Bone and alveolar bone
Dr Jamal Naim
PhD in Orthodontics
Functions of bone
Support and protect the skeletal functions.
Bone stores minerals, especially calcium and
phosphorous, which are mobilized according to the
Bone protects the internal organs.
Bone marrow manufactures the blood elements.
Bone remodeling is responsible for the development,
growth, movements, fracture and repair.
Location: Present in the deepest layer of periosteum
and lining the vascular canals of compact bone.
Origin: It is mesenchymal in origin.
Function: According to the function needed they divide
by mitosis to give any type of bone cells
Morphology: It resembles mesenchymal cell with pale
stained nucleus and little esinophilic cytoplasm.
Compact bone (ivory bone):
It forms the main part of the shafts of the long bone
and covers the cancellous bone e.g. ribs and flat
bones of the skull.
Its lamellae are arranged in 3 patterns:
outer circumferential lamellae
beneath the periosteum.
inner circumferential lamellae
adjacent to the endostium
It is the unite structure of the compact bone and is
called the Haversian system or osteon.
The Haversian system if formed of Haversian canal
which is surrounded by (4-20) concentrically
The Haversian canal contains B.Vs., nerves, C.T.
and lined by osteoprogenitor cells.
Osteocytes are arranged concentrically in
the osteons (they anastomose with each
others by their process).
Haversian canals connected to each others
or to the outer surface or to the bone
marrow spaces with Volkmann's canal.
The Haversian systems are separated from each
others by the interstitial lamellae.
They represent the remnants of an old resorbed
and remodeled bone.
It is present in the central part of the flat bone.
It is formed of connected bone trabeculae in the
form of network to give maximum rigidity.
In between the bone trabeculae, there are bone
The bone trabeculae have osteocytes.
This type of bone is characterized by:
Irregular arrangement of the collagen fibers.
Great number, large size and irregular arrangement of
Increase in the organic substance and decrease in the
inorganic contents so; it appears radiolucent in X-ray.
This type of bone is resorbed completely and is replaced
by lamellar bone.
3. Bundle Bone
It is referred to the bundles of principal fibers of
either the periosteum or PDL continue into the
bone as sharpeys fibers.
It is found adjacent to the periosteum and periodontal
ligament (areas of tension).
It is characterized by the presence of the Sharpey's
It has less number of cells than Woven bone; but more
calcium salts than lamellar bone. So it appears more
radio-opaque and called lamina dura.
Its fibers are arranged parallel to the socket wall.
In X-ray the
is referred to
The alveolar process is that bone containing the alveoli.
It consists of:
an outer (lingual and buccal) cortical plate (compact
A central spongiosa (spongous bone) and
Alveolar bone (bone lining the alveolus), (bundle
The alveolar bone and the cortical plate meet at the alveolar
crest (1.5 to 2 mm below the level of CEJ).
divided into the:
alveolar bone proper
lining of the tooth socket or alveolus
bone is also called the cribriform plate because of
the many holes through which Volkmann’s canals
pass (from the alveolar bone into the PDL)
also called bundle bone because Sharpey’s fibers insert
into this bone (Sharpey’s fibers = portion of the
fibers of the PDL)
these fibers are inserted at a 90 angle into the ABP –
but are fewer in number than those found at the
consists of plates of compact bone that surround the
varies in thickness from 0.1 to 0.5mm
can see a portion of the ABP on radiographs lamina
most cervical rim = alveolar crest – slightly apical to
the CEJ in healthy patients
b. supporting alveolar bone
has the same components as ABP
but is considered to be cortical and trabecular bone –
different arrangement of bony plates
cortical bone is made up of cortical plates of compact bone
found on the facial and lingual surfaces
plates are usually 1.5 to 3mm thick over the posterior teeth
and can vary over the anterior teeth
trabecular bone is located between the ABP and the plates
of the cortical bone (cross section of mandible)
alveolar bone can be resorbed with age (edentulous)
the underlying basal bone is less affected with age –
because it does not need the presence of teeth to
loss of teeth + alveolar bone can results in loss in the
vertical dimension of the face – “Popeye” facial
after tooth extraction the clot is replaced with
later remodelled as mature secondary bone, very
similar process to fracture repair in skeletal bone