Fem /certified fixed orthodontic courses by Indian dental academy

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INDIAN DENTAL ACADEMY
Leader in continuing dental education

NOBILITY IN THOUGHTS
BELIEF IN ACTION
AIMED IN THE RIGHT DIRECTION

INTRODUCTION TO THE FINITE ELEMENT
METHOD
---- DR. CHETAN JAYADE
ASST. PROF.
DEPARTMENT OF ORTHODONTICS
S.D.M. DENTAL COLLEGE

My involvement with FEM
FEM Course at B.V.B, Hubli
FEM Course at MSRSAS, Bangalore

Why the need for orthodontists to know about
FEM?
An increase in the scope for research
A need for basic understanding about the engineering
areas of application.

SCOPE OF THE TALK
•An overview of FEA and it’s increasing role in
research
• To understand the capabilities and the limitations
• The role of a clinician in a research study involving
FEA
•Studies in various branches of Medicine and
dentistry involving FEA

SCOPE OF THE TALK
•Usage of FEA in Orthodontics
•Sources of understanding FEA
•An introduction to Rapid Prototyping
•Uses of Rapid Prototyping in Dentistry

BIOMEDICAL ENGINEERING
An amalgamation of the medical and engineering
specialties
-- The human genome project
-- CAD/CAMand othercomputerised
application areas

BIOMEDICAL ENGINEERING
Basic Research Clinical
Combination

BASIC RESEARCH
Experimental
Numerical Analytical
---FEA
---NON-FEA

WHAT IS FEA?
It is a means of discretizing a continuous structure
into sub-domains called Finite Elements.

WHAT IS FEA?
Essentially an attempt at simulating a physical
object and analysing it’s behaviour when
subjected to various circumstances

WHY FEA?
•Accuracy
•Reproducibility
•No usage of materials
•Generation of intra-material results

FINITE ELEMENT ANALYSIS(FEA)
Termed by Clough in 1960
Gained popularity in the civil and the Aerospace
industry

First introduced to the dental arena in the 1970’s
Growth model documented by MOSS in 1980.

Current upsurge in interest due to
a)Potential of applicability
b)Desktop management

Basic steps---
a)Pre-processing
b)Processing
c)Post-processing

Pre-Processing basically involves modelling of the
structure being studied.
Probably the most crucial step.

Pre-Processing --- Newer possibilities of modelling
of complex structures
a)3-DCT scanning
b)3-DLaserscanner
c)Voxel modelling

In Pre-processing, the structure being studied is
discretised into smallerunits termed the
elements.
Each element is free to get displaced in all the
three planes of space.

The element co-ordinates (x,y,z) can be either
a) Global Co-ordinate systemor
b) The Local Co-ordinate system

Various categories of elements exist.
Examples are
--- Shell element
---Beam element
---Truss element etc.

EXAMPLES OF ELEMENTS

These elements are connected at certain points termed
‘Nodes’.
The joining of elements into nodes and eliminating
duplicate nodes is termed as “Meshing”

The mesh size is a crucial determinant of the accuracy
of the result.
However, it is inversely related to the time involved in
the analysis.

The meshed model is now a free floating body. To
simulate the exact structure, the material
properties are assigned and boundary conditions
enforced.

Material properties : The minimumproperties to be
assigned are a) The Modulus of elasticity and
b)Poisson’s ratio.

Material properties : Modulus of elasticity(Young’s
modulus)refers to the stiffness of the material
within it’s elastic range.
E = Stress
Strain

Modulus of elasticity of dental structures are :
a) Enamel --- 65 GPa
b) Dentin -- 15 GPa
c) Alveolarbone – 10 GPa
d) Periodontal ligament – 0.05 GPa

Material properties : Poisson’s ratio denotes the strain
imposed on the material relative to the axis of the
load applied.
P = Strain perp. to the force
------------------------------------
Strain parallel to the force

Poisson’s ratio fordental structures are:
a) Enamel -- 0.32
b) Dentin -- 0.28
c) Alveolarbone –- 0.33
d) Periodontal ligament-- 0.3

FINITE ELEMENT ANALYSIS (FEA)
Afterassigning the material properties, the material is
constrained identical to the real situation.
The freedom of the body to be displaced is termed as
the “degrees of freedom”.
Each element has six degrees of freedom.

FINITE ELEMENT ANALYSIS (FEA)
The final step in Pre-processing is the application of
loads. These can be eitherforce ormoments and be
directed at any node in all the three planes of
space.

