Week 10 - Eruption and Shedding Flashcards
(47 cards)
How does primary and permenent dentition develop?
simultaneously as the jaws increase in size from infancy to adolescence. Upper and lower jaws grow at about the same rate
What does the jaw accommodate development of during infancy?
20 deciduous teeth
What does the jaw accommodate for at 4-5 years of age?
20 erupted teeth and 28 developing teeth
What does the jaw accommodate for at 8-12 years of age?
there is a mixed dentition stage that involves the concomitant exfoliation of deciduous teeth and eruption of permanent teeth
What is tooth eruption?
movement of a tooth from its site of development within the alveolar process to its functional position in the oral cavity
What three stages is tooth eruption divided into?
- Pre-eruptive stage
- Pre-functional eruptive stage/eruptive phase
- Functional phase/post-eruptive phase
What occurs during the pre-eruptive phase?
where there is growth of jaws, growth of tooth buds, along with remodeling of the body crypt
What direction do teeth have a tendency to grow? migrate?
grow distally and migrate mesially into their position
When does mesial migration occur?
when there is resorption of the mesial wall with concomitant apposition of bone on the distal wall
Over time, jaws increase in size to accommodate for teeth. They increase in:
- Length (anterior posterior) of jaw
- Width of jaw (coronal plate)
- Alveolar ridge height
- Buccal-lingual width of alveolus
Describe how deciduous teeth develop and how the tooth germs grow
the deciduous teeth develop within the jaw and have considerable room. However, the individual tooth germs grow rapidly and due to jaw length, they become crowded anteriorly
What happens to teeth as jaws increase in length?
the crowding is alleviated by migration of teeth distally which allows a more even distribution
What happens to teeth as jaws increase in size?
the developing teeth move outward (facially) and towards the oral cavity (upward or downward)
What happens to permanent developing molars because of jaw length?
Because of the jaw length, the permanent developing molars have angled inclination (mesially) prior to and during eruption and achieve vertical alignment only when jaw length is sufficient to allow it
Where do permanent teeth drift?
Permanent teeth drift mesially to take position in-between roots of primary teeth. Start distally and then drop down (??)
What are the theories of tooth eruption?
Most frequently cited theories are root growth, bone remodeling, and periodontal ligament formation
What are other factors that influence tooth eruption?
- Parathyroid hormone (influences mineralization and resorption of roots)
- MMPs produced by fibroblasts, osteoclasts, macrophages
What are root growth theories?
Elongation of the roots in relation to stability of the fundus of the socket allows tooth to erupt
What are vascular pressure theories?
Increase hydrostatic pressures in the apical dental sac or periodontal ligament
What are selective bone deposition and resorption theories?
- Coronal bone resorption concomitant with bone apposition in the fundus area
- Shifting of the tooth in an erupted path because you have bone being removed superiorly and bone being deposited inferiorly shifting things upwards into place
What is pulpal pressure theory?
- Tissue pressure differential in the pulp compared to the PDL
- As the tooth grows, you decrease pressure in pulp chamber (lower than PDL) causes PDL to increase pressure onto the tooth, pushing it upwards
What is the periodontal and gingival fiber ligament theory?
- Cells (myofibroblasts) exert traction on the tooth through the collagen network and cell-to-cell contacts
- Contraction of fibers push tooth up in a coronal direction
Describe the pre-functional eruptive stage/eruptive phase
due to pressure on fundus, root growth, and bone resorption/deposition
What happens in the pre-functional stage as the permanent tooth erupts?
causes resorption on deciduous tooth in front of it
