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:
            end well
(100–200 μm) into the tubules in the mineralized
dentin.
Dentin is a mineralized connective tissue that is
covered by enamel in the crown and cementum in the
root, as well as enclosing the innermost pulp.
www.drcube.org
Because of these odontoblastic cell
processes dentin is considered a
living tissue, with the capability of
reacting
to
physiologic
and
pathologic stimuli. These processes
extend beyond the DEJ into the
enamel forming enamel spindles,
which are responsible for sensitivity
sensation during cavity preparation
in enamel.
Dentin formation begins immediately
before enamel formation. The most
recently formed layer of dentin is
always on the pulpal surface.
www.drcube.org
• Odontoblasts generate an extracellular collagen matrix as they begin to move away
from adjacent ameloblasts.
• Mineralization of the collagen matrix, facilitated by modification of the collagen matrix
by various non-collagenous proteins, gradually follows its secretion and deposition of
intrafibrillar mineral crystals into the collagen fibrils.
• This unmineralized zone of dentin is immediately next to the cell bodies of odontoblasts
and is called predentin.
www.drcube.org
Dentin formation begins at areas subjacent to the
cusp tip or incisal ridge and gradually spreads, at
the rate of ~4 μm/day, to the apex of the root. In
contrast to enamel formation, dentin formation
continues after tooth eruption and throughout the
life of the pulp.
The dentin forming the initial shape of the tooth is
called primary dentin and is usually completed 3
years
after
tooth
eruption
(in
the
case
of
permanent teeth).
www.drcube.org
Dentinal Tubules
The dentinal tubules are small canal that remain from the process of dentinogenesis and
extend through the entire width of dentin, from the pulp to the DEJ.
Each tubule contains the cytoplasmic cell process (Tome's fiber) of an odontoblast and is
lined with a layer of peritubular dentin, which is much more mineralized than the
surrounding intertubular dentin . The tubules comprise about 10% of dentin volume.
www.drcube.org
In mature dentin, the odontoblastic process extends
within the dentinal tubule to about one-third the
dentinal thickness.
The number of tubules increases from 15,000 to
20,000/mm2 at the DEJ to 45,000 to 65,000/mm2 at
the pulp.
The lumen of the tubules also varies from the DEJ to
the pulp surface. In coronal dentin, the average
diameter of tubules at the DEJ is 0.5 to 0.9 μm, but
this increases to 2 to 3 μm near the pulp.
www.drcube.org
Tubules are generally oriented perpendicular to the
DEJ. Along the tubule walls are small lateral openings
called canaliculi or lateral canals.
The lateral canals are formed as a result of the
presence of secondary (lateral) branches of adjacent
odontoblastic processes during dentinogenesis.
www.drcube.org
Dentinoenamel Junction
It is the transition between the highlymineralized
enamel and the collagen-containing dentin.
DEJ must resist fracture and separation under the
extreme fo

            Quiz: