Over the last decades, the growing support of 3D data has led to develop comparative morphometric and qualitative methods to increase the number of fossils suitable for more comprehensive dental analysis [1]. Enamel thickness figures prominently in studies of human evolution, particularly with hominoid taxonomy, phylogeny, and paleodiet [2, 3]. Attention has focused on molar teeth, recently utilising advanced technologies with novel protocols [3]. Despite important results achieved thus far, further work is needed to investigate all tooth classes. We apply a recent approach developed for anterior teeth [4] to investigate 3D enamel thickness of hominin canines. MicroCT data of 38 unworn/lightly worn Homo sapiens (Early: n= 4; Upper Paleolithic: n=4; Recent: n=21) and Neandertal (n=9) permanent lower canines were segmented using Avizo 7 to reconstruct 3D digital models of the teeth. The cervical line was digitized on each 3D model using the spline function in Rapidform XOR to separate crown from root dentine. Volumes of enamel and of crown dentine, and the enamel-dentine junction surface were measured to compute Relative Enamel Thickness (RET). Mean RET value for Neandertals (12.7±1.8) falls below the mean computed for H. sapiens (Upper Paleolithic= 15.6±2.9; Early=14.0±1.9; Recent=15.5±2.6). Results of the permutation test between Neandertal and recent humans support the significant difference in RET (p=0.0055), a useful index for the taxonomic discrimination between modern humans and Neandertals. This preliminary study confirms this trend for lower permanent canines [2], using a 3D protocol which is reproducible, has little subjectivity, and is particularly effective for the uneven contour of cervical enamel in anterior teeth. In recent literature, although the majority of datasets are based on micro-CT scans, the analysis of dental tissues in Neandertal and H. sapiens permanent lower canines have been performed on virtual longitudinal sections [2, 5]. Our preliminary 3D analysis of permanent lower canines support the general findings that Neandertal have thinner enamel than H. sapiens, as observed in molars. Future contributions will incorporate increased sample sizes and include worn teeth to investigate whether the RET index continues to discriminate between Neandertal and H. sapiens canines. Acknowledgements: We thank all the curators and collaborators that granted us access to the dental material and the CT-operators at MPI-EVA. References:[1] Le Cabec, A., Tang, N., Tafforeau, P., 2015. Accessing Developmental Information of Fossil Hominin Teeth Using New Synchrotron-Microtomography Based Visualization Techniques of Dental Surfaces and Interfaces. PLoS ONE 10(4): e0123019. doi:10.1371/journal.pone.0123019[2] Smith, T.M., Olejniczak, A.J., Zermeno, J.P., Tafforeau, P., Skinner, M.M., Hoffmann, A., Radovcic, J., Toussaint, M., Kruszynski, R., Menter, C., Moggi- Cecchi, J., Glasmacher, U.A., Kullmer, O., Schrenk, F., Stringer, C., Hublin, J.-J., 2012. Variation in enamel thickness within the genus Homo. J. Hum. Evol. 62,395e411.[3] Olejniczak, A.J., Smith, T.M., Feeney, R.N.M., Macchiarelli, R., Mazurier, A.,Bondioli, L., Rosas, A., Fortea, J., de la Rasilla, M., Garcia-Tabernero, A., Radovcic, J., Skinner, M.M., Toussaint, M., Hublin, J.-J., 2008. Dental tissue proportions and enamel thickness in Neandertal and modern human molars. J. Hum. Evol. 55, 12e23.[4] Benazzi, S., Panetta, D., Fornai, C., Toussaint, M., Gruppioni, G., Hublin, J-J., 2014. Technical Note: Guidelines for the digital computation of 2D and 3D enamel thickness in hominoid teeth. Am. J. Phys. Anthropol. 2014 Feb;153(2):305-13.[5] Feeney, R.N.M., Zermeno, J.P., Reid, D.J., Nakashima, S., Sano, H., Bahar, A., Hublin, J-J., Smith, T.S., 2010. ’Enamel thickness in Asian human canines and premolars’. Anthrop. Sci., 118 (3):191-198.

