LABORATORY OF BIOLOGICAL STRUCTURE MECHANICS INSTITUTE OF HIGH PERFORMANCE COMPUTING - Singapore...

LABORATORY OF BIOLOGICAL STRUCTURE MECHANICS

www.labsmech.polimi.it

INSTITUTE OF HIGH PERFORMANCE COMPUTING - Singapore

Meditech Meeting on:

“Innovations in Materials and Manufacturing of Dental Devices”

Cardiff MediCentre, 29th March 2007

Thermal-mechanical reliability of Ti/HAp-based endosseous dental implant in severe conditions of Bruxism

Giuseppe Cevola

2

Giuseppe Cevola 29/03/07

Outline

• Introduction

• 3D FEM Modelling

mandibular bone

FGMs (Functionally Graded Materials) endosseous dental implant

• Mechanical loading conditions

occlusive loading

bruxism loading

• FGMs composition’s parametric studying

• Thermal-mechanical Studying & Bruxism conditions

• Conclusions and future developments

3


Bruxism is a disorder of the masticatory

system characterized by teeth grinding

and clenching

Bruxism is considered

• aetiological factor for temporomandibular disorders (TMD)• tooth wear (attrition)• loss of periodontal support • failure of dental restorations

Introduction

4


Introduction

The most common current dental implants are:

ENDOSSEOUS Sub-PERIOSTEAL

5


Endosseous dental implant performance requirements:

• biocompatibility: osteointegration

• thermal/mechanical reliability: residual stress due to

production (Hot Isostatic Pressing, Spark Sintering)

Introduction

6


The success of the endosseous dental implant integration is due to:• Lack of clinical signs and symptoms of pathology• Lack of mobility

• Radiographically stable interface

Introduction

Adaptive capacity: load-bearing biological structures that bond with bone

• Dynamic Modeling process

• Remodeling process

Clark M. Stanford

Biomechanical and functional behavior of implants

Adv Dent Res 13:88-92, June, 1999

Radiographically stable interface

7


Used Materials

Groundbreaking dental implants are designed using Functionally

Graded Materials (FGM’s) made of Ti/HAp – Graduality along vertical

direction:

• Titanium and its alloys• Bioceramics : Hydroxyapatite (HAp) as coating, Zirconia

• Titanium: upper part (occlusive loading)• HAp: lower part (bone contact)

Introduction

8


Outline

• Introduction


mandibular bone



occlusive loading

bruxism loading


• Thermal-mechanical studying & Bruxism conditions


9


3D FEM models

Mandibular bone segment (35.25 mm) FGM’s endosseous dental implant

(first lower molar)

obtained by

Computed Tomography (CT) images

of Human mandibular bone

Computed Tomography (CT) images

of Titanium dental implant (Bioform®)

Modelling

10


Mandible Computed Tomography image

Modelling

11


Modelling

Completed Model

The materials are supposed

isotropic with linear-elastic

behaviour Toparli M, Sasaki S. Finite element analysis of the temperature and thermal stress in a postrestored tooth.

J Oral Rehabil 2003;30:921–926.

12


Implant mechanical performances are evaluated by means peri-implant-bone stresses:• von Mises stress• First principal stress• Third principal stress

Higher peri-implant tensile and compressive stresses would imply:• implant-bone bond failure• bone absorption

Modelling

Buccal-Lingual

section

Mesial-Distal

section

S.C.Huang, C.F.Tsai

Finite element analysis of a dental implant

Biomedical Engineering-Applications, Basis & communications

Vol.15 No.2 April 2003

13


Outline

• Introduction


mandibular bone



occlusive loading

bruxism loading




14


TWENTY-SECOND BIENNIAL MEETING

7–10 June 2001, Lugano, Switzerland

Journal of Oral Rehabilitation 2002 29; 872–889 Upper and lower dental appliances containing miniaturestrain-gauge transducers.

