Differential effect of scaffold shape on dentin regeneration.

The effect of scaffold shape on dentin regeneration is not well understood. In this study, porous hydroxyapatite/beta-tricalcium phosphate (HAp/beta-TCP), powdered HAp/beta-TCP, and polyglycolic acid (PGA) fiber mesh were used as scaffolds and transplanted with cultured porcine dental pulp-derived cells into the backs of nude mice. Samples were harvested after 6 weeks. Newly-formed hard tissue was observed in all transplants. When porous HAp/beta-TCP was used, dentin-like hard tissue was observed on the inner wall with minimum cell inclusions and odontoblast-like cells were aligned adjacent to the hard tissue. When HAp/beta-TCP powders or PGA were used, bone-like hard tissues showed cell inclusions and cell alignment was not observed. Hard tissue from the HAp/beta-TCP block group was positive for type I collagen, osteonectin, bone sialoprotein and dentin sialoprotein (DSP), which are markers for dentin. This result was confirmed by in situ hybridization with a dsp probe. Only the aligned cells were positive with an antisense probe. On the other hand, hard tissue from other scaffolds showed incomplete expression of both bone and dentin markers and they were negative for osteonectin and DSP. These results suggest that scaffold shape affects the type of tissue regenerated by dental pulp-derived cells.