Development of swellable local implants of a polyethyleneimine-poly(vinyl pyrrolidone) (PEI-PVP) hydrogel as a socket filler

In this study, hydrogels composed of polyethyleneimine (PEI) and poly(vinyl pyrrolidone) K90 (PVP) cross-linked with various concentrations (0, 0.125, 0.25 and 0.5%) of glutaraldehyde were evaluated as a hydrogel filler for the local delivery of lidocaine after tooth extraction. The drug-release kinetics, swellability, cy-totoxicity and wound healing after tooth extraction of these non-cross-linked and cross-linked PEI-PVP hydrogels were examined in male beagles and compared to values using Spongostan®. Results demonstrated that the extent of cross-linking influenced the swelling of the resulting hydrogel, but the drug-release rates were similar. No significant changes were observed in gingival fibroblasts in contact with the PEI- PVP hydrogels or Spongostan®. In the in vivo study, PEI-PVP hydrogels showed good retention in the socket for 2 days and showed comparable wound-healing rates within 2 weeks with those of Spongostan®. In conclusion, PEI-PVP hydrogels are suitable for use as socket-dressing materials, and the release of local anaesthesia from PEI-PVP hydrogels can be sustained for a desirable period of time to prevent pain after a tooth extraction.