[Ivorian typology: study of the crown dimensions of the first permanent molar].


A dental morphology study is of great importance because it allows norms to be established which are adapted to the Ivorian situation. After a study of the canal morphology, we became involved in a study of the canal dimensions of the first permanent molars amongst Ivorian children. As a part of the 260 mouldings taken from 67 boys and 63 girls, we measured the following diametres: the diametre masio-distal (O-M-D) taken between the edge of the mesial bone and the edge of the distal bone. the biggest vestibulo-lingual coronary diametre (OV-LC). the diametre of the vestibulo-lingual at the level of the occlusal table (OV-LC). The data collected allowed us to reach the following conclusions: the first secondary molar with a M-D diametre (10.64 mm) is more important than the M-D diametre of its homologeous upper (10.15). however there is no significant difference between the OV-LC diametre of the first maxillary molar and that of the first mandibular molar. concerning the M-D or V-L diametres, the difference between the left side of the maxillary as with the mandibular is negligble. It's worth noting that the first permanent molar is smaller for girls when compared to boys, as well as their M-D diametres compared to their V-L. A comparative study between the TALLEC and MARSEILLIER plates showed that: the first upper molar for Ivorian children has a M-D diametre practically identical to that of European children, however the V-L and OV-LC diametres are smaller. the first bottom molar slightly bigger in all M-D and V-L diametres in Ivorian children in comparison to European children.