Tooth Development Flashcards
define histogenesis
differentiation of undifferentiated cells to make new tissues
define mineralised dental tissues
enamel, dentine, and cementum
define unmineralised dental tissues
dental pulp
periodontium
define dental lamina
contributes to development of teeth
define vastibular lamina
contributes to the vestibule of the mouth, delineating the lips and cheek from the teeth formation of the sulcus
define initiation stage
first stage of tooth development
define bud stage
second stage of tooth development
define cap stage
third stage of tooth development, in which the tooth germ grows into a cap stage
define bell stage
fourth stage, in which differentiation occurs to furthest extent and starts to resemble a bell
define crown stage
fully developed tooth
define external enamel epithelium
outer layer of cuboidal cells that limits the enamel organ
define stellate reticulum
of epithelial origin, behave like mesenchymal cells, synthesis of collagen I, II and III
define stratum intermedium
two or three layers of cells sitting above IEE
define inner enamel epithelium
columnar shaped cells rich in RNA, connected to each other by desmosomes
define ectomesenchyme
interesting group of cells whose origin is very controversial. Some think neural crest others mesodermal somites
at what week does mesenchyme migrate in to initiate events of tooth development
week 6
to allow condensation of ectomesenchyme to occur what protein switches on what growth factor?
protein - lef-one switches on fgf8
what does the primary epithelial band give rise to?
dental lamina
vestibular lamina
what does the vestibular lamina form?
vestibule between teeth and lips/cheek
what does the lingual side of the primary epithelial band give rise to?
dental lamina
what does the labial/buccal side of the primary epithelial band give rise to?
vestibular lamina
does the formation of the tooth bud take place at the dental lamina or vestibular lamina?
dental lamina
how does the vestibule form?
signals tell cells to die off
by what week should the vestibule be formed?
12
tooth development is 3 overlapping phases, what are they?
initiation
morphogenesis
histogenesis
what does the epithelium in tooth development give rise to?
enamel
hyaline layer of root
what does the mesenchyme in tooth development give rise to?
dentine
pulp
cementum
periodontium - PDL and bone
at what week does initatiation of tooth development take place?
6
which tissue initiates tooth development?
epithelium
what are the stages of tooth development?
bud stage
cap stage
bell stage
crown stage
late bell stage
what are the contents of the tooth germ?
enamel organ
dental papilla
dental follicle
what are the 4 layers of the enamel organ?
inner enamel epithelium
stratum intermedium
stellate reticulum
outer enamel epithelium
what does the dental papilla form
odontoblasts (dentine) and pulp
what does the dental follicle form?
cementum, PDL and bone
what is the role of inner enamel epithelium?
forms ameloblasts which form enamel
what is the role of stratum intermedium?
synthesis and transport to from IEE
what is the role of the stellate reticulum?
maintenance of shape and protection
what is the role of the outer enamel epithelium?
maintenance of shape and exchange
what are enamel knots?
area of developing enamel which sends out signals
what is enamel niche?
as dental lamina breaks down, it surrounds the outside
what is the enamel septum?
forms between outer and inner epithelium cells, changes shape from cap to bell
what growth factors diffuse into mesenchyme. bind to cells and switch on gene msx1 and stop pax9 from developing to allow the tooth to start to initiate?
small cytokines
what genes are activated in repsonse to factors being produced in the mesenchyme in the bud stage once msx1 and pax9 are switched on?
msx2, p21, bmp2
what genes are involved in enamel knot signalling?
the switch on by msx2 and p21 of a certain amount of cell death