Enamel white spot lesions can remineralise using bio-active glass and polyacrylic acid-modified bio-active glass powders

Objective: To evaluate the potential of bio-active glass (BAG) powder and BAG containing polyacrylic acid (PAA-BAG) to remineralise enamel white spot lesions (WSL). Methods: 32 human enamel samples with artificial WSLs were assigned to 4 experimental groups (n = 8); (a) BAG slurry, (b) PAA-BAG slurry, (c) "standardised'' remineralisation solution (positive control) and (d) de-ionised water (negative control). Mechanical properties of enamel were assessed using surface and cross-section Knoop microhardness. Micro-Raman spectroscopy in StreamLine (TM) scan mode was used to scan lesion cross-sections. The intensity of the Raman phosphate peak at 959 cm(-1) was fitted and measured producing depth profiles analysed using a double-step fitting function. A further 20 samples (n = 5) were used to obtain 3D images of surfaces using non-contact white light profilometry permitting measurement of lesion step height in relation to the sound enamel reference level, and to scan the lesion surface using scanning electron microscopy (SEM). Data were analysed statistically using one-way ANOVA with Tukey's HSD post-hoc tests. Results: BAG, PAA-BAG and the remineralisation solution exhibited statistically significantly higher surface and cross-section Knoop microhardness compared to the negative control. Micro-Raman spectroscopy detected significantly higher phosphate content within the treated groups compared to the negative control group. Lesions' depth was not significantly reduced. SEM images revealed mineral depositions, with different sizes and shapes, within BAG, PAA-BAG and the positive control groups. Conclusion: BAG and PAA-BAG surface treatments enhance enamel WSL remineralisation, assessed by the resultant improved mechanical properties, higher phosphate content and morphological changes within the artificial lesions. (C) 2013 Elsevier Ltd. All rights reserved.