Browsing by Author "Schuh, Christina MAP"

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    Microfabrication-based engineering of biomimetic dentin-like constructs to simulate dental aging
    (2024) Álvarez Martínez, Simón Esteban; Morales, José; Tiozzo-Lyon, Paola; Berrios Segovia, Pablo Germán; Barraza Montenegro, Valentina Maríia; Simpson, Kevin; Ravasio, Andrea; Monforte Vila, Xavier; Teuschl-Woller, Andreas; Schuh, Christina MAP; Aguayo Paul, Sebastián
    Human dentin is a highly organized dental tissue displaying a complex microarchitecture consisting of micrometer-sized tubules encased in a mineralized type-I collagen matrix. As such, it serves as an important substrate for the adhesion of microbial colonizers and oral biofilm formation in the context of dental caries disease, including root caries in the elderly. Despite this issue, there remains a current lack of effective biomimetic in vitro dentin models that facilitate the study of oral microbial adhesion by considering the surface architecture at the micro- and nanoscales. Therefore, the aim of this study was to develop a novel in vitro microfabricated biomimetic dentin surface that simulates the complex surface microarchitecture of exposed dentin. For this, a combination of soft lithography microfabrication and biomaterial science approaches were employed to construct a micropitted PDMS substrate functionalized with mineralized type-I collagen. These dentin analogs were subsequently glycated with methylglyoxal (MGO) to simulate dentin matrix aging in vitro and analyzed utilizing an interdisciplinary array of techniques including atomic force microscopy (AFM), elemental analysis, and electron microscopy. AFM force-mapping demonstrated that the nanomechanical properties of the biomimetic constructs were within the expected biological parameters, and that mineralization was mostly predominated by hydroxyapatite deposition. Finally, dual-species biofilms of Streptococcus mutans and Candida albicans were grown and characterized on the biofunctionalized PDMS microchips, demonstrating biofilm-specific morphologic characteristics and confirming the suitability of this model for the study of early biofilm formation under controlled conditions. Overall, we expect that this novel biomimetic dentin model could serve as an in vitro platform to study oral biofilm formation or dentin–biomaterial bonding in the laboratory without the need for animal or human tooth samples in the future.
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    Ultrastructural characterisation of young and aged dental enamel by atomic force microscopy
    (2022) Leiva Sabadini, Camila Andrea; Schuh, Christina MAP; Barrera Rojas, Nelson Patricio; Aguayo Paul, Sebastián
    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.