The document discusses the anatomy and function of alveolar bone. It defines alveolar bone as the part of the maxilla or mandible that supports and protects the teeth. It develops during fetal life and eruption of teeth. The alveolar bone consists of cortical plates and cancellous trabeculae that provide support. Osteoblasts, osteocytes, and osteoclasts maintain the bone through formation and resorption. The alveolar bone anchors teeth, absorbs forces, and supplies vessels to supporting tissues. Loss of alveolar bone can occur in periodontal disease.

1. ALVEOLAR BONE

2. ALVEOLAR BONE
 DEFINITION
 DEVELOPMENT
 PARTS OF THE ALVEOLAR BONE
 COMPOSITION
 CELLS OF ALVEOLAR BONE
 BONE FORMATION
 BONE RESORPTION
 FUNCTIONS OF ALVEOLAR BONE
 DISCUSSION
 CONCLUSION

3. DEFINITION
 The part of maxilla or mandible that supports and
protects the teeth is known as alveolar bone.

4. DEVELOPMENT
 2nd month of fetal life, maxilla &
mandible forms a groove – containing
tooth germs, alveolar nerves &
vessels
 Bony septa develop between the
adjacent tooth germs
 Primitive mandibular canal is
separated from dental crypts by a
horizontal plate of bone
 An alveolar process develops only
during the eruption of the teeth

5. PARTS OF THE ALVEOLAR BONE
Alveolar process consists of
1. An external plate of cortical bone formed by
haversian bone and compacted bone lamellae
2. The inner socket wall of thin compact bone
called the alveolar bone proper which is seen as
the laminadura in radiographs
3. Cancellous trabaculae, between these two
compact layers, which act as supporting alveolar
bone.
4. Bones of the jaw include the basal bone, which is
the portion of the jaw located apically, but
unrelated to the teeth

6. External plate of cortical bone
 The thickness of the compact cortical bone on the
superficial /outer aspects of the alveolar process is
closely tooth dependent
 In the incisors canines and pre molar regions the buccal
cortical plate is thin and sometimes missing at the
coronal parts of the root
 In case of tipping of a tooth the vestibular cortical bone
becomes thin whereas the lingual cortical plates
thicken

7. Alveolar Bone Proper
 Called Bundle bone as numerous bundles of Sharpey’s fibres pass into it from
the Periodontal ligament.
 The radiographic term - Lamina dura , appearing as dense white line.
 Break in continuity of lamina dura at the proximal aspects of crest of
interdental septum has been considered as the earliest radiographic change in
periodontitis.

8. CANCELLOUS BONE
 The lamellae are apposed to each other to form trabeculae arranged in a
random fashion.
 Trabeculae surround marrow spaces.
 The medullary cavities are filled with marrow – red when there is active
production of blood cells or yellow when aging results in its conversion to a
fat storage site.

9. Trabaculae
Type I – Regular and horizontal ladder like arrangement
Type II – Irregularly arranged
Numerous and delicate

10. Interdental Septa & Interradicular Septa
 The bone between adjacent single or
multirooted teeth.
 Consists of cancellous bone bordered
by the socket wall of approximating
teeth and the facial and lingual
cortical plates .
 Bone between the roots of
multirooted teeth .
 Both of them contain perforating
canals of Zukerkandl & Hirschfeld
[nutrient canals].

11. Basal Bone
 It is the osseous tissue of the mandible and the maxilla
excepting the alveolar process.
 Anatomically, there is no distinct boundary that exists
between the body of the maxilla/mandible and their
alveolar process.

12. Maxillary Alveolar Process
 Consists of Buccal and palatal alveolar plates, between which lie
the sockets of individual teeth.
 Between each socket lies interalveolar or interdental septa.
 The floor of the socket is termed fundus.
 The rim of the socket is termed alveolar crest

13. Mandibular Alveolar Process
 Consists of Buccal and lingual alveolar plates joined by
interdental and interradicular septa.
 The form and depth of each socket is related to the morphology
of the roots of the mandibular teeth.

14. Periosteum
 The outer surface of bone is covered with periosteum.
 The Periosteum is composed of two layers of specialized
connective tissue.
 The outer or fibrous layer is mainly formed from dense
collagenous fibers and fibroblasts.
 The inner/cellular/cambium layer contains functional
osteoblasts, their precursors and a rich vascular supply.
 The Periosteum is important during growth, regeneration of
periodontal defects and healing around implants.

15. Endosteum
 The medullary cavities and spaces are covered by
Endosteum.
 The Endosteum is a very thin and delicate
 Membrane consisting of a single layer of osteoblasts.
 Its architecture is similar to the cambium layer of the
periosteum because of the presence of osteoprogenitor
cells.

16. BONE ORGANISATION
Compact Bone
 Deposited in the form of lamellae
arranged as parallel layers at the
periosteal & endosteal surfaces known
as circumferential lamellae.
 In concentric layers around the
vascular canal [ Haversian canal ]
known as concentric lamellae.
 The Haversian canal together with the
concentric lamellae is known as an
Harversian system / osteon.
 Haversian canals are connected to
each other and to the outside surfaces
of the bone by short, transverse
Volkmann canals.
Lamellated Bone (Haversion
System)
A – Haversion Canal
B – Interstitial
lamellae

17. Composition of Alveolar bone
 2 basic constituents:
1. Cells consist of osteoblasts, osteoclasts, and osteocytes
2. Extra cellular matrix

19. Inorganic (2/3rd)
• Ca
• PO4
• Hydroxyapatite
• Carbonate
• Citrate
• Na
• Mg
• F1
Organic (1/3rd)
Type I Non Collagen
• Osteocalcin
• Osteonectin
• BMPs
• Phosphoprotein
• Proteoglycan
Composition

