2. CONTENTS
2
Prosthodontic considerations
Review of literature
Conclusion
References
Introduction
Definition
Function
Classification & physiology
Composition
Anatomy & Development
Alveolar bone
Residual ridge resorption
3. INTRODUCTION:
3
•Bone is a metabolically active organ, composed of both mineral
and organic phases. Specially designed for its role as the load
bearing structure of the body.
•It is formed from a combination of dense, compact and
cancellous ( trabecular ) bone that is reinforced at points of
stress.
4. Bone is a specialized connective tissue in
which the intercellular substance is
mineralized.
4
According to GPT 8- The hard portion of the
connective tissue which constitutes the majority of
the skeleton; it consists of an inorganic or mineral
component and an organic component (the matrix
and cells); the matrix is composed of collaganous
fibers and is impregnated with minerals, mainly
calcium phosphate (approx. 85%) and calcium
carbonate (approx. 10%), thus imparting the quality
of rigidity—called also osseous tissue.
5. FUNCTIONS:
It gives shape and support for the body.
It provides attachment for muscles and
tendons.
It protects vital organs of the body.
Serves as site for storage of minerals.
It provides medium; the marrow for
development of blood cells.
5
6. BASED ON DEVELOPMENT:
1.ENDOCHODNRAL BONES
2.INTRAMEMBRANOUS BONES
BASED ON MICROSCOPIC APPEARANCE:
1.MATURE BONE(LAMELLAR BONE)
COMPACT BONE CANCELLOUS BONE
2.IMMATURE BONE
6
7. BASED ON SHAPE:
1. LONG BONES
2. SHORT BONES
3. FLAT BONES
4. IRREGULAR BONES
5. SESAMOID BONES
7
8. ANATOMY: STRUCTURE OF
BONE
A typical long bone consist of following
Diaphysis
Epiphysis
Metaphysis
Articular cartilage
Periosteum
Medullary or marrow cavity
Endosteum
8
9. All bones have a dense outer sheet of COMPACT
BONE (or) CORTICAL BONE and a central
medullary cavity.
Medulla may be filled with red/yellow marrow and
shows a series of trabeculae. It is also called
TRABECULAR, SPONGY (OR) CANCELLOUS
BONE.
PERIOSTEUM
ENDOSTEUM
9
STRUCTURE OF BONE
11. 1.OUTER CIRCUMFERENTIAL LAMELLAE:
At periosteal and endosteal
surfaces the lamellae are arranged in parallel
layers surrounding bone called circumferential
lamellae.
2.INNER CONCENTRIC LAMELLAE:
Deep to circumferential lamellae
the lamellae are arranged in concentric layers
called concentric lamellae.
11
LAMELLAE OF
BONE
12. HAVERSIAN SYSTEM/OSTEON:
Haversian canal & concentric
lamellae together called as osteon/haversian system.
HAVERSIAN CANAL:
The vascular canal present at the
centre of concentric lamellae.
12
13. VOLKMAN’S CANALS:
Adjacent haversian systems are
connected by volkmann’s canals, channels that
contain blood vessels creating a rich vascular
network through out compact bone.
13
16. OSTEOBLASTS
•Osteoblasts are the cells that form bone.
• Type I collagen
•Express and release alkaline phosphatase, which has been shown
to be closely associated with new bone formation.
•Total alkaline phosphatase activity has been recognized as a
reliable indicator of osteoblast function
16
17. 17
The differentiation of osteoproginitor cells into
osteoblast is acclererated by some hormones
and some bone proteins called Skeletal growth
factors. Function-
1) Role in formation of bone matrix
2) role in calcification ( through the alkaline
phosphatase enzymes)
3) Synthesis of proteins.
20. OSTEOPROGENITOR CELLS
• The stem cell population that
give rise to osteoblasts are
termed Osteoprogenitor
cells.
• They are fibroblast-like cells,
with an elongated nucleus and a
few organelles.
