Synergistic Efficacy of a Biomimetic Hydroxyapatite-Citrate Complex for Dentin Hypersensitivity: An In Vitro and Clinical Study

Background To evaluate the synergistic effect of a novel Hydroxyapatite(HAP)-Citrate complex toothpaste on dentinal tubule occlusion and the relief of dentine hypersensitivity (DH). Methods For the in vitro study, bovine dentin discs were treated with a test toothpaste (HAP, potassium citrate and NaF), a control toothpaste (HAP and NaF), and a placebo toothpaste (NaF only) for 3 and 7 days. Tubule occlusion and mineralized layer formation was assessed using Scanning electron microscopy (SEM). For the clinical study, a 12-week, double-blind, randomized trial involving 129 subjects compared the test toothpaste to a bioactive glass-based positive control toothpaste and a placebo. The severity of DH, indicated by Schiff (air) and Yeaple (tactile), was evaluated at baseline, 2, 6, 8, and 12 weeks, with the last 4 weeks being a washout period. Results The HAP-Citrate complex toothpaste demonstrated significantly higher surface tubule occlusion rates, deeper intratubular occlusion, and thicker mineralized layer compared to HAP/NaF-only and placebo groups (p < 0.05) in in-vitro studies. In the 12-week clinical study, the HAP/Citrate toothpaste exhibited higher DH relief, with significant improvement in Schiff and Yeaple scores at 6 and 8 weeks compared to placebo (p < 0.05). Its desensitizing performance was comparable to the bioactive glass-based positive control. Notably, the reduction in air-stimulus sensitivity was sustained at the 12-week follow-up, four weeks after the subjects discontinued the product use. Conclusions The novel HAP-citrate complex toothpaste can build deep, protective mineral seal on dentin tubules. Its clinically proven performance makes it a superior, science-backed choice for effective sensitivity management. Registry: Chinese Clinical Trial Registry, TRN: ChiCTR2500115399, Registration date: 25 December 2025.