A bioactive radiopaque infiltrant for managing early enamel carious lesions - an in-vitro study.

OBJECTIVES: To develop a bioactive radiopaque infiltrant (BRI), compare its radiopacity and degree of conversion (DC%) to ICON, and evaluate its ion release, infiltration into artificial caries, and acid-resistant bioactivity. METHODS: BRI was prepared with 30% non-silanated fluoride-containing bioactive glass (FBG) and 70% radiopaque resin infiltrant (RI) comprising 2,2,2-tribromoethyl methacrylate, TEGDMA, and UDMA. Degree of conversion and radiopacity were measured via FTIR and digital radiography, with ICON as control. Artificial enamel lesions (n=10) were infiltrated with BRI (without HCl pre-conditioning) and divided into pH 4 and pH 7 immersion groups (n=5 each). Bioactivity was assessed by ISE, ICP-OES, XRD, and SEM. Penetration depth and mineral changes were tracked using X-ray microtomography (XMT) at baseline, 8 weeks, and 23 weeks. RESULTS: BRI showed significantly higher DC (84.9%) than ICON (74%) and radiopacity of 3.2 mm Al equivalent (vs. 2.0 mm for enamel). Sustained Ca²⁺ and F⁻ release over 23 weeks was greater at pH 4 than pH 7. XRD and SEM confirmed hydroxyapatite formation on infiltrated surfaces, while XMT revealed radiopacity increases consistent with progressive mineral deposition. CONCLUSION: A 30% FBG loading maintained both resin penetrability and sustained bioactivity. CLINICAL SIGNIFICANCE: This novel BRI enables radiographic monitoring of proximal early caries while providing acid-buffering protection, offering a potential advance over conventional non-bioactive infiltrants.