• Their life cycle may involve
upto about eight cell divisions
before reaching the osteoblast
stage.
• They reside in the layer of
cells beneath the osteoblast
layer, in the periosteal region, in
the periodontal ligament or in
the marrow spaces.
20
21. OSTEOCLAST
• Originate from hematopoietic
tissue
• Fusion of mononuclear cells
(blood derived monocytes) to
form a multinucleated cell
• Very large, 5-50 nuclei
• Active on less than 1% of
bone surface
• Mobile and capable of
migrating
• Acidophilic cytoplasm
• Active osteoclasts- ruffled
border facing bone (hydrolytic
enzymes are secreted)
• Increases surface area
21
22. • Several osteoclasts excavating a large area of bone
which is the leading edge of resorption is termed as the
Cutting cone.
• Released cytokines [ Bone Morphogenic Proteins &
Insulin like Growth Factor] stimulate stem cells to
differentiate into osteoblasts.
• These osteoblasts secrete osteoid known as Filling
cone.
22
24. 24
Lape´rine O, Cloitre A, Caillon J, Huck O, Bugueno IM, Pilet P, et al Interleukin-
33 and RANK-L Interplay in the Alveolar Bone Loss Associated to Periodontitis.
26. SEQUENCE OF EVENTS IN BONE REMODELLING
• the osteoclasts excavate the layer of bundle bone and
then resorb the supporting bone.
• They remove all the mineralized material, so that the
periodontal ligament fiber bundles become detached at
their point of insertion in bone.
• The periodontal ligament anchorage is locally lost
• Mononucleated phagocyte-like cells come in contact with
the bone surface; these cells may complete resorption and
deepen the lacunae
26
27. • After sometime, resorption ceases and osteoclasts are
replaced by osteoblasts
• Osteoblasts deposit on to the resorbed bone surface a
thin coating of noncollagenous Matrix proteins.
• The osteoblasts get entrapped =osteocytes.
• Fragments of lamellae from old bone haversian
systems=interstitial lamellae.
27
32. REGULATORS OF BONE
FORMATION
• The overall integrity of bone is controlled by hormones,
proteins secreted by hematopoietic bone marrow cells
and bone cells.
HORMONES
• Parathormone
• calcitonin
• Vitamin D3
• Glucocorticoids
• Thyroid Hormone
• Growth Hormone
• Insulin
32
33. LOCAL REGULATORS
• Platelet derived growth factor
• Insulin growth factors
• Transforming growth factor-β
• Bone morphogenetic protein
• Fibroblast growth factor
33
34. 34
HORMONES THAT EFFECT HOMEOSTASIS OF BONE TISSUE AND
REMODELLING
Hormone Function
Human growth hormone
(HGH)
General growth of all body
tissues, including bone
Sex hormones ( estrogens
and testosterones)
Increase bone building
activity of osteoblasts
Insulin and thyroid
hormones (T3, T4)
Promote normal bone
growth and maturity
Parathyroid hormone Increase the number and
activity of
osteoclast,promotes
recovery of Ca2+ from
urine, and promotes
formation of calcitriol .
Calcitonin (CT) Inhibits activity of
osteoclasts, speed up
Ca2+absorption from blood,
and accelerates Ca2+
38. 38
• Sufficient amount of calcium and phosphorus
(component of hydroxy apatite), the primary salts
that makes the bone matrix hard, must be included
in the diet.
• Magnesium deficiency - Inhibit the activity of
osteoblasts
• Boron - A factor in bone growth
• Manganese deficiency - Inhibits laying down of
new bone tissue
Minerals needed for bone remodeling
39. 39
Several vitamins like vitamins D, C, A, and B12, play a role in bone
remodeling.
The most active form of vitamin D is calcitriol. Acting as a
hormone, it promotes removal of calcium from bone. On the other
hand,it retards calcium loss in urine, which makes it available for
deposit in bone matrix.
Vit C deficiency causes decrease collagen production, which
retards bone growth and delays fracture healing .
