Tooth Development Flashcards
Autocrine
Self regulated- cell releases something that acts on its own receptors
paracrine
cell talks to neighbor
endocrine
release into the blood stream- talks to every one
intracrine
signalling molecule never leaves cell-acts on self
cell-matrix intereactions
dictate morphogenesis and differentiation
Cranial neural crest derivatives
ganglia/ nerves, adrenal medulla, ectomesnchyme of bones and teeth
Primary Epithelial Bands
mark sites of jaws
Six stages of crown development
1) Initiation- induction
2) Bud Stage- proliferation
3) Cap Stage- Proliferation, diff. morphogenesis
4) Bell Stage- P, d, m
5) Apposition Stage- Induction and proliferation
6) Maturation Stage- maturation
Bud Stage is precurser to
enamel organ
Dental epithelium
controls what is going to happen
Cap Stage
caused by unequal proliferation of bud cells
ectomesenchymal cells condense to become dental papilla and dental sac
tooth germ = enamel organ, dental papilla and dental sac
Successional dental lamina forms on lingual side of dental lamina ( will give rise to permanent tooth)
Enamel knot
signalling center. found at base of enamel organ inside the cap shape
dental papilla becomes
periodontia
stellate reticulum
rich in GAGS
supports enamal production
stratum intermedium
rich in alkaline posphatase,
supports enamel production
Bell stage
Continued differentiation produces 4 distinct layers
1) outer enamel epithelium
2) stellate reticulum
3) stratum intermedium
4) inner enamel epthelium
Cervical loop
junction of OEE (outer enamel epithelium) and IEE
this causes the shape and size of roots
Outer Enamel Epthelium
protective barrier for enamel organ
Inner Enamel Epithelium
differentiate into ameloblasts- enamel forming cells
Apposition Stage
organic matrix of enamel and dentin are laid down followed by initial calcification- causes series of reciprocal inductions
1) IEE cells differentiate into preameloblasts- cells become polarized
2) preameloblasts induce outer DP cells to differentiate into preodontoblasts which become odontoblasts.
3) odontoblasts take off and basement membrane disintegrates (DEJ is formed)
4) predentin stimulates preameloblasts to become ameloblasts and retreat. (secretions immediately calcify to 25% full mineralization)
Ameloblast Life Cycle
1) IEE Cell
2) Preameloblast- cell reverses polarity
3) Initial Secretory ameloblast- no Tomes process- prismless enamel
4) secretory ameloblast- Tomes process- enamel prisms
5) smooth-ended maturation ameloblast- removal of protein and water
6) ruffled-ended maturation ameloblast- introduction of inorganic material
7) preotective ameloblast- enamel cuticle
Maturation Stage
Dentin is mineralizes as it is deposited , globular dentin produced first, then fuse together.
mantle dentin is closest to DEJ (higher mienral content, collagen fibers perpendicular to DEJ)
remaining dentin is circumpulpal dentin (lower mineral content and collagen fibers parralel to DEJ)
