Periodontium 1 Flashcards
The Periodontium includes what 4 things?
- cementum
- Periodontal ligament
- Boney tooth socket
- Gingiva facing the tooth = junction, sulcular & epithelium.
___ guides the root development.
Hertwig’s root sheath
T or F, the Peridontium developed in sync with the roots.
True!
What is the overall timeline for periodontal development? (6)
- initiation of root dentogenesis precedes periodontal development
- HERS separates from root dentin
- Osteoblasts, cementoblasts, PDL fibroblasts differentiate to their appropriate locations.
- Cementoblasts & osteoblasts secrete their organic matrix which is type I collagen.
- Then the PDL fibroblasts secrete their organic collagen matrix.
- The organic matrices of the cementum and bone mineralize AROUND the ends of the PDL fiber securing it to the bone and cementum!
What PDL developmental steps happen before eruption?
- Collagen fiber bundles added apically
- Orientation of collagen fibers bundles change. oblique –> horizontal.
What PDL developmental steps occur after eruption?
- Thickness of collagen fiber bundles increases.
- PDL fiber bundles become more coronal
The development of the Peridontum proceeds from ____ to ____.
CEJ to root Apex
Describe Primary Cementum…
- First formed
- Mainly acellular
- Coronal 2/3 of root
- Most important in attachment
Describe Secondary Cementum…
- Formed second after at least 1/2 of root is formed around the time of eruption.
- Mainly cellular
- Apical 2/3 of root
- Overlaps primary cementum in the middle 1/3 of tooth.
____ is the pre dentin adjacent to the pulp
unmineralized dentin
____ is a group of collagen fibers oriented at right angles tot he DCJ.
Fiber Fringe
Fiber fringe extends into the ______.
Unmineralized dentin
As you move coronally, what happens to the fiber fringe?
fibers get longer indication further maturation, however the dentin remain unmineralized which allows the collagen fibers of theses two tissues to intermingle further.
*Eventually the dentin mineralizes enclosing the fiber fringe ends within the mineralized dentin matrix.
Firm attachment between cementum and dentin is due to the fact that…..
collagen fibers of these two tissues intermingle BEFORE mineralization.
What happens to the cementoblasts of the primary cementum?
They DONT get entrapped in the ECM they are making, instead they retreat toward location of future PDL and become part of it.
The Adult PDL contains remnants of HERS called _________.
Epithelial rest of Mallasez
What happens to the cementoblasts of the secondary cementum?
Due to the rapid formation of the secondary cementum, they are trapped in the ECM they make.
Cells for the epithelial components of the peridontium arise from ________.
Epithelial precursors
Sulcular epithelium arises from _________.
Embryonic oral epithelium
Junctional epithelium arises from _____.
reduced enamel epithelium
All connective tissue components of the peridontium including the PDL, bony lining of the tooth socket and cementum arise from the ________.
Dental follicle
The cementum forming cells are derived from ____________.
Both Dental follicle and HERS
What are the 3 molecules implicated in cementogenesis?
- growth factors = Implicated in Cementoblast Induction
- Transcription factors = implicated in cementoblast Differentiation
- Extra cellular matrix Molecules = implicated in Cementogenesis.
What are Bone morphogenetic proteins (BMP’s)?
secreted growth factors that have been implicated in serving as an inducing signal that itially triggers cementoblast differentiation.
*Binds collagen
What is the downstream transcription factor to BMP?
RunX = thought to be important in up regulating proteins that characterize differentiated cementoblasts.
*Binds Collagen
