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The crown of the tooth, which is influenced by the shape of the inner enamel epithelium, also takes shape during this stage. Throughout the mouth, all teeth undergo this same process; it is still uncertain why teeth form various crown shapes—for instance, incisors versus canines. There are two dominant hypotheses. The "field model" proposes ...
There are hundreds of genes expressed and involved in regulating tooth morphogenesis. [28] [29] Although a single gene defect may contribute to hypodontia, more studies propose that hypodontia is the result of one or more points of closely linked genetic mutations, or polygenic defects. [30] [31] [32]
In fish, Hox gene expression regulates mechanisms for tooth initiation. [1] [2] However, sharks continuously produce new teeth throughout their lives [3] [4] [5] via a drastically different mechanism. Shark teeth form from modified scales near the tongue and move outward on the jaw in rows until they are eventually dislodged. [6]
Dentinogenesis imperfecta (DI) is a genetic disorder of tooth development.It is inherited in an autosomal dominant pattern, as a result of mutations on chromosome 4q21, in the dentine sialophosphoprotein gene (DSPP).
Specific genes play a role in determining the number and pattern of teeth that develop in an individual, and mutations or variations in these genes can result in the formation of extra teeth. An individual can inherit a genetic predisposition to hyperdontia from its parents. [7]
Researchers note that genetic mutations which regulate tooth growth could cause teeth to grow abnormally. [medical citation needed] Some of these genetic conditions associated with this disease are also related with hormonal imbalances and are likely related to the pituitary gland, resulting in deviant tooth growth. [2]
Amelogenesis imperfecta can have different inheritance patterns depending on the gene that is altered. Mutations in the ENAM gene are the most frequent known cause and are most commonly inherited in an autosomal dominant pattern. This type of inheritance means one copy of the altered gene in each cell is sufficient to cause the disorder.
One working gene and one non-working gene are inherited, one from an affected parent and one from a non-affected parent, which then result in a 50% chance of the child inheriting the genetic disorder. Anodontia alone will not have an effect on any other body part besides teeth being missing.