3D enamel thickness in Neandertals and Homo sapiens permanent lower canines

BUTI, LAURA;BENAZZI, STEFANO
2015

Abstract

Over the last decades, the growing support of 3D data has led to develop comparative morphometric and qualitative methods to increase the number of fossils suitable for more comprehensive dental analysis [1]. Enamel thickness figures prominently in studies of human evolution, particularly with hominoid taxonomy, phylogeny, and paleodiet [2, 3]. Attention has focused on molar teeth, recently utilising advanced technologies with novel protocols [3]. Despite important results achieved thus far, further work is needed to investigate all tooth classes. We apply a recent approach developed for anterior teeth [4] to investigate 3D enamel thickness of hominin canines. MicroCT data of 38 unworn/lightly worn Homo sapiens (Early: n= 4; Upper Paleolithic: n=4; Recent: n=21) and Neandertal (n=9) permanent lower canines were segmented using Avizo 7 to reconstruct 3D digital models of the teeth. The cervical line was digitized on each 3D model using the spline function in Rapidform XOR to separate crown from root dentine. Volumes of enamel and of crown dentine, and the enamel-dentine junction surface were measured to compute Relative Enamel Thickness (RET). Mean RET value for Neandertals (12.7±1.8) falls below the mean computed for H. sapiens (Upper Paleolithic= 15.6±2.9; Early=14.0±1.9; Recent=15.5±2.6). Results of the permutation test between Neandertal and recent humans support the significant difference in RET (p=0.0055), a useful index for the taxonomic discrimination between modern humans and Neandertals. This preliminary study confirms this trend for lower permanent canines [2], using a 3D protocol which is reproducible, has little subjectivity, and is particularly effective for the uneven contour of cervical enamel in anterior teeth. In recent literature, although the majority of datasets are based on micro-CT scans, the analysis of dental tissues in Neandertal and H. sapiens permanent lower canines have been performed on virtual longitudinal sections [2, 5]. Our preliminary 3D analysis of permanent lower canines support the general findings that Neandertal have thinner enamel than H. sapiens, as observed in molars. Future contributions will incorporate increased sample sizes and include worn teeth to investigate whether the RET index continues to discriminate between Neandertal and H. sapiens canines. Acknowledgements: We thank all the curators and collaborators that granted us access to the dental material and the CT-operators at MPI-EVA. References:[1] Le Cabec, A., Tang, N., Tafforeau, P., 2015. Accessing Developmental Information of Fossil Hominin Teeth Using New Synchrotron-Microtomography Based Visualization Techniques of Dental Surfaces and Interfaces. PLoS ONE 10(4): e0123019. doi:10.1371/journal.pone.0123019[2] Smith, T.M., Olejniczak, A.J., Zermeno, J.P., Tafforeau, P., Skinner, M.M., Hoffmann, A., Radovcic, J., Toussaint, M., Kruszynski, R., Menter, C., Moggi- Cecchi, J., Glasmacher, U.A., Kullmer, O., Schrenk, F., Stringer, C., Hublin, J.-J., 2012. Variation in enamel thickness within the genus Homo. J. Hum. Evol. 62,395e411.[3] Olejniczak, A.J., Smith, T.M., Feeney, R.N.M., Macchiarelli, R., Mazurier, A.,Bondioli, L., Rosas, A., Fortea, J., de la Rasilla, M., Garcia-Tabernero, A., Radovcic, J., Skinner, M.M., Toussaint, M., Hublin, J.-J., 2008. Dental tissue proportions and enamel thickness in Neandertal and modern human molars. J. Hum. Evol. 55, 12e23.[4] Benazzi, S., Panetta, D., Fornai, C., Toussaint, M., Gruppioni, G., Hublin, J-J., 2014. Technical Note: Guidelines for the digital computation of 2D and 3D enamel thickness in hominoid teeth. Am. J. Phys. Anthropol. 2014 Feb;153(2):305-13.[5] Feeney, R.N.M., Zermeno, J.P., Reid, D.J., Nakashima, S., Sano, H., Bahar, A., Hublin, J-J., Smith, T.S., 2010. ’Enamel thickness in Asian human canines and premolars’. Anthrop. Sci., 118 (3):191-198.
2015
Proceedings of the European Society for the study of Human Evolution 4
64
64
Buti, Laura; Cabec, Adeline Le; Feeney, Robin N.M.; Hublin, Jean-Jacques; Benazzi, Stefano
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11585/582098
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