The effect of nanohydroxyapatite serum and toothpaste on prevention of enamel demineralization around orthodontic brackets: an in vitro study.

Abstract

Objectives: This prospective in vitro study aimed to evaluate the preventive effects of nanohydroxyapatite (nanoHAP), delivered as serum and toothpaste, in comparison with fluoride toothpaste, on enamel demineralization and surface microhardness around orthodontic brackets.

Materials and methods: Forty-eight human enamel specimens were randomly allocated to three groups (n = 16). In Group 1, samples were brushed twice daily with fluoride toothpaste (1450 ppm) for 30 days, and nanoHAP serum (30% concentration) was applied during the final 10 days. Group 2 received only nanoHAP-containing toothpaste (10% concentration), while Group 3 was treated with fluoride toothpaste (1450 ppm) throughout the entire period. Orthodontic brackets were bonded to all specimens prior to a 14-day pH cycling regimen. Knoop microhardness was assessed on the buccal enamel surface at occlusal and cervical regions, 50 and 150 μm from the bracket margins, at depths of 10, 50, and 90 μm, without removing the brackets. DIAGNOdent was used for non-invasive enamel surface assessment before and after pH cycling. Data were analyzed using ANOVA and Duncan's post hoc test (α = 0.05).

Results: Significant differences were observed based on treatment material, positions, and their interactions (P < 0.05). Group 1 (nanoHAP serum + fluoride) showed significantly higher microhardness values and lower DIAGNOdent scores compared to Groups 2 and Group 3, indicating superior protection against demineralization.

Conclusions: Short-term application of nanoHAP serum for 10 days, in combination with regular fluoride toothpaste, significantly reduces enamel demineralization around orthodontic brackets in vitro and may be a promising adjunctive strategy for preventing white spot lesions during orthodontic treatment.