1. Anatomy Flashcards
What is the difference between parakeratinized and orthokeratinized nuclei
Parakeratinized has nuclei
Orthokeratinized does not
Name the clear cells
- Merkel - Sensory
- Langherhan - Defense cells & present antibodies
- Melanocytes - Produce melanin
What is the normal radiographic width of PDL space
0.01 - 0.25 mm
What is the turnover of Junctional Epithelium
1 - 6 days.
What are the 2 layers of the basement membrane
- Papillary
2. Reticular
What is the blood supply to the PDL
Superior and Inferior Alveolar Arteries
What is the difference between woven bone and lamellar bone
Woven Bone: Immature bone with osteoblasts and calcified collagen fibers
Lamellar: More mature bone
Where is Lamellar bone found
Cortical Bone
Where is bundle bone found, what does it belong to?
Around the tooth, it belongs to the tooth
It is 1 mm thick
It resorbs following extraction of teeth no matter what
What type of collagen is present in bone
Type I
What are the stages of tooth development
- Bud
- Cap
- Bell
What are ameloblasts derived from
Enamel Organ / Dental Organ
What is formed from the dental papilla
- Pulp
2. Dentine
What is derived from the dental follicle
- PDL
- Bone
- Cementum
Discuss how root structure develops starting at the bell stage
IEE + REE combine to form cervical loop
Cervical loop divides into Hertwigs Epithelial Root Sheath
Papilla contacts HERS - forms osteoblast
Follicle brakes down, causing cementoblast to differentiate exposing dentine
Further away fibroblast between collagen form PDL
How does active eruption occur
Oblique orientated fibers pull down the tooth
How does attachment of JE to tooth surface develop
Primarily from OEE and REE
Discuss cementum
Acellular / Cellular
Made of type I and III collagen
Primary acelluar cementum laid down first, has intrinsic fibers
As this thickens it meets the PDL and traps fibers called extrinsic fibers
What are Sharpeys fibers
Fibers trapped in bone
What is secondary cementum
Cellular cementum in the apical 1/3
What is Afibrillar cementum
Thin layer at the enamel junction
What forms intrinsic fibers
Cementum
What forms extrinsic fibers
Bone
How does enamel meet cementum
- Gap - 5%
- Butt - 30%
- Overlay - 65%
What are the main PDL fiber groups
Apical Oblique Radicular Trans Septal Alveolar Horizontal
AORTA H
What are the gingival fiber groups
- Dentogingival
- Dentoperiosteal
- Alveologingival
- Circumferential
- Semi Circular
- Transgingival
- Intergingival
- Trans Septal
What type of collagen in PDL
Type 1 - 80%
Type 3 - 20%
What other fibers in PDL apart from collagen
Eutectin
Oxytalin
What is between the PDL fibers
- Ground Substance
- Fibronectin
- Glycosaminoglycans
- Water
Where are osteoclasts derived from
Monocytes / Macrophages in the presence in RANKL
How does the JE attach to the tooth
Hemi Desmosomes
What are the tissues of the periodontium
Gingiva
CT attachment
PDL
Alveolar Bone
What are the 3 zones of epithelium in the periodontium
- Oral Epithelium
- Crevicular / Sulcular Epithelium
- Junctional Epithelium
What are the layers of the epithelium from inferior to superior
- Basale
- Spinosum
- Granulosum
- Corneum
Discuss the stratum basale
Cuboidal Cells
Lots of mitochondria
LMW keratin
High mitotic activity
Discuss the stratum spinosum
Polyhedral in shape
Less cell division
Higher molecular weight proteins present
Discuss the stratum granulosum
Cells flatten out
Lots of keratohyaline granules
Not present in NON KERATINIZED EPITHELIUM
Discuss the stratum corneum
Keratohyaline granules disappear
Describe the oral epithelium
All 4 epithelium stem cells present
Most parakeratinized
Prominent Rete pegs
Slower turnover - 6 to 12 days
Describe the sulcular epithelium
Basal, Spinous and Granular layers present
Thinner
Non Keratinized
From gingival crest to junctional epithelium
Few Rete Pegs
Discuss the Junctional Epithelium
Non keratinized
Thin ( 3 -4 Cells thick)
Short turnover
What is the lamina densa
The attachment adjacent to enamel
What is the lamina lucida
Where hemidesomosomes of the epithelium cell BM attach
At what level do JE attach to the tooth
At or slightly coronal to the CEJ
What is the blood supply to the cancellous bone
- PDL
- Periosteum
- Bone itself
What is the lamina dura
A radiographic term for the radio dense line along the socket wall
How does passive eruption occur
Migration of the gingiva due to the splitting of tje secondary epithelial attachment
Splitting stops at CEJ
What does the secondary epithelium attachment become
Junctional Epithelium
How are cells bound to tthe basement membrane
Type 4 collagen - basal lamina
Type 7 Collagen - papillary layer
Why is the JE vulnerable to bacterial insults
Wide intracellular spaces
So bacteria can penetrate
