what-when-how
In Depth Tutorials and Information
related to OI described herein are mostly seen in OI
types III and IV because there they exist both quantita-
tively and qualitatively.
8,9
The dentition in type V has
not been reported, other than unlike types I-IV, these
individuals do not have DI.
1
DENTINOGENESIS IMPERFECTA
(DI) AND OI
Color
One of the most striking dental defects of OI patients
is the odd color of the dentin showing through the
enamel.
3,8,9
The color may vary from light gray to dark
gray with different tints of yellow. When the gray domi-
nates, the tooth appears translucent and merits the term
“opalescent” (
Figure 33.1
). A yellow tint exists when
the pulp becomes completely obliterated and the tooth
loses its luminosity. Different pigments,
7
including
blood pigments, may also be responsible for different
dental shades. When Lindau et al.
10
used different bio-
logical techniques in order to investigate dentin mor-
phology of OI teeth, they found inclusions of remnants
of blood vessels, and suggested that the dentin devel-
oped so rapidly that the blood vessels were encom-
passed therein.
In any case, the defective collagen I is not necessarily
the cause of the odd color because there are individu-
als who have the same color defects who do not suffer
from DI associated with OI, but from opalescent dentin
(also referred to as non-syndromic DI) that has an auto-
somal dominant mode of inheritance. Their phenotype
does not involve the skeleton, and the gene involved
(dentin sialophosphoprotein,
DSPP
) is located at chro-
mosome 4q21.3, and is not a collagen gene (more on
this gene and its protein products, dentin phosphopro-
tein and dentin sialoprotein, below).
3,7-11
In OI patients, the colorations are more pronounced
in the primary dentition. In the permanent denti-
tion these colorations are not evenly distributed, and
the mandibular incisors and the first molars are more
affected than the other teeth.
7
O'Connell and Marini
found that the dental color was not predictive of the
dentin fragility except in the primary dentition, where
they found that a yellow-brown tone coincided with
an increased incidence of severe attrition and enamel
fracture.
12
Older children and especially adolescents
with DI are often embarrassed by their discolored
teeth. Different types of veneers can sometimes hide the
problem, but are not strong enough to withstand bit-
ing forces or to keep susceptible teeth from cracking.
Bleaching is not recommended because the discolor-
ation is not in the enamel.
13
FIGURE 33.1
Typical shade of gray as seen in the dentition of a
13-year-old patient with OI. Notice the negative anterior overjet indic-
ative of a Class III malocclusion.
Spontaneous Dental Fractures and Enamel Loss
The dentin around the pulp (circumpulpal dentin) is
weaker than the enamel subjacent dentin (mantle den-
tin). This results in spontaneous fractures of the whole
tooth.
3,9
In addition, enamel appears to chip away
from the tooth, exposing areas of defective soft dentin.
Some authors maintain that the usual scalloping inter-
face between the dentin and the enamel is absent, and
that this absence weakens the union between the two
tissues.
9
However, the interface scalloping can differ
from one tooth to another, and even within the same
tooth.
7
Other authors believe that the loss of enamel
is due rather to this dentin frailty that exists mostly at
the junction of the mantle and the circumpulpal area
(
Figure 33.2
).
10
It is our experience that some denti-
tions undergo more chipping and fracturing than oth-
ers regardless of discolorations. If the teeth are wearing
excessively, “caps” (also called crowns, often made
out of stainless steel for the baby teeth in the back of
the mouth or they may be tooth-colored plastic in the
front of the mouth) will probably need to be placed on
at least some of the teeth. Caps serve to keep the teeth
in place and encourage proper development of the jaw.
More specialized treatment may be more appropriate
for permanent teeth.
13
Size and Shape
Defective type I collagen is certainly a cause of
adverse modifications of the dentin matrix, its poor
mineralization density and its abnormal fibrillar struc-
ture.
6
Dentin phosphoprotein (a major non-collagenous
portion of the matrix) may be another such cause. Other
factors, such as cysteine interfering with the glycine of
the precollagen molecules, will cause disturbances in
the shape and diameters of the collagen fibers.6
6
