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, thirty bovine dentin discs were randomly divided into three groups with ten specimens each: group A, a test toothpaste (HAP, potassium citrate and NaF), group B, a control toothpaste (HAP and NaF), and group C, a placebo toothpaste (NaF only). After 3 and 7 days of simulated brushing, tubule occlusion and mineralized layer formation was assessed using Scanning electron microscopy (SEM). 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. Data were analyzed using ANOVA to compare differences between groups, with a significance level set at p < 0.05. RESULTS: In the in-vitro study, the HAP-Citrate complex toothpaste demonstrated rapid and effective occlusion. After 3 and 7 days, it achieved a dentinal tubule occlusion rate of 96.0 ± 2.1% and 99.7 ± 0.7%, significantly surpassing the placebo group (43.5 ± 10.1% and 76.4 ± 7.3%, respectively; p < 0.05). Notably, the HAP-Citrate complex exhibited superior deep-sealing capabilities compared to the standard HAP control toothpaste. At day 7, the HAP-Citrate group showed an intratubular occlusion depth of more than 40 μm (vs. 13 μm in the HAP control) and formed a surface mineralized layer of more than 5 μm thick (vs. 1 μm in the HAP control). In the clinical trial, the HAP-citrate toothpaste showed significant DH relief, with Schiff and Yeaple score improvements of 21.39% and 100.85% respectively at 8 weeks compared to placebo (p < 0.05), comparable to the 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.