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OUTLINE
• The FEA of the 3.5 mm Bicon Implant-Abutment-Bone system under central occlusal loads
• Mechanics of the Tapered Interference Fit in a 3.5 mm Bicon Implant
WHAT IS A DENTAL IMPLANT?
Dental implant is an artificial titanium fixture (similar to those used in orthopedics)
which is placed surgically into the jaw bone to substitute for a missing tooth and its root(s).
Surgical Procedure
STEP 1: INITIAL SURGERY
STEP 2: OSSEOINTEGRATION PERIOD STEP 3: ABUTMENT CONNECTION STEP 4: FINAL PROSTHETIC RESTORATION
Success Rateslower jaw, front – 90 – 95%lower jaw, back – 85 – 90%upper jaw, front – 85 – 95%upper jaw, back – 65 – 85%
History of Dental Implants
In 1952, Professor Per-Ingvar Branemark, a Swedish surgeon, while conducting research
into the healing patterns of bone tissue, accidentally discovered that when pure titanium comes into direct contact with the living bone
tissue, the two literally grow together to form a permanent biological adhesion. He named this
phenomenon "osseointegration".
First Implant Design by Branemark
All the implant designs are obtained by themodification of existing designs.
John Brunski
Com
pari
son
of I
mpl
ant S
yste
ms
Astra Tech.
ITI
Bicon
OUTLINE
• The FEA of the 3.5 mm Bicon Implant-Abutment-Bone system under central occlusal loads
• Mechanics of the Tapered Interference Fit in a 3.5 mm Bicon Implant
The FEA of the 3.5 mm BiconImplant-Abutment-Bone system under
central occlusal loads
Assumptions:
• Analyses were linear, static and assumed that materials were elastic, isotropic and homogenous.
• 100% osseointegration is assumed between bone and implant. Bone and implant are assumed to be perfectly bonded.
• The stresses in the bone due to the interference fit betweenimplant and abutment is assumed to be relaxed after the insertion of the abutment.
Finite Element Model
29117 Solid 45 Brick Elements (32000 limit)
Symmetry boundary conditions on two cross-sections
and fixed in all dofs from the bottom of the bone.
V
H
RESULTS
Effect of bone’s elastic modulus on the overall stress distribution: Different finite element analyses are run by varying bone mechanical properties surrounding the implant. (1-16 GPa)
The properties of the bone depends on the location in the jaw, the gender and age of the patient.
Force: Vertical 100 N Bone Modulus: 16 GPa
Force: Vertical 100 N Bone Modulus: 1 GPa
Force: Lateral 20 N Bone Modulus: 16 GPa
Force: Lateral 20 N Bone Modulus: 1 GPa
• Both the stress distribution and the stress levels are effected significantly as the bone modulus is varied.• CT scan data may be a good source for obtainingpatient dependent implant designs.
Maximum vertical and lateral load carrying capacity ofthe bone: The failure limit of the bone due to fatigue is 29 MPa. [Evans et al.]
Force: Vertical 920 N Bone Modulus: 10 GPa
Force: Lateral 40 N Bone Modulus: 10 GPa
Lateral loads cause approximately 25 times higher stresses in the bone than the vertical loads.
OUTLINE
• The FEA of the 3.5 mm Bicon Implant-Abutment-Bone system under central occlusal loads
• Mechanics of the Tapered Interference Fit in a 3.5 mm Bicon Implant
Mechanics of the Tapered Interference Fitin a 3.5 mm Bicon Implant
Perfectly elastic large displacement non-linear contact finite element analysis for different insertion depths.
Elastic-plastic large displacement non-linear contactfinite element analysis for different insertion depths.
Different implant-abutment assemblies are performedfor 0.002”, 0.004”, 0.006”, 0.008” and 0.010” insertiondepths.
Axisymmetric model is used.
100% osseointegration is assumed between bone and implant. Bone and implant are assumed to be perfectly bonded.
Bone is assumed to be elastic, isotropic and homogenouswith a Young’s modulus of 10 GPa.
Finite Element Model
Perfectly elastic large displacement non-linear contact finite element analysis for different
insertion depths.
Perfectly Elastic Finite Element Results
0
50000
100000
150000
200000
250000
300000
350000
400000
450000
500000
0.47 0.49 0.51 0.53 0.55 0.57 0.59Vertical Position
Co
nta
ct
Pre
ss
ure
(P
) p
si
Interference depth: 0.002 in
Interference depth: 0.004 in
Interference depth: 0.006 in
Contact pressure increases linearly with insertion depth.
After 0.004” insertion depth, it is seen that plastic deformation occurs in the implant.
An elastic-plastic model is needed.
Yield Strength of Ti-6Al-4V 139,236 Psi
Elastic-plastic large displacement non-linear contact finite element analysis for different
insertion depths
Stress(MPA)
% Strain
Bilinear Isotropic Hardening Model
Contact Pressure Distribution for Different Insertion Depths
Elastic-Plastic Finite Element Results
0
50000
100000
150000
200000
250000
300000
0.45 0.47 0.49 0.51 0.53 0.55 0.57 0.59Vertical Position
Co
nta
ct
Pre
ss
ure
(P
) p
si
Interference depth: 0.004 in
Interference depth: 0.006 in
Interference depth: 0.008 in
Interference depth: 0.010 in
Contact pressure increases non-linearly with largerinsertion depths.
Von
Mis
es S
tres
s D
istr
ibut
ion
in th
e Im
plan
tYield Strength of Ti-6Al-4V 139,236 Psi
Von
Mis
es S
tres
s D
istr
ibut
ion
in th
e B
one
Yield Strength of Bone 8,702 Psi
FUTURE WORK
Comparison of different implant designs in terms of stress distribution in the bone due to occlusal loads.
Modeling non-homogenous bone material properties by incorporating with CT scan data.
Comparison of different implant-abutment interfaces