Normal bilateral occlusive loading:

Molar region : 400-650 N

Premolar region : 222-445 N

Canine region : 133-334 N

Incisive region : 89-111 N

K.J. Anusavice, Phillips Science of Dental Materials,

W.B.Saunders Co., New York, (1996)

Molar region unilateral occlusive loading :

30% smaller than one obtained during

bilateral loading

Mechanical loading conditions:Experimental data

15


First lower molar

Bruxist bilateral clenching loading

molar region : 790 N

transversal force: 50 N

Journal of Oral Rehabilitation 2001 28; 485-491

K. Nishigawa Department of Fixed Prosthodontics, The University of Tokushima

School of Dentistry, Tokushima, Japan

Mechanical loading conditions:Experimental data

16


Outline

• Introduction


mandibular bone



occlusive loading

bruxism loading




17


m

h H

zHV

ht VV 1

Exponential law between composition and longitudinal coordinate

h = hydroxyapatite

t = titanium

FGMs composition’s parametric studying

HA Volumetric Fraction along the FGM Dental Implant

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 1 2 3 4 5 6 7 8 9 10 11 12 13

FGM Dental Implant Lenght [mm]

HA

Vo

lum

etr

ic F

rac

tio

n

m=0.1m=0.2m=0.5m=1m=2m=5m=10

Increasing value of Ti along the implant lenght

18


Outline

• Introduction


mandibular bone



occlusive loading

bruxism loading




19


Thermal-mechanical Studying

Changing temperature implant performances: ΔT = 0°CVon Mises, Mesial/Distal Section, DT=0

0.5

1.5

2.5

3.5

4.5

5.5

6.5

100500 100550 100600 100650

Nodes along M/D section

Vo

n M

ises

Str

ess

[MP

a]

Von Mises, Buccal Lingual Section, DT=0

0.5

1.5

2.5

3.5

4.5

5.5

6.5

100100 100120 100140 100160 100180 100200

Nodes along B/L section

Vo

n M

ises

Str

ess

[MP

a]

First Principal Stress, Mesial/Distal Section, DT=0

-3.5

-3

-2.5

-2

-1.5

-1

-0.5

0

0.5

1

100500 100520 100540 100560 100580 100600 100620 100640 100660


Firs

t Pri

ncip

al S

tres

s [M

Pa]

m=0.1 m=0.2 m=0.5 m=1 m=2 m=5 m=10 Ti

First Principal Stress, Buccal/Lingual section, DT=0

-3.5

-3

-2.5

-2

-1.5

-1

-0.5

0

0.5

1

1.5

100100 100120 100140 100160 100180 100200


Fis

rst

Pri

nc

ipa

l S

tre

ss

[Mp

a]

20



Third Principal Stress, Mesial/Distal Section, DT=0

-9

-8

-7

-6

-5

-4

-3

-2

-1

0

100500 100550 100600 100650


Th

ird

Pri

nc

ipal

Str

ess

[M

Pa

]

Third Principal Stress, Buccal/Lingual section, DT=0

-9

-8

-7

-6

-5

-4

-3

-2

-1

0

100100 100120 100140 100160 100180 100200

Nodes along B/L sectionT

hir

d P

rin

cip

al S

tres

s [M

Pa]

m=0.1 m=0.2 m=0.5 m=1 m=2 m=5 m=10 Ti

Changing temperature implant performances: ΔT = 0°C

21



Von Mises Stress, Buccal/Lingual Section, Occlusal Loading

1

2

3

4

5

6

7

8

9

10

100100 100110 100120 100130 100140 100150 100160 100170 100180 100190 100200


Vo

n M

ise

s S

tre

ss

[M

Pa

]

m_5_-20

m_5_+20

m_5_0

Von Mises Stress, Buccal Lingual Section, Occlusal Loading

1.5

2.5

3.5

4.5

5.5

6.5

7.5

8.5

9.5

100100 100110 100120 100130 100140 100150 100160 100170 100180 100190 100200


Vo

n M

ises

Str

ess

[MP

a]

m_2_+20

m_2_0

m_2_-20


1

2

3

4

5

6

7

8

100100 100110 100120 100130 100140 100150 100160 100170 100180 100190 100200


Vo

n M

ise

s S

tre

ss

[M

Pa

]