Vit A helps to control the activity , distribution, and co-ordination
of osteoblasts and osteoclasts during development. Its
deficiency results in a decreased rate of growth in the skeleton.
Vit B12 may play a role in osteoblast activity.
VITAMINS NEEDED FOR BONE REMODELLING
40. DEFINITION:
It is defined as that part of maxilla
and mandible that forms and supports the sockets
of teeth.
40
ALVEOLAR BONE
41. FUNCTIONS OF ALVEOLAR BONE
1.Houses roots of teeth and anchors roots of teeth to
alveoli.
2.Helps to distribute occlusal forces generated
during tooth contact.
3.Supplies vessels to periodontal ligament.
4.Houses and protects developing permanent teeth.
while supporting primary teeth.
5.organizes eruption of primary and permanent
teeth. 41
42. 42
WOLF‟S LAW
Wolff's law is a theory developed by the
German anatomist and surgeon Julius Wolff
(1836–1902) in the 19th century that states
that
Bone reacts to mechanical functional stress
through an adaptive process resulting in a
change of its external and internal
architecture to better withstand this stress.
If loading on a particular bone increases, the
bone will remodel itself over a period of time
to become stronger to withstand greatest
strength with least amount of material
43. 43
BENNINGHOFF’SSTRESS TRAJECTORIES
It states that lines of orientation of bony
trabeculae corresponds to the pathways of
maximal pressure and tension that bony
trabeculae are thicker in the region where the
stress is greater.
In Maxilla – frontonasal buttress, malar
Zygomatic buttress,pterygoid buttress
In Mandible - Condyle, Gonial angles, Coronoid
process
44. DEVELOPMENT OF ALVEOLAR BONE
• Alveolar process consists of bone which is formed both
by cells from the dental follicle (alveolar bone proper) &
cells which are independent of tooth development
• 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
44
46. • Alveolar bone proper
• Supporting alveolar
bone
BASED ON THE
FUNCTIONAL
ADAPTATION
• Hypocalcemic
• Normal
• Hypercalcemic
KEVITTS
CLASSIFICATIO
N
46
49. LINLOW 1970
• CLASS I BONE STRUCTURE: this ideal bone type
consists of evenly spaced trabeculae with small
cancellated spaces
• CLASS II BONE STRUCTURE: this bone has slightly
larger cancellated spaces with less uniformity of the
osseous pattern
• CLASS III: BONE STRUCTURE: large marrow filled
spaces exists between bone trabeculae
49
Gintaras J, Marius K . Clinical and Radiological Classification of the Jawbone Anatomy in Endosseous
Dental Implant Treatment . J Oral Maxillofac Res 2013; 4 (2) : e2, p.1.
50. 50
Gintaras J, Marius K . Clinical and Radiological Classification of the Jawbone Anatomy in Endosseous
Dental Implant Treatment . J Oral Maxillofac Res 2013; 4 (2) : e2, p.1.
51. MISCH BONE DENSITY
CLASSIFICATION:
•D1 Dense cortical bone
• D2 Thick dense to porous cortical bone on crest
and coarse trabecular bone within
•D3 Thin porous cortical bone on crest and fine
trabecular bone within
•D4 Fine trabecular bone
• D5 Immature, nonmineralised bone
51Misch CE. Contemporary Implant Dentistry. Mosby An imprint of Elsevier, 3rd Ed;
55. 55
STRUCTURE OF ALVEOLAR PROCESS
It has 2 parts:
1.. Alveolar bone proper — also called cribriform plate
or lamina dura.
2.Supporting alveolar bone has 2 layers of bone
Compact lamellar bone Layer of bundle bone------this is
the layer that PDL fibres insert into.
Cortical plate( compact lamellar bone)---- forms
inner & outer plates.
Spongy bone ( cancellated bone)--- fills in area b/w
cortical plates of bone.
