Pretend you are a teacher preparing a quiz for the text I will provide. 
            Each quiz question should follow the format below. 
            Ensure that you carefully recheck the questions and answers for accuracy. 
            The output should be a ready-to-use list of dictionaries for the Python eval function:

            [

                    "question": "WRITE THE QUESTION HERE",
                    "options": ["A) OPTION_1", "B) OPTION_2", "C) OPTION_3", "D) OPTION_4"],
                    "answer": INDEX_OF_CORRECT_ANSWER_IN_OPTIONS_LIST,
                    "explanation": "EXPLAIN WHY THE ANSWER IS CORRECT"

            ]

            Text:
            e organic dentin matrix
and regulates mineralization.
Mature
dentin
is
45%
-
50%
inorganic
or
mineralized material, 30% organic material, and
25% water. The organic material is approximately
90% type I collagen and 10% non-collagenous
proteins.
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The crystalline formation of mature dentin mainly
consists of calcium hydroxyapatite with the chemical
formula of Ca10(PO4)6(OH)2.
The calcium hydroxyapatite found in dentin is similar
to that found in a higher percentage in enamel and in
lower percentages in both cementum and bone tissue.
In addition, the crystals in dentin are platelike in shape
and 30% smaller in size than those in enamel.
The thickness of the apatite crystals varies from 3.5
nm near the DEJ to about 2 nm close to the pulp.
Small amounts of other minerals, such as carbonate
and fluoride, are also present. The mineral content of
dentin increases with age.
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Structurally there are two main types of dentin which are:
1. Intertubular dentin: the primary structural
component of it is the hydroxyapatite- embedded
collagen
matrix
between
tubules.
Intertubular
dentin forming the bulk of dentin structure.
2. Peritubular dentin: it is the hypermineralized
dentin limited to the walls of dentinal tubules. The
walls of the dentinal tubules (peritubular dentin) in
the
primary
dentin
gradually
thicken,
through
ongoing mineral deposition, with age. The dentin
therefore becomes harder, denser, and, because
tubular fluid low becomes more restricted as the
lumen spaces become smaller, less sensitive.
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The increased amount of mineral in the primary dentin
is defined as dentin sclerosis. Dentin sclerosis resulting
from aging is called physiologic dentin sclerosis.
The dentinal tubules in the Outer Dentin which is
near
the
DEJ
are
relatively
far
apart
and
the
Intertubular dentin makes up 96% of the surface area.
In the Inner Dentin, the tubules diameters are larger
and the distance between tubule centers is half that of
tubules at DEJ. Thus, the intertubular matrix area is
only 12% of the surface area, and the permeability of
inner dentin is about eight times more permeable than
the dentin near DEJ.
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Physiologic and Tertiary Dentin
Some of the variations in the dentinal tissue occur
during its natural sequence of development or aging,
while other variations result from the effects of
external factors on the tooth, such as caries, injury, or
wear. An understanding of these variations in the
dentinal tissue is important because they are related
to the long-term success of dental procedures and
therapies.
Physiologic dentin
Odontoblasts synthesize and secrete extracellular
organic matrix, which, following mineralization, forms
the primary and secondary physiologic dentin
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Formed relatively quickly until root formation is
completed by odontoblasts. The first-formed,
150-μm-thick layer of primary dentin subjacent to
the enamel is termed mantle dentin.
It differs from other primary dentin in tha

            Quiz: