The alveolar bone develops along with tooth formation and undergoes remodeling throughout life. It is composed of an outer cortical plate and inner spongy bone containing osteocytes, osteoblasts and osteoclasts. The alveolar bone proper surrounds tooth roots and anchors the periodontal ligament via Sharpey's fibers. Continuous remodeling is mediated by bone multicellular units consisting of osteoclasts that resorb bone, followed by osteoblasts that form new bone. This coupling between resorption and formation maintains alveolar bone morphology according to tooth size, shape and position.

1. By Shreeja Nair
Post Graduate Student
Dept. of Periodontics ,
GDC,ahmedabad.

2. CONTENT
DEFINITION
COMPOSITION OF BONE .
DEVELOPMENT OF ALVEOLAR PROCESS
STRUCTURE OF ALVEOLAR PROCESS
HISTOLOGY OF ALVEOLAR BONE
GROSS MORPHOLOGY
NERVE SUPPLY OF ALVEOLAR BONE
BLOOD SUPPLLY OF ALVEOLAR BONE
LYMPHATIC DRAINAGE OF ALVEOLAR BONE
CELLS OF BONE

3. MODELLING AND REMODELLING OF BONE
BONE COUPLING
FACTORS REGULATING BONE FORMATION
FACTORS REGULATING BONE RESORPTION
REGULATION OF BONE BY SYSTEMIC HORMONES
REFERENCES

5. • Together with the root cementum and periodontal ligament,
the alveolar bone constitutes the attachment apparatus of the
teeth.
• Since alveolar processes develop and undergo remodelling
with tooth formation and eruption, they are tooth dependent
bony structures.
• Therefore the size, shape, location and function of teeth
determine their morphology.

6. • Forms when tooth erupts to provide osseous attachment to the
forming PDL, disappears gradually after tooth is lost.
• Develops and undergo remodeling with tooth formation, hence
tooth-dependent bony structures.
• Size, shape, location and function of teeth determine their
morphology.

7. Inorganic material – 65%
Hydroxyapatite
Calcium Phosphate
Organic material – 35%
Collagen (Type – I) 88% - 89%
Noncollagen 11% - 12%
- Glycoproteins 6.5% - 10%
- Proteoglycans 0.8%
- Sialoproteins - 0.35%
- Lipids - 0.4%
Only a subset of BMPs, most
notably BMP 2,4,6,7,9 has
osteoinductive activity.
COMPOSITION :

8. • It is the major organic component in mineralized bone tissues.
• Type I collagen(>95%) is the principle collagen in mineralized
bone, together with Type V collagen (<5%), forms heterotypic
fiber bundles that provide the basic structural intergrity of
connective tissues.
• Alveolar bone contains type I, V, III, XII collagen. Type XII is
found to be expressed under conditions of mechanical strain.
• Sharpey’s fibers- Type III with I.
• Type III and Type XII- produced by produced by fibroblasts
during the formation of periodontal ligament.
• Type I, V, XII collagens are expressed by osteoblasts.

9. Osteocalcin - also known as bone gamma-carboxyglutamic acid-containing protein
(BGLAP), is a noncollagenous protein found in bone and dentin.
• Because it has gla domains, its synthesis is vitamin K dependent.
• Osteocalcin is secreted solely by osteoblasts
• In bone mineralization and calcium ion homeostasis, it is a calcium binding protein.
Osteonectin - is a glycoprotein in the bone that binds calcium. It is secreted by
osteoblasts during bone formation, initiating mineralization and promoting mineral
crystal formation.
• Osteonectin also increases the production and activity of matrix metalloproteinases,
a function important to invading cancer cells within bone.
Osteopontin (OPN) and bone sialoprotein - also known as bone
sialoprotein I and II res (BSP-1 or BNSP) –plays role in mineralization and bone
remodelling.

10. DEVELOPMENT OF ALVEOLAR PROCESS

11. Meckel’s cartilage

12. • Maxilla & mandible develop-- 1st
branchial arch or mandibular
arch.
• The maxilla forms within the maxillary process & mandible
forms within the fused mandibular processes of mandibular
arch.
• Both jaw bones start as small centres of intramembraneous
ossification around stomodeum

14. For its development & maintenance
Morphology of Alv. Bone depends on
Size
Shape
position of teeth
If teeth are lost, Alv bone undergoes atrophy
If teeth congenitally missing – Alv. Bone not developed

16. BASED ON
FUNCTIONAL
ADAPTATION
BASED ON
FUNCTIONAL
ADAPTATION
Basal boneBasal boneAlveolar
process
Alveolar
process
Alveolar
bone proper
Alveolar
bone proper
Supporting
alveolar
bone
Supporting
alveolar
bone
Cortical plates
buccal ,lingual
Cortical plates
buccal ,lingual
Spongy boneSpongy bone

