Teeth Flashcards
Teeth are grossly divided into:
root and crown
Portion of tooth embedded in bone
called:
tooth root
Portion of tooth embedded in part of jaw called
___
alveolar ridge
Portion of tooth embedded in tooth socket called
___
alveolus
Portion of tooth that projects into
oral cavity—
crown
Tooth is Protected by layer of highly
mineralized ____, covers crown
enamel (E),
___ is a hard, translucent
substance, containing < 1% organic
material & 96-98% hydroxyapatite
Enamel
Enamel is Secreted by tall, ______ of
enamel organ
columnar ameloblasts
Ameloblasts degenerate when ____, after which the enamel cannot be
replaced by new synthesis
the tooth
erupts
Apical, secretory end of ameloblast forms
_____
(microtubules & secretory vesicles)
single, large process, Tome’s process
Enamel mineralization is _____,
resulting in highly calcified enamel rods
or prisms—roughly hexagonal, ~4-8m in
diameter
non-uniform
Enamel mineralization is non-uniform,
resulting in highly calcified ____—roughly hexagonal, ~4-8m in
diameter
enamel rods
or prisms
Enamel rods extend from ameloblasts at
enamel surface to ____
junction
dentino-enamel junction
Bulk of tooth composed of less
mineralized ___
dentine
(Dentine) Secreted by odontoblasts of dental
papilla as _____
non-mineralized pre-dentine
T/F: Matrix vacuoles (Ca2+ and PO4-) play a
key role in mineralization of dentine
matrix [like odontoblasts].
True
Dentine contains ____ collagen and ___
Type I collagen and GAGs
Dentine arranged in ____—
hollow, parallel tubes radiating from
pulp cavity
dentine tubules
Dentine arranged in dentine tubules—
hollow, parallel tubes radiating from
____
pulp cavity
Dentine arranged in dentine tubules—
hollow, parallel tubes radiating from
pulp cavity—
Contain long, rod-like cytoplasmic
processes of odontoblasts (aka _____)
Tome’s
fibers
___ contains
support structures—e.g., sensory
nerves & blood vessels
Central pulp cavity
Dentine innervated by ___
myelinated
nerves
____ is mesodermal in
origin; resembles primitive
mesenchyme
Dental pulp
Dental Pulp: Richly supplied by capillaries from
arterioles running with ____
periodontal
ligament
Tooth root is covered by a
thin layer of ___
cementum
Tooth root covered by cementun secreted by cementoblasts which mature into ____
cementocytes
Cementocytes that lie
against the surface of the
periodontal ligament
probably produce new
cementum by ____
appositional
growth.
Region of tooth between root & crown is ___
neck
of tooth
Neck of tooth is Protected by masticatory oral mucosa called
____ ; covers upper portion of
alveolar ridge
gingiva (= gums);
Gingiva sometimes divided into
attached and free gingiva
gingiva covering upper alveolar bone
attached gingiva
gingiva forming cuff~neck of tooth
free gingiva
Space between free gingiva & crown called
___
gingival sulcus or crevice
Gingival sulcus Lined by ______—very thin, only
2-3 cells thick, easily breached by bacteria =>
periodontal disease, gingivitis
crevicular epithelium
Tissues that surround & support tooth
collectively referred to as ____—
include epithelium, cementum, periodontal
ligament & alveolar bone
periodontium
periodontium includes: (4)
epithelium, cementum, periodontal
ligament & alveolar bone
Cementum layer anchored to bone
of alveolus with ____
fibers of
periodontal ligament or
membrane
Cementum layer anchored to bone
of alveolus with fibers of
periodontal ligament or
membrane—composed of dense,
collageous fibers, called ____
Sharpey’s
fibers
Run at oblique angle, support tooth
in socket
* Allows slight movement of tooth
during mastication
sharpeys fibers
May see occasional clusters of
epithelial cells within ____t—vestigial epithelial rests
(of Malassez)
periodontal
ligament
(cap stage) Tooth formed between opposing layers
of epithelial cells—
____ of enamel organ &
____ of dental papilla
ameloblasts ; odontoblasts
enamel is of ____ origin
ectodermal
Dentine, cementum, pulp, &
periodontal ligament are ___ origin
mesodermal
(cap stage) 6th week of fetal development, a
horseshoe-shaped epithelial ridge
arises from ____
oral epithelium
(cap stage) ~6th week of fetal development, a
horseshoe-shaped epithelial ridge
arises from oral epithelium
* Forms ____ in position of
future jaws
dental lamina
(cap stage) In each quadrant, lamina develops
several globular, ectodermal swellings
(one for each deciduous tooth) =>
Superficial half forms ___ ;
deep half forms ____
enamel organs ; dental papilla
(early bell stage) Cells of epithelial tooth bud
develop into the ___
enamel organ
(early bell stage) cells of epithelial tooth bud develop into the enamel organ. Become a bell-shaped structure
with a core of loosely arranged
stellate cells & peripheral layer of
cuboidal/low columnar epithelium
(external & internal enamel
epithelium). Meet at ____
cervical loop.
(early bell stage) Internal enamel epithelium
differentiates into layer of
ameloblasts & 2-3 cell thick
_____
stratum intermedium
(early bell stage) Mesenchyme condense to form
_______. Row of
odontoblasts develop at junction
with ameloblasts.
dental papillae
(early bell stage) Permanent tooth arises from side-
growth of ___
dental lamina.
Enamel organ initially____-shaped (cap
stage)
cup-shaped
Cells of enamel organ progressively
differentiate, become ____, with extracellular matrix of
GAG’s
stellate
reticulum
enamel later form bell-shaped structure in ___ stage
bell stage
(bell stage) Cells lining outer, convex surface of
enamel organ become ____
external
enamel epithelium
(bell stage) Cells lining concave surface of
enamel organ form____, differentiate into tall,
columnar ameloblasts (A)
internal enamel
epithelium
(bell stage) Cells lining concave surface of
enamel organ form internal enamel
epithelium, differentiate into _____
tall,
columnar ameloblasts (A)
—enamel formation
Amelogenesis
(odontogenesis) Deep to developing enamel organs
is primitive mesenchyme; develops
into ___
dental papilla
(odontogenesis) Cells lining convex surface of
dental papilla develop into
___
odontoblasts
—dentine
formation
Dentinogenesis
(late bell stage) Development of ameloblasts
induces differentiation of
_____, but calcification
of dentine induces deposition
of enamel
odontoblasts
(late bell stage) Development of ameloblasts
induces differentiation of
odontoblasts, but calcification
of dentine induces ___
deposition
of enamel
(late bell stage) Tooth formation initiated by
deposition of organic _____ by odontoblasts on
surface of dental papilla—later
calcified into dentine
pre-
dentine
____
secondarily induces enamel
production by ameloblasts
Calcification of dentine matrix
Odontoblasts have odontoblast
processes, embedded in
dentine matrix—form ___
dentine
tubules
(odontogenesis) Enamel forms in mineralized
columns of ____, separated
by less mineralized interprismatic
material
enamel rods
(odontogenesis) Enamel forms in mineralized
columns of enamel rods, separated
by _____
less mineralized interprismatic
material
Subsequent to deposit of dentine &
enamel, dental lamina ____
fragments &
atrophies
At time of tooth eruption, enamel
organ & ameloblasts ___
degenerate
Overlying mucosa ___ as
tooth erupts, exposing crown
separates
Dental papilla shrinks, becomes
___, surrounded by dentine
dental pulp
(late bell stage) Dental papillae enclosed by
dentine to become ___
pulp cavity
(late bell stage) ____- a
proliferation of epithelial
cells located at the cervical
loop of the enamel organ.
Hertwig epithelial root sheath
initiates the formation of
dentine in the root by
causingthe differentiation of
odontoblasts from the dental
papilla.
Hertwig’s root sheath
The root sheath eventually
disintegrates with the
___, but
residual pieces that do not
completely disappear are
seen as epithelial cell rests
periodontal ligament
After tooth formation is complete, small
amounts of ____continue to be produced,
may eventually obliterate pulp cavity
2’ dentine
Overall shape of enamel organ determines 3-D
shape of ___
tooth crown
Outer rim of enamel organ known as ____
epithelial
sheath of Hertwig (= Hertwig’s root sheath,
HERS)
Outer rim of enamel organ known as epithelial
sheath of Hertwig determines ____
cross-sectional outline of tooth
Surrounding mesenchyme forms dental follicle
(DF) => ___
periodontal ligament
___ of permanent teeth develop as
buds from dental lamina & “deciduous” enamel
organ
Enamel organs
In case of ____, dental lamina proliferates
caudally to form enamel organs of 2’ dentition
molars
In humans, tooth development
begins ~___ week of fetal
development
6th week of fetal development
In humans, tooth development
begins ~6th week of fetal
development—but tooth
eruption does not occur until ___ after birth
6-
30 months
premolars usually have ___ roots
2
molars usually have ___ roots
2-4 roots
Between 6-12 years of age,
deciduous teeth replaced by
___
permanent dentition
____, administered during
development of permanent
dentition incorporated into enamel
=> yellow discoloration of teeth
Tetracycline
Orthodontia accomplished by
osteoblast & osteoclast activity in
___
alveolus
___—results when weak
acids in food & drink erode
calcified enamel, augmented by
bacterial action
Dental caries
____helps harden enamel &
kills bacteria
Fluoride
Caries may extend into dentine or
pulp cavity, produce abscesses or
death of tooth =>
root canal
___—caused by
accumulation of calcified food &
bacterial debris (plaque) in
gingival sulcus => widening of
gingival sulcus, possible
inflammation & destruction of
periodontal ligament
Periodontal disease
inflammation of gums—
gingivitis
Inflammation of periodontal
ligament—
periodontitis
