The document discusses alveolar bone, which forms the sockets for teeth. It defines alveolar bone and describes its functions, including housing tooth roots and distributing forces. The document outlines the development of alveolar bone from mesenchymal cells and its ongoing remodeling. It details the histology of alveolar bone, including its cellular components like osteoblasts, osteoclasts, and osteocytes. The document also examines the composition, structure, blood supply and clinical considerations of alveolar bone.

2. ALVEOLAR BONE

3. Contents
INTRODUCTION
DEFINITION
FUNCTION OF ALVEOLAR PROCESS
DEVELOPMENT OF ALVEOLAR PROCESS
BONE ANATOMY
BONE MARROW
HISTOLOGY OF BONE
COMPOSITION
BONE FORMATION
STRUCTURE OF ALVEOLAR PROCESS
INTERDENTAL SEPTUM

4. CELLULAR COMPONENT
MATRIX COMPONENT
BONE REMODELLING
BONE RESORPTION
OSSEOUS TOPOGRAPHY
VASCULAR SUPPLY
LYMPHATIC DRAINAGE
CLINICAL CONSIDERATIONS
CONCLUSION
REFERENCES

5. INTRODUCTION

6. ‘‘The alveolar process is the portion of the maxilla and
mandible that forms and supports the tooth sockets” (Carranza
, 10th ed).
“The alveolar process is that bone of the jaw containing
the sockets(alveoli) for the teeth” (Ten Cate’s ,7th ed).
“The alveolar process is defined as the parts of the maxilla and
the mandible that form and support the sockets of the teeth”
(Lindhe,4th ed).

7. FUNCTIONS
Houses the roots of teeth
Anchors the roots of the teeth to the alveoli, which is achieved by insertion of
sharpey’s fibres into the alveolar bone proper.
Helps to move the teeth for better occlusion
Absorbs & distributes the occlusal forces(tooth contact)
Supplies vessels to periodontal ligament
Houses & protects developing permanent teeth while supporting primary teeth
Organizes tooth eruption

8. DEVELOPMENT OF ALVEOLAR BONE
The bone is formed from both cells of dental follicle- alveolar
bone proper & cells which are independent of tooth
development
Maxilla & Mandible-1st brachial arch or mandibular arch
The maxilla forms within the alveolar process & mandible
forms within the fused mandibular processes of mandibular
arch
Both jaw bones start as small centres of intramembranous
ossification around stomodeum

10. 8th week in utero
Alveolar process develops
from dental follicle during
tooth eruption
Bell stage – developing bone
becomes closely related
Size of alveolus is dependent
upon the size of growing tooth
germ
Resorption-inner wall of the
alveolus. Deposition-outer wall
Developing teeth lie in a
trough of bone- Tooth Crypt
Teeth separated from each
other by the development of
interdental septa
With the onset of root
formation, interradicular
bone develops in
multirooted teeth.
When deciduous tooth is
shed, its alveolar bone is
resorbed
Gradually incorporated into
maxillary or mandibular
body
Permanent tooth moves into
place, developing its own
alveolar bone from its own
follicle

12. BONE MARROW
•Embryo & New Born
RED BONE
MARROW
•Adults
YELLOW BONE
MARROW

13. Foci of Red Bone Marrow
Maxillary &
Mandibular Molar
& Premolar area,
Symphysis, Ramus
of Mandible

14. HISTOLOGY OF BONE
All bones have dense outer sheet of compact bone and central
medullary cavity which is filled with red or yellow bone marrow.
The outer aspect of compact bone is surrounded by condensed fibero-
collagen layer, the PERIOSTEUM which contains an inner cellular layer and
outer fibrous layer
The inner surface of compact and cancellous bone are covered by thin
cellular layer called ENDOSTEUM

15. PERIOSTEUM AND ENDOSTEUM

16. PATTERN OF LAYERING OF COMPACT BONE

18. BONE FORMATION
Before 8th week, the human embryonic skeleton is made of fibrous
membranes and hyaline cartilage.
 The development of bone from a fibrous membrane is called
intramembranous ossification. Alveolar Process develops via this process
 The replacement of hyaline cartilage with bone is known as endochondral
ossification

