IADR Abstract Archives
Human Dental Enamel Crystallite Orientation Varies Periodically Within Prisms
Objectives: Presently, very little is known about the variation or organisation of crystallite orientations within individual prisms in human dental enamel. This intra-prismatic hierarchical structural level warrants investigation to understand how crystallites grow to dictate the overall hierarchy. This study aimed to map the spatial variation in the direction of dental enamel crystallites within prisms to better understand the role of intra-prismatic structural variations.
Methods: Fast scanning synchrotron X-ray nanodiffraction microscopy (S-XRDM) at the ID01 beamline of the European Synchrotron Radiation Facility was utilised to map the spatial distribution of enamel integrated (0 0 2) Bragg reflection intensity and crystal lattice-tilt. Bragg intensity and lattice-tilt mapping provide information regarding the relative quantity of crystallites oriented along the long axes of prisms and the angular deviation of crystal plane(s) from this orientation, respectively. The S-XRDM results were compared with micrographs obtained by quantitative backscattered electron microscopy.
Results: We identified periodic intra-prismatic bands of high Bragg intensities (HIs) and high tilt angles (HTs) oriented along the long axes of prisms and measuring 1.33 ± 0.26 μm and 2.10 ± 0.28 μm in width, respectively, indicating periodic deviations in the direction of crystallites within prisms. The dimensions, quantities and locations of the HI and HT bands varied as a function of tooth location. These intra-prismatic structural features were more prominent near the dentine and enamel surface compared to the enamel bulk.
Conclusions: The results documented here indicate that, contrary to previous established assumptions, groups of crystallites may change directions periodically within prisms. These results open new possibilities for modelling this hierarchically oriented and aligned mineralised tissue, that may aid optimisation of design and development of high-performance dental materials with identical physical and chemical properties to dental enamel.
Methods: Fast scanning synchrotron X-ray nanodiffraction microscopy (S-XRDM) at the ID01 beamline of the European Synchrotron Radiation Facility was utilised to map the spatial distribution of enamel integrated (0 0 2) Bragg reflection intensity and crystal lattice-tilt. Bragg intensity and lattice-tilt mapping provide information regarding the relative quantity of crystallites oriented along the long axes of prisms and the angular deviation of crystal plane(s) from this orientation, respectively. The S-XRDM results were compared with micrographs obtained by quantitative backscattered electron microscopy.
Results: We identified periodic intra-prismatic bands of high Bragg intensities (HIs) and high tilt angles (HTs) oriented along the long axes of prisms and measuring 1.33 ± 0.26 μm and 2.10 ± 0.28 μm in width, respectively, indicating periodic deviations in the direction of crystallites within prisms. The dimensions, quantities and locations of the HI and HT bands varied as a function of tooth location. These intra-prismatic structural features were more prominent near the dentine and enamel surface compared to the enamel bulk.
Conclusions: The results documented here indicate that, contrary to previous established assumptions, groups of crystallites may change directions periodically within prisms. These results open new possibilities for modelling this hierarchically oriented and aligned mineralised tissue, that may aid optimisation of design and development of high-performance dental materials with identical physical and chemical properties to dental enamel.