Biomimetic remineralization of human dentin using promising innovative calcium-silicates hybrid “smart” materials

Introduction: Biomimetic remineralization concept is an innovative method to remineralized interfibrillar and intrafibrillar dentine and to prevent demineralization of carious dentine with bioactive “smart” restorative materials. The chemical-physical properties and bioactivity of two innovative experimental “smart” biomaterials were assessed. The hypothesis was that these materials enhances remineralisation through the interaction of calcium-hydroxide from materials with phosphate from soaking fluids, in presence of silica. Methods: Hybrid materials composed by an experimental resin (HTP-M) and calcium-fluoro-aluminosilicate powder (named wTC-Ba or FTC-Ba) were prepared. Powders contained tri- and dicalcium-silicate, tricalcium-aluminate, calcium sulphate, barium sulphate. Sodium fluoride was included in FTC-Ba. HTP-M resin consisted of HEMA, TEGDMA, polyacrylic acid, EDMAB and camphorquinone. Vitrebond (resin-reinforced glass-ionomer cement) was tested as control. Calcium- and fluorine-releasing (ppm) and pH of soaking water were measured (after 3,24 hours, 7,14,28 days) using ion-selective electrodes. The solubility i.e. the percent difference in original mass of specimens (8mm diameter and 1.6mm thick) immersed in 15 ml of deionized water at 37 ◦C (ISO 6876) was evaluated after 24 hours. The water uptake i.e. the percent change in original weight by specimens immersed in 15 ml of deionized water at 37 ◦C (ISO 6876) was assessed at 1,6,24 hours. The bioactivity (apatite formation ability) was assessed by ESEM-EDX and micro-Raman after soaking in simulated body fluid. Results: All the experimental materials release calcium (Table 1) and basify the soaking medium (pH 8.2-10) (tab.3). Vitrebond resulted unable to release calcium. Both experimental Fluoride containing materials released fluoride more than Vitrebond, p < 0.01 (Table 2). Apatite formation was observed only on the experimental materials. A correlation was observed between calcium release and solubility. Conclusions: Calcium-fluoro-aluminosilicate composite resins have remineralizing ability. The ion release promotes/allows the formation of bone-like carbonate-apatite and/or fluorapatite with a great advantage for dentin remineralisation and a potential use as sealants and adhesive clinical applications.