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2018 ; 233
(2
): 135-145
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Early development of the human dentition revisited
#MMPMID29745448
Hovorakova M
; Lesot H
; Peterka M
; Peterkova R
J Anat
2018[Aug]; 233
(2
): 135-145
PMID29745448
show ga
In this review, classical data on the early steps in human odontogenesis are
summarized and updated with specific insights into the development of the upper
and lower embryonic jaws to help in understanding some oral pathologies. The
initial step of human odontogenesis is classically characterized by two parallel
horseshoe-shaped epithelial laminae. These originate from the oral epithelium and
an ingrowth into the jaw mesenchyme: the internal dental lamina gives rise to
deciduous tooth primordia, while the external vestibular lamina represents the
developmental base of the oral vestibule. However, a more complex situation was
revealed by recent studies combining analyses of the dental and adjacent oral
epithelia on histological sections and computer-aided three-dimensional (3D)
reconstructions during the 2nd month of human embryonic development. The dental
epithelium forms a mound, where swellings appear later, corresponding to the
individual primordia of deciduous teeth. External to the developing deciduous
dentition, the 3D reconstructions do not show any continuous vestibular lamina
but instead a complex of discontinuous epithelial bulges and ridges. The patterns
of these epithelial structures and their relationship to the dental epithelium
differ not only between the upper and lower jaws but also between the lip and
cheek segments in each jaw. Knowledge of early odontogenesis may help in
understanding some oral pathologies. For example, the human lateral incisor has a
dual origin: it arises in the area of fusion between the medial nasal and
maxillary facial processes and involves material from these two regions. Such a
dual origin at the site of fusion of facial processes represents a predisposition
to developmental vulnerability for the upper lateral incisor, resulting in its
frequent anomalies (absence, hypoplasia, duplication), especially in patients
with a cleft lip and/or jaw. Other pathologies, such as a minute supernumerary
tooth, desmoplastic ameloblastoma or extraosseous odontogenic cysts are located
external to the upper or lower dentition, and might be derived from structures
that transiently appear during early development of the oral vestibule in humans.
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