CADMMST2015

Submission of project

Presenter

Shiladitya Paul 15MM60005 mmst 1st sem. School of medical science & techn. iit kgp

Under guidance of

Prof, Arghya Deb

Ph.D.(Princeton Univ)

Associate Professor, Civil EngineeringCo-Prof-in-Charge, Centre for Railway Research, Civil Engineering,

IIT KGP

Project Title

•Finite Element Analysis of Dental Implant Using Abaqus Software

What is A Dental Implant?

• Development of an ideal substitute for missing teeth has been one of the long-term aims of dentistry. A dental implant is a biocompatible screw-like titanium ‘fixture’ that is surgically placed into the jawbone.

• An implant post or abutment and permanent tooth can be attached in a variety of designs.

What is the Benefit?

• The long-term benefits of dental implants include improved appearance, comfort, speech and self-esteem.

• With the dental implant, the patient can eat more conveniently .

• embarrassment caused by removable partial and full dentures can be eliminated. In addition the implant is

• able to protect the remaining natural teeth, stop bone loss and restore facial skeletal structure

Overview of some availablecommercial short and mini implants

What is FEA?• Finite element analysis (FEA) is a

computerized method for predicting how a product reacts to real-world forces, vibration, heat, fluid flow, and other physical effects.

• Finite element analysis shows whether a product will break, wear out, or work the way it was designed. It is called analysis, but in the product development process, it is used to predict what is going to happen when the product is used.

What is ABAQUS?

• Abaqus FEA (formerly ABAQUS) is a software suite for finite element analysis and computer-aided engineering, originally released in 1978. The name and logo of this software are based on the abacus calculation tool. The Abaqus product suite consists of five core software products:

.• Abaqus/CAE, or "Complete Abaqus Environment" (a backronym with an obvious root in Computer-Aided Engineering). It is a software application used for both the modeling and analysis of mechanical components and assemblies (pre-processing) and visualizing the finite element analysis result. A subset of Abaqus/CAE including only the post-processing module can be launched independently in the Abaqus/Viewer product.

• Abaqus/Standard, a general-purpose Finite-Element analyzer that employs implicit integration scheme (traditional).

• Abaqus/Explicit, a special-purpose Finite-Element analyzer that employs explicit integration scheme to solve highly nonlinear systems with many complex contacts under transient loads.

• Abaqus/CFD, a Computational Fluid Dynamics software application which provides advanced computational fluid dynamics capabilities with extensive support for preprocessing and postprocessing provided in Abaqus/CAE.

• Abaqus/Electromagnetic, a Computational electromagnetics software application which solves advanced computational electromagnetic problems.

Samples

Human Body Parts

dental implant types

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Osteoplant Dental Implant

Steps of Dental Implant Surgery

Missing molar in the mandible, to be treated with a dental implant-supported restoration

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After flap elevation, the cortical bone is visible

Dental implant with an abutment to be placed in the ridge created by the missing molar

Implant is placed in the ridge

Occlusal view of the implant after 2 months of healing

Abutment is prepared and attached to the implant

Porcelain-fused metal implant-supported restoration in use with optimum treatment planning

Abaqus Analysis2D or 3D?

• The 3D model of the implant will contain >50000 dof.

• So we were supposed to use 2D model using axisymmetric solid CAXA model.

• But that facillity was not in Abaqus which we were using.

• So, we have used CAX4R.

Parts• PARTS

• A Abutment• S screw• CC Cortical

Bone• CB Cancellous

Bone.

