Alveolar Bone

1. Gingiva

2. PDL

3. Cementum

4. Alveolar bone

4 principal components of the periodontium

Ectomesenchymal tissues

The alveolar process develops from the ?

cribriform plate, bundle bone, or lamina dura on radiographs

Alveolar bone proper is aka ?

Alveolar bone proper

forms inner wall of tooth socket; insertion site for Sharpey’s fibers

Alveolus (tooth socket)

bony cavity within the alveolar process that houses and supports the root of each tooth

Alveolar crest

forms the most coronal portion of the alveolar process; normally lies approx. 1-2 mm apical to the CEJ

Fenestrations and dehiscences

localized defects in the cortical alveolar bone that exposes portions of the tooth root

fenestration

an isolated “window” of missing cortical bone in which the marginal (alveolar crest) bone remains intact

dehiscence

a more extensive defect in which the loss of cortical bone extends coronally to involve the alveolar crest

• prominent root anatomy

• thin cortical bone

• facial tooth positioning

• orthodontic tooth movement

• occlusal trauma

factors associated with fenestrations and dehiscences

osteons or haversian systems

densely packed lamellae arranged into cylindrical units

bundle bone

refers to the incorporation of the terminal portions of the Sharpey’s fibers into the bone

bone lamellae

organized layers of mineralized bone matrix that contribute to the strength and structural organization of alveolar bone while minimizing weight

interstitial lamellae

remnants of older osteons left behind after bone remodeling

concentric lamellae

arranged in rings around the Haversian canal within each osteon

lamellar bone

Mature, highly organized bone characterized by parallel collagen layers and superior mechanical strength

woven bone

Immature bone that forms rapidly during growth, fracture repair, and early socket healing before gradually being replaced by lamellar bone through bone remodeling

bone marrow spaces

cavities located between the trabeculae of cancellous alveolar bone and are filled with either red or yellow marrow

canaliculi

microscopic channels that allow the diffusion of nutrients and waste products while facilitating cell-to-cell communication among osteocytes

nutrient canals

small channels within the alveolar bone that transmit blood vessels, lymphatic vessels, and nerves between the bone marrow spaces and the PDL

volkmann canals

Transverse or oblique channels in compact bone that connect adjacent Haversian canals

volkmann canals

their primary function is to provide vascular and neural communication by connecting blood vessels throughout the bone

osteoprogenitor cells

precursor cells capable of differentiating into osteoblasts during growth, repair, and regeneration

extracellular matrix

the strength and resilience of alveolar bone depend on its ?

Type I

Collagen type in the organic matrix (or osteoid)

periodontal ligament vessels

nourish the alveolar bone proper and maintain the vitality of the attachment apparatus

periosteal vessels

supply the cortical plates and contribute significantly to bone repair following injury or surgery

intraosseous vessels

nourish the cancellous bone and bone marrow spaces while supporting hematopoiesis and bone metabolism

bone metabolism

the continuous processes of bone formation and bone resorption that maintain skeletal integrity and mineral homeostasis

bone modeling

alters the overall shape and size of bone during growth and tooth eruption through independent formation and resorption

bone remodeling

a lifelong process in which osteoclast-mediated resorption is followed by osteoblast-mediated bone formation at the same site

Mechanical regulation

Functional forces stimulate bone remodeling according to the principle that bone adapts to mechanical stress

Wolff’s Law

states that bone remodels in response to the magnitude and direction of functional loading

Molecular regulation

Bone remodeling is controlled by signaling molecules produced by osteoblasts, osteocytes, immune cells, and periodontal tissues

RANK-RANKL-OPG signaling system

Principal molecular regulator of bone remodeling

RANKL

stimulates osteoclast differentiation and bone resorption by binding to RANK receptors on osteoclast precursors

Osteoprotegerin (OPG)

A decoy receptor protein that prevents bone breakdown by binding to RANKL and blocking osteoclast development

Parathyroid hormone (PTH)

• increases osteoclast activity indirectly

• raises blood calcium levels

• promotes bone resorption

Calcitonin

• inhibits osteoclast activity

• reduces bone resorption

• helps preserve bone mass

Vitamin D

• enhances intestinal calcium absorption

• supports mineralization

• essential for normal bone development

Estrogen

• suppresses osteoclast activity

• maintains bone density

Growth hormone

• stimulates osteoblast activity

• promotes skeletal growth

Horizontal bone loss

Most common bone loss pattern

• occurs when alveolar crest is uniformly reduced while remaining generally parallel to a line connecting the CEJ of adjacent teeth

• reflects generalized destruction of periodontal support

Vertical (angular) bone loss

• occurs when resorption progresses unevenly

• create infrabony pockets that may be favorable for regenerative periodontal therapy because portions of the surrounding bone remain intact

1-2 mm apical to CEJ

normal alveolar crest level