Substructured flexible multibody model for simulating toothbrush cleaning process

Effective brushing is the basis for maintaining the oral health of millions of people. Since the 1960s, brushing has been described in mathematical models, but mainly through empirical in vivo and in vitro studies. The development of new materials and devices dedicated to the removal of oral biofilm, with a view to environmental sustainability, has necessitated the development of modern brushing simulation models. With the aim of making the estimation of the cleaning performance of a toothbrush quantitative, and in order to set up a numerical tool for supporting the design and optimization of the brushing operations, the present study describes the development of a novel computational model. It is able to estimate the forces exchanged between the bristles of the toothbrush and the tooth surface through numerical simulations. The innovative modeling approach, based on discrete flexible multibody techniques, allowed a three-dimensional description of the behavior of the bristles, obtaining accurate results with reasonable computational time. The verification of the model is performed through a dedicated test bench performing controlled movements. The comparison between the numerical model and experimental results demonstrates the reliability of the approach. The proposed approach is also tested on a complex three-dimensional case of brushing in order to verify the behavior in complex scenarios. The proposed novel simulation model has proven to be able to simulate the brushing action of a toothbrush composed of thousands of bristles on a detailed and three-dimensional dental surface.