2-14. HYPOPLASIA
In hypoplasia (figure 2-14), there is a lack of development or a defective
development of the enamel of the tooth before its eruption. In deciduous teeth, enamel
hypoplasia can be caused by a disturbance in the enamel formation before birth and, for
some deciduous teeth, after birth. In permanent teeth, enamel hypoplasia can only be
caused by some disturbance after birth since enamel formation of the permanent
dentition begins at birth. Enamel prisms are deposited by the enamel organ in a definite
pattern to form the crown of the tooth. A local disturbance may interfere with this
process and result in defective development. The degree of the defect (hypoplasia)
varies from mild, shallow depressions or grooves to extensive grooves or pits arranged
in horizontal rows around the crown. These grooves or pits extend into the enamel as
far as the dentinoenamel junction. The defect may be a lack of development of all or
part of the enamel, leaving exposed dentin. Hypoplastic enamel and poorly formed
dentin can be attributed to various causes or combinations of causes, such as infectious
diseases (scarlet fever, measles, pneumonia), rickets, or hereditary factors. Trauma to
primary teeth may cause a localized hypoplastic defect in a developing permanent tooth
(called Turner's tooth). Prevention is much better than treatment. A physician who
provides good health supervision (including proper treatment of infant disease) and
NOTE:
Interruption of the enamel developmental process results in irregular enamel
formation or lack of enamel formation. Restorative treatment may be required
because of susceptibility to decay and to improve appearance.
Figure 2-14. Enamel hypoplasia.
2-15. ANODONTIA
Anodontia, which means absence of teeth, is an anomaly in which the enamel
organ fails to form. Some (partial anodontia) or all (total anodontia) of the teeth may fail
to develop. Cases in which only part of the tooth fails to form are considered forms of
hypoplasia.
MD0511
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