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PhD Defense - Thomas BERTIN
| When |
Dec 20, 2018
from 01:30 to 04:30 |
|---|---|
| Where | Salle des thèses CRC Monod Campus |
| Contact Name | Thomas BERTIN |
| Attendees |
Laudet, Vincent, PU Sorbone Université Rapporteur Tucker, Abigail, Professor, King’s College of London Rapporteure Farges, Jean-Christophe PU-PH, Université Lyon 1 Examinateur Tafforeau, Paul, Chercheur ESRF Examinateur Vico, Laurence, DR ISERM, Université de Saint Etienne Examinatrice Viriot, Laurent, PU, Université Lyon 1 Directeur de Thèse Thivichon-Prince, Béatrice, MCU-PH Université Lyon 1 Co-directrice de thèse |
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Summary
Dental replacement consists in the formation of a new tooth which will take the place of a former tooth, allowing for a renewal of the dental tissues as well as their environment (periodontium). Because of the strong link between the replacement of the teeth and periodontal tissues, I explored among extant and fossil amniotes the diversity of tooth replacement, attachment and implantation modes. This work presented two objectives: to clarify the terminology associated with replacement, implantation and attachment and to review the current knowledges and hypothesis concerning the diversity and the evolution of the three features. In a second part, I studied continuous tooth replacement in archosaurians. First we characterized the dentition and teeth of two representatives of the last groups of toothed-birds, Hesperornis and Ichthyornis. Second, I studied the mechanisms of dental development and replacement in the Nile crocodile embryo, through X-ray microtomography and Notch pathway gene expression study. We observed successively two types of teeth, surface and submerged teeth, which present a very similar development at morphological and molecular level. The main difference is the interruption of the development in the surface teeth. In a third part, I investigated one alternative to continuous tooth replacement in the common warthog that presents different adaptations of its dentition to highly abrasive diet because of the teeth mesial drift, and all the physiological processes associated with. Thus dental replacement has been achieved by different mechanisms throughout evolution. The study of tooth replacement encompasses different phenomenon that must be studied through both development and evolution to comprehend them.