The study aimed to investigate the rechargeability of ion-releasing dental material specimens immersed in distilled water for 25 months, which depleted their ion-releasing ability. Four restorative dental materials (alkasite composite, giomer, glass-ionomer, and composite material) presented with 24 specimens were studied after topical treatment with a concentrated fluoride gel. The effect of resin coating on the ion uptake and release was investigated on additional 42 specimens of restorative dental materials with coatings. The composite materials were coated with two adhesive systems, whereas the glass-ionomer was coated with the special coating resin. After topical fluoride exposure, ion release and specimen mass were measured at 1, 2, 3, 4, 5, 6, 7, and 14-day intervals using an ion-selective electrode and an analytical balance, respectively. The cumulative fluoride levels for the uncoated specimens of alkasite composite were significantly higher than those of giomer and glass-ionomer cement, with no statistically significant difference between the latter two materials. The conventional composite had the lowest cumulative concentration of fluoride ions (p < 0.05). The adhesive systems affected the fluoride recharge and reduced the ion concentrations absorbed by the specimens. Specimens coated with universal adhesive showed significantly higher ion release compared to universal fluoride-releasing adhesive or special coating resin for glass-ionomers (p < 0.05). No statistically significant change in specimen mass was observed during the 14-day period. Surface coating with adhesive systems as well as special coating resin for glass-ionomers affects the fluoride recharge process.

Single-shade and simplified-shade resin composites are designed to simplify clinical application through enhanced color adjustment potential. However, compositional modifications used to simplify shade selection may affect the physicochemical and mechanical properties of these composites, especially during extended water exposure, which occurs in the oral cavity. This study aimed to evaluate the degree of conversion, water sorption, solubility, and microhardness of two single-shade composites (Omnichroma and Essentia Universal), one simplified-shade composite (Tetric Plus), and a conventional composite (Tetric Prime) as a reference material. Disk-shaped specimens (d = 6 mm, h = 2 mm) were stored in distilled water at 37 °C for 3 months to evaluate water sorption and solubility. Vickers microhardness was measured before and after 3 months of water immersion. Degree of conversion was evaluated immediately and after 1 and 3 days. The single-shade composite Omnichroma exhibited the highest degree of conversion, but also the highest water sorption (21.7 μg/mm³), and was the only material that showed a positive solubility value (2.9 μg/mm³). In contrast, the reference composite showed the highest microhardness (51.8–60.2 VH). Omnichroma and Tetric Plus demonstrated lower microhardness than the reference material, whereas Essentia Universal showed significantly lower microhardness (38.4–42.1 VH) despite nominally high filler content. These findings indicate that degree of conversion, water sorption, solubility, and microhardness differed among the tested products and appeared to depend on their specific composition rather than on the color-adjustment concept alone.