58. EDENTULOUS INTRAORAL BONY CHANGES:
The loss of teeth means not only the loss of the
clinical crown but also the supporting tissues, the
periodontal ligament and alveolar bone.
When the alveolar bone is lost, the resultant
residual ridge is progressively resorbed throughout the
life of the individual (Atwood, 1971)
58
Atwood DA. Reduction of residual ridges: a major oral disease entity. J
Prosthet Dent. 1971 Sep;26(3):266-79.
59. Alveolar ridges :The alveolar ridge vary greatly in size
and shape and their form is dependent on the following factors:
Developmental structure : The individual variation
in bone size and its degree of calcification.
The size of the natural teeth : Large teeth are
usually suppourted by bulky ridge, small teeth by narrow
ridges
59
Atwood DA. Reduction of residual ridges: a major oral disease entity. J
Prosthet Dent. 1971 Sep;26(3):266-79.
60. The amount of bone lost prior to the extraction
of the teeth : periodontal disease results in the destruction of
the alveolar process. If the natural teeth are retained until gross
alveolar loss has occurred the resultant alveolar ridges will be
narrow and shallow.
The amount of alveolar process removed during
the extraction of the teeth : During extraction the buccal
alveolar plate is fractured and removed with the tooth.
60
Atwood DA. Reduction of residual ridges: a major oral disease entity. J
Prosthet Dent. 1971 Sep;26(3):266-79.
61. The rate and degree of resorption : During the six
weeks after the extraction of the teeth the rate of resorption is rapid.
During the second six weeks it begins to slow down. At the end of
three months the immediate post-extraction resorption is complete
and there after it continues throughout life.
The effect of previous dentures : ill-fitting or dentures
occluding with isolated groups of natural teeth, may cause rapid
resorption of the alveolar process in the areas where they cause
excessive load or lateral stress.
61
62. MAXILLARY DENTURE-BEARING AREA:
Well-developed but not abnormally thick ridges
and a palate with a moderate vault.
This is a favourable formation because: The
center of the palate presents an almost flat horizontal
area and this will aid adhesion. The roomy sulcus allows
for the development of a good peripheral seal. The well-
developed ridges resist lateral and antero -posterior
movement of the denture.
62
63. HIGH V-SHAPED PALATE USUALLY
ASSOCIATED WITH THICK BULKY RIDGES:
This may be an unfavourable formation because: The forces
of adhesion are not at right angles to the surfaces when counteracting
the normal displacing forces of gravity and so peripheral seal is
essential
63
64. FLAT PALATE WITH SMALL RIDGES AND
SHALLOW SULCI:
This may be an unfavourable formation because: The ill-
developed or resorbed ridges do not resist lateral and antero -
posterior movement of the denture. The sulci being shallow do not
form a good peripheral seal, unless the width of the denture
periphery is adequate.
64
65. RIDGES EXHIBITING UNDERCUT AREAS.:
These are unfavorable because:
Frequently the flanges of the denture need to be trimmed in
order to be able to insert it and this may reduce the effectiveness of
the peripheral seal.
65
66. MANDIBULAR DENTURE BEARING AREA:
Broad and well developed ridges.
This is a favourable formation because:
The provides a large area on which to rest the denture and
prevents lateral and anteroposterior movement. The surface
presented for adhesion is as large as it can ever be in a lower jaw.
The lingual, labial and buccal sulci are satisfactory for developing a
close peripheral seal.
66
67. WELL DEVELOPED BUT NARROW OR KNIFE LIKE
RIDGES:
These are unfavourable because:
The pressure of the denture during clenching and
mastication on the sharp ridge will cause pain.
Adhesion and cohesive forces are negligible.
67
68. FLAT AND ATROPHIC RIDGES:
68
These are unfavourable because:
No resistance is offered to anteroposterior or lateral
movements.
Frequently found to have resorbed to the level of
attachments of the mylohyoid , genioglossus and
buccinator muscles and if the denture base is made
sufficiently narrow so as not to encroach on these
structures, its area is too small for the denture to
function correctly.
