In vivo evaluation of a 3D-printable polyurethane-acrylate soft denture liner

The purpose of this study was to evaluate the in vivo biological response of a newly developed 3D-printable polyurethane-acrylate-based soft denture liner (SDL) following direct contact with oral mucosa, focusing on cytocompatibility, epithelial integrity, and inflammatory responses.

A polyurethane-acrylate SDL formulation optimized for additive manufacturing was fabricated using digital light processing (DLP) 3D printing. Cytotoxicity was assessed in vitro using L929 fibroblasts according to ISO 10993-5 guidelines through microscopic observation and MTT assays. For in vivo evaluation, plate-shaped SDL specimens were applied to the buccal mucosa of Sprague-Dawley rats, with sutured sham controls. Animals were sacrificed at 24 h (day 1) and 72 h (day 3). Histological assessment was performed using hematoxylin and eosin staining, while epithelial integrity and differentiation were evaluated by immunohistochemistry for E-cadherin and pan-keratin. Inflammatory and collagen-related gene expression was analyzed using RT-qPCR.

The SDL extracts showed no cytotoxic effects at any concentration, with cell viability exceeding 97% in all groups. Histological analysis revealed no epithelial disruption, inflammatory cell infiltration, or tissue damage in SDL-applied mucosa. Epithelial thickness exhibited a mild increase from day 1 to day 3 in both sham and SDL groups, with no significant intergroup differences. E-cadherin and pan-keratin expression patterns remained comparable between groups at all time points. RT-qPCR demonstrated a transient increase in inflammatory markers at day 1, which resolved by day 3 without sustained inflammation.

The newly formulated 3D-printable polyurethane-acrylate SDL demonstrated excellent biocompatibility and preserved oral mucosal integrity in vivo, supporting its potential clinical application as an alternative to conventional soft denture liners.