20. CALCIFICATION
 Process of deposition of insoluble calcium salts in a tissue
 Widely conceded that the first formed solid phase is
amorphous. This phase is subsequently transformed to
hydroxyapatite
Amorphous calcium phosphate appears as microscopic
spheres 30-100 nm in diameter, comprising randomly
packed apatite crystals each of about 0.95 nm diameter

21. THEORIES OF CALCIFICATION
NUCLEATION THEORY (SEEDING THEORY)
 Neumann and Neumann (1953) put forward a theory of epitactic nucleation based
on the concept of seeding or epitaxy
A nucleus is formed, probably in relation to collagen, effective in aggregating calcium
and phosphate ions
The hydroxyapatite crystals then grow spontaneously by addition of these from the
saturated surrounding fluids

22. ALKALINE PHOSPHATASE THEORY (ROBINSON’S PHOSPHATE
THEORY)
This enzyme hydrolyses a broad range of organic phosphate
containing substrates and increases the local inorganic phosphate
concentration.
This enzyme resides in matrix vesicles budding from cell
membranes of chondrocytes, osteoblasts and odontoblasts.
Alkaline phosphatase hydrolyses inhibitor of hydroxyapatite
formation and also provides inorganic phosphates for the
formation of hydroxyapatite crystals

23. MATRIX VESICLE THEORY
Matrix vesicles are small membrane bound structures, 25 to 250 nm in diameter,
lying free in the matrix
These vesicles are rich in phospholipids, especially phosphatidyl serine, a lipid with
high affinity for calcium ions.
Matrix vesicles accumulate Ca2+ and their membrane furnish binding sites for the
nucleation of hydroxyapatite crystals.

24. CLASSIFICATION
ALVEOLAR BONE PROPER
SUPPORTING ALVEOLAR
BONE
A. BASED ON FUNCTIONAL ADAPTATION

25. HISTOLOGICALLY
MATURE IMMATURE
WOVEN BONE
CANCELLOUS
BONE
SPONGY
BONE

26. LINLOW 1970
• The ideal bone type consists of evenly spaced trabeculae with small
cancellated spaces
CLASS I BONE STRUCTURE
• This bone has slightly larger cancellated spaces with less uniformity
of osseous pattern
CLASS II BONE STRUCTURE
• Large marrow filled spaces with exists between bony trabeculae
CLASS III BONE STRUCTURE

27. LEKHOLM & ZARB (1985)
Quality 1
• Homogenous
compact
bone
Quality 2
• Thick layer of
compact
bone around
a core of
dense
trabecular
bone
Quality 3
• Thin layer of
cortical bone
around
dense
trabecular
bone
• Favourable
strength
Quality 4
• Thin layer of
cortical bone
around low
density
trabecular
bone

28. MISCH CLASSIFICATION OF BONE DENSITY

29. STRUCTURE OF ALVEOLAR BONE

30. MAXILLA/MANDIBLE
ALVEOLAR PROCESS
BUNDLE BONE LAMELLAR BONE
INTERRADICULAR
SEPTA
INTERDENTAL SEPTA
INNER & OUTER
CORTICAL PLATES
TRABECULAR BONE
ALVEOLAR BONE
PROPER
BASAL BONE

31. Alveolar Bone
External plate of
cortical bone
• Formed by haversian
bone & compact bone
lamellae
Inner Socket Wall
• Thin compact bone
known as ABP seen as
lamina dura in
radiographs.
• Histologically, it contains
the cribriform plate
through which the
neurovascular bundles
link the pdl with the
cancellous bone
Cancellous trabeculae
• Present between the 2
layers as supporting
alveolar bone
• Interdental septum
consists of cancellous
supporting bone
enclosed within
compact border

32. ALVEOLAR BONE PROPER
EXTERNAL
COMPACT BONE
SPONGY
BONE

34. Alveolar Bone Proper
Thin layer of compact bone
Continuation of the cortical plate & forms the
tooth socket
 Surrounds the root of the teeth & gives
attachment to the principal fibres of the
periodontal ligament
Referred to as Cribriform plate - reflects a sieve
like appearance produced by numerous vascular
canals
Also known as bundle bone as numerous
bundles of sharpey’s fibers pass into the
periodontal ligament