When the area is increased to encroach on the
muscles they may move the dentures when they
contact.
70. RESIDUAL RIDGE CONTOUR
The edentulous areas where a fixed prosthesis is
to be provided may be overlooked during the treatment
planning phase. Unfortunate, any deficiency or potential
problem that may arise during the fabrication of a pontic
is often identified only after the teeth have been prepared
or even when the master cast is ready.
.
70
71. Proper preparation includes a careful
analysis of the critical dimensions of the
edentulous areas:
Mesiodistal width.
Buccolingual diameter.
Occlusocervical distance.
Location of the residual ridge
71
72. The contour of the edentulous ridge should be carefully evaluated
during the treatment planning phase.
An ideally shaped ridge has a smooth, regular surface of
attached gingiva , which facilitates maintenance of a plaque-
free environment.
Its height and width should allow placement of a pontic that
appears to emerge from the ridge and mimics the appearance
of the neighboring teeth.
Facially, it must be free of frenum attachment and of
adequate facial height to sustain the appearance of interdental
papillae.
72
73. SIEBERT has classified residual ridge deformities into
three categoris :
Class I defect – faciolingual loss of tissue width with
normal ridge height.
Class II defect- loss of ridge height with normal
ridge width.
Class III defect – a combination of loss in both
dimensions.
73
74. Loss of residual ridge contour may
lead to
unesthetic open gingival embrasures (“Black
triangles”),
food impaction, and
percolation of saliva during speech.
74
75. Surgical Modification Although residual ridge width may
be augmented with hard tissue grafts, this is usually not
indicated unless the edentulous site is to receive an
implant.
1. Roll technique – uses soft tissue from
the lingual side of the edentulous site. The epithelium is
removed, and the tissue is thinned and rolled back,
thereby thickening the facial aspect of the residual ridge.
75
76. 2.Pouches may be prepared in the facial aspect of
the residual ridge, into which subepithelial or
submucosal grafts may be inserted.
76
77. 3. Interpositional graft is a wedge-shaped
connective tissue graft which is inserted into a pouch
preparation on the facial aspect of the residual ridge.
77
79. AVAILABLE BONE:
Available bone describes the amount of bone in the
edentulous area considered for implantation and is
measured in:
Height
Width
Length
Angulation
Crown-Implant body ratio
79
Misch CE. Contemporary Implant Dentistry. Mosby An imprint of Elsevier, 3rd Ed; 2008.
80. AVAILABLE BONE HEIGHT:
The height of available bone is measured from the
crest of the edentulous ridge to the opposing landmark,
such as maxillary sinus, mandibular canal, maxillary
nares,inferior border of the mandible, maxillary canine
eminence region etc.
80
81. The minimum height of the available bone for
endosteal implants is in part related to the density of the
bone. The more dense bone may accommodate a
shorter implant.
The minimum bone height for a predictable long-term
endosteal implant survival is 10mm
81
82. AVAILABLE BONE WIDTH:
Width is measured between the facial and lingual
plates at the crest of the potential implant site. The
crest is supported by a wider base.
The root form implant of 4.0mm crestal diameter
usually require more than 5.0mm of bone width to
ensure sufficient bone thickness and blood supply
around the implant for predictable survival. These
diamensions provide more than 0.5mm bone on each
side of the implant at the crest.
82
83. AVAILABLE BONE LENGTH
The mesio -distal length of available bone in an
edentulous area is often limited by adjacent teeth or
implants. The root from implants of 4.0mm crestal
diameter usually require a minimum mesio -distal length
of 7mm.
83
84. AVAILABLE BONE ANGULATION:
Ideally the bone angulation should be such that
the long axis of the implant can be placed parallel to
the long axis of the restoration.
In edentulous areas with ridge and wider root form
implants a modification upto 30 degree can
achieved.