m_0.5_-20

m_0.5_0

m_0.5_+20


0

1

2

3

4

5

6

7

8

100100 100110 100120 100130 100140 100150 100160 100170 100180 100190 100200


Vo

n M

ise

s S

tre

ss

[M

Pa

] m_0.2_+20

m_0.2_0

m_0.2_-20

Changing temperature implant performances: ΔT= + 20°C and -20°C

22



First Principal Stress, Buccal/Lingual Section, Occlusal Loading

-3.00E+00

-2.00E+00

-1.00E+00

0.00E+00

1.00E+00

2.00E+00

3.00E+00

4.00E+00

5.00E+00

100100 100110 100120 100130 100140 100150 100160 100170 100180 100190 100200


Fir

st

Pri

nc

ipa

l Str

es

s [

MP

a]

m_5_-20

m_5_+20

m_5_0

Fisrt Principal Stress, Buccal Lingual Section, Occlusal Loading

-3.50E+00

-2.50E+00

-1.50E+00

-5.00E-01

5.00E-01

1.50E+00

2.50E+00

3.50E+00

4.50E+00

100100 100120 100140 100160 100180 100200


Fir

st P

rin

cip

al S

tres

s [M

Pa]

m_2_-20

m_2_0

m_+20

First Pricipal Stress, Buccal/Lingual Section, Occlusal Loading

-3.5

-2.5

-1.5

-0.5

0.5

1.5

2.5

3.5

100100 100110 100120 100130 100140 100150 100160 100170 100180 100190 100200


Fir

st

Pri

nc

ipa

l Str

es

s [

MP

a] m_0.5_+20

m_0.5_0

m_0.5_-20

First Principal Stress, Buccal/Lingual Section, Occlusal Loading

-4

-3

-2

-1

0

1

2

3

4

100100 100120 100140 100160 100180 100200


Fir

st P

rin

cip

al S

tres

s [M

Pa]

m_0.2_+20

m_0.2_0

m_0.2_-20

Changing temperature implant performances: ΔT= + 20°C and -20°C

23



Von Mises Stress, Implant Buccal/Lingual section, Bruxism

3

8

13

18

23

28

33

38

100100 100110 100120 100130 100140 100150 100160 100170 100180 100190 100200


Von

Mis

es S

tres

s [M

Pa]

m=0.2

m=0.5

m=2

Ti

Third Principal Stress, Implant Buccal/Lingual Section, Bruxism

-55

-45

-35

-25

-15

-5

100100 100110 100120 100130 100140 100150 100160 100170 100180 100190 100200


Thir

d Pr

inci

pal S

tres

s [M

Pa]

m=0.2

m=0.5

m=2

Ti

First Principal Stress, Implant Buccal/LingualSection, Bruxism

-18

-13

-8

-3

2

7

100100 100120 100140 100160 100180 100200


Fir

st P

rin

cip

al S

tres

s [M

Pa]

m=0.2

m=0.5

m=2

Ti

Bruxism Conditions: Clenching load & grinding force

24


Outline

• Introduction


mandibular bone



occlusive loading

bruxism loading




25


Conclusions and future developments

So far

m = 2 composition withstands the highest von Mises and first principal

stresses in all the implants, with temperature reduction of 20°C

In progress

On the basis of provided experimental data (K. NISHIGAWA School of Dentistry, Tokushima, Japan ) the bruxism behaviour is in progress

Future works

Would be desirable to carry-out fatigue analysis for the implant-bone bond

The residual stresses due to the technological processes can neglect the

hosting oral changing temperature effect?

26


Acknowledgment

• Dr. WANG Fang, PhD. Institute of High Performance Computing Singapore,

External Advisor

• Prof. Estevam Barbosa de Las Casas, Universidade Federal de Minas Gerais,

Belo Horizonte, BRASIL

• Prof. K. Nishigawa, School of Dentistry, Tokushima, Japan

• Prof. F. Lobbezoo, Department of Oral function, Academic Centre for Dentistry

Amsterdam (ACTA), Amsterdam, The Netherlands

Are gratefully acknowledged for their assistance and contributions

• Prof. Roberto Contro, Prof. of Biomechanics, Politecnico di Milano, Italy

• Prof. Pasquale Vena, Assoc. of Biomechanics, Politecnico di Milano, Italy

• Dr. Dario Gastaldi, PhD. of Material Engineering, Politecnico di Milano, Italy

Are also acknowledged for their kind assistance and useful discussions

27


Thank you!

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