Influence of Incremental Lines upon the Com- Pressive Strength of Sperm Whale Dentin

Compressive properties of sperm whale dentin were measured as a function of orientation of incremental lines. With respect to the general incremental lines' direction, three specimen orientations were selected: longitudinal, oblique (45°) radial and transverse radial. The machined cylindrical specimens were compressed in a mechanical testing machine. A load cell provided with the force values developed on the samples and a displacement transducer yielded the corresponding deformation values. The resulting stress-strain curves provided with values of proportional limits, ultimate compressive strengths and elastic moduli for each of the specimen orientation investigated. It was found that while the ultimate compressive strength values did not differ statistically with specimen orientation, proportional limits and elastic moduli showed some significant differences. Based on a possible functional adaptation, a theory has been formulated which correlates the results obtained with the growth patterns found in sperm whale dentin.