PHYSIOLOGY OF BONE AND ITS PROSTHODONTIC IMPLICATIONS

PHYSIOLOGY OF BONE
PRESENTED BY- DR. GAURI PATIL (1ST YEAR MDS)

CONTENTS
• INTRODUCTION
• PHYSIOLOGY OF BONE- 1. MACROSCOPIC STRUCTURES
2. MICROSCOPIC STRUCTURES
3. CHEMICAL COMPOSITION
• REMODELING OF BONE
• DISORDERS OF BONE
• PROSTHODONTIC IMPLICATIONS- 1. RESIDUALL RIDGE RESORPTION
2. BONE SUBSTITUTES

Bone or osseous tissue is a specialized rigid
connective tissue that forms the skeleton.
Bone is composed of a tough organic matrix
that is greatly strengthened by deposits of
calcium salts.
Also, other part is inorganic content
containing mainly hydroxyapatite crystals.
Average compact bone contains by weight
about 30 per cent matrix and 70 per cent
salts.
K Sembulingam - Essentials of Medical Physiology, 6th Edition
Guyton-Physiology-11th edition.

MACROSCOPIC
CLASSIFICATION OF BONE

Randolph_R_Resnik_Misch's_Contemporary_Implant_Dentistry_Elsevier, 4th edition.
WOVEN BONE
LAMELLAR BONE
COMPOSITE BONE
BUNDLE BONE

WOVEN BONE
• Woven bone varies considerably in
structure; it is relatively weak,
disorganized, and poorly mineralized.
• The first bone formed in response to
wound
healing.
• Osteocytes are very few in number.

LAMELLAR BONE
• Lamellar bone, a strong, highly organized,
well-mineralized tissue,
makes up more than 99% of the adult
human skeleton.
• When new lamellar bone is formed, a
portion of the mineral component
(hydroxyapatite) is deposited by
osteoblasts during primary mineralization.
Secondary mineralization, which completes
the mineral component, is a physical
process (crystal growth) that requires many
months

BUNDLE BONE
Bundle bone is a functional adaptation
of lamellar structure to allow
attachment of tendons and ligaments.
Perpendicular striations, called
Sharpey’s fiers, are the major
distinguishing characteristics of bundle
bone. Distinct layers of bundle bone
usually are seen adjacent to the PDL
along physiologic bone forming
surfaces.

COMPOSITE BONE
• Composite bone is an osseous tissue formed by the deposition of lamellar bone within a
woven bone lattice, which is a process called cancellous compaction.
• When the bone is formed in the compaction configuration, the resulting composite bone
forms structures known as primary osteons.
Although composite bone may be high-quality, load-bearing osseous tissue, it is eventually
remodeled into secondary osteons.

MICROSCOPIC
CLASSIFICATION OF BONE

Bones have two layers of structures:
1. Outer compact bone
2. Inner spongy bone.
In most of the bones, both compact and spongy
forms are present. However, the thickness of
each type varies in different regions.

Different cells are responsible for the
formation, resorption, and
maintenance of osteoarchitecture.
TYPES
• osteogenic cells, which form and
maintain bone, and
• osteoclasts, which resorb bone.
Osteogenic cells have variable
morphology including
osteoprogenitors, pre osteoblasts,
osteoblasts, osteocytes, bone lining
cells representing different
maturational stages.

OSTEOBLASTS
• The osteoblasts arise from the giant
multinucleated primitive cells called the
osteoprogenitor cells
• Mononucleated cells that synthesize the
organic matrix of bone.
• The secretory products of osteoblasts include
1. type I collagen, the dominant component of
the organic matrix,
2. small amounts of type V collagen and
proteoglycans, and
3. several noncollagenous proteins.

BONE LINING CELLS
• These are less implicated in the production of matrix proteins.
• They cover most surface of adult skeleton.
• It has been postulated that bone lining cells retain their gap junctions with osteocytes, creating
a network that functions to control mineral homeostasis and ensure bone vitality.

