2. CONTENT
ALVEOLAR BONE AND ALVEOLAR PROCESS
FUNCTIONS OF ALVEOLAR BONE
STRUCTURAL ELEMENTS OF ALVEOLAR BONE
-BONE CELLS
• OSTEOPROGENITOR CELLS – STEM CELLS
• OSTEOBLASTS – FORMS BONE
• OSTEOCYTES – MAINTAINS BONE
• OSTEOCLASTS – RESORBS BONE
SHARPEY’S FIBERS
VASCULAR SUPPLY AND LYMPHATIC VESSELS
GROSS MORPHOLOGY OF ALVEOLAR BONE
STRUCTURES OF ALVEOLAR BONE
3. ALVEOLAR BONE
Alveolar bone or alveolar process is that portion of maxilla
and mandible that supports the roots of the tooth.
If the teeth is lost the alveolar process disappears.
It is composed of 2 parts the alveolar bone proper and the
supporting bone.
4. Since the alveolar process develop and undergo remodeling
with the tooth formation and eruption, they are tooth
dependent bony structures.
The alveolar process contains
a region of compact bone
adjacent to the periodontal
ligament called LAMINA DURA.
It is called processus alveolaris
in maxilla and pars alveolaris in
the mandible bone.
5. Functions of alveolar process
It supports the tooth roots on the facial and on the
palatal/lingual sides.
It is the one responsible for the separation of teeth from
mesial and distal.
Also contributes to absorption and distribution of occlusal
pressure produced in tooth to tooth contact.
6. Structural elements of bone
Bone cells
• Osteoprogenitor cells – stem cells
• Osteoblasts – forms bone
• Osteocytes – maintains bone
• Osteoclasts – resorbs bone
Bone matrix
Sharpey’s fibres
Vascular supply and lymphatic drainage
7. Osteoprogenitor cells
Stem cells derived from the mesenchyme.
Possess mitotic potential and the ability to differentiate into
mature bone cells.
Resemble mesenchymal cells and are spindle – shaped, with
pale – staining elongated nuclei and sparse cytoplasm(small
amount of ER and poorly developed golgi complex).
Mostly found in the inner portion of the periosteum, in the
endosteum, and within vascular canals of compact bone.
8. osteoblasts
Uninucleated cells.
Synthesize both collagenous and non collagenous bone
proteins.
Osteoblasts also synthesize the enzyme alkaline phosphatase,
which is needed locally for the mineralization of osteoid.
The precursor cell of the osteoblast is the preosteoblast.
Osteoblasts have all the characteristics of hard tissue -forming
cells.
When the bone is no longer forming, the surfaces of the
osteoblasts become inactive and are called lining cells.
9. osteocytes
These are osteoblasts secreted in the bone matrixes that are
entrapped in lacunae.
An osteocyte lies in its own lacuna and contacts its
neighboring osteocytes cytoplasmically through canaliculi.
The most important function of osteoblast – osteocyte
complex is to prevent hypomineralization of bone by
continually pumping calcium back to the bloodstream.
10. osteoclasts
Derived from a monocytic – macrophage system, which are
responsible for bone resorbtion.
They are multinucleated cells with fine, fingerlike cytoplasmic
processes and are rich in lysosomes that contain tartrate –
resistant acid phosphatase(TRAP).
Osteoclasts lie in the resorbtion craters known as howship’s
lacunae on the bone surface or in deep resorption cavities
called cutting cones.
These bone cells can only resorb mineralized bone matrix.
11. Bone matrix
Bone matrix consists of organic and inorganic components.
The association of these substances gives bone its hardness
and resistance.
The organic component is composed of collagen fibers with
predominately type 1 collagen(95%) and amorphous material,
including glycosaminoglycans that are associated with
proteins.
12. Osteoid is uncalcified organic matrix.
Inorganic matter represents about 50% of the dry weight of
bone matrix.
Composed of abundant calcium and phosphorous as well as
smaller amounts of bicarbonate, citrate, magnesium,
potassium, and sodium.
Calcium forms hydroxyapatite crystals with phosphorous but
is also present in an amorphous form.
15. sharpey’s fibers
Sharpey’s fibers are the
terminal ends of principal
fibers(of PDL) that insert into
the cementum and into the
periosteum of the alveolar
bone.
A study on rats suggests
that the three-dimensional
structure of sharpey’s fibers
intensifies the continuity
between the PDL fiber and the
alveolar bone (tooth socket),
and acts as a buffer medium
against stress.
16. Vascular supply of alveolar process
Alveolar process of the maxilla
• Anterior and posterior alveolar arteries (branch from the maxilla and infraorbital
arteries).
Alveolar process of the mandible
• Inferior alveolar arteries (internal).
• Periosteal branches of submental and buccal arteries (external).
18. Gross morphology
Alveolar socket
Also called dental
alveolus.
Are sockets in the jaws in
which the roots of teeth
are held in the alveolar
process with the
periodontal ligament.
19. Interdental septa
• “septa” – in latin, it means
“fence” or “wall”.
• Are plates of bone that separate
each individual sockets from one
another.
Inter – radicular septa
• Are thin plates of bone that separate the roots of multi – rooted teeth.
20. Cribriform plate
Also called as bundle bone.
A type of alveolar bone so called because of the ‘bundle’ pattern
caused by continuation of principal (sharpey’s) fibers into it.
Is the compact layer of bone lining the tooth socket (alveolar
socket).
Reflects the sieve – like appearance produced by numerous
Volkmann’s canals passing from the alveolar bone to the PDL.
Numerous sharpey’s fiber pass through it.
21. Structures of alveolar bone
cortical plate
Outer bony plate of varying thickness,
which is the outside wall of the maxilla
and mandible, covered with periosteum.
Continuous with the lamina cribriformis at
the orifice of the alveoli – alveolar crest.
Consists of haversian systems (osteons) and
interstitial lamellae.
Thicker in the mandible than maxilla.
Generally greater on the lingual than on the
buccal/facial aspect.
22. spongiosa
Are spongy (or cancellous/trabecullar) bone between the 2
bony plates and between the lamina cribriformis of adjascent
teeth or roots.
Consists of delicate trabeculae, between which are narrow
spaces, filled mostly with fatty marrow.
Regions of maxillary tuberosity and the angle of mandible.
23. Periosteum and endosteum
Layers of differentiated osteogenic connective tissue covers all
bone surfaces.
Tissue covering outer surface of bone is termed as
periosteum.
Tissue lining the internal bone cavities is called endosteum.