84
85. CROWN-IMPLANT BODY RATIO:
The crown height is measured from the occlusal
or incisal plane to the crest of the ridge and the
endosteal implant height from the crest of the ridge
to its apex.
The greater the crown height, the greater the
lever arm with any lateral force.
85
86. DIVISIONS OF AVAILABLE BONE:
Division A (Abundant bone)
Division B (Barely sufficient Bone)
Division C (Compromised bone)
Division D (Deficient bone)
86
87. VARIABLE BONE DENSITY-WHY?:
Cortical and trabecular bone are constantly modified
by either modeling or remodeling .
In bone modeling there is independent sites of
formation and resorption and results in the change of
the size or shape of bone.
In bone remodeling the resorption and formation
are at the same site that replaces previously existing
bone and primarily affects the internal turnover of bone.
87
88. These adaptive phenomena of modeling and
remodeling of bone have been associated with the
alteration of the mechanical stress environment within
the host bone.
Macmillan and Parfitt noted that-
•Bone is most dense around the teeth.
• Density of bone around the crest region is more
compared to the regions around the apices.
•Generalized trabecular bone loss occurs in regions
around a tooth from a decrease in mechanical
stress.
88Misch CE. Contemporary Implant Dentistry. Mosby An imprint of Elsevier, 3rd Ed; 2008.
89. FROST reported a model of four zones for compact
bone as it is related to mechanical adaptation to stress
•Pathological overload zone
•Mild overload zone
•Adapted window zone
•Acute disuse window zone
89Misch CE. Contemporary Implant Dentistry. Mosby An imprint of Elsevier, 3rd Ed; 2008.
91. In 1971, Atwood D A, described when the alveolar bone
is lost, the resultant residual ridge is progressively
resorbed throughout the life of the individual
91
Atwood DA. Reduction of residual ridges: a major oral disease entity. J Prosthet
Dent. 1971 Sep;26(3):266-79.
92. Gintaras J, Marius K. in 2013, described about different
classifications of bone by
•Linlow,
•Lekholm and Zarb,
•Misch
• They concluded saying that the classification
systems proposed here based on anatomical and
radiological jawbone quantity and quality evaluation
is a helpful tool for planning of treatment strategy
and collaboration among specialists.
• Further clinical studies should be conducted for new
classification validation and reliability evaluation.
92
Gintaras J, Marius K . Clinical and Radiological Classification of the Jawbone Anatomy in Endosseous
Dental Implant Treatment . J Oral Maxillofac Res 2013; 4 (2) : e2, p.1.
93. 93
• Kovacic I , persic S et al. in 2018 discussed
about the rehabilitation of an extremely resorbed
edentulous mandible by short and narrow dental
implants after insertion they were loaded with
mandibular overdentures and after the followup
of 2 years they observed the increase in quality
of life scores(OHRQoL) and chewing function
compared to removable prosthesis.
• And this improvements remain unchanged
throughout the observational period
Kovacic I , persic S et al rehabilitation of an extremely resorbed edentulous
mandible by short and narrow dental implants .case reports in dentistry
2018;(8)
94. 94
• An understanding of the fundamental
physiology, metabolism, and biomechanics of
bone and assessing the quality and quantity is
essential for placing and restoring with
prosthesis and to get the best treatment
outcomes.
95. 1. Guyton & Hall textbook of medical physiology,10th
edition.
2. Mohan H, Mohan S . Essential of pathology for
dental students . 4th ed, Jaypee Publications: New
Delhi: 2000.
3. Misch CE. Contemporary Implant Dentistry. Mosby
An imprint of Elsevier, 3rd Ed; 2008 .
4. Lindhe J, Lang NP. Clinical periodontology and
implant dentistry. 5th ed vol1, Wiley Blackwell pub;
victoria Australia : 2008.
5. Gintaras J, Marius K . Clinical and Radiological
Classification of the Jawbone Anatomy in
Endosseous Dental Implant Treatment . J Oral
Maxillofac Res 2013; 4 (2) : e2, p.1.
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