PL: An Engineer’s Approach to Designing and Assessing Dental Restorations

It is our pleasure to invite you to our event as follows;

Public Lecture on: An Engineer’s Approach to Designing and Assessing  Dental Restorations

Date      : Friday, 3^rd January 2014

Venue   : Lecture Hall Level 9
Postgraduate & Research Tower
Faculty of Dentistry,
University of Malaya

Time     : 10.00am

Should you have further inquiries, do feel free to contact DRMC at:

03-7967 6454 or email at najmi@um.edu.my

Registration : Kindly RSVP before 1^st January 2014

Your attendance to this programme would be highly valuable and we do hope all of you will be able to attend the program. 

Below is information on program;

Speaker:

Professor Dr. Alex Fok

Dr Fok obtained his BEng and PhD, both in Mechanical Engineering, from the University of Manchester, UK. He has expertise in structural and stress analysis, having spent 4 years working as a structural analyst in the nuclear industry after gaining his PhD. Prior to moving to Minnesota, he was Senior Lecturer in Mechanical Engineering at the University of Manchester.

Dr Fok’s research activities cover a range of topics in solid mechanics, nuclear graphite technology and biomechanics, both at a fundamental level and related to practical applications. These include statistical analysis of brittle failure, fractal finite elements, micro-structural modeling of materials, material characterization using full-field strain measurement and inverse methods, multiple fracture from dynamic stresses, buckling of thin embedded shells and the biomechanics of dental restorations. The
finite element method forms the main tool of his research.

In 2007, Dr Fok accepted the invitation of the University of Minnesota School of Dentistry to become Director of the Minnesota Dental Research Center for Biomaterials and Biomechanics (MDRCBB). Established as an industry-academic collaboration with funding from the 3M Foundation and 3M Dental Products Division, the MDRCBB works closely with the industry on the development of new dental products and biomaterials.

Dr Fok’s current research activities include shape optimization of dental restorations, shrinkage strain measurement using digital image correlation, nondestructive examination of interfacial debonding using acoustic emission and development of alternative bond tests for dental materials. Together with colleagues from the Dental School, he has recently been awarded an NIH grant looking at the possible effect of bacterial activities on the degradation of composite restorations. He has also been successful
in securing two grants from the DOE, one with colleagues from the Department of Civil Engineering, to continue his work on nuclear graphite.

Abstract

One of the main roles of engineers is to transform raw materials such as metals, plastics and cement into structures or devices of certain shapes that perform various functions. These include things such as tools, buildings and vehicles. In a similar vein, restorative dentists transform dental materials such as composites and ceramics into different types of restorations and materials such as titanium and gold alloys into prosthesis of varied designs that poses their own peculiar biomechanical challenges. Examples include inlays, fixed and removable prosthesis and implants. Dentists are therefore engineers in their own rights but not many recognize this parallel.

The aim of this lecture is to encourage dentists to think more like engineers, and to showcase the available engineering tools that could facilitate the design of better and longer-lasting dental restorations. The tools covered in this presentation include the triangle of structural design, Digital Image Correlation (DIC), measurement of Acoustic Emission (AE), micro-computed tomography (micro-CT), Finite Element Analysis (FEA) and shape optimization.
 The golden triangle of structural design consists of the three elements: material, shape and function. Simple examples from restorative dentistry will be used to illustrate the interaction between these elements when considering different restoration designs. The same examples will also be used to demonstrate the general principle of formulating, evaluating and ranking the different designs, from which the most suitable can be selected in a rational manner.
 FEA is a powerful numerical simulation tool which aids the understanding of the mechanical behavior of dental restorations and, more importantly, how they may fail before they were physically built for testing. It could therefore potentially spare wasted
effort and resources in making, testing or even using designs that are ultimately not fit for their purpose.
 Based on the principle of biological adaptive growth, shape optimization can assist in designing restorations that distribute stresses more favorably within themselves as well as the supporting tissues. Such optimized restorations will have better longevity and lesser impact on the surrounding host tissues.
 DIC, often referred to as the virtual strain gauge method, determines the deformation of an object by tracking unique features on its surface from optical pictures taken at different times. Through the generated full-field strain maps, it allows visualization of the mechanical impact of an implant system on the surrounding bone, the strains created in a composite restoration that has undergone polymerization or the failure process of interfacial debonding as it happens.
 The measurement of AE, which are high-frequency elastic waves transmitted through solids, enables the detection and monitoring in real time the development of micro-cracks in restorations. An innovative adoption of this technique for detecting debonding in composite restoration due to polymerization shrinkage will be demonstrated in the presentation.
 Micro-CT derives the three-dimensional internal structures of an object through a series of microradiographs, or two-dimensional projections, taken at different angles. It is a nondestructive method which allows the examination of internal defects or damage of a restoration without physically destroying it. Coupled with the use of a contrast agent, it is now possible to use micro-CT to quantitatively assess the volume of leakage around the margins of a restoration.
Examples will be used to illustrate how these engineering tools can be used in combination to design and validate dental restorations that are more efficient and longer-lasting in performing their oral functions. We will see how the three components in structural design – material, shape
and function – influence one another as the restorations evolve into their optimized shapes.

— Thank you & we look forward to seeing you soon!