Bone is a mineralized connective tissue
that performs the function of
support, protection and locomotion
ALVEOLAR PROCESS :
It is defined as the parts of the maxilla
and mandible that form and support the
sockets of the teeth.
5. OSTEOGENESIS :
The process of bone formation is
Endocondral Intra- membranous
bone formation bone formation
6. ENDOCHONDRAL BONE FORMATION :
In this type, the bone formation of a
cartilagenous model which is subsequently
replaced by bone.
Mesenchymal cells become condensed at the
site of bone formation.
Some mesenchymal cells differentiate into
chondroblasts & lay down hyaline cartilage.
The cartilage is surrounded by a membrane
called perichondrium.This is highly vascular &
contains osteogenic cells.
7. The intercellular substance
surrounding the cartilage cells
becomes calcified due to the influence
of enzyme alkaline phosphatase
secreted by the cartilage cells.
Thus the nutrition to the cartilage
cells is cut off leading to their
death which results in formation of
empty spaces called primary
The blood vessels & osteogenic
cells from the perichondrium
invade the calcified matrix which is
now reduced to bars or walls due
to eating away of the calcified
matrix. this leaves large empty
spaces between the walls called
8. The osteogenic cells from the perichondrium
become osteoblasts & arrange themselves
along the surface of there bars of calcified
The osteobleasts lay down osteoid which
later becomes calcified to form a lamella
of bone. Then another layer of osteoid is
secreted & this goes on & on. Thus the
calcified matrix of cartilage acts as a
support for bone formation.
9. INTRA-MEMBRANOUS BONE FORMATION :
In this type of ossification, the
formation of bone is not preceded by the
formation of a cartilagenous model, Instead
bone is laid down directly in a fibrous
Loose mesemchymal tissue
10. At the site of bone
formation, mesenchymal cells
Some mesenchymal cells lay down
bundles of collagen fibres.
Some mesenchymal cells
differentiated into osteoblasts.
11. These osteoblasts secrete a
gelatinous matrix called osteoid
around the collagen fibres.
They deposit calcium salts into the
osteoid leading to conversion of
osteoid into bone lamellae.
Now the osteoblasts move away
from the lamellae & a new layer o
osteoid is secreted which also gets
12. COMPOSITION : BONE
crystals Non Collagen
calcium type I
13. GROSS STRUCTURE OF BONE ;
The interdental septum
14. ALVEOLAR BONE PROPER :
It surrounds the roots of the tooth & gives attachment
to the principal fibers of the periodontal ligament.
It also known as the cribiform plate as it is perforated
by many openings; through which branches of the
interalveolar nerve & vessels pass into the
Histologically bundle bone & lamellaler bone
BUNDLE BONE :
The bone which lines the socket in which sharpey’s
fibers are embedded is known as bundle bone.
Contains more calcium salts per units area than other
It also know as lamina dura because of its
15. SUPPORTING ALVEOLAR BONE :
It is the bone that surrounds the alveolar bone proper &
gives support to the socket.
Consists of cortical plates & spongy bone ( cancellous
CORTICAL PLATES :
Consists of compact bone & form the outer & inner
plates of the alveolar process.
Thinner in maxilla than in the mandible.
Thickest in the premolar & molar region of the
It is the bone which fills the space between the outer
& inner plates &the alveolar bone proper.
Consists of heavy trabeculae with bone marrow
16. THE INTERDENTAL SEPTUM :
Consists of cancellous bone bordered by the socket
walls of approximating teeth & the facial & lingual
If roots are too close
together, an irregular window
can appear in the bone adjacent
The outside of all compact bone is covered by a thin
connective tissue membrane called the periosteum.
The internal surface of compact bone as well as the
entire surface of the cancellous bone are covered by
a single layer of bone cells called the endosteum.
18. OSTEON :
It is the structural & metabolic unit of the lamellar
It consists of haversian canal in the center which
harbors a blood vessels.
This is surrounded by concentric, mineralized
lamellae to form the osteon; known as concentric
Spaces between the different osteon is filled with
19. HAVERSIAN SYSTEM :
Consists of the haversian canal & the volkmann’s canal.
Haversian canal located in the center of the osteon.
Volkmann’s canal are the connecting vessels which
connect the haversian canal.
