Zinc-calcium-fluoride bioglass-based innovative multi-functional dental adhesive with thick adhesive-resin film thickness.

Apart from producing high bond strength to tooth enamel and dentin, a dental adhesive with bio-therapeutic potential is clinically desirable, aiming to further improve tooth-restoration longevity. In this laboratory study, an experimental two-step universal adhesive, being referred to as Exp_2UA, applicable in both etch-and-rinse (E&R) and self-etch (SE) mode and combining a primer, containing 10-methacryloyloxydecyldihydrogen phosphate (10-MDP) as functional monomer with chemical binding potential to hydroxyapatite, with a bioglass-containing hydrophobic adhesive resin, was multifactorially investigated. In addition to primary property assessment, including measurement of bond strength, water sorption, solubility and polymerization efficiency, the resultant adhesive-dentin interface was characterized by TEM, the filler composition analyzed by EDS and the adhesive's bioactive potential estimated by measuring long-term ion release and assessing its anti-enzymatic and anti-bacterial potential. Four representative commercial adhesives served as reference/controls. Application in both E&R and SE mode resulted in durable bonding performance to dentin, as evidenced by favorable 1-year aged bond-strength data and a tight interfacial ultra-structure that, as examined by TEM, remained ultra-morphologically unaltered upon 1-year water-storage aging. TEM revealed a 20-µm thick hydrophobic adhesive layer with a homogeneous bioglass filler distribution. Adequate polymerization conversion resulted in extremely low water sorption and solubility. In-situ zymography revealed reduced endogenous proteolytic activity, while Streptococcus mutans biofilm formation was inhibited. In conclusion, the three/two-step E&R/SE Exp_2UA combines high bonding potential and bond-degradation resistance with long-term ion release rendering the adhesive anti-enzymatic and anti-bacterial potential.