Mechanism

• A dental implant resembles a screw constructed from titanium and is surgically placed into the bone to serve as the new root . Once the implant successfully fuses with the bone, an abutment is placed on top of the implant to serve as the platform that protrudes out of the gums, and the implant crown can then be seated on the abutment permanently

Cortical Bone

CoOrdinates(0,0)(0,5)(6.25,0)(7.5,0)(0,0)

Cancellous Bone

CoOrdinates(0,5) (0,10)(2.5,10)(2.5,15)(5,15)(6.25,15)(0,5)

Axisymmetricshell

ScrewCoOrdinates(0,10)(0,20)(2.5,20)(1.5,20)(1.5,10.1)(0,10.1)AxiSymmetricshell

AbutmentC0Ords(2.5,15)(2.5,2.5)(3.5,2.5)(5,20)(3.75,18.5)(3.75,15)(2.5,15)Axi SymmShell

Materials PropertyPART Young’s Modulus Poisson’s Ratio

Cortical Bone 13xE9 0.3

Cancelleous Bone 95x E8 0.25

Screw(Titanium) 105xE9 0.32

Abutment(Zirconium) 105xE9 0.3

What is Young’s modulus?

Poisson Ratio

Assembly

Interaction

I Interaction zoom

Step

Boundary Condition

Load

LoadName Vertical

Step Static General

Type Pressure

Region Vertical

Distribution Uniform

Magnitude 600

Name Horizontal

Step Static General

Type Pressure

Region Horizontal

Distribution Uniform

Magnitude 100

Mesh

0.3 0.2 0.1 0.05

MeshCentral Quad

Element Standard Linear

Family Axisymmetric Stress

Results 0.3 mess

Mesh size 0.2

Mesh 0.1

Mesh 0.05

Analysis• What is S Mises?• Von Mises stress• .Using this information an engineer can say his

design will fail, if the maximum value of Von Mises stress induced in the material is more than strength of the material.

• The concept of Von mises stress arises from the distortion energy failure theory.

.

S Max Principal

• Maximum Principle Stress Theory - According to this theory failure will occur when the maximum principal stress in a system reaches the value of the maximum stress at elastic limit in simple tension. This theory is approximately correct for cast iron and brittle materials generally.

Variation of position of S max & S mises with respect to mesh size

Mesh Size 0.3 0.2 0.1 0.05

S Max position

Medial lower corner of screw

Medial lower corner of screw

Medial lower corner of abutment

Lateral lower corner of screw

S Mises position

Lateral lower corner of screw

Lateral lower corner of screw

Lateral lower corner of screw

Lateral lower corner of screw

Variation of values of S max & S mises with respect to mesh size

Mesh Size 0.3 0.2 0.1 0.05

S Max value

+2.54xE2 +1.983xE2 +2.347xE2 +3.193xE2

S Mises Value

+1.721xE3 +2.11xE3 +2.336xE3 +2.938xE3

Conclusion • Considering the above s mises and max

principal value which have been plotted at the same site shows that maximum stress will occur lateral lower corner of screw and will lead to all related complication

• Though in comparison with the paper it says no serious stress fracture was found.

Complications: Broken Implant

Intraoral picture of a broken implant due to excessive loading after 1 year of use

Advantages of FEA study• FEA studies have several advantages over

clinical, pre-clinical, and in vitro studies. • Patients will not be harmed by the application

of new materials and treatment modalities that have not been previously tested.

• Animals will not suffer from these biomechanical studies.

Disadvantages of FEA study

• All of these applications are being performed on a computer, with critical limitations and assumptions that will clearly affect the applicability of the results to a real scenario.

• Simplifications are made for all simulated models; therefore, the models should be compared with each other within the same study.

Summary• FEA is a numerical stress analysis technique and is

extensively used in implant dentistry to evaluate the risk factors from a biomechanical point of view.

• Simplifications and assumptions are the limitations of FEA studies.

• Although advanced computer technology is used to obtain results from simulated models, many factors affecting clinical features such as implant macro and micro design, material properties, loading conditions, and boundary conditions are neglected or ignored. Therefore, correlating FEA results with preclinical and long-term clinical studies may help to validate research models

Acknowledgements

• Prof A.DEB , Associate Professor, Civil Engineering, IIT KGP

• Other members of Project Group• Stuff members of CAD Lab• IIT KGP free broadband service

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