35. It appears as dense white lines in the
radiographs- Lamina Dura
Break in the continuity of lamina dura at the
proximal aspects of crest on interdental
septum has been considered as the earliest
radiographic change in periodontitis

36. Bundle Bone
 Contains thick collagen bundles arranged
parallel to each other
Rate of formation is slow resulting in resting
lines between adjacent lamellae
 Characterized by attachment of periodontal
ligament fibres
 Present at the inner wall of socket

37. SUPPORTING BONE
Spongy bone (anatomic term)/ Trabecular bone (radiographic term)/ Cancellous
bone (histologic term)
Presence of trabeculae enclosing irregular marrow spaces lined with a layer of thin,
endosteal cells
Matrix consists of irregularly arranged lamellae separated by incremental &
resorption lines

38. RADIOGRAPHIC APPEARANCE
TYPE I –REGULAR
INTERRADICULAR & INTERDENTAL TRABECULAE
HORIZONTAL IN A LADDER LIKE ARRANGEMENT.
COMMON IN MANDIBLE
TYPE II- IRREGULARLY ARRANGED
NUMEROUS, DELICATE INTERDENTAL &
INTERRADICULAR TRABECULAE
COMMON IN MAXILLA

39. CORTICAL BONE SPONGY BONE
About 85% of bone About 15% of bone
Lesser turnover than
spongy bone
High turnover
Remodels about 3% of its
mass each year
Remodels about 25% of its
mass each year
Mechanical/protective layer More metabolic function

40. INTERDENTAL SEPTUM
Bony partition that separates the adjacent alveoli
Coronally, septa is thin & consists of only fused
inner cortical plates
Apically septa is thicker & contains intervening
cancellous bone
If interdental space is narrow, septum may
consists of only cribriform plate
If roots are too close together, an irregular
window can appear in the bone between adjacent
roots

41. ALVEOLAR CREST
Formed when the inner & outer
cortical plates meet
Margin is thin & knife edged in
vestibular surfaces of anterior &
rounded/beaded in posterior teeth
Most prominent border of
interdental septum

42. INTERRADICULAR SEPTA
The bone between the roots of
multi rooted teeth
Both of them contain perforating
canals of Zukerkandl & Hirschfield

43. BASAL BONE
Osseous tissue of the mandible & the
maxilla except the alveolar process
Anatomically, there is no distinct
boundary between the body of the
maxilla/mandible & their alveolar
process

44. HISTOLOGY

45. Bone matrix
INORGANIC
COMPONENT
Collagen
matrix
Non
collagenous
protein
Osteocalcin
Osteopontin &
Bone
Sialoprotein
Osteonectin
Proteoglycan
Lysyl Oxidase
& Tyrosine
Rich Acidic
Matrix Protein
Calcium
Hydroxyapatite
crystals

46. 2/3RD INORGANIC MATRIX 1/3rd ORGANIC MATRIX
Calcium Type I collagen(90%)
Phosphate Osteopontin , bone sialoprotein
Hydroxyl carbonate Osteocalcin and osteonectin
Citrate Bone morphogenetic protein, phosphoprotein
and proteoglycans
Sodium, magnesium and fluorine
ions(traces)
Paracrine factors including cytokines,
chemokines and growth factors.
Mineral salts –hydroxyapatite(60%)
crystals of ultramicroscopic size and
constitute 2/3rd of bone structure.

47. TYPES OF COLLAGEN FOUND IN ALVEOLAR BONE
COLLAGEN TYPE PROPOSED FUNCTION
TYPE I PRINCIPAL COLLAGEN TYPE PROVIDES TENSILE STRENGTH
TYPE III FOUND THROUGHOUT THE TISSUE PROVIDES TENSILE STRENGTH
TYPE V DIFFUSE FILAMENTOUS
DISTRIBUTION
CONNECTOR BETWEEN BASEMENT
MEMBRANE & STROMA, PROMOTES
CELL ATTACHMENT & MIGRATION

