||Fig 14. Hypocalcification
Hypocalcification (Figure 14) refers
to a condition in which the enamel is normal, but
the enamel quality is poor. This condition can be
heritable or can be caused by local factors (e.g.,
habitual sucking on citrus fruits, frequent and prolonged
consumption of highly acidic carbonated drinks, extensive
plaque deposits that are not removed daily).
Amelogenesis imperfecta (AI) (Figure
15) is a heritable defect in the enamel that occurs
in between 1 in 4,000 and 1 in 14,000 individuals.
The most widely accepted classification system for
AI considers mode of inheritance and clinical manifestations.
Autosomal dominant, recessive, and X-linked inheritance
patterns of AI have been
reported. The clinical appearance of the enamel ranges
from normal in color to yellow or brown, and enamel
thickness ranges from normal to thin (enamel that
often chips and erodes easily). Depending on the AI
type, the teeth can be extremely sensitive to thermal
and chemical stimuli. Treatment of AI is based on
||Fig 16. Dentinogenesis
Dentinogenesis imperfecta (DI) (Figure
16) is a heritable defect in the dentin
that originates early during tooth development. In
all three types of DI, the teeth have a variable blue-gray
to yellow-brown discoloration that appears opalescent
because of the defective, abnormally colored dentin
shining through the translucent enamel. Because of
the lack of support of the poorly mineralized underlying
dentin, the enamel commonly fractures from the teeth,
leading to rapid wear and attrition. Treatment of
individuals with DI depends on severity of discoloration
and propensity for enamel loss.
Enamel coloration can be extrinsic or
intrinsic. Extrinsic coloration (Figure 17) is normally
due to environmental stains and is likely to occur
when teeth are covered with plaque and are inadequately
brushed or when the stains adhere to calculus deposits.
Black, green, and orange stains on the crowns of the
teeth are common with this condition. Extrinsic coloration
may occur when a child who is anemic is taking a liquid
iron supplement or when a child is not brushing his
teeth (or having his teeth brushed by a parent).
Intrinsic coloration is due to blood-borne pigments
(e.g., congenital porphyeria, drug administration,
ingestion of tetracycline during pregnancy or any
time before age 8) or ingestion of excessive fluoride.