OSTEOCYTES
• Concerned with maintenance of bone.
• Osteocytes are small flattened and rounded
cells, embedded in the bone lacunae. These cells
are the major cells in developed bone and are
derived from the matured osteoblasts.

OSTEOCLASTS
• Osteoclasts are the bone cells that are
concerned with bone resorption
(osteoclastic activity).
• Osteoclasts are the giant phagocytic
multinucleated cells found in the lacunae of
bone matrix.

OSSIFICATIO
N
INTRAMEMBRANOUS BONE
FORMATION
1.ENDOCHONDRAL BONE
FORMATION
SUTURAL BONE GROWTH

INTRAMEMBRANOUS BONE
FORMATION

BONE RESORPTION
• Destruction of bone matrix and removal of
calcium (osteoclastic activity).
BONE FORMATION
• Development and mineralization of new matrix
(osteoblastic activity).
BONE
REMODELING

ABSORPTION OF BONE—FUNCTION OF THE
OSTEOCLASTS
• Osteoclastic activity is the process that
involves destruction of bone matrix,
followed by removal of calcium
• Some substances released from
membranous extensions of osteoclasts case
resorption, such as:
1. Collagenase
2. Phosphatase
3. Lysosomal enzymes
4. Acids like citric acid and lactic acid.

SEQUENCE OF EVENTS DURING BONE
RESORPTION
Citric acid and lactic acid
cause acidifiation of the area
and decrease pH to 4.
Lysosomal enzymes are
activated at this pH.
Activated enzymes digest or
dissolve the collagen.
Enzymes also dissolve the
hydroxyapatite and form
solution of bone salts.
All the dissolved materials are
now released into ECF.
Some elements enter the blood
Remaining elements are cleaned
up by the macrophages
A shallow cavity is formed in the
bone resorbing compartment.
Guyton-Physiology-11th edition.

DEPOSITION OF BONE BY THE
OSTEOBLASTS- OSTEOBLASTIC ACTIVITY
• Osteoblastic activity is the process which
involves the synthesis of collagen and
formation of bone matrix that is
mineralized.

FACTORS REGULATING BONE REMODELING
Event Stimulating factors Inhibiting Factors
Bone formation 1. Growth hormone
2. Calcitonin
3. Insulin
4. Testosterone
5. Estrogen
6. Insulin-like growth factor
7. Transforming growth factor-β
8. Skeletal growth factor
9. Bone-derived growth factor
10. Platelet-derived growth factor
Cortisol
Mineralization 1. Calcitonin
2. Insulin
3. Vitamin D
Cortisol
Bone resorption 1. Parathormone
2. Thyroxine
3. Cortisol
4. Prostaglandins
5. Interleukin-1
6. Estrogen
7. Calcitonin
Testosterone

MINERALIZATION
First, a large quantity of calcium phosphate is deposited.
Afterwards, the hydroxide and bicarbonate ions are gradually
added causing the formation of hydroxyapatite crystals.
The process of mineralization is accelerated by the enzyme
alkaline phosphatase, secreted by osteoblast.
The completely mineralized bone surrounds the osteoblast.

Expanding “V” principle
• Enlow’s expanding “V”
principle states that many
facial bones or part of the
bone follows a V pattern
of enlargement
• The overall growth
changes are the result of
downward and forward
translation of the maxilla
and simultaneous surface
remodelling
Orthodontics- The Art and Science, Bhalahi 5th Edition book

ALVEOLAR
BONE
• It is that portion of maxilla and mandible that forms and supports
the tooth socket. It provides osseus attachment to the forming
periodontal ligament.
• - Morphologically it can be divided into – Alveolar bone proper
– Supporting alveolar bone

CLASSIFICATION
Order 6 : Depressed
Order 5 : Low, well rounded
Order 4 : Knife-edge
Order 3 : High, well rounded
Order 2 : Post extraction
Order 1 : Pre-extraction
•ATWOODS CLASSIFICATION
Klemetti E. A review of residual ridge resorption and bone density. The Journal of prosthetic dentistry. 1996 May 1;75(5):512-4.

