Functional PDMS-Based Photocurable Resins for LCD-MSLA Additive Manufacturing of Maxillofacial Prostheses: Formulation–Structure–Property and Biological Relationships

Maxillofacial prosthetic rehabilitation requires elastomeric materials that combine mechanical performance, dimensional stability, aesthetic reproducibility, and biological safety with compatibility with digital manufacturing. This study developed three photocurable polydimethylsiloxane (PDMS)-based formulations for liquid crystal display masked stereolithography (LCD-MSLA) and evaluated formulation- and pigmentation-related differences in their physicochemical, mechanical, dimensional, chemical, and biological behaviors. Formulations with different PDMS/copolymer/silica ratios were assessed under unpigmented, natural-pigment, and synthetic-pigment conditions and compared with a commercial silicone reference. Mechanical behavior, thermal stability, color, solvent degradation, apparent porosity, dimensional stability during accelerated aging, fibroblast viability, Candida albicans biofilm metabolic activity, and ATR-FTIR functional-group conversion were evaluated. Conversion increased from 63%–77% after printing to 74%–89% after 80 °C/2 h post-curing, indicating further consumption of reactive functionalities. M1 showed the most favorable tear-resistance and elongation profile, whereas M2 exhibited the lowest apparent porosity and lowest numerical RMSE among experimental formulations during aging. Natural-pigment conditions generally showed higher fibroblast viability than synthetic-pigment counterparts; however, all material-exposed groups remained below the 70% viability threshold in the indirect-contact assay; pigment type did not significantly affect C. albicans biofilm metabolic activity within formulations. Overall, formulation composition strongly influenced material performance, with M1 and M2 showing complementary mechanical and dimensional/microstructural advantages, supporting further optimization for personalized maxillofacial prosthetic applications.