juliana tms 2011

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J. Ivancik and D. Arola

Laboratory for Advance Materials and Processes (LAMP)

Department of Mechanical Engineering

University of Maryland Baltimore County

TMS 2011


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A

B

Enamel

Dentin

Pulp

1 mm

Peripheral dentin

A

1 m

B

Inner dentin

1 m

tubules

Dentin content (weight%)

70% mineral, 20% organic 10% fluid


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Giannini et al., Dent Mater, 2004.

61.6 16.3 MPa

48.7 16.7 MPa33.9 8 MPa

UTS

Iwamoto et al.,J Biomed Mater Res A, 2003.


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Arola et al., Biomaterials, 2007

Endurance limitAt 107 cycles (10 yrs);

=45 : e=53 MPa

=0 : e=44 MPa

=90 : e=23 MPa


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Demineralization*

Excavation**Pitt Ford, The Restoration of Teeth, 1992 Arola et al, J. Mat Sci.:Materials in Medicine, 1998

500 m

In an examination of 102 cracked teeth,only 5 were unrestored [Cameron,

1976].

Over 50% of teeth with failedrestorations show signs of fracture orcracking [White, 1996].

Restoration


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Develop further understanding of the structure -property relationships that contribute to the fatiguecrack growth behavior of dentin.

Establish the importance of tubule density on theresistance to fatigue crack initiation and rate ofincremental growth.


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3rd molars 17 age 72 years

2.0

4.0

2.0

1.0

a 1.0

6.0

All dimensions in mm


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time (s)

Pmax

Pmin

Load (N)

Fatigue loadsload controlR = Pmin/Pmax = 0.5, 0.110 < Pmax < 20 Nfrequency=5 Hz

ProtocolHBSS hydration bathmode I cyclic loadingmeasure crack length at Ni


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KP

B Wf

a

W

P

P

a4.0

Bajaj et al., Biomaterials, 2006.

Paris law parameters

Paris law (Region II)

High

Low


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10-8

10-7

10-6

10-5

0.0001

0.001

0.01

0.7 0.8 0.9 1 2

K (MPa.m0.5

)

da/dN(mm/cycle)

Fatigue crack growth within young human dentin

10-8

10-7

10-6

10-5

0.0001

0.001

0.01

0.7 0.8 0.9 1 2

innercentralperipheral

K (MPa.m0.5

)

da/dN(mm/cycle)

10-8

10-7

10-6

10-5

0.0001

0.001

0.01

0.7 0.8 0.9 1 2

inner

centralperipheral

K (MPa.m0.5

)

da/dN(mm/cycle)


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Location

Paris Law Parameters

mC

(mm/cycle).(MPa*m0.5)-m

Peripheral

(N=12)27.15 3.8d,e 1.78E-10a

Central

(N=12)24.8 3.2d 1.16E-07b

Inner(N=8)

29.1 4.7e 6.26E-05c

Means indicated by different letters are significantly different at p


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0.6

0.8

1.0

1.2

1.4

0 1x104 2x104 3x104 4x104 5x104 6x104

Lumen density/mm2

Kth(

MPa*m

0.5)

Image processing

Stress intensity thresholdvs. lumen density


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2.0

4.0

6.0

8.0

10.0

12.0

0 1x104

2x104

3x104

4x104

5x104

6x104

Lumen density/mm2

LogC(mm/cy

cles*MPa.m

0.5)-m

Fatigue crack growth coefficientvs. lumen density

Image processing


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100 m 50 m


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The FCG resistance of young dentin is dependent on thetubule density.

The effective crack growth rate for young dentin increasesfrom the superficial region to deep dentin. Cracks in deepdentin exhibit an incremental growth rate that is at least 1000times larger than that of peripheral dentin.

Cracks in deep dentin undergo initiation of fatigue crack

growth at a lower intensity range than those in superficialdentin. The stress intensity threshold of deep dentin is atleast 50% lower than that of superficial dentin.


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This work was made possible by a fellowship from theNational Institute for Dental and Craniofacial Research(T32DE07309-11).

The investigation was also supported by grant R01 DE016904

from the National Institute of Dental and CraniofacialResearch (Dwayne D. Arola, PI).

juliana tms 2011

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