Objectives: To evaluate the desensitizing effect of nano-hydroxyapatite (n-HAP) on dentine hypersensitivity (DH). Sources: Seven electronic databases were searched on April 27, 2018. Study selection: Randomized clinical trials (RCTs) were included based on the PICO strategy: Participants - Humans with DH; Intervention - n-HAP-containing desensitizing; Comparison - n-HAP-free treatments or placebo/negative control; and Outcomes - relief of DH. The risk of bias was classified by the Cochrane guidelines. Five meta-analyses were performed to evaluate the efficacy of n-HAP with regard to pain assessment stimuli (primary outcome); comparison of n-HAP with other treatments or placebo/negative control, and effectiveness of at-home and in-office n-HAP use (secondary outcomes). The quality of the evidence was evaluated using the GRADE. Data: Six RCTs with 4 weeks of follow-up were included in the meta-analysis. For the primary outcome, n-HAP showed a better desensitizing effect for evaporative stimuli (SMD -1.09 [-1.24, -0.94], p < 0.00001) and tactile stimuli (SMD -0.93 [-1.42, -0.43]) than other treatments (p = 0.0002). However, there was no difference between n-HAP and other treatments for the cold stimuli (SMD -0.17 [-0.81, 0.48], p = 0.61). In an overall analysis, n-HAP-containing treatment showing the most significant desensitizing effect (SMD -0.93 [-1.19, -0.68], p < 0.00001) with a high quality of evidence for pooled results. In the secondary outcomes, n-HAP showed the best effect in the overall analysis (p < 0.05) with moderate quality evidence. Conclusions: The n-HAP-containing treatment showed better clinical performance than other treatments for DH relief. However, long-term follow-up RCTs are required in the future before definitive recommendations can be made. Clinical significance: Dentin hypersensitivity is a common global condition and its multifactorial etiology has led to the development of several treatments. The n-HAP-containing treatment showed greater DH relief when compared to other desensitizing agents, placebo or negative control.
