periodontium Flashcards
gomphosis
- cementum
- PDL
- alveolar bone
- gingiva
enamel organ is derived from
oral ectoderm
after mineralization, ameloblasts
shrink from columnar to cuboidal cells
-become part of the “reduced enamel epithelium”
what eventually surrounds the enamel
reduced enamel epithelium
2 cell types of REE
- reduced ameloblasts (cannot divide)
2. external cells (can divide)
external cells of REE eventually give rise to
junctional epithelium
proliferation steps
- proliferative cells (basal, adjacent to gingiva ct) migrate up
- ameloblasts displaced and eventually all are exfoliated
- JE replaces REE, from coronal end downwards
3 parts of gingival epithelium
- oral epithelium
- sulcular epithelium
- junctional
oral epi
-Keratinized or para keratinized
sulcular epi
NON-keratinized
-permeable => allow flow of GCF
junctional epi
- base of sulcus
- joins gingiva to tooth
- 0.71-1.35mm
- 15 - 30 cells thick (coronal
- 4-5 cells thick (apical)
- NON-keratinized
cells attach to tooth surface (enamel) by
hemi desmosomes
in disease state, the gingival fibers
migrate down as the bone gets destroyed
can grow a new attachment after a disease
long junctional epi
*only on root surface below CEJ
muco-gingival junction
marks the change from NK to K
-between alveolar mucosa (NK) and attached gingiva (K)
biologic width
distance between level of bone and CEJ
biologic width
JE + connective tissue attachment
5 types of gingival fibers
1) dentogingival
2) alveologingival
3) circular
4) dentoperiosteal
5) transeptal
dentogingival
- most numerous
- cementum to free and attached gingiva
alveologingival
alveolar crest to free and attached gingiva
circular
goes around the soft tissue of the tooth
dentoperiosteal
cementum, over the alveolar crest, and into bone
transeptal
between teeth
5 types of PDL fibers
- alveolar crest
- horizontal
- oblique
- apical
- interradicular
alveolar crest
cementum below CEJ downward towards alveolus
horizontal group
(below alveolar crest) goes to bone
oblique
- most numerous
- cementum upward to alveolar bone
apical
apical cementum to alveolar bone
interradicular
between roots of multirooted teeth (molars)
white opaque layer that shows up on radiograph
lamina dura
PDL
found -between cementum and inner cortical plate of alveolar bone
-specialized CT that provides supportive, nutritive, and sensory function
osteoclasts and odontoclasts are derived from
blood borne macrophages
how is PDL formed
- unorganized CT initially
- short fiber bundles extend
- ligament mesenchymal cells secrete TYPE I COLLAGEN which assemble into bundles
- remodled into PDL (from CEJ downwards)
2 ways of classifying cementum
cellular connotation or fibrillar connotation
cellular connotation
1) acellular
2) cellular
acellular cementum
- no cells
- provides attachment
cellular cementum
- cementocytes
- adaptive role
fibrillar connotation
1) intrinsic
2) extrinsic
3) mixed
4) afibrillar
intrinsic
- fibers made by CEMENTOBLASTS
- parallel to cementum surface
extrinsic
- sharpey’s fibers
- continuous with PDL
- made by PDL FIBROBLASTS
- perpendibular to cementum surface
- tooth anchorage
mixed
both extrinsic and intrinsic
afibrillar
no type I collagen fibers
cementum types
1) acellular afibrillar (AAC)
2) acellular extrinsic fiber (AEFC)
3) cellular intrinsic
4) cellular mixed
acellular afibrillar cementum (AAC)
- no fibrils or cementocytes
- produced by CEMENTOBLASTS
- pre-eruptive enamel maturation
- CORONAL cementum
acellular extrinsic fiber cementum (AEFC)
- type I collagen, part of sharpeys fibers and continuous with PDL
- made by FIBROBLASTS
- densely packed
- pre and post eruptive
- CERVICAL 2/3 OF ROOT
- TOOTH ANCHORAGE
cellular intrinsic fiber
- cementocytes
- intrinsic fiber (made from CEMENTOBLASTS)
- pre and post
- SITES OF REPAIR
cellular mixed
- APICAL THIRD OF ROOT AND FURCATIONS
- cementoblasts trapped => cementocytes
- intrinsic run between extrinsic (not as dense)
- extrinsic more irregular path
- CEMENTOBLASTS AND FIBROBLASTS
