Impact of 1,500 ppm NaF solution at different pH levels on the mechanical and physicochemical properties of CAD-CAM...

Commercial toothpaste contains 1,500 ppm NaF to prevent caries; however, the effect of NaF on tooth restorative materials is not fully understood. This study investigated the impact of a 1,500 ppm NaF solution at different pH levels on the mechanical and physicochemical properties of CAD-CAM materials. Aqueous 1,500 ppm NaF solutions were prepared at pH levels 3, 5, and 7. Four CAD-CAM blocks -lithium disilicate glass, feldspathic porcelain, polymer-infiltrated ceramic network, and resin composite- were immersed in the solutions at 37°C for 10 days. Samples were evaluated for surface roughness, flexural modulus, strength, Vickers hardness, and water sorption/solubility. Results indicated that NaF solutions dissolved silica components, increasing surface roughness and water solubility and reducing hardness, especially at lower pH levels. Flexural properties remained mostly unchanged. These findings suggest that acidic NaF solutions more strongly degrade the surface properties of CAD-CAM materials.