Abstract Enamel prism is the main microstructural unit of mammalian enamel which composed
of hundreds of bioapatite nanocrystals. Prism structure plays a key role in the excellent
mechanical performance of dental enamel during millions of chewing cycles without
significant remodeling. Thus, quantitative understanding of prism architecture is
of utmost importance for biomechanical materials design. To characterize enamel prism
orientation quantitatively, a novel image processing method has been developed. Our
method is based on scanning electron microscopy images of etched enamel surface and
consists of an ellipse fitting procedure, which provides a numerical approximation
of prism shape and orientation in the studied cross section. The obtained analytical
data allow to construct color coded orientation maps, which provide quick and useful
insight into the microstructure of enamel. Besides striking visualization, orientation
maps allow to extract and plot the rich information on the azimuthal and inclination
angles of the prisms as function of location. Numerical data on prism arrangement
can be analyzed using statistical tools over large areas, which paves the way towards
quantifying comparative investigation of prism arrangement either in dentistry research
or evolution biology. The application of the method is demonstrated for a distal?mesial
cross-section of sound human tooth enamel. Highlights Scanning electron microscopy
images of etched enamel surface are analyzed using ellipse fitting. Geometrical parameters
of the fitted ellipses provide numerical data of thousands of prisms. Prism arrangement
is visualized on color coded orientation maps and analyzed using statistical tools.