48. CELLS
OSTEOGENIC
CELLS
OSTEOCLASTIC
CELLS
OSTEOCLASTS
OSTEOBLASTS OSTEOPROGENITOR CELLS
BONE LINING CELLS
OSTEOCYTES

49. OSTEOBLASTS
Osteoblasts are mononucleated, basophilic, plump
cuboidal or slightly flattened cells
Found on the forming surfaces of growing or
remodelling bone
 Activated by growth factors such as:
1. BMP
2. TGF
3. ILGF

50. MORPHOLOGY
Basophilic, plump cuboidal/ slightly elongated cells
Rich in synthetic & secretory organelles- rough endoplasmic reticulum, golgi
apparatus, secretory granules & microtubules
Also contain other organelles associated with cell metabolism- mitochondria &
endosomal/lysosomal elements & an extensive cytoskeleton

51. OSTEOBLASTS
During embryonic
development,
intramembranous bone
of maxilla & mandible
initially forms the
osteoblasts from the
condensation of
mesenchymal cells of
facial region & further
form the bony alveoli
Arises during tooth
development when the
cells of dental sac
differentiate into various
lineages

52. FORMATION OF OSTEOBLASTS
Derived from undifferentiated pluripotent mesenchymal stem cells
Osteoprogenitor cells are divided into 2 types :
DETERMINED
OSTEOGENIC
PRECURSOR CELLS
Differentiate under influence
of systemic & bone derived
growth factors
INDUCIBLE
OSTEOGENIC
PRECURSOR CELLS
May differentiate into bone
forming cells when
stimulated

53. FUNCTIONS
Formation of new bone via synthesis of various proteins & polysaccharides
Regulation of bone remodeling & mineral metabolism
Exhibit high level of alkaline phosphatase on outer surface of plasma membrane which is used
as cytochemical marker to distinguish pre-osteoblast from fibroblasts
Recognize the resorptive signal and transmit it to the osteoclast
Produce Type I Collagen & Non-Collagenous bone proteins like Sialoprotein, Osteopontin,
Osteonectin
Controlling influence in activating osteoclasts
It contains receptors for parathyroid hormone & regulates the osteoclastic response to this
hormone

55. OSTEOCYTES
As the osteoblasts form the bone matrix, they get entrapped
within the matrix they secrete, and are called Osteocytes
Within the bone matrix, osteocyte reduce in size creating a space
around it called osteocytic lacuna
 Narrow extensions of these lacunae form channels called
canaliculi

56. FUNCTIONS
The canaliculi penetrate the bone matrix & permit diffusion of nutrients, gases & waste
products b/w osteocytes and blood vessels
Osteocytes also sense the change in environment & send signals that affect response of other
cells involved in bone remodelling
This interconnecting system maintains the bone integrity & bone vitality

57. OSTEOCLASTS
Originate from hematopoietic tissue
The cytoplasm of osteoclast show acid phosphatase
containing vesicles and vacuoles

58. MORPHOLOGY
 Fusion of mononuclear cells to form a
multinucleated cell
 Very Large,5-50 nuclei
Mobile & capable of migrating
Lie in Howship’s Lacunae
Acidophilic Cytoplasm
Increase surface area
Active osteoclast have a ruffled border facing bone

59. At periphery of ruffled border, plasma
membrane is smooth & closely apposed to the
bone surface
 Adjacent cytoplasm devoid of cell organelles,
rich in actin, vinculin & tannin proteins
associated with integrin mediated cell adhesion.
This region is called sealing zone
 This zone creates an isolated environment in
which resorption can take place

60. OSTEOCLAST FORMATION

63. BONE RESORPTION
Process of removal of mineral & organic components of extracellular matrix of
bone by osteolytic cells known as osteoclasts
Ten- cate’s sequence of resorptive process:
1. Attachment of osteoclasts to mineralized surface of bone
2. Creation of sealed acidic environment through action of proton pump, which
demineralizes bone & exposes the organic matrix
3. Degradation of exposed organic matrix to its constituent amino acids by the
action of released enzymes, such as Acid Phosphatase & Cathepsin
4. Sequestering of mineral ions & amino acids within the osteoclast

