Viscoelastic Properties of Dental Pulp Tissue and Ramifications on Biomaterial Development for Pulp Regeneration

• We investigated the viscoelastic behavior of native pulp tissue harvested from a miniature pig.
• We proposed to incorporate the information obtained into the biomaterial selection process.
• Viscoelastic properties of native pulp, agarose, alginate, and collagen were compared.
• Pulp tissue and hydrogels showed similar gel-like behavior.
• Collagen (at 2% wt/vol) yielded the closest viscoelastic behavior to that of the native tissue, but deviation of other biomaterials could be minimized by tailoring concentrations and other properties.
• Viscoelastic and biomechanical properties of dental pulp tissue provide valuable inputs for biomaterial selection.

IntroductionA critical step in biomaterial selection effort is the determination of material as well as the biological properties of the target tissue. Previously, the selection of biomaterials and carriers for dental pulp regeneration has been solely based on empirical experience.MethodsIn this study, first, the linear viscoelastic material functions and compressive properties of miniature pig dental pulp were characterized using small-amplitude oscillatory shear and uniaxial compression at a constant rate. They were then compared with the properties of hydrogels (ie, agarose, alginate, and collagen) that are widely used in tissue regeneration.ResultsThe comparisons of the linear viscoelastic material functions of the native pulp tissue with those of the 3 hydrogels revealed the gel-like behavior of the pulp tissue over a relatively large range of time scales (ie, over the frequency range of 0.1–100 rps). At the constant gelation agent concentration of 2%, the dynamic properties (ie, storage and loss moduli and the tanδ) of the collagen-based gel approached those of the native tissue. Under uniaxial compression, the peak normal stresses and compressive moduli of the agarose gel were similar to those of the native tissue, whereas alginate and collagen exhibited significantly lower compressive properties.ConclusionsThe linear viscoelastic and uniaxial compressive properties of the dental pulp tissue reported here should enable the more appropriate selection of biogels for dental pulp regeneration via the better tailoring of gelation agents and their concentrations to better mimic the dynamic and compressive properties of native pulp tissue.