Synergistic biomineralization of dentin driven by polar amino acids for dentin tubule occlusion

Dentin hypersensitivity, caused by exposed dentinal tubules, remains a significant clinical challenge. Conventional biomineralization using hydroxyapatite (HAP) often fails to achieve rapid nucleation and durable tubule occlusion. This study aims to develop a biomimetic mineralization strategy that leverages the synergistic interplay of specific polar amino acids to actively direct HAP deposition and enhance dentin occlusion efficacy.

Mineralization kinetics of isolated and combined polar amino acids were quantitatively evaluated to identify the optimal templating conditions for HAP nucleation. The optimized combination of (tyrosine and lysine) with HAP was applied in vitro to demineralized dentin models for 1 to 7 days. The efficacy of tubule occlusion, structural integration, and chemical stability was systematically characterized using scanning electron microscopy, focused ion beam-transmission electron microscopy, and rigorous acid-challenge assays.

The combination of positively charged and neutral polar amino acids synergistically accelerated HAP nucleation kinetics. In vitro application promoted rapid, dense, and deep occlusion of dentinal tubules. Crystallographic analysis confirmed the formation of a structurally integrated mineralized layer with strong chemical homology to native dentin (Ca/P ratio: 1.67 vs. 1.72). Moreover, the layer maintained significant occlusion integrity following prolonged acid challenges.

This biomimetic mineralization paradigm, driven by a synergistic combination of polar amino acids, overcomes the limitations of passive HAP filling by achieving rapid, deeply integrated, and chemically stable dentinal tubule occlusion. It provides a highly translatable foundation for the development of advanced desensitizing biomaterials.