Scientific Reports volume 12, Article number: 7830 (2022 ) Cite this article
Human teeth are mechanically robust through a complex structural composite organisation of materials and morphology. Efforts to replicate mechanical function in artificial teeth (typodont teeth), such as in dental training applications, attempt to replicate the structure and morphology of real teeth but lack tactile similarities during mechanical cutting of the teeth. In this study, biomimetic typodont teeth, with morphology derived from X-ray microtomography scans of extracted teeth, were 3D printed using an approach to develop novel composites. These composites with a range of glass, hydroxyapatite and porcelain reinforcements within a methacrylate-based photopolymer resin were compared to six commercial artificial typodont teeth. Mechanical performance of the extracted human teeth and 3D printed typodont teeth were evaluated using a haptic approach of measuring applied cutting forces. Results indicate 3D printed typodont teeth replicating enamel and dentine can be mechanically comparable to extracted human teeth despite the material compositions differing from the materials found in human teeth. A multiple parameter variable of material elastic modulus and hardness is shown to describe the haptic response when cutting through both human and biomimetic, highlighting a critical dependence between the ratio of material mechanical properties and not absolute material properties in determining tooth mechanical performance under the action of cutting forces.
Teeth have outstanding mechanical properties that are yet to be replicated using engineering routes. Current artificial teeth (typodont teeth) are typically made from engineering materials that result in significant mechanical differences from human teeth1, although replications of shape and colour have been successfully achieved2,3. In dental education biomimetic typodont teeth reduce the use of extracted human teeth for training3,4,5,6, however, the need to mimic the mechanical properties of human teeth, not just morphology, is significant in most areas of dentistry. Approaches to replicate the mechanical function of human teeth, and more generally of all teeth, is challenging due to the complex dependency between tooth morphology, material composition and material organisation. Attempts to engineer a tooth with comparable mechanical properties must consider all these parameters as well as reconcile manufacturing routes that will be more rapid than the relatively slow biological processes that were employed to develop human teeth. Finally, the mechanical functions are additionally complex with a range of loading regimes experienced by a human tooth7. Here, the resistance of a human tooth to mechanical cutting is considered due to its importance in tactile feedback during filling procedures in dental training; a common high-volume usage for typodont teeth. The development of a biomimetic tooth, therefore, requires an understanding of the complex interaction between materials in established manufacturing processes to deliver appropriate mechanical performance comparable to a human tooth.