D514 - Lecture 7: Enamel | Questions with
Complete Solutions
what is mineralized epithelial and complex bioceramic tissue covering the tooth
crown?
enamel
what is the primary site of attack of dental caries?
enamel
is enamel brittle or ductile?
brittle
what below enamel supports it to prevent fractures?
dentin
why is enamel translucent?
high mineral content
what influences the color of enamel?
thickness variations - thinner enamel is more yellow
how is enamel formed?
through a process typical of biomineralization where ameloblasts fabricate an organic
extracellular protein matrix
as enamel matures, what is replaced by mineralized tissue?
organic material and water
when are ameloblasts lost?
,after eruption
is mature enamel cellular or acellular?
acellular
can mature enamel renew?
no
what is the chemical composition of mature enamel?
- 99% inorganic components,
- 1% organic components,
- 3% water
which portion of mature enamel composed of crystalline calcium phosphate in the
form of hydroxyapatite?
A. inorganic
B. organic
A
which portion of mature enamel composed of amelogenin, ameloblastin, enamelin
and tuftelin?
A. inorganic
B. organic
B
why can only empty space be seen in place of enamel when using histological
sections?
, mineral portion has been dissolved and the trace organic portion has been washed away
what is the structural unit of enamel that is formed by bundles of long hydroxyapatite
crystals?
enamel rod
where do enamel rods extend from?
the DEJ to enamel surface
where are enamel rods shortest?
areas with thin enamel
what is the average length of an enamel rod?
2 mm
what do hydroxyapatite crystals look like in cross section?
hexagonal
how much larger are hydroxyapatite crystals in enamel than those of mineralized
connective tissue?
4 times
where is interrod enamel found?
outside the circular enamel rods at oblique angles to enamel rods
what is the 3/4ths of the rod cylinder is a thin, non-calcified network of enamel
organic matrix that separates enamel rods from interrods; primarily found around the
head of the rod?
rod sheath
Complete Solutions
what is mineralized epithelial and complex bioceramic tissue covering the tooth
crown?
enamel
what is the primary site of attack of dental caries?
enamel
is enamel brittle or ductile?
brittle
what below enamel supports it to prevent fractures?
dentin
why is enamel translucent?
high mineral content
what influences the color of enamel?
thickness variations - thinner enamel is more yellow
how is enamel formed?
through a process typical of biomineralization where ameloblasts fabricate an organic
extracellular protein matrix
as enamel matures, what is replaced by mineralized tissue?
organic material and water
when are ameloblasts lost?
,after eruption
is mature enamel cellular or acellular?
acellular
can mature enamel renew?
no
what is the chemical composition of mature enamel?
- 99% inorganic components,
- 1% organic components,
- 3% water
which portion of mature enamel composed of crystalline calcium phosphate in the
form of hydroxyapatite?
A. inorganic
B. organic
A
which portion of mature enamel composed of amelogenin, ameloblastin, enamelin
and tuftelin?
A. inorganic
B. organic
B
why can only empty space be seen in place of enamel when using histological
sections?
, mineral portion has been dissolved and the trace organic portion has been washed away
what is the structural unit of enamel that is formed by bundles of long hydroxyapatite
crystals?
enamel rod
where do enamel rods extend from?
the DEJ to enamel surface
where are enamel rods shortest?
areas with thin enamel
what is the average length of an enamel rod?
2 mm
what do hydroxyapatite crystals look like in cross section?
hexagonal
how much larger are hydroxyapatite crystals in enamel than those of mineralized
connective tissue?
4 times
where is interrod enamel found?
outside the circular enamel rods at oblique angles to enamel rods
what is the 3/4ths of the rod cylinder is a thin, non-calcified network of enamel
organic matrix that separates enamel rods from interrods; primarily found around the
head of the rod?
rod sheath
