IADR Abstract Archives
Population Characterization Based on Dentin Trait: Lower Second Premolar Transverse Crest
Objectives: The enamel-dentin-junction (EDJ) carries valuable taxonomic information that can be used to define and characterize populations. Yet, most of the morphological traits utilized in the anthropological research (e.g. ASUDAS and geometric morphometric analysis) are based on the outer enamel surface, which is more subjected to attrition and environmental changes. Transverse crest in the lower second premolar was previously described as an enamel feature, which presented morphological variability between populations. The purpose of the current study was to define and analyze the transverse crest trait in the dentin layer using 3D geometric morphometric methods.
Methods: 74 lower second premolars were segmented from micro-CT volume data in Amira 6.3 (FEI, Germany) to obtain 3D digital surfaces of the EDJ. The transverse crest shape was subsequently digitized in the EVAN Toolbox 1.71 (ET, http://evan-society.org), using 12 equally spaced sliding semilandmarks along the curve connecting two anatomical landmarks: protoconid and metaconid dentin horn tips. Two additional landmarks were placed in the deepest points of mesial and distal fossae to describe the relative position of transverse crest on the occlusal surface of EDJ.
All gathered coordinates were superimposed using Generalized Procrustes Algorhitm (GPA), following by a Principal Component Analysis (PCA) to examine shape variation in the sample and the distribution of each group in shape space.
The study sample comprised of modern humans from different geographical populations, upper Paleolithic, early anatomically modern humans and Neanderthals (NEA).
Results: We observed a significant separation between the studied populations on the PCA plot of the EDJ transverse crest trait shape.
Conclusions: Based on the results, we concluded that the morphology of the dentin transverse crest in the lower second premolar can serve as a reliable trait to distinguish between populations; therefore, it should be considered as a tool for population analysis.
Methods: 74 lower second premolars were segmented from micro-CT volume data in Amira 6.3 (FEI, Germany) to obtain 3D digital surfaces of the EDJ. The transverse crest shape was subsequently digitized in the EVAN Toolbox 1.71 (ET, http://evan-society.org), using 12 equally spaced sliding semilandmarks along the curve connecting two anatomical landmarks: protoconid and metaconid dentin horn tips. Two additional landmarks were placed in the deepest points of mesial and distal fossae to describe the relative position of transverse crest on the occlusal surface of EDJ.
All gathered coordinates were superimposed using Generalized Procrustes Algorhitm (GPA), following by a Principal Component Analysis (PCA) to examine shape variation in the sample and the distribution of each group in shape space.
The study sample comprised of modern humans from different geographical populations, upper Paleolithic, early anatomically modern humans and Neanderthals (NEA).
Results: We observed a significant separation between the studied populations on the PCA plot of the EDJ transverse crest trait shape.
Conclusions: Based on the results, we concluded that the morphology of the dentin transverse crest in the lower second premolar can serve as a reliable trait to distinguish between populations; therefore, it should be considered as a tool for population analysis.