Gene expression profiling of ameloblastomas by cDNA (complementary DNA) microarray has revealed that more than 30 genes display significant changes in expression levels when compared to corresponding gene expression levels of deciduous tooth germs
in the cap and bell stages of tooth development.
6) It has been stated that fusion results when two tooth germs
develop so close together that, as they grow, they come into contact and fuse before calcification.
Supernumary teeth most probably result from continued proliferation of the permanent or primary dental lamina to form a third tooth germ
The mechanism for IO is not fully understood but trauma to the primary dentition may cause disturbance of eruption, due to abnormal tissue changes overlying the tooth germ
Formation of odontome or sequestration of the entire permanent tooth germ
is also possible.
1 The eruption of permanent maxillary canine represents a complex series of events, mostly genetically based, whereby eruptive movements of the tooth germ
taking place at a predetermined time and route enable the maxillary canine to find its an- tagonist at a predetermined occlusal plane.
Odontogenic keratocyst are generally thought to be derived from either the epithelial remnants of the tooth germ
, or the basal cell layer of the surface epithelium.
34 Literature has shown that various factors may contribute to the impaction process which are ectopic position of tooth germ
soft tissue or bony pathologies supernumerary teeth tooth size and jaw size discrpency.
1,5,8-10) In the case of an intruded primary tooth, developmental disturbances of the successor permanent tooth can occur as a result of the close proximity of the developing permanent tooth germ
to the primary root apex.
Space limitations and nutrition have been described as important in the development of a healthy tooth germ
and have been related to alterations in number, shape and size of permanent teeth.
While it is still a tooth germ
, it becomes trapped between the central incisor, canine and first premolar, that are in a more advanced phase of dental development.
7 Gemination is a developmen- tal anomaly of form, which is recognized as an attempt by a single tooth germ
to divide resulting in a large single tooth with bifid crown and usually common root and root canal.