Odontogenesis Flashcards
Define odontogenesis
the process of tooth development
Name the stages of odontogenesis
Initiation Bud Cap Bell Late Bell
Describe what occurs during initiation
Week 6:
A band of thickened epithelial cells begins to form in a horse-shoe shape in each developing jaw, called the primary epithelial band, which gives rise to the dental lamina and the vestibular lamina.
Describe what occurs during bud stage
Week 8:
At 10 sites along the dental lamina of each primary epithelial band, the epithelial cells grow towards the underlying ectomesenchyme and form a ‘bud’ shape.
The ectomesenchyme condenses around the bud/enamel organ.
What is the fate of the vestibular lamina?
The vestibular lamina grows alongside the dental lamina but then begins to breakdown to form the sulcus between the teeth and cheeks.
Describe what occurs at cap stage
Week 11:
DENTAL PAPILLA - formed by the condensing ectomesenchyme
ENAMEL ORGAN - formed by epithelial cells - now takes on a cap shape as it grows around the papilla.
DENTAL FOLLICLE - formed by another collection of ectomesenchyme cells which surrounds both the enamel organ and the dental papilla and supplies it with blood and nerves.
Describe what happens at bell stage
Week 11:
Tooth germ takes on a bell shape and begins to resemble the future tooth.
Dental lamina breaks down and is separated from oral epithelium.
Cells of the enamel organ histodifferentiate into 4 distinct layers.
What are the 4 distinct layers of the enamel organ in nell stage?
Outer enamel epithelium
Stratum intermediate
Stellate reticulum
Inner enamel epithelium
3 components of tooth germ?
Enamel organ
Dental papilla
Dental follicle
Summarise what the INNER ENAMEL EPITHELIUM and the STRATUM INTERMEDIUM do
enamel production!
Summarise what the STELLATE RETICULUM and the OUTER ENAMEL EPITHELIUM do
maintain the shape
Describe what occurs during late bell stage
Week 17:
The hard tissues of the tooth are formed
IEE cells - stop dividing, form ameloblasts –> form enamel.
Dental papilla grows larger, forms odontoblasts –> forms dentine.
Root development - dental papilla forms root dentine, dental follicle forms cementum.
How is root formation controlled?
Hertwig’s epithelial root sheath - a collection of cells found where IEE & OEE meet at the cervical root.
Describe the 3 transitory structures of the tooth germ
Enamel knot - cap - signalling centre in enamel organ
Enamel niche - cap - dental lamina dissected
Enamel septum - aides change from cap-bell.
What may occur if the dental lamina doesn’t disintegrate?
May persist to give:
- supernumerary teeth
- odontogenic cysts
- odontogenic tumour
