Periodontium II

Question 1

What is cementum made of?

Answer 1

Type I collagen fibers within a mineralized matrix.

Cementum has intrinsic cementoblasts and extrinsic fibroblasts.

The matrix is composed of hydroxyapatite.

Question 2

How long is cementum deposited?

Answer 2

Throughout life.

Question 3

Does cementum have a blood or nerve supply?

Answer 3

No, neither –> avascular.

This makes grafts challenging.

Question 4

At the cementoenamel junction (CEJ), does the enamel and cementum meet up perfectly?

Answer 4

No, it only meets perfectly in about 30% of the teeth in the mouth.

About 10% of the teeth have no contact btw enamel and cementum

About 60% of teeth have an overlapping contact of enamel and cementum

Question 5

What are the two types of cementum?

Answer 5

Primary: created during tooth eruption and normal development.

Secondary: in response to damage post development.

Question 6

Where are the different locations that cementum is found and named for?

Answer 6

1. Radicular cementum

2. Coronal cementum

Question 7

What different types of cellular cementum are there?

Answer 7

1. Cellular cementum: at the apical 1/3, so formed later in development. Thick!
2. Acellular cementum: at the cervical 1/3, only fibers, formed at beginning of development. Thin!

Question 8

Does all cementum have collagen fibrils in its matrix?

Answer 8

No, there are two types of cementum based on this:
Fibrillar cementum
Afibrillar cementum

Question 9

What are the 3 classifications for where matrix fibers originate?

Answer 9

1. Extrinsic fiber: collagen is deposited somewhere other than cementum…such as fibroblasts at the PDL
2. Intrinsic fiber: Collagen is deposited directly on the cementum by cementoblasts
3. Mixed fiber

Question 10

What is the resorption lacunae?

Answer 10

The area of cementum resorption in response to trauma.

A pit or concavity found in bones undergoing resorption, frequently containing osteoclasts. Similar lacunae also may be found in eroding surfaces of cementum.

Question 11

What are Sharpey’s fibers?

Answer 11

Matrix of connective tissue consisting of bundles of strong collagenous fibers connecting periosteum to bone. They are part of the outer fibrous layer of periosteum, entering into the outer circumferential and interstitial lamellae of bone tissue.

These are the principal fibers of the PDL. They connect to both the alveolar bone and the cementum.

Question 12

When does hypercementosis take place?

Answer 12

From local factors: trauma, inflammation, unopposed teeth, root fracture.

From systemic factors: acromegaly, and pituitary gigantism, Paget disease, Vit A deficiency.

Question 13

Where is the alveolar process?

Answer 13

The jawbone portion that holds the teeth.

Question 14

What is the spongey bone called?

Answer 14

Cancellous bone.

The smooth, hard bone = Compact bone.

Question 15

What is the layer of compact bone that forms and lines the tooth socket?

Answer 15

The alveolar bone proper –> can see it as a white line in the radiograph.

This is where the Sharpey’s fibers attach.

AKA “Lamina dura” when viewing it on the radiograph. Can see the bundle bone.

AKA “cribriform plate.”

Question 16

Where is the alveolar crest?

Answer 16

The highest portion of bone.

Question 17

What is the cancellous bone?

Answer 17

The bone in-between the teeth. Cancellous bone is called trabecular bone because of the holed trabeculae.

Aka “spongy bone”.

Osteocytes live in the lacunae and everything is irregularly arranged.

Question 18

What are the main components of alveolar bone?

Answer 18

1. Inorganic matrix: made of Calcium, and Phosphate, mineral salts
2. Organic matrix: made of collagen and proteins (like osteopontin)
3. Cells such as osteoblasts and osteoclasts

Question 19

How is the compact bone arranged?

Answer 19

Haversian systems!

Haversian canals contain blood and lymph. Osteons with osteocytes surround the canal.

These osteons are aligned along the lines of stress and can change as the stress on the bone changes.

Question 20

Does alveolar bone proper exist without teeth?

Answer 20

Alveolar bone proper is tooth dependent. No tooth = loss of compact bone = less blood supply = bone shrinkage.

Question 21

Where are the mesenchymal cells located in the bone?

Answer 21

In the periosteal layer.

Question 22

What arteries supplies blood to the teeth and periodontal tissue?

Answer 22

Superior or inferior alveolar artery

Question 23

What arteries supply the gingiva?

Answer 23

The supraperiosteal blood vessels:

sublingual, mental, bucca, facial, greater palatine, infraorbital, posterior superior alveolar artery (PSA)

Question 24

What type of nerve receptors are located in the periodontium?

Answer 24

Nociceptors and mechanoreceptors.

Question 25

Which ganglion houses the trophic centers for the pain, touch, and pressure nerves?

Answer 25

Semilunar ganglion, via the trigeminal nerve.

Question 26

Which nerves service the maxilla?

Answer 26

1. Infraorbital nerve: labial of incisors
2. PSA: buccal of the posterior teeth
3. Greater Palatine nerve: palatal gingiva

Question 27

Which nerves service the mandible?

Answer 27

1. Sublingual nerve: lingual of mandible
2. Mental Nerve: Labial up to the canine teeth
3. Buccal nerve: gingiva at the buccal of the molars

Question 28

Where is the lymphatic drainage?

Answer 28

1. Mandible anterior: submental nodes
2. Palatal gingiva of the maxillary: deep cervical group
3. Buccal gingiva of the maxilla: submandibular nodes
4. Third molars: jugulo digastric group

Question 29

What two main bony protuberances are there?

Answer 29

1. Exostosis: facial side

2. Torus: on the palate

Question 30

What is a fenestration?

Answer 30

A window defect in the bone - can see through to the root of the tooth underneath

Question 31

What is a dehiscence?

Answer 31

Not the same as a fenestration, but is recession of bone –> “lack of marginal bone”

Question 32

What differentiates periodontitis from gingivitis?

Answer 32

For periodontitis, the inflammation has progressed from just the gingiva and progressive destruction of the periodontal ligament and alveolar bone occurs.

When the bone is destroyed, there is significant attachment loss.

Question 33

How deep is a healthy sulcus?

Answer 33

0.69 - 1.8 mm (or 2 - 3 mm as measured by a probe in the clinic)

Question 34

How deep must the sulcus be to be called a “pocket” and have disease?

Answer 34

> 3mm

Question 35

What is a furcation?

Answer 35

A little space at the natural bifurcation of the tooth. These are graded I - IV.

I–incipient
II–furcal bone loss, not thru and thru.
III–thru and thru; not clinically visible.
IV–thru and thru visible clinically

Question 36

When assessing a periodontal pocket, bone loss is classified. What is vertical bone loss and horizontal bone loss?

Answer 36

1. Vertical bone loss: intrabony and involves multiple walls (1, 2, or 3 walls).
2. Horizontal bone loss: Suprabony and is only in one direction, parallel to the occlusal plane.

Question 37

How is vertical bone loss classified?

Answer 37

Based on the remaining number of bony walls.

Ex: If much of the bone is gone and only on wall still exists before the adjacent tooth, then it is a class1.