DIRECTION OF BONE RESORPTION
Maxilla: upward and
inward
Become
progressively
smaller
Direction and
inclination of the roots
of the teeth and the
alveolar process
Mandible:
downward and
outward
Become wider
Anterior teeth: inclined
upward and forward of
occlusal plane
Zarb GA, Bolender CL, Carlsson GE. Boucher's prosthodontic treatment for edentulous patients. St. Louis: Mosby; 1997 Jan.

WHAT HAPPENS DURING WOUND HEALING?
•Usually results in intense
but localized modeling and
remodeling responses.

HEALING OF SOCKET
• The healing of an extraction socket is a specialized example of healing by secondary intention.
• The extraction of a tooth initiates a series of reparative processes involving-
Hard tissue
(Alveolar
bone)
Soft tissues
(Periodontal
ligament,
Gingiva)
44
Steiner GG, Francis W, Burrell R, Kallet MP, Steiner DM, Macias R. The healing socket and socket regeneration. Compend Contin Educ Dent. 2008 Mar;29(2):114-6, 118, 120-4
BIOLOGICAL EVENTS OCCURING IN THE SOCKET AFTER TOOTH EXTRACTION

HEALING AFTER PLACEMENT OF IMPLANT
•Dental implants are surgically placed directly into native or
regenerated bone.
•A series of cellular and molecular events take place on the
oral mucosa.
•Osseointegration was defined by Brånemark as a direct
structural and functional connection between ordered living
bone and the surface of a load-carrying implant.
45
Politis C, Schoenaers J, Jacobs R, Agbaje JO. Wound Healing Problems in the Mouth. Front Physiol. 2016 Nov

MECHANISM IN OSTEOINTEGRATION
The healing process with the implants is the
same normal bone healing, either primary bone
healing or secondary bone healing.

• The healing of bone following implant installation is a
complex process that apparently involves different
events in different compartments of the surgical site.
• The soft tissue that surrounds dental implants is
termed peri‐implant mucosa.
• Migration and proliferation of epithelial cells lead to
the formation of a junctional epithelium, which
lengthens the contact interface between the implant
surface .
• Maturation of the peri-implant mucosa occurs
between 6 to 12 weeks following implant placement.
47
Jan Lindhe “Clinical periodontology and implant dentistry” 5th edition, Blackwell Publishing

48
Mineralized bone
tissue around the
implant is
compressed and
exhibits a series
of microfractures
Blood vessels,
particularly in the
cortical portion,
of the canal will
collapse
Nutrition to the
bone in this
portion is
compromised
Affected tissues
most often
become non‐vital.
press fit that is when : the inserted implant is
slightly wider than the canal prepared in the
host bone.
Jan Lindhe “Clinical periodontology and implant dentistry” 5th edition, Blackwell Publishing

FOUR BONE CATEGORIES DESCRIBED BY MISCH LOCATED IN THE
EDENTULOUS AREAS OF THE MAXILLA AND MANDIBLE

BONE DISORDERS
OSTEOPOROSIS
RICKETS
OSTEOMALACIA
PAGETS DISEASE
OSTEOPETROSIS
OSTEOGENESIS IMPERFECTA
FIBROUS DYSPLASIA
Shafer’s Textbook of Oral Pathology, 7th edition.