17. - Roentgenograms permits the
classification of the spongiosa of the
alveolar process in to two main types.
Type : I :- interdental and
interradicular trabecular are regular
and horizontal in a ladder like
arrangement.
More common in mandible.
Type : II :- shows irregularly
arranged, numerous delicate
interdental and interradicular
trabecular.
More common in maxilla.
Roentgenographically

18. The alveolar process is composed of
two parts. They are
(1)Alveolar bone proper
(2)Supporting alveolar bone
STRUCTURE OF ALVEOLAR PROCESS :

19. 1 Alveolar bone proper :
It consists of a thin lamella of bone that
surrounds the root of the tooth and give
attachment to principle fibers of the
periodontal ligament.
- It is perforated by many openings
that carry nerves and blood vessels in to
the periodontal ligament therefore it is
called cribriform plate.
C
A
B

20. - Consist of lamellated bone and
bundle bone.
The bundle bone is that bone in which
the principal fibers of the periodontal
ligament are anchored.
The term “bundle bone” was chosen
because the bundles of the principal
fibers continue in to bone as sharpey’s
fibers.

21. 2. Supporting alveolar bone
It is that part of the bone
which surrounds the
alveolar bone proper and
gives supports to the
socket.
- It consists of two parts :
a Cortical plates
b Spongy bone :

22. a. CORTICAL PLATES : (1.5-3mm thick in
posterior tooth region and thickness varies in anterior
region )
- It consists of compact bone and form the outer
and inner plates of the alveolar processes.
- It is continuous with the bony maxilla and
mandible and is much thicker in the mandible than
in the maxilla. They are thickest in the mandibular
premolar and molar regions especially on the buccal
side.
- In the maxilla the outer cortical plate is
perforated by many small openings through which
blood and lymph vessels pass. In the mandible it is
dense.

24. b. SPONGY BONE :
- It fills the area between cortical plates and the alveolar
bone proper.
- In the region of the anterior teeth of both jaws the
supporting bone is usually thin, so no spongy bone is found
here.

26. Figure shows Haversian system
Histology of Alveolar bone :

27. The interdental and interradicular
septa contain the perforating canals of
Zuckerkandl and Hirschfeld (Nutrient
canals),which house the interdental and
interradicular arteries ,veins ,lymph
vessels and nerves.
Nutrient canal
Tooth

29. • Outer alveolar plate
• Inner alveolar plate
• Interdental septum
• Interradicular septum
29

30. The shape of the outlines of the crest of the alveolar septa in the
roentgenogram is dependent on the position of the adjacent teeth.
1.5-2mm – always maintained through out the life and is
constant.
Diagram of relation between CE junction of
adjacent teeth shape of crest of alveolar septa
CREST OF ALVEOLAR BONE :

31. • Formed when the inner and outer cortical plates meet
• The margin is thin & knife edged in vestibular surfaces of anterior
and rounded/beaded in posterior teeth
• Most prominent border of interdental septum
• Runs roughly parallel to CEJ, 1-3mm apical to it, with greater
distance seen in older individuals
• Ritchey & Orban 1953
• Average distance between CEJ & crest - 1.08mm
• Increases with age - 2.81mm
• Gargiulo et al 1961
31

32. • Bony partition that separate the adjacent alveoli
• Coronally septa is thin and consists of only fused inner cortical plates
• Apically septa is thicker and contain intervening cancellous bone
• Mesiodistal angulation of interdental septum is parallel to line drawn
between CEJ of approximating teeth (Ritchey et al, 1953)
• If interdental space is narrow, septum may consist of only cribriform
plate
• If roots are too close together, an irregular window can appear in the
bone between adjacent roots

33. • The bone between the roots of multirooted teeth .
• Both of them contain perforating canals of Zukerkandl & Hirschfeld
[nutrient canals].
33

34. 34

35. 35

37. • Fenestration- Isolated areas in
which root is denuded of bone
and root surface covered only by
periosteum and overlying
gingiva
• Dehiscence- Denuded area
extends through marginal bone

38. Nerve Supply of Alveolar Bone

39. Blood Supply of Alveolar Bone

41. • Undifferentiated mesenchymal cells and hemotopoetic stem
cells – under certain circumstances they divide and transform
in to osteoblasts and osteoclasts.
y

43. Osteoblasts :
Derived from multipotent UNDIFFERENTIATED mesenchymal
cells or alternatively from perivascular cells (PERICYTES).
Secretes both “collagenous(type 1 collagen) and non collagenous”
bone matrix – OSTEOID .
Osteoblasts exhibit high level of alkaline phosphatase on their outer
plasma membrane - believed to contribute - initiation of bone
mineralization.
During osteogenesis osteoblasts secrete GF
OSTEOGENIC LINE OF CELLS :
TGF-β
BMP
PDG-F
IGF’S
2,7 -osteoinductive

