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:
            ittle and can be fracture 
without support of dentin which characterized 
by elasticity to absorb the heavy occlusal loads. 
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3 
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Support: Tooth strength and rigidity are 
provided 
by 
intact 
dentinal 
substrate. 
Resistance of tooth to fracture is significantly 
lowered with increasing depth and width of 
cavity preparation. Therefore, a conservative 
initial 
approach 
that 
combines 
localized 
removal of carious tooth structure, placement 
of a bonded restoration, and placement of 
sealant is recommended. If large preparations 
are required, the dentist should consider 
placement of onlay or crown. Also, higher 
concentrations of tooth-whitening (bleaching) 
agents, may have adverse effects on the 
fracture toughness of dentin. 
4 
Protection: Protective encasement for 
the pulp. As a vital tissue without 
vascular supply or innervation, it is 
nevertheless able to respond to thermal, 
chemical or tactile external stimuli 
because of the presence of dentinal 
tubules that permit stimuli transmission 
to the pulp. 
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5 
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Dentin can be distinguished from enamel (during tooth preparation), by: 
Dentin is normally yellow-white and slightly 
darker than enamel. In older patients, dentin is 
darker and become brown or black in cases in 
which it has been exposed to oral fluids, old 
restorative materials or slowly advancing caries. 
Color 
1 
Dentin surfaces are more opaque and dull, being 
less reflective to light than enamel surfaces, 
which appear shiny. 
Reflectance 
2 
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Dentin can be distinguished from enamel (during tooth preparation), by: 
When moving an explorer tip over the tooth, enamel 
surfaces provide a sharper, higher pitched sound than 
dentin surfaces. 
Sound 
4 
Dentin is softer than enamel, sharp explorer tends to catch 
and hold in dentin. The hardness of dentin averages one 
fifth that of enamel, and its hardness near the DEJ is about 
three times greater than near the pulp. Although dentin is 
a hard, mineralized tissue, it is flexible. This flexibility helps 
support the more brittle, less resilient enamel. Dentin is 
not as prone to fracture as is the enamel rod structure. 
Hardness 
3 
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Dentin can be distinguished from enamel (during tooth preparation), by: 
Ename
l 
Dentin 
Whitish blue or white 
gray 
Yellowish white or slightly 
darker than enamel 
Sharp, high-pitched sound 
on moving fine explorer tip 
Dull or low-pitched sound on 
moving fine explorer tip 
Hardest structure of the 
tooth 
Softer than enamel 
More shiny surface and 
reflective to light than dentin 
Dull and reflects less light 
than enamel 
Reflectanc
e 
Hardnes
s 
Sound 
Colo
r 
www.drcube.org Permeability of Dentin 
Permeability of Dentin 
The permeability of dentin can compromise its 
protective function because of the presence of 
dentinal tubules, which are very important 
during formation of dentin, however, when the 
external layer of enamel and cementum is 

            Quiz: