Tooth Development Flashcards
the mature tooth rests in a boney
socket and is held in place by
_________
connective tissue
during initiaton of tooth development, ectoderm lining stomodeum gives rise to _______ and then to _______; adjacent to deeper ectomesenchyme, which is derived from the ________ where both tissue types are separated by a _______
oral epithelium, dental lamina, neural crest
cells, basement membrane
the bud stage begins around the ______ week
eighth
the main process of the bud stage is ________
proliferation
the bud stage begins the growth of dental lamina into bud shape that penetrates growing ________
ectomesenchyme
the cap stage begins around the ________ week
ninth to tenth
the main processes of the cap stage are _______, _______, and ________
proliferation, differentiation, morphogenesis
the cap stage begins with the formation of tooth germ as _______ forms into cap shape that surrounds inside mass of _______ , with an outside mass of dental sac (DS), both from the
ectomesenchyme
enamel organ (EO), dental papilla(DP)
the bell stage begins around the _________ week
eleventh to twelth
the main processes of the bell stage inlcude ________, _______, and _______
Proliferation, differentiation, morphogenesis
during the bell stage the differentiation of enamel organ into bell shape with ______ cell types and dental papilla into ______ cell types
four, two
the apposition stage begins at various times and the main processes include ______ and ______
induction, proliferation
during the apposition stage the dental tissue types are secreted in successive layers as _______.
matrix
the maturation stage begins at various times and the main process is _________
maturation
during the maturation stage, the dental tissue types fully ________ to mature form
mineralize
_______ is a process wherein one tissue directs the development of another adjacent tissue and mediated by ________ or factors released by the ________
induction, cell-contact, inducing
tissue
induction signals usually regulate ________ thereby leading the target cells toward differentiating into a specific cell type
gene transcription,
Induction can be ______ and _______ so that tissue A induces
tissue B and in turn later on tissue B then induces tissue A
serial, reciprocal
Primary Epithelial band gives rise to ______ and ________
Dental lamina, Vestibular Lamina
the epithelial band is a result of _______ and change of orientation of mitotic cells
mitosis
meckel’s cartilage is part of the ectomesenchyme that gives rise to part of the _______ and mental portion of the _______
inner ear, mandible
The ________ is requisite for tooth development
mandibular epithelium
the ectomesenchyme cells will become the _______
dental papilla
two important ligands involved in tooth development include __________ and __________
fibroblast growth factors (FGF), bone morphogenetic proteins
Transcription factors are proteins in the nucleus that regulate the
pattern of _______
gene expression
Ectoderm derived FGF-8 regulates gene expression in ________
ectomesenchyme
FGF-8 induces _______ and ______ in
ectomesenchyme very early in development
Lhx-6, Lhx-7
FGF-8 is highly expressed in the ______ arch ectoderm but if the ______ arch ectoderm is used in culturing experiments the expression of FGF-8 is low and tooth placodes do not form
first, second
Expression of the PAX9 transcription factor in ectomesenchymal cells is required to differentiate into __________
DENTAL ectomesenchymal cells
dental placode formation requires _________ for mitosis, ________ for apoptosis and cell division and _________
transcription factor p63, tumor necrosis factor, ectodysplasin
Ectodysplasin (Eda) transmembrane
protein that can be cleaved by ______ to produce a secreted form, involved in morphogenesis were loss of function causes ______ and over expression caused _______
furin, fewer teeth, extra teeth
sonic hedgehog (shh) has roles in ______ development, _______ differentiation, ______ morphogenesis, ______ development, and forming the ______ of the body
limb, neural, facial, hair and feather, midline
sonic hedgehog is important for _______ and ________
invagination, tooth development
Once ectomesenchyme has been
under the control of the epithelium in early tooth development it now is competent to drive tooth formation from ________ and later on the _______ takes over
skin epithelium, neural crest
during tooth bud proliferation the _______ invaginates and moves into the ectomesenchyme that is made up of _________
oral ectoderm, neural crest cells
the tooth bud stage is the stage where the ______ has a significant effect directing the development of the tooth
ectoderm
The ectoderm of the dental lamina plus the underlying ectomesenchyme develop into the _______
tooth germ
during the cap stage as the ectoderm develops and invaginates
into the ectomesenchyme it begins to surround the cells that will become the _______
dental papilla
the six molecules involved in the bud and cap stages includes _____, ______, _____, ______, _____ and _____
msx-1, bmp-4, bmp-2, SHH, activin-BA, Pax-9
SHH is needed for the _____ stage
cap
activin-BA and Pax-9 permit development past the ____ stage
bud
The cap stage sees the formation of the dental organ (tooth germ) which includes the ________, _______ and ________
Enamel organ, Dental papilla, Dental follicle
The enamel organ is attached to the
ectoderm by the _________,
has an _____ enamel epithelium, an ______ enamel epithelium all surrounding a _______
dental lamina, outer, inner, stellate reticulum
Within the enamel organ, cells of the developing stellate reticulum secrete ________ accumulate which are ______ and draw in _____
glycosaminoglycans
(GAGs), hydrophilic, water
Water accumulation forms stellate reticulum by separating cells that remain attached in part through _______
desmosomes
the stellate reticulum is transient and lost after ______ formation
enamel
the enamel organ will eventually form the _______ of the tooth
enamel
the dental papilla will eventually form the _______ and ______ of the tooth
dentin, pulp
the dental sac/follicle will eventually form the _____, ______, and ______
