Chitosan-bioglass complexes promote subsurface remineralisation of incipient human carious enamel lesions

Objectives To test the in vitro subsurface remineralisation efficacy of chitosan-bioglass complex on artificial white spot lesions.Methods: 64 artificial enamel white spot lesions were created by acidic gel and equally separated for static and 7d pH-cycling models. In each model, samples were assigned to 4 groups: (1) bioglass application on chitosan pre-treated lesions (CB); (2) chitosan-bioglass slurry (CBS); (3) "standard" remineralisation solution (RS - positive control); (4) deionised water (NC - negative control). Before each treatment using remineralising agents, 3-minute pellicle was formed on lesions' surfaces. Mineral content changes, surface and subsurface microhardness and ultrastructure were evaluated by Raman intensity mapping, Knoop microhardness and scanning electron microscopy, respectively. Data were statistically analysed using one-way ANOVA with Tukey's test (p < 0.05 is considered as significant). Results Chitosan-bioglass complexing was found to exhibit greater mineral regain and recovery of surface and subsurface microhardness compared to "standard" remineralisation solution and control groups, after static and dynamic pH-cycling remineralisation for 7 days (p < 0.05). Specifically, dense precipitations with Ca/P ratios similar to that in pure hydroxyapatite (HA) were observed on surfaces and subsurfaces which filled the porosities in the dynamic pH-cycling group, leaving no prismatic enamel structure exposed. Conclusions Chitosan-bioglass complex is positive in promoting subsurface mineral deposition in spite of the presence of a short-term salivary pellicle. Clinical significance chitosan-bioglass complexing may provide an alternative clinical strategy in remineralising early enamel carious lesions as well as desensitizing exposed porous vital dental tissues clinically.