Engineering for Dentistry

Oct 4, 2019

by John Kosowatz

Alex Fok is a professor in the University of Minnesota’s School of Dentistry and director of the Minnesota Dental Research Center for Biomaterials and Biomechanics. With expertise in stress and structural analysis, his research covers a range of topics in the biomechanics of dental restorations. One of his goals is to instill more rigorous engineering principals into design and assessment of dental restorations and treatments. With degrees in mechanical engineering from the University of Manchester, and in mathematics from the University of Oxford, here he explains digital dentistry and the need for more and better engineering in dentistry. Professor Fok is a panelist at ASME’s upcoming conference: VisualizeMED: Modeling the Future of Medicine.

Q: One of your goals is to instill more rigorous engineering principles into the design of dental restorations and treatments. What has been lacking, and how are you attacking the issue?

A.F.: Traditionally, the design of dental restorations has been based on experiences passed down by dentists from generation to generation. While modern engineering tools, such as the finite element method, have been used, the design process is still very much that of trial and error, changing the dimensions here and there and see what impact they have on the stress level.
 
I am attacking this issue by introducing bio-inspired shape optimization techniques to help automate the design process so as to increase its efficacy in coming up with more durable dental restorations. Specifically, the stresses calculated in a finite element analysis are used as feedback via a user material subroutine to modify the dimensions or material properties, in a fashion similar to bone remodeling, to optimize the designs. 

Q: You’ve wanted to encourage dentists to think more like engineers. Why and how? Does this require a deep change in thinking or analysis? 

A.F.: Like any load-bearing structure, a dental restoration has to conform to a certain shape, withstand a certain load and last for a sufficiently long period. But despite being one of the most mechanical disciplines in the medical field, dentists lack basic training in the principles of mechanics.
 
Whenever the opportunity arises, I would point out to them the interaction among load, shape and material, i.e. the golden triangle for structural analysis, in a dental restoration. For example, in the restoration of carious teeth, the replacement of a non-adhesive amalgam with resin-based composites that can be bonded to tooth tissues leads to a radical change in the shape of the cavity preparation that houses the restoration.
 
Further Reading: Bioengineering Blog

Q: How are engineering tools evolving to aid in the design of better dental restoration?

A.F.: The development of digital image processing and CAD/CAM tools allows the design and manufacture of dental restorations to be performed by dentists at the chairside.  However, structural analysis, let alone shape optimization, is still glaringly missing in the design process. Manufacturers of these chairside systems should really consider incorporating, at the very least, structural analysis into their software package so as to ensure the mechanical performance of the restorations thus designed.

Q: What is the industry’s role in the work of Minnesota Dental Research Center for Biomaterials and Biomechanics?

A.F.: Being part of a dental school, the center performs the important role of connecting the industry to the practitioners. On the one hand, the industry has been rather responsive to the needs of dentists in terms of coming up with better dental materials.
 
On the other hand, the center has been proactive in developing new test methods for evaluating the new materials being developed. It is important that we continue this collaboration to ensure the practicality and robustness of future dental materials.

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Q: How do you describe the development of biomaterials and where they are being used in dental practice?

A.F.: Traditionally, the focus of dental biomaterials development has been the replacement of carious tooth tissues or lost dentitions in the form of direct filling materials or indirect restorations such as crowns and bridges.

As I mentioned, CAD/CAM technologies are now routinely used for making indirect restorations, but mostly through reductive manufacturing. 3D printing or additive manufacturing is beginning to be used for making these restorations, but the materials currently available are limited. Thus, stronger polymeric materials are being developed for 3D printing and these can lead to more versatile designs, for example, restorations with functionally graded properties.

Learn More about Engineering for Dentistry at ASME’s Visualize MED: Modeling the Future of Medicine
 
John Kosowatz is senior editor.