IADR Abstract Archives
2D Texture Mapping of Dental Enamel Affected by MMP-20 Mutation
Objectives: To map enamel ultrastructure including crystallographic texture and orientation, and density of a tooth affected by hypomature Amelogenesis Imperfecta (AI) with known MMP-20 mutation. Our aim is to correlate the quality and quantity of enamel tissue to the mode of inheritance of AI to better inform diagnosis and bespoke treatment regimens.
Methods: An MMP20-affected permanent canine tooth and its corresponding control were scanned intact by a high resolution micro computed tomography (μ-CT) for quantification of mineral density and identification of regions within the tooth where the mutation has most affected enamel structure. Teeth were then cut to obtain 360 µm buccolingual sections to be scanned by synchrotron X-ray diffraction (SXRD) at XMaS beamline at the European Synchrotron Radiation Facility. 2D diffraction images were azimuthally integrated along the 002 plane; subsequently peak fitting was performed, and contour maps for texture analysis for the whole crown were generated via Mofit software. Quantification of enamel mineral density was carried out within specified region of interests using Fiji.
Results: MMP20-affected enamel presented lower mineral density of 1.66 g/cm3 compared to 2.31 g/cm3 in healthy control tooth. Contour texture maps revealed two population of crystallites in both specimens, with angular separation of 35○. SXRD analysis of enamel texture showed that population 1 had the predominant contribution with a clear difference in texture magnitude between the AI affected tooth and healthy enamel, where MMP-20 affected enamel showed generalized lower texture across enamel thickness with the most affected regions being at the buccal part of the cusp and the cervical region. Whereas population 2 showed higher texture comparable to healthy enamel.
Conclusions: MMP-20 is a critical protein for proper crystallite organization across the bulk of the enamel. Its mutation leads to significant decrease in mineral density that can be correlated to decreased crystallite texture.
Methods: An MMP20-affected permanent canine tooth and its corresponding control were scanned intact by a high resolution micro computed tomography (μ-CT) for quantification of mineral density and identification of regions within the tooth where the mutation has most affected enamel structure. Teeth were then cut to obtain 360 µm buccolingual sections to be scanned by synchrotron X-ray diffraction (SXRD) at XMaS beamline at the European Synchrotron Radiation Facility. 2D diffraction images were azimuthally integrated along the 002 plane; subsequently peak fitting was performed, and contour maps for texture analysis for the whole crown were generated via Mofit software. Quantification of enamel mineral density was carried out within specified region of interests using Fiji.
Results: MMP20-affected enamel presented lower mineral density of 1.66 g/cm3 compared to 2.31 g/cm3 in healthy control tooth. Contour texture maps revealed two population of crystallites in both specimens, with angular separation of 35○. SXRD analysis of enamel texture showed that population 1 had the predominant contribution with a clear difference in texture magnitude between the AI affected tooth and healthy enamel, where MMP-20 affected enamel showed generalized lower texture across enamel thickness with the most affected regions being at the buccal part of the cusp and the cervical region. Whereas population 2 showed higher texture comparable to healthy enamel.
Conclusions: MMP-20 is a critical protein for proper crystallite organization across the bulk of the enamel. Its mutation leads to significant decrease in mineral density that can be correlated to decreased crystallite texture.