Osteoporosis is defined as a “skeletal
disorder characterized by compromised bone
strength predisposing a person to an
increased risk of fracture’’
Lane NE. Epidemiology, etiology, and diagnosis of osteoporosis. American journal of obstetrics and gynecology. 2006 Feb 1;194(2):S3-11.
PRIMARY
SECONDARY

• Due to menopausal estrogen loss and aging.
• Type I - loss of trabecular bone owing to estrogen lack at
menopause
• Type II- loss of cortical/trabecular bone due to long-term
remodeling inefficiency, dietary inadequacy.
Primary osteoporosis

Secondary Osteoporosis
DRUGS RELATED
ACROMEGALY
MALABSORPTION
STATES
RHEUMATOID
ARTHRITIS
GLUCOCORTICOIDS
ADDISON’S DISEASE

PAGETS DISEASE
• Characterized by excessive and abnormal
remodeling of bone.
• The excessive remodeling gives rise to bones that
are extensively vascularized, weak, enlarged, and
deformed with subsequent complications.
• middle-aged and elderly patients.
• Paget’s disease of bone is characterized by
enhanced resorption of bone by giant
multinucleated osteoclasts with formation of
disorganized woven bone by osteoblasts. This
process evolves through various phases of activity,
followed by a quiescent stage

• Bisphosphonates (also called di-phosphonates) are a class of drugs that
prevent the loss of bone mass
• Inhibits osteoclastic activity
• Also useful in metastatic bone disease
BISPHOSPHONATE THERAPY
Watts N. Bisphosphonates, statins, osteoporosis, and atherosclerosis.(Featured CME Topic: Osteoporosis). Southern medical journal. 2002 Jun 1;95(6):578-83.

• There are 2 classes of BPs which have different mechanisms of
action:
• Non nitrogen containing BPs are taken up by the osteoclast and
cause cell apoptosis through activation of pathway.
• Nitrogen containing BPs are not metabolized and affect protein
prenylation of osteoclast by inhibiting farnesyl diphosphate (FPP)
synthase, a key enzyme of the mevalonate pathway .
MECHANISM OF ACTION

ESTROGEN REPLACEMENT THERAPY (ERT)
Indication: Used to prevent osteoporosis (FDA indication is for prevention)
Mechanism:
↓ osteoclast activity,
Acts on osteoblast to ↓ production of IL- 6
↑ production of osteoprotegerin, there by interfering with recruitment of osteoclast
precursors.
Dose: Estrogen: 0.625mg od, Progesterone 2.5mg qd (if uterus present)

RESIDUAL RIDGE
RESORPTION MANAGEMENT

RESORPTION PATTERN
• Generally women show more RRR than men.
• During the first year following extraction
Reduction in residual ridge height: Maxilla 2–3 mm
Mandible 4-5 mm
• After this, the process will continue but with reduced intensity.

CONSEQUENCES OF RRR
Apparent loss of sulcus width and depth.
Displacement of the muscle attachment closer to the crest of the residual ridge.
Loss of vertical dimension of occlusion.
Reduction of lower face height.
An anterior rotation of the mandible.
Increase in relative prognathia.
Hansson S, Halldin A. Alveolar ridge resorption after tooth extraction: A consequence of a fundamental principle of bone physiology. Journal of dental biomechanics. 2012;3.

TREATMENT
Proper design of denture:
• Optimal tissue health prior to making impression.
• Impression procedures:
Minimal pressure impression technique.
Selective pressure impression technique: places stress on those areas that best resist
functional forces

TREATMENT
Conventional
technique
Functional
impression
technique
Elastomeric
technique
Admix
technique
All green
technique
Final Impression techniques for resorbed ridges:

TREATMENT
Border moulding
done with green
stick compound.
Final impression
made using zinc
oxide eugenol
impression paste.
Impression
recorded using
open mouth
technique.
CONVENTIONAL TECHNIQUE (Boucher)
Yadav B, Jayna M, Yadav H, Suri S, Phogat S, Madan R. Comparison of different final impression techniques for management of resorbed mandibular ridge: a case report. Case reports in dentistry. 2014 Aug 10;2014.

