Physicochemical, Mechanical, and Biological Characterization of a Sodium Fluoride-Functionalized Photopolymer Resin for 3D Printing and Its Potential Use as a Fluoride-Releasing Coating Material

Background: Three-dimensional printing has enabled the development of customized materials with additional functional properties. This study evaluated a photopolymerizable resin (Bio Scaffolds1) functionalized with sodium fluoride (NaF) to determine fluoride release and assess the effects of NaF incorporation on the physicochemical, mechanical, and biological properties of the material and its potential use as a surface coating. Methods: Control and experimental groups containing 3 wt%, 5 wt%, and 7 wt% NaF were fabricated using digital light processing (DLP). The samples were characterized by flexural strength, contact angle, Fourier-transform infrared spectroscopy, Raman spectroscopy, thermogravimetric analysis, degree of conversion, fluoride release, and cytotoxicity in human gingival fibroblasts using the MTT assay. Results: The 3 wt% NaF group exhibited the highest flexural strength (29.017 ± 7.033), whereas NaF incorporation reduced the degree of conversion, particularly in the NaF5% Y NaF7% groups (43.38 %± 16.47%, 46.70 %± 14.49%). Spectroscopic and thermogravimetric analyses showed that the main features of the polymer matrix were retained after NaF incorporation, although concentration-dependent changes were also observed. Fluoride release increased with NaF concentration, reaching 32.44, 57.55, and 85.40 ppm after 28 d for the 3%, 5%, and 7% NaF groups, respectively. Throughout the 14-day evaluation, the NaF-containing formulations maintained MTT metabolic activity comparable to that of the unmodified resin control under the tested conditions. Conclusions: The NaF-functionalized resin successfully released fluoride while maintaining no cytotoxicity under the evaluated conditions. The 3% NaF formulation provided the best balance between mechanical strength and fluoride release. However, validation of coating formation and enamel protection is required before clinical translation.