DEH 103: Histology & Embryology
Chapters 5 & 6: Development, Eruption, and Shedding of Teeth
Chapters 5 & 6: Development, Eruption, and Shedding of Teeth
This is the vertical movement of the tooth.
Active eruption
This occurs with aging, recession no actual tooth movement.
Passive eruption
What are the 3 phases involved in eruption?
- Pre-eruptive phase
- Pre-functional phase
- Functional phase
FYI: This is a continous process that ends only when the tooth is lost
This phase includes the time of tooth initation until the time of crown completion.
Pre-eruptive phase
This phase starts with root formation and ends when teeth reach occlusal contact.
Pre-functional eruptive phase
What are the 4 major events durring the pre-functional phase?
- Root formation: proliferation of the root sheath and rooth dentin; formation of pulp tissue
- Movement: incisal or occlusal movement due to the need for space of the enlarging roots; reduce enamel epithelium fusing with the oral epithelium.
- Penetration: into the oral cavity
- Intraoral occlusal or incisal movement: until clinical contact with opposing crown occurs, apical shipt of gingival attachment.
This is an overlying tissue change that is formed by the dental follicle.An inverted triangular area of degenerating connective tissue is formed.
Eruption pathway
These are follicular fibers that will guide the tooth movements in the eruption pathway.
Gubernacular cord
What is the function of an osteoclast during the pre-functional phase?
They function to resorb hard tissue by secreting hydrlytic enzymes. They will be modified b/c they will increase their surface area to maximize their resorption function.
What are the 2 phases of hard tissue resorption?
- Extracellular: mineral is separated from colalgen
- Intracellular: osteoclasts ingest these fragments
This is a region at the apex of the root which accomodates the growing root. Fibroblasts are abudant in this reion to form collagen fibers and calcifed trabeculae at the apex.
Fundic region
This is the phase after teeth are functioning and as long as theya re present.
Functional phase
How long does it take for root formation to be completed?
- 1-1.5 years for primary teeth after occlusion is made
- 2-3 years for permenent teeth after occlusion is made
What are 4 types of tooth movement?
- Occlusal / incisal
- Horizontal
- Rotation & lateral movement
- Mesial drift
What is mesial drift?
Lateral movemement of the tooth on both sides of the mouth, woards the mildline. Contacts wear due to mastication. Pressure on the mesila side of the scoket causes resprotion of lamina dura and tension of the PDL on the disal side which causes growth and shit in the position of tooth socket.
True/False:
1st permanent molars develop approximately where they will erupt. However, mandibular 2nd and 3rds develop in the ramus with the occlusal table pointed distal?
False: 2nd and 3rd are in the ramus with the occlusal table pointed mesial
Where do maxillary 2nd and 3rd molars develop and what direction is their occlusal tables pointed?
- Maxillary tuberosity
- Occlusal surfaces bucally & distal
This is the term for 2 dentitions (primary / permenent).
Diphyodont
This is the loss of primary dentition by the physiologic resorption of their roots.
Shedding
What are some key deifferences in primary and permenent dentiion?
- Primary enamel is prismless
- Primary enamel is 1/2 as thick
- Primary enamel is less pigmented
- Primary dentin softer
- Primary pulps larger
- Primary have less nerves
True/False
Tooth development takes place in many stages (it is continuous). The primary and permenent teeth have the same stages of development.
True
Teeth develop from ____ to ____ and ____ before ____?
- Anterior
- Posterior
- Mandibular
- Maxillary
True/False:
Teeth have the shortest developmental period of any set of organs in the body.
False: longest developmental period
What are the 6 stages of tooth growth?
- Initation stage
- Bud stage
- Cap stage
- Bell stage
- Apposition stage
- Maturation stage
When is the initiation stage occuring?
3th -7th week in utero
When is the bud stage occuring?
8th week in utero
When does the cap stage occur?
9th -10th weeks in utero
When does the bell stage occur?
11-12th weeks in utero
When do the apposition and maturation stages occur?
It varies per tooth
Odontogenesisi starts with the initiation stage at 6-7 weeks prenatal. The stomodeum is lined by ___ which gives rise to ____.
- Ectoderm
- Oral epithelium
What forms the enamel organ which in turn forms enamel.
Oral epithelum
What forms the dental papilla which in turn forms the dental papilla?
Mesenchymal cells
By the end of the 7th week what has happend?
Growth of the oral epithelium has occured giving rise to the dental lamina.
What is the dental lamina?
It is a layer of epithelial cells that gives rise to the 20 primary tooth buds.
This forms a cleft that becomes the vesibule of the oral cavity. It has rapid cell enlargment and then degeneration.
Vestibular lamina cells
This stage is characterized by rounded, localized growth of epithelium surrounded by mesenchymal cells.
Bud stage
Lable 1-3
- Tooth bud
- Oral epithelium
- Mesenchyme
This forms into the primary teeth and will continue to grow into the ____ to form the permanent teeth.
- Primary lamina
- Successional lamina
This is what forms into the permanent molars.
General lamina
Durring the cap stage (9-10 weeks) what 3 things continues to occur?
- Proliferation
- Differentiation
- Morphogenesis
-
- 1 / 89
-
Cartes-fiches
This is the phase after teeth are functioning and as long as theya re present.
Functional phase
How long does it take for root formation to be completed?
- 1-1.5 years for primary teeth after occlusion is made
- 2-3 years for permenent teeth after occlusion is made
What are 4 types of tooth movement?
- Occlusal / incisal
- Horizontal
- Rotation & lateral movement
- Mesial drift
What is mesial drift?
Lateral movemement of the tooth on both sides of the mouth, woards the mildline. Contacts wear due to mastication. Pressure on the mesila side of the scoket causes resprotion of lamina dura and tension of the PDL on the disal side which causes growth and shit in the position of tooth socket.
True/False:
1st permanent molars develop approximately where they will erupt. However, mandibular 2nd and 3rds develop in the ramus with the occlusal table pointed distal?
False: 2nd and 3rd are in the ramus with the occlusal table pointed mesial
Where do maxillary 2nd and 3rd molars develop and what direction is their occlusal tables pointed?
- Maxillary tuberosity
- Occlusal surfaces bucally & distal
This is the term for 2 dentitions (primary / permenent).
Diphyodont
This is the loss of primary dentition by the physiologic resorption of their roots.
Shedding
What are some key deifferences in primary and permenent dentiion?
- Primary enamel is prismless
- Primary enamel is 1/2 as thick
- Primary enamel is less pigmented
- Primary dentin softer
- Primary pulps larger
- Primary have less nerves
