LONDON, UK: Many dental students have reported frustration with typodont teeth that require significantly more force to cut than extracted teeth, thus changing the “feel” of the procedure. In response, a team of researchers from two universities and from the oral health innovation division of GlaxoSmithKline Consumer Healthcare have designed a novel experiment in order to evaluate the “feel” and force required to cut into artificial teeth and to find a way to 3D-print better-quality teeth for practice.
The study results indicated that the amount of force required for cutting into the typodont teeth currently available on the market varied greatly from the force required for cutting into extracted teeth. The degree of force required could also change drastically based on the layer of the tooth being cut. The team’s goal therefore was to match natural teeth in mechanical response and morphology with better-designed 3D-printed typodont teeth. The use of radiographic micro-CT provided high-resolution imaging of natural teeth and imaging data compatible with 3D printing.
DTI spoke with two of the team’s researchers, Dr Alexander Cresswell-Boyes, a postdoctoral research associate and teaching fellow at the Barts and the London School of Medicine and Dentistry at Queen Mary University of London, and Prof. Asa Hilton Barber, dean of the School of Engineering at London South Bank University, about what the experiment’s results might mean for dental students.
Dr Cresswell-Boyes, Prof. Barber, how do you hope manufacturers of artificial teeth might respond to the findings of your study?
Dr Cresswell-Boyes: What we found from the study is that recreating physical properties such as hardness is not necessarily useful in creating artificial teeth for students. Since students often complain about the “feel” of these teeth, we wanted to create a method of measuring that “feel” and comparing current artificial teeth with extracted teeth. Our study did not include a large number of teeth from manufacturing companies, but from the select few that were chosen, you can see the variety of forces required to cut the teeth. Especially when cutting dentine, a couple of the artificial teeth were close to matching that of the extracted ones; however, the artificial enamel tells a different story. In one instance, the artificial enamel required more than four times the cutting force than that required for cutting real enamel.
Prof. Barber: Companies should work with us to scale up and mass-produce! As our work uses 3D imaging to produce teeth, we can manufacture a range of teeth incorporating a variety of shapes or mimicking decay conditions, so there really are many opportunities for manufacturers to benefit from our research.
Do you see the concept of developing 3D-printed teeth that require a similar cutting force to that required for extracted teeth to be only beneficial for student learners, or could you envision other uses of the results generated by the experiments?
Dr Cresswell-Boyes: The scope of the project was initially to develop teeth better suited for dental students; however, the same products could easily be used for dental educators as well. Being able to use something that’s more realistic would help educators in teaching about real-life situations. As we learnt the hard way in the project, no two teeth are the same! The research discussed in the study could also be translated to medical use. Giving surgical students and professionals a realistic specimen would allow them to practise a procedure multiple times before encountering a patient. The novelty of 3D printing is that you would be able to recreate patient-specific cases.
Prof. Barber: The obvious area to expand into is dental prosthetics. This would require consideration of different materials as well as more understanding of performance over time, but the potential to replace a decayed tooth with a prosthesis would be beneficial.
Your team came up with a new methodology during the study. Do you have any recommendations for teams who wish to conduct similar studies or take your research a step further? Did you identify any further areas of study?
Dr Cresswell-Boyes: The same set-up is also currently being used to assess the machinability of ceramic blocks used in CAD/CAM milling for inlays and crowns—comparing the amount of force needed to cut certain materials. We are also looking at trying to marry up the results of the quantifiable “feel” with the qualitative “feel” in order to find out what other aspects or senses are required in recreating a realistic tooth.
Prof. Barber: We have a follow-up paper being prepared on the methodologies used and have certainly had interest in these methodologies as well as in the performance of the typodonts used in the study. For example, dental schools have been interested in the methodologies being used to assess whether students might apply higher forces when performing dental restoration on the artificial typodont teeth than the forces applied on real teeth.
As teachers, could you explain some of the benefits of including student input in the development of new technologies?
Dr Cresswell-Boyes: With this project in particular, the end goal was to develop a product specially for students. So being able to have student feedback is an invaluable tool. We want to create something that students enjoy using as well as something from which they’ll learn a great deal. Having their feedback and input has allowed us to design something that will hopefully help with their education and learning.
Prof. Barber: This is a more general question, and it is perhaps an important one in thinking about how to solve problems. An individual rarely has all the information or ideas required to solve a problem, especially as many problems in dentistry or other disciplines are becoming increasingly complex. I have always been open and transparent with my students in explaining the problems, and I appreciate their ability to present ideas so that we can jointly solve the problem.
Do you have any further comments you would like to share with our readers, either about the study or about other projects in which you are involved?
Dr Cresswell-Boyes: This is very much a work in progress. As we work with students and educators, we are making constant refinements to materials and methodology. Our goal is to openly share this research, including all the methodology and 3D model data, with other dental schools in order to create a network of users and collaborators through whom these teeth can be further improved and made more accessible to students.
Prof. Barber: My interest will continue to lie in understanding both human and non-human teeth. I think there is considerable scope for developing the mechanical properties of modified or artificial teeth for health benefits. Ultimately, for dentistry, I see parallels with hospitals where public health strategy is pushing to keep people out of the hospitals. So, the ultimate goal is that nobody has to go to see the dentist. Consumer health products are still some distance from achieving this, but it is interesting that this work uses the same 3D printing that is now finding its way into peoples’ homes. Perhaps these technologies might become more developed in the home.
The study, titled “Composite 3D printing of biomimetic human teeth”, was published on 12 May 2022 in Scientific Reports.
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