TREATMENT
Jaw relations(horizontal and vertical) are recorded prior to the
final impression.
Tissue conditioners are applied on mandibular tissue surface.
Patient is asked to close the mouth in pre recorded vertical
dimension and is asked to perform functional movements
Three applications of tissue conditioners done at an interval
of 8-10 minutes and functional movements were recorded.
Final impression was made with light body addition silicone
material with closed mouth technique
FUNCTIONAL IMPRESSION TECHNIQUE (Winkler)

TREATMENT
ELASTOMERIC IMPRESSION TECHNIQUE
Heavy body material is
loaded onto the
peripheral areas of the
tray and across the
posterior seal area
The impression tray is
placed into the
patient’s mouth
After the custom tray
is border moulded
Tray adhesive is
applied
Final impressions is
made using light body

TREATMENT
Primary impression of
the edentulous arch is
made using irreversible
hydrocolloid impression
material, cast is poured
and trays are fabricated
For secondary
impression, Impression
compound and green
stick compound are
mixed in the ratio of 3 : 7
parts by weight and are
placed in a bowl of water
at 60 degrees Celsius.
Kneaded to a
homogenous mass that
provides a working time
of about 90 seconds.
Wax spacer is removed;
this homogenous mass is
loaded and patient is
made to do various
tongue movements.
ADMIX TECHNIQUE (Mc Cord and Tyson)
Yadav B, Jayna M, Yadav H, Suri S, Phogat S, Madan R. Comparison of different final impression techniques for management of resorbed mandibular ridge: a case report. Case reports in

TREATMENT
Green stick compound
is kneaded to a
homogenous mass
Loaded on the special
tray and border
moulding is done.
Final impression made
using zinc oxide
eugenol paste.
ALL GREEN TECHNIQUE
Yadav B, Jayna M, Yadav H, Suri S, Phogat S, Madan R. Comparison of different final impression techniques for management of resorbed mandibular ridge: a case report. Case reports in
dentistry. 2014 Aug 10;2014.

BONE SUBSTITUTES
• A bone graft is defined as a living tissue capable
of promoting bone healing, transplanted into a
bony defect, either alone or in combination with
other materials .
• A bone substitute is a natural or synthetic
material, often containing only a mineralized
bone matrix with no viable cells, that is able to
achieve the same purpose.
• TYPES OF GRAFTS
1. Allografts
2. Autografts
3. Xenografts
Zhao, R.; Yang, R. et al, Bone Grafts and Substitutes in Dentistry: A Review of Current Trends and Developments. Molecules 2021, 26, 3007.

CHARACTERISTICS OF AN IDEAL BONE GRAFTING MATERIAL
• To provide mechanical support and stimulate osteo-regeneration, with the ultimate goal of
bone replacement.
• The four fundamental biological properties of osseointegration, osteogenesis,
osteoconduction, and osteoinduction, are paramount in performing this role effectively.

• The ability of graft to produce new bone owing to the presence of viable
osteoprogenitor/osteogenic precursor cells
• Eg- Autograft
OSTEOGENESIS
• The ability to induce stem cells to differentiate into mature bone cells owing to the
presence of bone growth factors.
• Eg- Allograft
OSTEOINDUCTION
• A graft to serve as a scaffold and allow the ingrowth of neovasculature and
infiltration of osteogenic precursor cells into the graft site
• Eg- Alloplast, Allograft
OSTEOCONDUCTION
77
Misch C, Bone-grafting materials in implant dentistry Implant dent 1993;2:158-167.

AUTOGRAFT
• It is very osteogenic, easily
revascularized, and rapidly
incorporated in healing bone
• Active bone remodeling occurs by 4
weeks of graft placement.
• Osteoblasts lay osteoid that
surrounds the core of dead bone
78

ALLOGRAFT
• Three main types of bone allografts:
1. Frozen,
2. Freeze-dried
3. Demineralized freeze-dried bone
(DFDB).
Allografts forms bone by
the osteoinductive or
osteoconduction
phenomenon
Therefore bone
formation is slower and
less in volume as
compared with
autogenous grafts
ALLOPLAST
• Bone substitutes, and include the calcium phosphate materials such as HA or
tricalcium phosphate (TCP).
• The mode of bone formation : Osteoconduction
79

CONCLUSION
•Bone forms the main supporting structure for fixed
prosthesis .
•The knowledge of microscopic and macroscopic anatomy
helps in preservation of the health of the tissues .
Increase knowledge of bone physiology.
Raise the awareness of major risk factors various
disorders.
Prosthodontic implication.