What Does The Computer Do During The
Processing?
a) Solving of differential equations.
b) Assemblage into matrices
c) Summation of the matrix equations

The equation for the simplest linear static analysis is
represented as :
[F] = {K} {u}
The non-linearanalysis is solved usually by what is
termed as the “Newton-Raphson method”

Post-Processing --
a) Graphical output
b) Numerical output
c) Animated output

ROLE OF A MEDICAL ORA DENTAL
PROFESSIONAL DURING A RESEARCHWORK
INVOLVING FEA
• Planning a feasible study
• Software to be used
• Type of Model – 2-Dor3-D
• Type of analysis

ROLE OF A MEDICAL ORA DENTAL
PROFESSIONAL DURING A RESEARCHWORK
INVOLVING FEA
Software to be used
• Accuracy
• Analysis modules
• Mainframe capabilities

AREAS OF APPLICATIONS
BIOMECHANICAL MECHANICAL
Orthodontics
Prosthodontics
Oral Surgery
Periodontics

ORTHODONTIC USAGE
Alternative to cephalometry
Growth assessment
Stress pattern generation

ORTHODONTIC USAGE
• Limitations of conventional cephalometry in
establishing the exact areas of growth .
• Advantages of FEMin Growth studies

ORTHODONTIC USAGE
• Melvin Moss used the concept of Growth
tensors.
• Tensors, although being abstract entities, are
able to pinpoint the local growth
extensions(strains)

CONCEPT OF GROWTH TENSORS

ORTHODONTIC USAGE
Stress pattern generation ---
Nasomaxillary region
Mandible and condyle
Dento-alveolar
Attachments and othermaterials

ORTHODONTIC USAGE
Nasomaxillary region

MODELLING OF THE MANDIBLE

ANALYSIS OF THE MANDIBLE

MODELLING OF HUMAN TEETH

LOSS OF ATTACHMENT AND IT’S RELATION TO
THE M/F RATIOS

RELEVANCE OF USING TPA AS A SOURCE OF
ANCHORAGE

MODELLING OF ORTHODONTIC
BRACKETS

ANALYSIS OF STRESSES IN ORTHODONTIC
BRACKETS

ANALYSIS OF STRESSES IN ORTHODONTIC
BRACKETS AND ADHESIVES

A MODELLED STANDARD LOOP
FR

DISPLACED SHAPE OF THE LOOP

T Loop and L loop with angulated legs

A NEW FINDING

PROSTHODONTIC USAGE
Edentulous jaws
Complete dentures
Over-dentures
Crowns and Fixed partial dentures
Implants

STRESS ANALYSIS OF A CAST
RESTORATION

MODELLING OF AN IMPLANT IN THE
MANDIBLE

ANALYSIS OF THE IMPLANT

ORAL ANDMAXILLOFACIAL SURGERY
Surgical stresses generated
Stresses in the TMJ
Distraction osteogenesis stresses

MODELLING OF THE HUMAN TMJ

THE MODELLED TMJ

ANALYSIS OF THE TMJ- NORMAL MOVEMENTS

ANALYSIS OF THE TMJ - ENFORCED MOVEMENTS

PERIODONTICS
Stresses in the periodontium
Changes due to loss of bone support
Designing of oral resonators

ANALYSIS OF RESONATORS

USES OF FEA IN PALEONTOLOGY
-- A MODELLED DINOSAUR CRANIUM

SOURCES OF DATA
INTERNET – www.femur.wpi.edu
www.anamedic.com
www.feainfo.com
TEXTS : - Chandrupatla et.al
Lakshminarayan H.V
Champion Jr.

RAPIDPROTOTYPING
This refers to the process of production of
any physical object scanned via special devices.

RAPIDPROTOTYPING
USES:
a) Instrument designing
b) Maxillofacial surgery
c) Implantology

RAPIDPROTOTYPING
Output generation
a) 3-Dprinting
b) Stereolithography
c) Vacuumcasting
Facility of Rapid Prototyping available at the
IISC, Bangalore

USES OF RAPID PROTOTYPING
--CRANIOFACIAL DEFECTS

USES OF RAPID PROTOTYPING

APPLICATIONS OF RAPID PROTOTYPING

CONCLUSION
The interaction of Dental and Engineering fields
is at a new helm; we have tried to initiate a
fruitful togetherness.

THANK YOU
For more details please visit

Fem /certified fixed orthodontic courses by Indian dental academy

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