Study On The Effect Of Tooth Structure On The Mechanical Properties Of Bovine Teeth

The vast majority of mammalian have a heterodont dentition. Their teeth differentiate into a variety of patterns and then play different roles in the process of chewing. Also, a large number of studies indicate that the excellent performance of tooth enamel is closely related to its complex hierarchical structures formed by ranked assembly and arrangement. Therefore, charactering each tooth’s mechanical and tribological properties on the bovine dentition, finding out the influence of tooth features on its mechanical properties on multi-scales, can not only enrich the study of mammalian teeth, but also have important significance on both the study of the relationship between tooth enamel structure and its performance and the bionic of tooth enamel structure.This study mainly has two parts. Firstly, by using Agilent G200 nano-indentation/scratch tester, the mechanical and tribological properties of each bovine tooth’s enamel on the dentition were studied on the occlusal surface. Then, according to the test results, the finite element method was adopted to build macro-scale and micro-scale tooth models. The macro-scale model was used to simulate two tooth shape features observed during tests. And through the micro-scale model the sensitivity analysis was conducted on mechanical properties, considering the enamel rod’s sectional shape, the volume percentage between enamel rod and inter-rod enamel, and also the elastic modulus and Poisson’s ratio of these two parts formed enamel. The main conclusions are summarized as follows:1、Both the elastic modulus and hardness of three incisors decrease from mesial side to distal side. Those properties of the only canine are smaller than the second incisor but higher than the third. The elastic modulus of premolars and molars goes upwards but nearly the same. While the hardness of those teeth increases significantly. The incisors’ and the canine’s friction coefficient ranges from 0.13 to 0.16, smaller than that of the premolars and the molars, which is quite stable around 0.18. As to wear volume, the results show that the first and the second incisors, together with the second and the third premolars, are much larger than other teeth.2、The incisor’s wedge-shaped feature can improve feeding efficiency by increasing the stress of food under the same bite force. And the convex feature at both ends of lingual side, finding in some incisors, can protect teeth by increasing their strength and rigidity. The same analysis on molars’ model shows that the bigger tangential components of the applying force it is, the larger stress of tooth and alveolar bone is caused. And the feature of premolars and molars huddling together may effectively decrease the stress.3、The enamel rods cross sectional shape do have an influence to the intensity of stress. And, the influencer factors of inter-rod enamel’s elastic modulus and Poisson’s ratio are greater than enamel rod’s accordingly. Also, the volume ratio between enamel rod and inter-rod enamel also has an effect on stress intensity.