Periodontium

Question 1

What is the periodontium made up of?

Answer 1

Cementum
Alveolar bone
Periodontal ligament

Question 2

What is the periodontium?

Answer 2

Tissues that invest & support the tooth

Question 3

What is cementum?

Answer 3

Mineralized cementoid covering root dentin

Question 4

Characteristics of cementum

Answer 4

• Avascular, non-innervated tissue
• Covers & protects root dentin
• Anchors PDL fibers to tooth root
• Mineralized CT
• Softer than root dentin

Question 5

Physical/Chemical characteristics of cemetum

Answer 5

Has Type 1 Collagen and amphorous ground substances (AGS)

Question 6

What types of cells are found within the cementum?

Answer 6

Cementoblasts
Cementocytes

Question 7

What are cementocytes?

Answer 7

• Cell body situated in lacunae
• Cell processes in canaliculi radiate out ONLY toward the PDL

Question 8

Cementum Types

Answer 8

Acellular extrinsic fiber cementum
Cellular intrinsic fiber cementum

Question 9

Acellular extrinsic fiber cementum (AEFC)

Answer 9

-Primary cementum
- No cementocytes
- Covers cervical 2/3 of root
- Forms slowly during tooth eruption
- Plays major role in tooth attachment

Question 10

Cellular intrinsic fiber cementum (CIFC)

Answer 10

-Secondary cementum
- Contains cementocytes
- Covers apical 1/3 of root
- Forms rapidly
- Plays minor role in tooth attachment

Question 11

Fiber Collagen 1 Types
What is intrinsic fiber?

Answer 11

• Produced by cementoblasts
• Run parallel to the root surface

Question 12

Fiber Collagen 1 Types
What is extrinsic fiber?

Answer 12

• Produced by fibroblasts
• Sharpey’s fibers of PDL
• Run at right angles to root surface

Question 13

What are the 3 patterns of the Cementoenamel junction?

Answer 13

1. Cementum overlaps enamel ~60%
2. Cementum meets enamel ~30%
3. Gap between cementum and enamel ~10%

***these can occur developmentally or post-eruptive

Question 14

What can occur from exposed root dentin

Answer 14

Dentin hypersensitivity

Question 15

Clinical significance of cementum

Answer 15

Orthodontic tooth movement
- Cementum more resistant to resorption than alveolar bone
- Application of proper forces can move teeth through bone

Question 16

What is hypercementosis?

Answer 16

• Abnormal thickening of cellular cementum
• Tooth may become ankylosed

Question 17

Alveolar Process?

Answer 17

Portions of the maxilla and mandible that support the roots of the teeth

Question 18

Chemical composition of the Alveolar Process?

Answer 18

Alveolar bone contains more mineral than cementum

Question 19

What are the components of the alveolar process?

Answer 19

Alveolar bone proper
Cortical plate
- Inner plate: lingual/palatal surface
- Outer plate: buccal & labial surface
Central spongiosa (trabecular bone)

Question 20

Components of Alveolar Process:
What is the Alveolar bone proper?

Answer 20

• Also called: bundle bone, lamina dura and cribiform plate
• Specialized type of compact bone because the ends of the PDL fiber bundles insert into it
• Appears more radiopaque than the adjacent supporting bone
• NO periosteum present
• Remodeling rate may be high due to constant adaptation to tooth mvmts.

Question 21

Components of Alveolar Process:
What is the cortical plate?

Answer 21

• Composed of the inner and outer plates
• Covered WITH a periosteum
• Alveolar crest: junction of cortical plate and alveolar bone proper

Question 22

Components of Alveolar Process:
What is the Central spongiosa?

Answer 22

• Trabecular (spongy/cancellous) bone supporting alveolar bone proper & cortical plate
• Marrow is red in young & yellow in old aged

Question 23

Describe both of the Bony Septa in the alveolar process

Answer 23

Interdental septum
- located between roots of adjacent single-rooted or multi-rooted teeth
Interradicular septum
- located between roots of a single multirooted tooth

Question 24

What is an edentulous jaw?

Answer 24

A jaw with only basal bone
Lost alveolar process

Question 25

What is the periodontal ligament?

Answer 25

Soft connective tissues present between the cementum & the alveolar bone that supports and anchors the tooth to alveolar bone

Question 26

Periodontal ligament:
List all of the ligament cells present in the PDL

Answer 26

FU-CEOOO
Fibroblasts, Undiff. Mesenchymal cells, Cementoblasts, Epithelial rests of Malassez, Odontoclasts, Osteoclasts and Osteoblasts

Question 27

Periodontal ligament:
What are the Epithelial rests of Malassez?

Answer 27

Remnants of Hertwig’s epithelial root sheath

Question 28

Periodontal ligament:
What are principle fibers? What are the 2 classification?

Answer 28

• Fiber bundles exiting the cementum and alveolar bone proper to form the PDL
• Made of Type 1 Collagen

Classifications
1. Dentoalveolar group (tooth attached to alveolar bone)
2. Gingival group (part of gingiva

Question 29

Periodontal ligament:
What are the 5 groups of the Dentoalveolar group?

Answer 29

1. Alveolar crest
2. Horiztonal
3. Oblique (LARGEST)
4. Apical
5. Interradicular: extend from cementum of bifurcation to interradicular septum

Question 30

Periodontal ligament:
What are Sharpey’s Fibers?

Answer 30

• Perforating fibers
• Portions of PDL fibers embedded in the alveolar bone proper or cementum
• Fiber bundles inserting in bone are much larger than inserting in cementum

Question 31

Periodontal ligament:
What are interstitial spaces?

Answer 31

Spaces located between collagen fiber bundles

Question 32

Tooth Movements

Answer 32

1. Compression
   - On the side toward which tooth moves
   - Resorption of alveolar bone
2. Tension
   - On the side opposite to compression
   - Formation of alveolar bone