44.  Regulation of osteoclasts and deposition of bone matrix ( MACKIE 2003)
 Bone remodeling and mineral metabolism
 Mineralization of new bone
 Secrete type I collagen ,type V collagen, osteonectin, osteopontin ,RANKL,
osteoprotegerin, growth factors
 Osteocalcin and CBFA1
 Express alkaline phosphatase
 Recognize resorptive signal and transmit to osteoclast.
 CBFA-1 – regulate the expression of osteoprotegerin.

45. OSTEOCYTES : (NERVE CELLS OF BONE )
Most abundant bone cells .
Communicate with each other and with other cells on surface
of the bone via dendritic process encapsulated in canaliculi
Play role in calcium homeostasis
Exchange of metabolic and
biochemical messages occurs
between blood stream and canaliculi
Acts as mechanosensors instructing osteoclasts where
to resorb and osteoblasts where and
when to form (BOULPAEP AND BORON 2005 :
MANOLAGAS 2000 )

46. Osteoclasts : (2-10 or as many as 50 nuclei)
Generally occur in clusters.
They have prominent mitochondria,
lysozomes, vacuoles and
few endoplasmic reticulum.
Activity is controlled by PTH
They are found against the
bone surface, occupying shallow
depressions called Howship’s lacunae
surfaces or in deep resorption cavities
called cutting cones.

47. Sequence of events;
 Removal of mineral/inorganic Matrix
 Degradation of org. matrix
Morphologic Characteristics
Ruffled/ Striated border
Clear zone
MORPHOLOGY :
 40 to 100 microns in diameter
 15 to 20 closely packed nuclei
 Variable in shape

48. BONE LINING CELLS :
Similar to osteocytes – i.e., osteoblasts that do not get embedded
in newly formed bone ,gets adhered to the outer surface of the bone
…..when bone formation halts.

50. In the haversian canals, closest to the surface,
osteoclasts differentiate and resorb the haversian
lamellae and part of circumferential lamellae which is
replaced by proliferating loose connective tissue.
This area of resorption is called the cutting cone or
the resorption tunnel.
Light micrograph of bone turnover. A, Cutting cone in cross section.
Large multinucleated osteoclasts resorb an old osteon. B, Filling cone in
cross section. Uninucleated osteoblasts ring the partially formed osteon.

51. REMODELING involves the removal of discrete packets of old bone ,replacement
of these packets with newly synthesised protenaceous matrix and subsequent
mineralization of the matrix to form new bone . ( fernandez –tresguerres –hernandez
et.al 2006 )

52. Bone multicellular unit(BMU):
local groups of osteoblasts and osteoclasts involved in bone remodelling is called bone multicellular units (BMU).
- each unit is organized into "cutting cone" of osteoclasts reabsorbing bone followed by trail of osteoblasts reforming
the bone to fill defect
Osteoclast recruitment
Resorption
Osteoblast recruitment
Origination
Osteoid formation
Mineralization
Mineral maturation
Quiescence:
osteoblasts become resting bone lining cells on the newly formed bone surface

53. Coupling between bone formation and bone resorption refers to the process within basic
multicellular units in which resorption by osteoclasts is met by the generation of osteoblasts
from precursors, and their bone-forming activity, which needs to be sufficient to replace the
bone lost. There are many sources of activities that contribute to coupling at remodeling sites,
including growth factors released from the matrix, soluble and membrane products of
osteoclasts and their precursors, signals from osteocytes and from immune cells and signaling
taking place within the osteoblast lineage. Coupling is therefore a process that involves the
interaction of a wide range of cell types and control mechanisms.

54. 1. Platelet derived growth factor
2. Heparin binding growth factor
3. Insulin like growth factor
4. Transforming growth factor
5. Bone morphogenic protein

55. 1. IL 1
2. IL 6
3. TNF & Lymphotoxins
4. Gamma interferon
5. Colony stimulating factors
6. Prostaglandin & other Arachidonic Acid metabolites

56. 1. Parathyroid hormone
2. 1,25 Dihydroxy vit D3
3. Calcitonin
4. Estrogen

57. • References:
• Orban’s oral Histology &Embryology.
• Fundaments of periodontics second edition by Thomos G.
wilson’jr ;Knneth S. Kornman
• Clinical periodontology 12th
edition by Neeman
,Takei,carranza
• Journal of clinical periodontology
• Contemporary Periodontics by Robert J. Jenco; Henry
M.Goldman ;D.Walter Cohen