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.
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
9.
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
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
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
19.
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.
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
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
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
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
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
54.
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
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
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
64.
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
66.
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
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.
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