The effects of trapping and blade angle of notched dentitions on fracture of biological tissues

Abstract

SUMMARYThe material properties of food can exert a significant influence on tooth morphology. Although the stiffness or toughness of a material is usually of prime concern, other aspects of material properties (such as extensibility) can be of equal importance. Previous experimental work on the effect blade shape has on fracturing biological materials indicated a notched blade greatly reduced the work required to cut tough tissue. As a notched blade both traps materials and cuts at an angle, it is not clear which of these features leads to increased cutting efficiency. This paper tests whether the ability to cut at an angle or trap the material has the greater effect on the work to fracture required to cut tough tissues with different levels of extensibility (asparagus and fish muscle). Results show that the work to fracture required to cut more extensible materials is reduced by up to 50% when a trapping mechanism alone is used in comparison with an angled blade alone. For less extensible materials, the trapping ability of a notch seems to have no effect, whereas the angled blade reduces work to fracture by up to 25% relative to a straight blade. The aspects of blade shape most important to the breaking down of foods depend upon the relative stiffness or toughness, as well as other material properties.

Finite element modeling of occlusal variation in durophagous tooth systems

“…Cutting teeth, like shark teeth or the carnivore carnassials, are often notched. These notches reduce the work needed to process malleable prey (Anderson and LaBarbera, 2008;Anderson, 2009;Anderson and Rayfield, 2012) though they can also concentrate stresses in the tooth, thus making tooth failure more likely (Whitenack et al, 2011).…”

Virtual experiments, physical validation: dental morphology at the intersection of experiment and theory

“…The occlusion of carnassial blades is actually quite complex [36], and again beyond the scope of this analysis to test. Experimental tests comparing a notched and straight blade combination to two opposing notched blades show very little difference in work to fracture [15]. Further experiments were done with two flat plates instead of blades to further test for agreement between the experiments and model.…”

“…The biological system we are focusing on is the processing of soft foods by teeth, as previously explored experimentally [14,15]. The evolution of food processing, the ability to physically break food down into ingestible pieces, is an important development in the history of vertebrate life, allowing animals to eat larger food items, including prey larger than their mouth opening.…”

“…Less focus has been given to the cutting of tough and/or extensible foods (animal tissues or fibrous plant materials) with bladed structures [14][15][16][20][21][22] (for a review, see [23]). There is a significant volume of literature concerning FE modelling of cutting in industry [24] including studies of the reaction of soft biological tissues to cutting dynamics [25,26] and measures of sharpness in scalpel blades [27,28].…”

“…Recent experimental work on the biomechanics of cutting biological tissues has used work to fracture, a measure of energy, as the metric to determine feeding efficiency [14,15]. Energy is the basic currency of biology; however, not all energy taken in during feeding is gained by the animal.…”