65. BONE REMODELLING
 Process by which bone is renewed to maintain
bone strength & mineral homeostasis
It involves continuous removal of old bone,
replacement with newly synthesized
proteinaceous matrix & subsequent
mineralization to form new bone
Bone formation & resorption are tightly
coupled during bone remodelling

67. OSSEOUS TOPOGRAPHY
•On the labial version margins of the bone are thinned to a knife edge &
present an accentuated arc in the direction of the apex
• On the lingual version margins of the bone are blunt, rounded & horizontal
rather than arcuate

68. FENESTRATION AND DEHISCENCE
Isolated areas in which the root is
denuded of bone and the root surface
is covered only by periosteum and
overlying gingiva are termed
fenestrations
When the denuded areas extends
through the marginal bone then defect
is called as dehiscence

69. VASCULAR SUPPLY

70. LYMPHATIC SUPPLY
• All third molars - Jugulodigastric lymph
nodes.
• Mandibular incisors - Submental lymph
nodes.
• Rest - Submandibular lymph nodes.
CP- DEEP CERVICAL LYMPH NODES
SME- SUB MENTAL LYMPH NODES
SMA -SUBMANDIBULAR LYMPHNODES
JD- JUGULO DIGRASTIC LYMPH NODES

71. CLINICAL CONSIDERATIONS
1.PHYSIOLOGIC MIGRATION OF TEETH: With
time and wear, proximal contact areas of
teeth are flattened, and the teeth tend to
move mesially
By the age of 40 years, this process results
in reduction about 0.5cm length of the
dental arch from the midline to the third
molar

72. 2.ORTHODONTIC TOOTH MOVEMENT
It is due to biologic plastic property
of the bone is possible to move the teeth
without disrupting their relation to the alveolar
bone. Bone is resorbed in pressure side and formed
on the tension side.
At the site of alveolar bone compression ,osteoclasts
proliferate and resorption of the superficial bone
takes place. While at site of tension ,osteoblasts are
activated to produce osteoid that subsequently
mineralize to form new bone
2. ORTHODONTIC TOOTH MOVEMENT :

73. EXCESSIVE FORCE must be avoided, because
it creates tissue damage, necrosis and root
resorption
LIGHT FORCES, however lead to controlled
tissue disruption and mild hyalinization of
the PDL on the compression side.

75. FIBROUS DYSPLASIA

76. OSTEOPOROSIS

77. CONCLUSION
Specialized function in the support of teeth. While there are
architectural specifications for alveolar bone that relate to its
functional role, the basic cellular and matrix components are
consistent with other bone tissues.
Many of the factors that regulate bone remodelling appear to
exert their effects either directly or indirectly through these
genes, which have become important targets for developing
pharmacological and clinical strategies to regulate the rate of
bone formation and resorption that is important for
maintenance of a healthy periodontium

78. REFERENCES
1. Carranza, Clinical periodontology ,The Tooth Supporting Structure (8th,9th,10th
ed)
2. Jan Lindhe, Text book of Periodontology and oral Implantology ,Bone as a
Tissue, (4th & 5th edition)
3. Newman,Takei,Klokkevold,Carranza’s Clinical Periodontology 11th edition.
4. S N Bhaskar Orban’s Oral Histology and Embryology, edition 13th edition .
5. Sodek J, Mckee M.D.Molecular and cellular biology of alveolar bone.
Periodontology 2000. vol(24),99-126
6. Thomas M.Hassell.Tissues and cells of the periodontium. Periodontology
2000.vol(3),19939-38
7. Changes in postmenopausal women with a history of periodontitis.J
Periodontol.1997;68(1):24-31

79. 8. Jiang SY, Shu R, Xie YF, Zhang SY. Age related changes in biological characteristics of human
alveolar osteoblasts. Cell Prolif.2010oct;43(5):464-70.
9. Barros S P, Silva M.A, Somerman M.J.Parathyroid hormone protects against periodontitis
associated bone loss.J Dent Res 2003;82(10):791-795
10. Payne JB, Zachs NR, Patil K .The association between estrogen status and alveolar bone
density changes in postmenopausal women with a history of periodontitis.J
Periodontol.1997;68(1):24-31

80. THANK YOU