20. CELLS OF ALVEOLAR BONE
 Osteoblasts
 Osteocytes
 Osteoclasts

21. Osteoblasts
 Basophilic, plump cuboidal / slightly elongated cells.
 Contain rough endoplasmic reticulum, numerous mitochondria vesicles and
Golgi complex.
 Produce
 - Type I collagen
 - Noncollagenous bone proteins like Sialoprotein, Osteopontin, Osteonectin
 - Growth factors –BMP, Transforming growth factor, insulin like growth
factor, platelet derived growth factor , fibroblastic growth factor

22. Osteocytes
 Osteocytes are the cells lying within the bone itself and are
‘entrapped’ osteoblasts.
 Osteocytes occupy spaces (lacunae) in bone and are defined
as cells surrounded by bonematrix.
 The lacunae are regularly distributed and many fine canals
called canaliculi radiate from them in all directions.

23. Osteoprogenitor cells
 The stem cell population that give rise to osteoblasts are termed
Osteoprogenitor cells.
 They are fibroblast-like cells, with an elongated nucleus and a few organelles.
 Their life cycle may involve upto about eight cell divisions before reaching the
osteoblast stage.
 They reside in the layer of cells beneath the osteoblast layer, in the periosteal
region, in the periodontal ligament or in the marrow spaces.

24. OSTEOCLAST
 Osteoclasts are large, multinucleated cells responsible for bone
resorption.
 Osteoclasts lie in resorption bays called Howship’s lacunae.
 That part of the cell that lies adjacent to the bone, where
resorption is occurring is striated in appearance and is called
the ‘ ruffled border’.

25.  Osteopontin and bone sialoprotein - cell adhesion proteins
(adhesion of osteoblasts and osteoclasts)
 Paracrine factors including cytokines, chemokines, and
growth factors
 All these factors play a prominent role in the development
of alveolar processes

26. Bone formation
.
 As the process of bone formation progresses, the osteoblasts
come to lie in tiny spaces (lacunae) within the surrounding
mineralized matrix and are then called osteocytes.
 Calcium and phosphorus are derived from the blood plasma
and from nutritional sources.
 Regulators of Bone formation
HORMONES
• Parathormone
• Vitamin D3
• Glucocorticoids
• Thyroid Hormone
• Growth Hormone
• Insulin
LOCAL REGULATORS
• Platelet derived growth factor
• Insulin growth factors
• Transforming growth factor-β
• Bone morphogenetic protein
• Fibroblast growth factor

27. Bone Resorption
 It is the process of removal of mineral and organic components of
extracellular matrix of bone by osteolytic cells called osteoclasts.
Sequence of events of Bone resorption
 First phase - Formation of osteoclast progenitors in the hematopoietic
tissues.
 Second phase - Activation of osteoclasts at the surface of mineralized bone.
 Third phase - Activated osteoclasts resorbing the bone.

29. Re-modeling of Bone
• Replacement of old bone by new bone
• Systemic balance of osteoblastic and osteoclastic
activity
• Bone forming activities – intensely dark lines
* Resting lines *
• Resorption activities – dark scalloped lines
* Reversal lines *
A - Resting lines
B - Reversal
lines

30. Functions of Alveolar bone
 Holds the socket of the teeth
 Anchors the roots of the teeth to the alveoli, which is
achieved by the insertion of Sharpey’s fibers into the
alveolar bone proper
 Helps to move the teeth for better occlusion
 Helps to absorb and distribute occlusal forces generated
during tooth contact
 Supplies vessels to periodontal ligament
 Protects developing permanent teeth, while supporting
primary teeth

31. Discussion
 Horizontal bone loss – crest of bone is perpendicular to
tooth surface
 Vertical or angular bone defects occur in an oblique
direction
 horizontal alveolar bone loss is seen more often than the
vertical bone defects in periodontal patients.

33.  Architecture refer to the relative position of interdental
bone to radicular bone
 Positive architecture if radicular bone is apical to
interdental bone
 Negative architecture if interdental bone is more apical
than radicular bone
 Flat architecture is reduction of interdental bone to same
height as the radicular bone.

35. Fenestration and
Dehiscence
Fenestration:
Isolated areas where root is denuded of bone
and root surface is covered by Periosteum and
gingiva.
Here the marginal bone is intact
Such defects occur on approximately 20% of the
teeth, more often on the facial bone than on the
lingual bone, more common on anterior teeth
and are frequently bilateral
Dehiscence:
Denuded areas extended through marginal
bone.
When the denuded areas extend through the
marginal bone, the defect is called a
DEHISCENCE

36. Prominent root contours , malposition, and labial protrusion of the
root combined with a thin bony plate are predisposing factors
Fenestrations and dehiscence are important because they may
complicate the outcome of periodontal surgery

37. OSSEOUS CRATERS

38. BULBOUS BONE CONTOUR

39. EXOSTOSIS

40. OSTEOPOROSIS
 Condition of fragile bone with increased susceptability to
fracture

41. OSTEOMALACIA
 Softening and weakening of bones in children due to lack of
vitamin D

42. OSTEOPETROSIS
 Failure of osteoclasts to resorb bone
 Increased bone density

43. OSTEOMYELITIS- rare & serious condition
 Via bloodstream or infected adjacent tissue

44. OSTEORADIONECROSIS
 An inflammatory condition of
bone that occurs after the bone
has been exposed to therapeutic
doses of radiation, for
malignancy of head & neck region
 It results in irreversible tissue
death
 The mandible is affected more
often than the maxilla

45. Conclusion
 The structure and integrity of the alveolar bone is one of
the deciding factors in the diagnosis and treatment
planning of periodontal patients