Day by day, the amount of digital data has been rapidly increasing on the Internet. The size of 3D objects is very large and these objects need fast transmissions. Moreover, 3D data security becomes increasingly important for many applications, e.g., confidential transmission, video surveillance, military and medical applications. In this paper we present two new approaches of 3D object data hiding without changing the position of vertices in the 3D space. The main idea of the two proposed methods is to find and to synchronize particular areas of the 3D objects used to embed the message. The embedding is done by changing the connectivity of edges in the selected areas composed of quadrangles. The first proposed approach of data hiding in 3D objects is based on minimum spanning tree (MST) while the second approach is based on the projection on a secret axis of the quadrangle centers. These methods are lossless in the sense that the positions of the vertices are unchanged. Moreover they are blind and do not depend of the order of the data in the files. These two approaches are very interesting when the 3D objects have been digitalized with high precision.