Clinical evidence of caries prevention by hydroxyapatite: An updated systematic review and meta-analysis

Objectives: A systematic review and meta-analysis were undertaken to update our 3-year-old meta-analysis to include RCTs, in vivo, and in situ clinical evidence that showed hydroxyapatite in oral care products can reduce dental caries. Data: Using the PICO guide, published clinical trials were searched where subjects (P) of all ages, with primary, mixed or permanent dentitions, using toothpastes, mouthwashes or gels containing hydroxyapatite as an active ingredient (I) were compared to subjects who used placebo or no intervention, or fluoride-containing positive controls (C), and the outcomes (O) were direct measurement of reduced dental caries or suitable proxy for reduced caries risk. Sources: PubMed, Scopus, EMBASE, and Web of Science databases were searched using search terms from previous searches. Study selection: All authors collectively agreed which studies to include after applying the exclusion/inclusion criteria. Eighteen studies were retrieved and analyzed. The studies were graded according to a National Institutes of Health grading system. Three authors decided on the final list of publications suitable for meta-analysis, and the meta-analysis was carried out using the public domain R statistical program. Results: After applying more specific inclusion criteria and assessment, out of 18 retrieved studies, 5 clinical trials and 8 in situ trials were included in the meta-analysis. Conclusions: The evidence for the effectiveness of fluoride-free, hydroxyapatite-containing oral care products in reducing dental caries, both from RCTs and in situ clinical trials, has expanded. More studies now show that hydroxyapatite is effective as an anti-caries active ingredient in the absence of fluoride. Clinical significance: As a sole active ingredient, considered safe if swallowed, hydroxyapatite is an ideal substitute for fluoride in toothpaste and mouthwash tailored for young children, and new data as presented in this review, demonstrated that hydroxyapatite-based oral care products can be used by people of all ages.