The study focuses on in vitro tracing of some fundamental changes that emerge in teeth at the initial stage of caries development using multiple approaches. The research was conducted on a mostly sound maxillary molar tooth but with a clearly visible natural proximal white spot lesion (WSL). Values of mineral density, reduced Young’s modulus, indentation hardness and creep as well as the molecular composition and surface microstructure of the WSL and bordering dentine area were studied. The results obtained were compared to those of sound enamel and dentine on the same tooth. A decrease of mechanical properties and mineral density both for the WSL and bordering dentine was detected in comparison to the sound counterparts, as well as increase of creep for the enamel WSL. Differences in molecular composition and surface microstructure (including the indenter impressions) were found and described. WSL induces a serious change in the state of not only the visually affected enamel but also surrounding visually intact enamel and dentine in its vicinity. The results provide the basis for future studies of efficacy of minimal invasive treatments of caries.

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Fissure caries in a form of brown spot lesion is a serious problem for patients. Having passed the dentine-enamel junction, cariogenic bacteria cause demineralization of dentine in its vicinity. Over time, the area of demineralization spreads deeper towards the pulp of the tooth, creating a gradient of strength characteristics in dentine. The aim of this work was to determine the mechanical properties and mineral density in the direction from the dentine-enamel junction to the dental pulp using nanoindentation and X-ray computed microtomography. The results can be used as control ones for the further research of remineralization techniques used in clinical practice.