Evaluation of experimental resin infiltrant containing nanohydroxyapatite on color stability and microhardness in demineralized enamel.

OBJECTIVE

The aim of the study was to evaluate the effect of the addition of 10% nanohydroxyapatite in an experimental resin infiltrant on color stability and mineral loss.

MATERIAL AND METHODS

Bovine enamel blocks were randomized into five groups (n = 27/group): SE (sound enamel); ICL (initial caries lesion); I (Icon®); E (experimental infiltrant); EH (experimental infiltrant containing 10% nanohydroxyapatite). Color evaluation (n = 15) was performed and CIELab* values were obtained at points T (baseline), T (14 days immersed on coffee solution), and T (28 days immersed) and data were calculated ∆E, ∆W, ∆L*, ∆a*, and ∆b*. Cross-sectional microhardness (n = 12) was performed and lesion area (∆S) was calculated. Images were obtained with polarized light optical microscopy at 40 × magnification (n = 5).

RESULTS

In color stability results, there was significant difference between time (14 and 28 days); ICL demonstrated significant difference among treated groups in all measures (∆L*, ∆a*, ∆b*, ∆E, ∆W) regardless of time; I and E demonstrated similar behavior on those measures and EH differed from I in ∆L*. For ∆S, ICL group showed a significant difference compared to I and EH groups, but did not differ from E.

CONCLUSION

The nanohydroxyapatite incorporation suggested an effective mineral recovery on initial caries lesion in depth; however, it showed high color variation, such as Icon. In terms of ∆S, I and EH had lower mineral loss, suggesting a reinforcement on initial caries lesion.

CLINICAL RELEVANCE

Commercial and experimental infiltrants containing nanohydroxyapatite present low color stability and might reinforce mineral in initial caries lesion.