Tailoring Gelatin-methacrylate for Human Dental Pulp Tissue Mimicry

Objectives: Objective: A therapeutic dental pulp tissue replacement would promote root maturation and retention of a diseased young permanent tooth. Characterization of the viscoelastic properties of human and porcine pulp tissue has prompted tuning of scaffold materials to better mimic the dental pulp extracellular matrix. The viscoelastic properties of photopolymerizable biomaterials, characterized in terms of elastic storage (G^′) and loss modulus (G^″), needed for design of suitable bioactive and 3D printable dental materials are not well understood. The objective of this study was to tune the elastic modulus G′, of methacrylated gelatin (GelMA) to match the reported storage modulus G′ of characterized human dental pulp tissue between 2-7 kPa.
Methods: Methods: Ultraviolet (UV) in-situ rheology was used to evaluate the time-dependent UV curing process, and the effect of UV intensity on the final storage modulus G^′ of 7.5% w/v GelMA. The time-dependent changes in moduli were characterized (at strain of 1% and a frequency of 1.5 Hz) using oscillatory time sweep measurements performed at 24°C with an ARES 2000 rheometer equipped with a disposable parallel plate system (20 mm, 300 µm gap, 365 nm). GelMA samples (125 uL) were first equilibrated for 30 seconds followed by irradiation at either 0.1, 3.0 or 6.0 mW/cm² for 450 seconds. Samples unexposed to UV irradiation (0.0 mW/ cm²) were treated as a control. N=3 samples/ experiment. One-way ANOVA followed by Tukey’s multiple comparisons was used to analyze the differences between groups.
Results: Results: The higher the light intensity, the faster the UV curing of 7.5% w/v GelMA. All three experimental groups meet the targeted viscoelastic G^′range (~4.2 to 5.8 kPa). The average final storage modulus G^′ after 450 seconds is statistically significant between the experimental and control groups.
Conclusions: Conclusion: Cell types native to human dental pulp can be encapsulated and crosslinked in 7.5% w/v GelMA at relatively low photocuring- light intensities to minimize cellular damage and facilitate remodeling of a photopolymerizable scaffold.