properties of epoxy/nanoclay composite”, Composites: Part A 37 (2006) 1890–1896.[49] H. Dodiuk-Kenig, K. Lizenboim, I. Eooelbaum, B. Zalsman and S. Kenig, The effect of hyper-branched polymers on the properties of dentak composites and adhesives, J. Adhesion Sci. Technol., 2004, Vol. 18, No. 15-16, 1723-1737.[50] H. Dodiuk-Kenig, Y. Maoz, K. Lizenboim, I. Eppelbaum, B. Zalsman and S. Kenig, The effect of grafted caged silica (polyhedral oligomeric silesquioxanes) on the properties of dental composites and adhesives, J. Adhesion Sci. Technol. 2006, Vol. 20, No. 12, pp. 1401-1412.[51] H. Dodiuk-Kenig, K. Lizenboim, S. Roth, B. Zalsman, W.A. McHale and M. Jaffe, Performance Enhancement of Dental Composites by Tailoring Nanostructure, Shenkar College for Engineering and Design, BJM Lab. Ltd., Premier Dental Products Company and New Jersey Institute of Technology. Department of Biomedical Engimeering.

Q-CORE Core Build-Up Material

TECHNICAL DATA

--550,000 – 600,000 cpViscosity, 1 rpm

> 100 %Al4049400 %AlRadiopacity

< 42o C26 ºCExotherm Temperature

< 10 min.40494:30 minSetting Time @ 37ºC

> 90 sec.40492:00 minWorking Time @ 22ºC

-40498.5

Depth of Cure [mm] Irradiation by Astralis 9 (Ivoclar-Vivadent) - Dental

Halogen Lamp – for 40 sec

-40494.6

Depth of Cure [mm] Irradiation by Demetron (Kerr) – Dental LED Lamp

– for 20 sec.

√-YesCompatible with LED

√-YesCompatible with Plasma ark light

lamp

√-YesCompatible with halogen light

> 80-90Hardness by Techlock Durometer

GS-709N, Type A

< 40.0 µg/mm34049< 40.0 µg/mm3Water Sorption

< 7.5 µg/mm34049< 7.5 µg/mm3Solubility

> 80 MPa4049214 MPaFlexural strength

> 100 MPa9917200 MPaCompressive Strength

ISO Standard Requirements

ISO Standard Reference No.

ValueMaterial’s Property