Ultrastructural characterisation of young and aged dental enamel by atomic force microscopy.

Recent advances in atomic force microscopy (AFM) have allowed the characterisation of dental-associated biomaterials and biological surfaces with high resolution. In this context, the topography of dental enamel - the hardest mineralised tissue in the body - has been explored with AFM-based approaches at the microscale. 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 intermittent contact (AC mode) imaging, HA crystals were characterised in both transversal and longitudinal orientation (respect to surface plane) with high resolution in environmental conditions. The external enamel surface displayed the presence of a pellicle-like coating on its surface that was not observable on cleaned specimens. Acid-etching exposed crystals that were imaged and morphologically characterised in high resolution 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. 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.

A therapeutic shock propels Schwann cells to proliferate in peripheral nerve injury.

Damage to the peripheral nervous system (PNS) is a prevalent issue and represents a great burden to patients. Although the PNS has a good capacity for regeneration, regeneration over long distances poses several difficulties. Several recent studies have addressed Schwann cells' limited proliferative capacity; however, a solution has yet to be found. Here, we examine the effects of extracorporeal shock wave therapy (ESWT) on Schwann cell isolation, culture, and proliferation rate. The study conducted demonstrated that Schwann cells treated with ESWT had significantly improved isolation, culture, and proliferative capacities. These findings represent a solution to a significant problem that hospitals and health-care providers face every year: how to treat long distance damage to the PNS with the limited proliferative capabilities of Schwann cells. Although these findings are promising, further studies must be conducted to address the molecular mechanisms by which ESWT alters Schwann cells and the potential implications for peripheral nerve damage and other prevalent illnesses. This study is a review article. Referred literature in this paper has been listed in the references part. The datasets supporting the conclusions of this article are available online by searching the PubMed. Some original points in this article come from the laboratory practice in our research centers and the authors' experiences.