REFERENCES
• Guyton-Physiology-11th edition.
• K Sembulingam - Essentials of Medical Physiology, 6th Edition
• Randolph_R_Resnik_Misch's_Contemporary_Implant_Dentistry_Elsevier, 4th edition.
• Shafer’s Textbook of Oral Pathology, 7th edition.
• Zhao, R.; Yang, R. et al, Bone Grafts and Substitutes in Dentistry: A Review of Current Trends and Developments. Molecules 2021, 26, 3007.
• Orthodontics- The Art and Science, Bhalahi 5th Edition book
• Steiner GG, Francis W, Burrell R, Kallet MP, Steiner DM, Macias R. The healing socket and socket regeneration. Compend Contin Educ Dent.
2008 Mar;29(2):114-6, 118, 120-4 passim.
• Klemetti E. A review of residual ridge resorption and bone density. The Journal of prosthetic dentistry. 1996 May 1;75(5):512-4.
• Atwood D.A. Reduction of residual ridges : A major oral disease entity. J. Prosthet. Dent. 26: 266-269 1971
• Zarb GA, Bolender CL, Carlsson GE. Boucher's prosthodontic treatment for edentulous patients. St. Louis: Mosby; 1997 Jan.
• Lane NE. Epidemiology, etiology, and diagnosis of osteoporosis. American journal of obstetrics and gynecology. 2006 Feb 1;194(2):S3-11.
• Watts N. Bisphosphonates, statins, osteoporosis, and atherosclerosis.(Featured CME Topic: Osteoporosis). Southern medical journal. 2002 Jun
1;95(6):578-83.
• Jan Lindhe “Clinical periodontology and implant dentistry” 5th edition, Blackwell Publishing
• Politis C, Schoenaers J, Jacobs R, Agbaje JO. Wound Healing Problems in the Mouth. Front Physiol. 2016 Nov 2;7:507.
• Hansson S, Halldin A. Alveolar ridge resorption after tooth extraction: A consequence of a fundamental principle of bone physiology. Journal
of dental biomechanics. 2012;3.
.

• Yadav B, Jayna M, Yadav H, Suri S, Phogat S, Madan R.
Comparison of different final impression techniques for
management of resorbed mandibular ridge: a case report. Case
reports in dentistry. 2014 Aug 10;2014.

1ST GENERATION-ORAL
BISPHOSPHONATE
• Minimally modified side chains (R1
R2) contain a chlorophenyl group.
• Metabolized into a non-hydrolysable ATP analog that accumulates
within
osteoclasts and induces apoptosis. which account for its antiresorptive
effect.
• Least potent.
Etidronate
Medronate
Clodronate
Tiludronate

2ND GENERATION-ORAL
BISPHOSPHONATE
• Contains nitrogen group (amino terminal) in
the side chain.
• Primarily inhibits bone resorption.
• Antiresorptive activity involves inhibition of multiple steps in
the pathway from mevalonate to cholesterol and isoprenoid lipids that are
required for the prenylation of proteins that are important for osteoclast
function.
• They are 10-100 times more potent than 1st generation BPs.
Alendronate
Pamidronate
Ibandronate

3RD GENERATION- IV
BISPHOSPHONATE
• Contain nitrogen atom within a heterocyclic ring.
• These are upto 10,000 times more potent than 1st
generation.
Risedronate,
Zoledronate

PHYSIOLOGY OF BONE AND ITS PROSTHODONTIC IMPLICATIONS

PHYSIOLOGY OF BONE AND ITS PROSTHODONTIC IMPLICATIONS

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