Targeted enamel remineralization with mineral-loaded starch particles.

BACKGROUND: Noninvasive caries treatments work topically, which may limit efficacy. The authors hypothesized that an alternative approach using mineral-loaded particles designed to target the subsurface of noncavitated caries lesions could be advantageous. This study shows in vitro proof-of-concept. METHODS: Mineral-loaded cationic starch (MLCS) particles were prepared, containing calcium, phosphate, and fluoride to provide fluoride-plus (FP) and fluoride-free (FF) alternatives. Particles were characterized for mineral loading and release. MLCS-FP and -FF treatments vs 1,000 ppm fluoride and deionized water controls were evaluated on natural smooth-surface caries lesions (n = 15 per group) after a 20-day protocol with immersion in artificial saliva with amylase and acid challenge. Treatment efficacy was assessed by microcomputed tomography, labeled fluorescence imaging, and blinded qualitative visual assessment. RESULTS: In aqueous suspension and absent amylase, particles showed sustained mineral ion release. The tomographic evaluation found significant (multivariable regression analysis, P < .05) restoration of lesion mineral density by MLCS-FP and MLCS-FF (42.9% and 38.6%, respectively) vs fluoride and negative controls (7.4% and -18%, respectively), particularly for the lesion subsurface (13.8% [13.0%], 15.9% [9.4%], -2.2% [7.3%], and -1.8% [4.0%] relative hydroxyapatite density for 0.25 through 0.45 μm lesion depth for FP, FF, fluoride, and deionized water, respectively). Visually reduced white opacity (Fisher exact test, P = .038, MLCS-FF vs fluoride) and labeled fluorescence (analysis of variance, P < .05 for MLCS-FF [75.4%], MLCS-FP [75.7%], fluoride [64.1%] vs negative control [-0.2%]) were observed. CONCLUSIONS: These foundational studies show the potential of mineral-loaded starch particles to remineralize enamel as a new approach to treating early caries by subsurface targeted mineral delivery. The in vitro study results indicated that targeted particles improved treatment efficacy, with the data supporting the superiority of MLCS-FP and FF formulations over control conditions for subsurface remineralization and visual esthetic.