Comparative Efficacy of Hydroxyapatite Toothpastes for Initial Caries Remineralization

Objectives: Nanohydroxyapatite (nanoHAP) in oral care formulations has been reported to serve as a reservoir for calcium and phosphate ions when applied intraorally. With the growing interest in non-fluoride products, the use of nanoHAP-containing toothpaste could serve as a favorable fluoride alternative for caries prevention and remineralization. The aim of this in vitro study was to compare the efficacy of various toothpaste formulations containing nanoHAP or fluoride in remineralizing initial caries lesions. Our null hypothesis was that the initial caries remineralization potential of the various toothpaste formulations would not differ significantly.
Methods: One hundred eighty bovine enamel blocks were randomly assigned to nine treatment groups (n=20): Crest Regular (1100ppm fluoride), ClinPro (5000ppm fluoride), Fygg (3.1% nanoXIM-nanoHAP), Boka (2.1% nanoXIM-nanoHAP), Dr. Jen (10% nanoHAP), Risewell Regular (10% microHAP), Risewell PRO (5% nanoXIM-microHAP), Just-Ingredients Powder (15% microHAP), and Revitin (CaCO3). Initial caries was produced on each block by 5-day demineralization in acidified gel. The lesion-bearing blocks were subjected to remineralization by daily pH-cycling consisting of a 2-minute acidic challenge, three 2-minute toothpaste treatments, and then storage in artificial saliva for the rest of the time for 14 days. Surface microhardness (SMH) of each lesion was measured before and after remineralization. Data was analyzed statistically (α<0.05) by paired t-test (intragroup comparisons) and ANOVA followed by Tukey tests (intergroup comparisons).
Results: Every product achieved a significant (p<.001) increase in SMH (remineralization). Percentage remineralization did not differ significantly among the toothpaste formulations, except Fygg toothpaste, which achieved significantly (p<.001) higher percent remineralization when compared to Boka, Dr. Jen, and Risewell Regular toothpastes.
Conclusions: This study demonstrated that nanoHAP toothpaste can effectively remineralize caries. Lack of significant difference in caries remineralization efficacy between nanoHAP and fluoride toothpaste suggests that nanoHAP toothpaste can serve as an alternative to fluoride for caries remineralization.