Effect of three different pastes on remineralization of initial enamel lesion: an in vitro study

Dental caries in enamel is unique as enamel is both acellular and avascular. Fluoride is one of the most effective remineralizing agents in caries prevention. The purpose of the study was to assess whether nano-hydroxyapatite and CPP-ACP can be used as an alternative to fluoride for remineralization of early carious lesions.

Initial artificial carious lesions were prepared in enamel with demineralization solution. The treatment materials used as remineralizing agents were Nano-hydroxyapatite (10%), CPP - ACP (10%), NaF (1000 ppm) and Deionized water (negative control). Surface microhardness (SMH) measurements were performed before/after demineralization and after 3, 6, 9 and 12 days of pH cycling and the percentage surface microhardness recovery (%SMHR) was calculated. The specimens were then examined by scanning electron microscope.

Percentage surface microhardness recovery of nano-hydroxyapatite and fluoride was significantly greater than CPP - ACP and negative control. There was no significant difference of %SMHR between n-HA and fluoride at different time periods in the pH cycling. SEM analysis revealed n-HA particles were deposited on the demineralized enamel surface which formed a new surface layer. When observed under SEM CPP - ACP failed to show any significant surface remineralization while surface globular crystal depositions with multiple discrete porosities were evident with fluoride.

It was concluded that nano-hydroxyapatite and fluoride had the potential to remineralize initial enamel lesions. CPP - ACP can be used as an effective adjunct to fluoride therapy but cannot be used as an alternative to fluoride.