High strain rate effects on mechanical properties of the human tooth enamel-dentin complex

The human dentition must withstand both everyday masticatory forces and occasional high-rate impacts, demanding exceptional mechanical performance from its mineralized tissues. Despite extensive characterization under quasi-static conditions, the dynamic response of dental hard tissues—particularly at strain rates associated with traumatic events—remains largely unexplored. This study investigates the effect of high strain rates on the compressive mechanical behavior of the enamel-dentin (ED) complex. Precisely machined specimens were prepared from healthy human premolars and tested under uniaxial compression using a high-speed servo-hydraulic testing system at strain rates of 10, 40, 70, and 100 s −1 ( n = 10 per strain rate). Full stress-strain curves were recorded, from which the maximum compressive stress, elastic modulus, strain at failure, and energy absorption were determined. With increasing strain rate, the maximum compressive stress increased by approximately 26%, while the elastic modulus nearly doubled, and the strain at failure and energy absorption decreased by approximately 33% and 16%, respectively. One-way ANOVA with Tukey's HSD post-hoc testing confirmed that strain rate significantly affected all four measured properties ( p < 0.01 for each). The observed rate sensitivity is attributed to the viscoelastic nature and hierarchical organic-inorganic architecture of the ED biocomposite. An empirical relationship was fitted to the data, enabling prediction of mechanical properties at intermediate strain rates within the tested range. These findings address a conspicuous gap in the literature on the dynamic behavior of teeth and provide insights for simulations of dynamic loading events, as well as informing the development of restorative materials and computational models.