FUNCTION: provides nutrition to the bone.
20. LAMELLAE :
Made up of osteocytes found within empty spaces
Mainly 3 types:
CIRCUMFERENTIAL LAMELLAE :
They are bony lamellae that surround the entire
bone, forming its outer surface.
CONCENTRIC LAMELLAE :
They form the bulk of the bone & osteon.
INTERSTITIAL LAMELLAE :
They are lamellae that found between adjacent
concentric lamellae. they fill the space between
the concentric lamellae.
21. BONE MARROW :
RED BONE MARROW :
Mainly found in the embryo & newborn.
They help in formation on RBCs & WBCs.
In adults, it is found in the
ribs, sternum, vertebrae, skull & humerus.
In the oral cavity, it is found in the maxillary
tuberocity, the maxillary molars, the mandibular
molars, the mandibular premolar areas, the
mandibular symphysis & the ramus angle.
YELLOW BONE MARROW seen as a zones of radiolucency
Radiographic ally :
It is a fatty marrow that does not produces red
&white blood cells.
22. CELLS :
These are bone forming cells
Origin: pluripotent stem cells
These are mononucleated cells
that synthesize collagenous & non
- collagenous bone matrix
It exhibits a high level of
alkaline phosphatase on their
outer plasma membrane.
When active……. They are
plump, cuboidal in shape.
When non-active……. They becomes
23. OSTEOCYTES ;
As the osteoblasts secrete the bone matrix, some
of the osteoblasts get entrapped in lacunae; they
are called osteocytes.
The space in the matrix occupied by an osteocyte is
called the osteocytic lacuna.
24. OSTEOCLASTS ;
These are bone resorbing cell that are multinucleated
, large & generally found in cluster.
Origin: circulating monocytes & local mesenchymal
The osteoclasts are found against the one surface
occupying shallow depressions called howship’s
25. OSSEOUS TOPOGRAPHY :
Normally : prominence of the
roots with the intervening
vertical depressions that taper
toward the margin.
On the labial version ; the
margins of the labial bone is
thinned to a knife edge
&presents an accentuated arc in
the direction of the apex.
On the lingual version ; the
margins of the labial bone is
blunt &rounded & horizontal
rather than arcuate.
26. FENESTRATIONS & DEHISCENCES :
Isolated areas in which the root is denuded of bone & the root
surface is covered only by periosteum & overlying gingiva are
When the denuded areas extends through the marginal bone then
defect is called a dehiscence.
Predisposing factors… prominent root
contours, malposition, labial protrusion of the root combined
with a thin bony plate.
Seen more often on facial bone than on lingual bone
More common on anteriorly than posteriorly
Occurs bilaterally 26
27. BONE TURNOVER (REMODELLING) :
The process by which the overall size & shape of bones
is established is referred to as bone remodeling.
Alveolar bone is a east stable of the periodontal
tissues because its structure is in a constant state of
Functional requirements Parathyroid
on the tooth hormone
Age related changes in Calcitonin
the bone cells
28. Manifested in 3 areas :
Adjacent to the periodontal ligament.
In relation to the periosteum of the facial & lingual
Endosteum surface of the marrow spaces.
Sequences of resorptive events ;
Attachment of osteoclasts to the mineralized
surface of bone.
Creation of a sealed acidic microenvironment
through the action of the proton pump, which
demineralizes bone &exposes the organic matrix.
Degradation of the exposed matrix by the action of
released enzymes such as acid phosphatase &
29. Endocytosis at the ruffled border of inorganic &
organic bone degradation products.
Translocation of degradation products in transport
vesicles & extra cellular release along the
membrane opposite the ruffled border.
Osteoblasts produce osteoid which later calcified.
Bundle bone has the highest turnover rate.
In lamellar, cancellous or spongy bone; half – moon
resorption cavity is created by osteoclasts &then
filled in with bone matrix by osteoblasts.
30. VASCULAR SUPPLY :
Derived from blood vessels branching off of
the superior or inferior alveolar arteries.
LMPHATIC DRAINAGE ;
Smallest lymph vessel ……. Lymph capillaries.
All third molars ……. Jugulodigastric lymph
Mandibular incisors ……. Sub mental lymph
Rest ……. Sub mandibular lymph nodes.