Dental surface restoration using Ca-caseinate bio/nano colloids: Converged roughness parameters reveal heterogeneous...

Dental erosion, the chemical dissolution of the tooth surface structures, is an increasing problem in the modern world due to growing trends toward acidic food consumption and can cause permanent dental hard tissue loss. A detailed understanding of the reactivity of dental surfaces to chemicals invading the oral cavity is necessary to devise effective countermeasures. We introduce the use of converged roughness parameters Sq_conv, i.e., roughness parameters calculated at a reduced field of view, to reflect the critical surface building blocks controlling the reactivity, as measured by white light vertical scanning interferometry. By analyzing Sq_conv maps and their histograms, we gain detailed spatiotemporal insights into the surface alterations during processes such as acidic tooth demineralization and remineralization of eroded dental surfaces, harnessing the potential of readily available, easy-to-apply Ca caseinate. Furthermore, the impact of fluoridation on the dental surface reactivity is investigated. We find that the reactivity of the dentine surface is inherently inhomogeneous, with rough surface features being more reactive to erosion/demineralization, remineralization, and fluoridation. Our data reveal that de- and remineralization are mechanistically reversible processes, and both are potentially inhibited by surface fluoridation. However, this can be avoided by utilizing fluoride addition during Ca caseinate remineralization in a combined approach to build up new material that is more resistant to acidic impact. We demonstrate that the growth of biomimetic hydroxyapatite during remineralization occurs at a rate 3 orders of magnitude slower than the demineralization.