Cementum, periodontal ligament, alveolar process
Enamel “knot” are clusters of non-
dividing epithelial cells and are part of the ______ enamel epithelium
inner
in the enamel knot there is expression of FGF4, _____ first, then ______, and then ______, _____, _____, and _____
p21, SHH, Bmp2,4,7, Fgf-4.9, Wnt-10b, Slit-1
the outer enamel epithelium serves as protective barrier for the ______
enamel organ
stellate reticulum supports the production of _________
enamel matrix
the stratum intermedium between the _____ enamel epithelium and _________ supports the production of _________
inner, stellate reticulum, enamel matrix
the inner enamel epithelium will differentiate into _______ that form enamel matrix
ameloblasts
outer cells of dental papilla will differentiate into ______ that form dentin matrix
odontoblasts
Central cells of dental papilla will differentiate into ________
pulp tissue
inner enamel epithelium cells are cuboidal with centrally placed nuclei and will differentiate into _______ epithelium
preameloblasts
preameloblasts epithelium cells are columnar with nuclei closer to the __________
stratum intermedium
during the bell stage the tooth assumes its ______
final shape
Early in the Bell Stage the tooth germ maintains contact with the ectoderm via the dental lamina and
proceeding through the Bell Stage
______ and _______ begin to form
enamel, dentin
________ is found in the inner enamel epithelium
Glycogen
_________ is found in the stratum intermedium
Alkaline phosphatase
The junction of the inner and outer enamel epithelium is the _______
cervical loop
in the later bell stage the dental
lamina break up so tooth no longer connected to _______
oral epithelium
the apposition stage is also called the secretory stage were _____ , ____ and ______ are secreted
dentin, cementum, enamel
_______ is where ectodermal tissue of the enamel organ and ectomesenchymal tissue of the dental papilla and dental sac interact to signal the other layer to differentiate and begin secretion
Reciprocal Induction
Preameloblasts induce the outer dental papilla cells to become _______
odontoblasts
Preameloblasts become polarized with the base of the cell located along the _______
stratum intermedium
________ are polarized in the opposite direction of the ameloblasts and the nucleus is at the opposite end of the cell from the ______
Odontoblasts, dentin
Polarized odontoblasts secrete _______ toward the preameloblasts
predentin
after predentin formation, preameloblasts are induced to
become presecretory and then secretory ameloblast which then secrete ______
enamel
Preameloblasts become _________ and they begin amelogenesis
ameloblasts
Tomes processes of
ameloblasts appear as the
enamel matrix is produced where predentin is made and
forms around ________
dentinal tubules
Dentinal tubules contain
odontoblastic processes and some odontoblast processes get surrounded by enamel at the tips and become _______
enamel spindles
the appositional stage is where _______ and _______ are formed
dentin, enamel
Amelogenesis imperfecta in the permanent dentition is a hereditary type of enamel dysplasia where the teeth have either _______ or _______ that chips off, leaving the yellow crowns of dentin, which undergo extreme attrition
no enamel, very thin enamel
Dentinogenesis imperfecta in the permanent dentition is a hereditary type of dentin dysplasia that results in _______ with an opalescent sheen, chipped enamel, and crowns of dentin with severe attrition
blue-gray teeth
The cervical loop is responsible for ___________
root formation
Inner enamel epithelium of
________ induces odontoblasts of the
root
Hertwigs root sheath (HERS)
After root dentin formation the
_______ disintegrates
HERS
Some epithelial cells of the HERS may remain as Cell rests of
_______, they may become cystic and are susceptible to infection and they end up being located in the ________
Malassez, Periodontal Ligament
after the HERS disintegrates, cells of dental sac contact root dentin and become _________ which lay down
cementum
cementoblasts
cells are surrounded by cementum and become _________
cementocytes
dental lamina forms at around ____ to ___ days
42, 48
the bud stage of deciduous incisors, canines and molars begins at ___ to ____ days
55, 56
bell stage for deciduous teeth and bud stage for permanent teeth begins at around _____ weeks
14
dentin and functional ameloblasts in deciduous teeth begins at around ____ weeks
18
dentin and functional ameleoblasts in permanent first molars begins at ____ weeks
32
primary dentition begins to form at around ______ weeks in utero
6-8
successional/permanent teeth from the successional lamina begin forming at the _____ week of gestation to ______ postnatal month
20th, 10th
the first molars begin forming at around the ______ week of gestation onward
20th
third molars begin forming at around the ______ of life
5th year
Successional lamina arises from the _______ and gives rise to ________
dental lamina, permanent teeth
the successional lamina gives rise to the _____, _____ and _____
incisors, canines, premolars
Permanent molars arise ______from dental lamina
de novo
the permanent molars grow _______ as jaw enlarges
posteriorly
The reduced enamel epithelium
appears as the tooth moves to
erupt and it consists of the fused _______ enamel epithelium, _________, __________ and ________
outer, stellate reticulum, stratum intermedium, ameloblasts
during eruption, as _______ enamel epithelium reaches ______
epithelium they fuse and epithelial integrity is maintained
reduced, oral
Central cells degenerate and
form the _________ and the rest of cells form the _______ epithelium and the ______ epithelium
eruption canal, junctional, gingival
the shape of a tooth is the result of ________ activity
differential mitotic
The type of tooth that develops once past the bud stage is dependent of the _______ and not the ______
ectomesenchyme, ectoderm
_______ genes are transcription factors actin in the nucleus to
regulate patters on gene expression and thus cell differentiation and
development
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