Odontogenesis Flashcards
what is odontogenesis
Formation of tooth tissues from stem cells originating in the ectoderm
when does Odontogenesis begin
6th embryonic week
what parts of the ectoderm are involved in tooth development
Epithelium and mesenchyme
what tissue contains stem cells that become the specialized cels that form tooth tissues
Odontogenic tissues
Fomation of dentin tissue
Dentinogenesis
Formation of enamel tissue
Amelogenesis
Formation of Cementum tissue
Cementogenesis
Formation of pulp tissue
Pulpogenesis
two histologic stages of odontogenesis
Epithelial stages
Tooth germ stages
Epithelial stages
Epithelial dental lamina stage
Epithelial bud stage
Epithelial cap stage
Epithelial bell stage (enamal organ)
when is the epithelium arranged in 4 distinct layers
At the bell stage
what are the epithelial stages based on
Histologic shapes of epithelial tissues
what happens in the tooth germ stage
the odontogenic and epithelial and mesenchymal tissues combine and cells of each induced specifically to become formative cells of dentin, enamel, cementum and pulp tissues
the 3 parts of the tooth germ and the type of cells that make them up
Enamel organ (bell):
Dental papilla: mesenchym
Dental Follicle: mesenchyme
the parts of the tooth germ give rise to
specialized cels that form tooth tissues
when does the primary dental lamina stage occur
6th embryonic week
what occures in the dental lamina stage
2 epithelial invagination in the lower anterior region of the lower jaw (upper happens later in the same week) decend into the ectomesenchyme
what are the 2 bands formed in the primary dental lamina stage
Facial: vestibular lamina
Lingual: primary dental lamina
what happens to the vestibular lamina
Cell death occurs in the cental of the vestibular lamina leading to the vestibular
what happens to the primary dental lamina
Cells arisisng for the dental laminae become the odontogenic epithelial part of a tooth germ
what happens in the epithelial bud stage
formation of epithelial buds at the deep end of the dental lamina
what is the epithelial bud
epithelial knots where a tooth is too be formed at the deep end of the dental lamina
what surrounds each epithelial bud
Mesenchymal tissue
how are epithelial bud cells separated from the primary dental lamina
Not separated, they are continuous
what separates the vestibular lamina from the the epithelial bud
Bands of epithelail cells
when do priimary buds form
Cental incisors: 6 weeks in utero
Second molar: 8 weeks in utero
when do permanent buds from
First molar: 4 months in utero
Central incisors: 5 months in utero
Second molar: 10 months postnatally
third molar: 5 years postnatally
how do 3rd molars look before year 5
look like a cyst
where does the secondary lamina form
Behind the primary dental lamina
why does the secondary dental lamina form
there is one for each succedaneous tooth
is there a secondary dental lamina for perminant molars
NO
what does the primary dental lamina give rise to
16 epithelial buds (10 primary and 6 permanent)
what happens at the cap stage
Odontogenic epithelium is in the shape of a cap
what is the enamel knock
Concentration of epithelial cells of the cap to serve as a signalling center
- determines if the tooth will develop to become and anterior or posterior tooth
where is mesenchym in the epithelial cup stage
In and outside of the epithelial cup
what happens in the epithelial bell stage
Epithelial cap undergoes growth and develops into a bell shaped epithelial structure
the other name for the peithelial bell
Enamel organ
layers of the epithelial bell stage from inside to outside
Inner epithelial layer
Stratum intermedium epithelial layer
Stellate reticulum epithelial layer
Outer epithelial layer
how many secondary dental lamina form in each arch
10 in each arch( one for each succidaneous tooth)
what does the secondary dental lamina arise from
The primary dental lamina (NOT THE ORAL EPITHELIUM)
what parts of the tooth germ are vascularized
Enamel organ: no
Dental papilla: yes
Dental Follicle: yes
what do the inner epithelial cells of the enamal organ differentiate into
Ameloblasts
what are ameloblasts
Specialized epithelial cells
what do the ameloblasts and other parts of the enamel organ form after the formation of the enamel is complete
a protective strucutre called the reduced enamel epithelium
what do the dental papilla stem cells become
Odontoblasts, fibroblasts, reserve cells that eventually become the pulp of the tooth
what does the dental follicle stem cells become
Cementoblasts, fibroblasts, osteoblasts, and reserve cells to become to periodontal ligament of the periodontium
how is the enamel organ attached to both mesenchymal parts of the tooth germ
Basal lamina
the space between the odontoblasts and the ameloblasts
the Future Dentinoenamel junction
what is the roll of the reduced enamel epithelium
Protects the enamel from surrounding connective tissue until the tooth enters the oral cavity
what is the cervical loop
The rim of the epithelial bell where the inner and outer epithelial layers meet
the doubled epithelial layer of the enamel organ
Hertwig’s epithelial rooth sheath
Roll of hertwigs epithelial root shealth
Determines rooth dentin outline
Determines number of root canals of a tooth (NOT ROOTS)
