BioDent Reference Point Indenter for Characterizing Mechanical Properties of Teeth

Objectives: To assess the BioDent reference point indenter (RPI) technique for measuring the mechanical properties of human teeth.
Methods: Using six, extracted human third molars, two 2-mm thick buccal-lingual coronal sections (N=12) from the mesial region were generated. The mechanical properties of each section, wet or dry (N= 6 sections/condition), were tested along the cervical line at 50-µm and 500-µm from the dentin-enamel junction in enamel (E50, E500) and similarly in dentin (D50, D500). Hardness, Young’s modulus and energy dissipation were calculated using the following measurement protocol: indentation force = 2N, indentation frequency = 2Hz, and indentations per measurement = 10 cycles. Using SEM images, indents were measured to generate hardness values. Young’s modulus was calculated based on a geometric method, and energy dissipation was calculated from the test curve.
Results: Based on an ANOVA (α=0.05), there was a significant increase in energy dissipation in wet dentin sections at both D50 and D500 compared to dry sections. There was also a significant increase in hardness of dry sections, at D500 only, compared to wet sections. However, at each dentin location or condition, there was no significant difference in Young’s modulus. Results in enamel were not reported because SEM indentation patterns indicated damage to the testing probe, making the characterization unreliable.
Conclusions: Using the novel BioDent technique, dentin hardness and Young’s modulus were similar to previously reported values with other techniques. However, the BioDent RPI was unable to characterize the mechanical properties of enamel; thus, modification of the testing probe material is warranted.