From Molecular Interactions to Clinical Potential: Harnessing Strontium–Calcium Polyelectrolyte Synergy in Dentin Biomimetic Dentin Repair and Mineralization

The study aimed to evaluate effects of calcium carbonate (CaCO 3 ) and strontium carbonate ( SrF₂ CaCO 3 ) polyelectrolyte-cation complexes on dentin adhesive bonding, mechanical properties and intrafibrillar mineralisation of dentinal collagen fibers. Following ethical approval, dentin discs were prepared from collected human premolars and treated with 1%SrF₂ CaCO 3 , 0.5%SrF₂ CaCO 3 , 2% SrF₂ CaCO 3 and distilled water for 15 days under controlled pH. Raman spectroscopy, transmission and scanning electron microscopy were performed to evaluate intrafibrillar mineralisation and topographical changes. Diffusional coefficient and density functional theory were calculated. Resin-dentin bond specimens were prepared and microtensile bond strength was measured. Statistical analysis was performed using a one-way ANOVA with subsequent post-hoc comparisons, with significance of p<0.05 . Raman spectroscopy demonstrated a concentration-dependent increase in dentin mineralisation, with enhanced phosphate and organic matrix signatures following SrF₂ CaCO 3 treatment. TEM and HRTEM confirmed organised intra- and extrafibrillar hydroxyapatite deposition, particularly in the 2% SrF₂ CaCO 3 group, showing aligned crystallites along the collagen axis and well-defined D-periodicity. SEM revealed progressive crystal elongation and surface densification with increasing concentration. Diffusion analysis indicated higher ionic mobility in modified groups, supported by DFT calculations showing increased Ca and P occupancy and crystallographic stability. µ-tensile testing demonstrated significantly improved bond strength in the 1% SrF₂ CaCO 3 and 2% SrF₂ CaCO 3 groups without compromising adhesive performance. The present study demonstrated the modification of dentinal surface using a range of concentrations of SrF₂ CaCO 3 as a multifunctional modifier indicating favourable bond strength and extensive crystallisation capability. The 2% SrF₂ CaCO 3 polyelectrolyte formulation has a significant potential for clinical application and offers a novel potential solution to address significant challenges in adhesive dentistry. Strontium/fluoride/calcium carbonate polyelectrolyte complexes promote biomimetic dentin remineralisation, enhance crystal organisation, and improve resin–dentin bond strength. This strategy offers a biologically guided approach to reinforce compromised dentin, potentially increasing the longevity and reliability of adhesive restorative procedures.