Ultrastructural characterisation of young and aged dental enamel by atomic force microscopy
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Date
2022
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Abstract
Recent advances in atomic force microscopy (AFM) have allowed the characterisation of dental-associated biomaterials and biological surfaces with high-resolution and minimal sample preparation. In this context, the topography of dental enamel – the hardest mineralised tissue in the body – has been explored with AFM-based approaches at the micro-scale. With age, teeth are known to suffer changes that can impact their structural stability and function; however, changes in enamel structure because of ageing have not yet been explored with nanoscale resolution. Therefore, the aim of this exploratory work was to optimise an approach to characterise the ultrastructure of dental enamel and determine potential differences in topography, hydroxyapatite (HA) crystal size, and surface roughness at the nanoscale associated to ageing. For this, a total of six teeth were collected from human donors from which enamel specimens were prepared. By employing AC mode imaging, HA crystals were characterised in both transversal and longitudinal orientation with high-resolution in environmental conditions. Sound superficial enamel displayed the presence of a pellicle-like coating on its surface, that was not observable on cleaned specimens. Acidetching exposed crystals that were imaged and morphologically characterised in highresolution at the nanoscale in both the external and internal regions of enamel in older and younger specimens. Our results demonstrated important individual variations in HA crystal width and roughness parameters across the analysed specimens; however, an increase in surface roughness and decrease in HA width was observed for the pooled older external enamel group compared to younger specimens. Overall, high-resolution AFM was an effective approach for the qualitative and quantitative characterisation of human dental enamel ultrastructure at the nanometre range. Future work should focus on exploring the ageing of dental enamel with increased sample sizes to compensate for individual differences as well as other potential confounding factors such as behavioural habits and mechanical forces.
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Atomic force microscopy, Dentistry, Biomaterials