Comparative Analysis of Confocal Microscopy Objective Magnifications on Dental Microwear Texture Analysis. Implications for Dietary Reconstruction in Caprines

Dental microwear texture analysis (DMTA) is a proxy used for characterising vertebrate palaeodiets in archaeological and palaeontological studies through the acquisition of 3D micro-texture height maps using confocal microscopy. Unlike previous techniques, DMTA is a quantitative method and enables reproducibility and repeatability. However, researchers working on DMTA have used different measurement equipment, softwares and microscopy objectives (magnification and numerical aperture). In the case of the objectives, DMTA widely uses 100x objective magnification, although successful applications at 20x and 50x have been reported. This study investigates the discriminative abilities at different magnifications, and discuss the advantages of each one. For this purpose, a set of 94 modern domestic and wild goats were analysed at 10x/0.30, 20x/0.45, 50x/0.80, and 100x/0.80. Our results demonstrate that all magnifications can discern between the seven groups of modern goats. However, 10x and 20x magnifications showed lower discrimination compared to 50x and 100x. Discriminant analyses revealed progressively refined distinctions at higher magnifications, with 100x yielding the best results. These findings support prior research suggesting the efficacy of 100x magnification in DMTA as the most optimal choice. However, it should be emphasised that high magnification and numerical aperture can present some limitations. Depending on the characteristics of the material studied and the microscope, an objective with lower magnification and numerical aperture may me more suitable.