Alveolar Bone

Question 1

When is the alveolar bone formed?

Answer 1

Formed during foetal growth, consisting of calcified matrix with osteocytes (bone cells) which originate from osteoblasts

Continual changes; however, retains same approximate form throughout life

Balance between deposition by osteoblasts and resorption by osteoclasts (renewal and remodelling)

Question 2

What is the function of the alveolar process?

Answer 2

It forms the bony sockets that provide support and protection for the roots of the teeth

Question 3

What is the alveolus?

Answer 3

The bony socket for the root of a tooth

Question 4

What are the characteristics of the alveolar bone proper?

Answer 4

Also known as the cribiform plate or lamina dura, it is part o fthe alveolus directly facing the roots of a tooth (lines the socket)

It is perforated by tiny channels containing blood, lymph vessels, and nerves, linking PDL with cancellous portion of bone

Vascular supply from branches of the superior and inferior alveolar arteries

Question 5

What is cancellous bone?

Answer 5

Also known as trabecular bone

Meshwork of spongy tissue / spongy appearance

Increased forces = increased trabeculae

• Heavy bite / stress = more sponge
• Red bone marrow fills the holes

Question 6

What is cortical bone?

Answer 6

Compact bone found on the facial and lingual surfaces of the alveolar bone

Question 7

What is the alveolar crest?

Answer 7

Most coronal part of the alveolar process

In health = 1 - 2mm apical to CEJ of tooth

From the facial / lingual aspect, it meets teeth in a scalloped line following the CEJ of the teeth

Question 8

What aspects of the alveolar bone do radiographs help identify?

Answer 8

Alveolar crest
Height
Slope
Interdental bone septum (may indicate periodontal disease)

(Horizontal, vertical, interproximal crater)

Question 9

What is the periosteum?

Answer 9

A dense layer of tissue that lines the outside of the bone and plays an active role in bone formation (fibrous outer layer is responsible for attachment of tissue to bone, cambium layer contains progenitor cells that develop into osteblasts)

Periosteum unstable if periodontal disease is present

Question 10

What factors affect the height and thickness of the bony plates (facial and lingual)?

Answer 10

1. Alignment of teeth
2. Angulation of the roots in the bone
3. Occlusal forces
4. Also affected by: function, age, disease related change, hormones, host factors, systemic disease

Question 11

How do occlusal forces affect the alveolar bone?

Answer 11

Normal = force applied to tooth when chewing, tooth is dispalced against PDL (which is resilient)

Increased forces = number and thickness of trabeculae are increased, bone may be added to external surface or inner/outer cortical planes

Reduced forces = number and thickness of trabeculae are reduced, bone resorbs and bone height is reduced (aka disuse or afunctional atrophy)