The document summarizes key aspects of bone physiology. It discusses the classification, structure, composition, and microscopic organization of bone. It describes the different bone cells including osteoblasts, osteoclasts, and osteocytes. It explains the two processes of bone formation: intramembranous ossification and endochondral ossification. It discusses Wolff's law of bone adaptation and remodeling, Frost's mechanostat theory of bone modeling and remodeling in response to forces. It also summarizes the various cellular and hormonal factors that regulate bone growth.
2. CONTENTS
β’ Introduction
β’ Classification of bone
β’ Structure of long bone
β’ Composition of bone
β’ Microscopic structure of bone
β’ Bone cells
β’ Osteogenesis
β’ Intramembranous ossification
β’ Endochondral ossification
β’ Wolffβs law
β’ Bone remodeling and modeling
β’ Frost theory
β’ Regulating factors of bone growth
β’ Conclusion
β’ References 2
3. INTRODUCTION
Bone is a specialized mineralized connective tissue made up of an organic matrix of
collagen fibrils embedded in an amorphous substance with mineral crystals
precipitated within the matrix.
Sridhar Premkumar . textbook of craniofacial growth, first edition,2011
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4. β’ BASED ON SHAPE AND SIZE
β’ BASED ON THE STRUCTURE
β’ BASED ON THE ARRANGEMENT OF COLLAGENOUS
MATRIX
β’ BASED ON THE DEVELOPMENT
CLASSIFICATION OF BONE-
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6. STRUCTURAL COMPOSITION OF BONE
Bone is blend of cells embedded in a stiff calcified intercellular matrix.
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7. MICROSCOPIC ORGANIZATION OF BONE
MATURE/LAMELLAR BONE
β’ Full strength of lamellar bone that supports an
orthodontically moved tooth is not achieved
until approximately 1 year after completion of
active treatment.
IB Singh - textbook of human histology, 6th edition
Graber Vanarsdall, orthodontics current principles and techniques, 6th edition 7
8. WOVEN BONE
β’ Crucial role in wound healing by
1. Rapidly filling osseous defects,
2. Providing initial continuity for fractures and osteotomy
segments, and
3. Strengthening a bone weakened by surgery or trauma.
β’ First bone to be formed in response to orthodontic loading .
IB Singh - textbook of human histology, 6th edition
Graber Vanarsdall, orthodontics current principles and techniques, 6th edition
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9. BUNDLE BONE
β’ It is a functional adaptation of lamellar structure to allow attachment of
tendons and ligaments.
β’ Perpendicular striations, called Sharpeyβs fibers, are the major distinguishing
characteristics of bundle bone.
IB Singh - textbook of human histology, 6th edition
Graber Vanarsdall, orthodontics current principles and techniques, 6th edition
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10. COMPACT BONE
IB Singh - textbook of human histology, 6th edition
Graber Vanarsdall, orthodontics current principles and techniques, 6th edition 10
11. CANCELLOUS BONE
IB Singh - textbook of human histology, 6th edition
Graber Vanarsdall, orthodontics current principles and techniques, 6th edition 11
13. OSTEOBLAST CELLS
Sridhar Premkumar . textbook of craniofacial growth, first edition,2011
IB Singh - textbook of human histology, 6th edition 13
14. OSTEOBLAST CELLS
Sridhar Premkumar . textbook of craniofacial growth, first edition,2011
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15. OSTEOCYTE CELLS
Sridhar Premkumar . textbook of craniofacial growth, first edition,2011
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16. OSTEOCLAST CELLS
Sridhar Premkumar . textbook of craniofacial growth, first edition,2011
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17. OSTEOCLAST CELLS
Sridhar Premkumar . textbook of craniofacial growth, first edition,2011
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18. OSTEOGENESIS
β’ BONE FORMS IN TWO BASIC MODES
1. INTRAMEMBRANOUS OSSIFICATION
2. ENDOCHONDRAL OSSIFICATION
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22. WOLFFβS LAW OF BONE
β’ The architecture of bone is such that it can best resist the forces which are
brought to bear upon it with the use of as little tissue as possible.
β’ It has been found that bone is formed in just the quantity and shape that will
enable it to withstand the physical demands made upon it, with the greatest
amount of economy of structure.
β’ This is the basis of Wolff's law of transformation of bone.
W R Proffit & H W Fields jr.- Contemporary orthodontics,4th edition
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23. W R Proffit & H W Fields jr.- Contemporary orthodontics,4th edition
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24. Modeling & Remodeling
Both trabecular and cortical bone grow, adapt, and turnover by means of two
fundamentally distinct mechanism
Modeling
Remodeling
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25. Filling and cutting cones
Graber Vanarsdall, orthodontics current principles and techniques, 6th edition
Frost hm. Wolff's law and bone's structural adaptations to mechanical usage: an overview for clinicians. The angle
orthodontist. 1994 jun;64(3):175-88 25
26. Bone Modeling and its drifts
TWO KINDS OF DRIFTS-
FORMATION
DRIFTS
RESORPTION
DRIFTS
Graber Vanarsdall, orthodontics current principles and techniques, 6th edition
Frost hm. Wolff's law and bone's structural adaptations to mechanical usage: an overview for clinicians. The angle
orthodontist. 1994 jun;64(3):175-88 26
27. Bone Remodeling
BMU
Basic Multicellular Unit (BMU) is a wandering team of cells that dissolve an area of
the bone surface and then fills it with new bone in Activation βResorption β
Formation (ARP) sequence.
Turns over about 0.05 mm3 of preexisting bone in about 4 months.
A BMUβs osteoclastic activity does couple biologically to its osteblastic activity.
Hill pa. Bone Remodelling. British journal of orthodontics. 1998 may;25(2):101-7
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29. Hill pa. Bone Remodelling. British journal of orthodontics. 1998 may;25(2):101-7
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30. RAP
β’ Regional acceleratory phenomena(RAP)
β’ Infection, injury and some tumors can make all normally ongoing local tissue
process accelerate.
β’ Usually this RAP hastens healing and improves local resistance to infection It
explain the increased modeling and remodeling in the mandible and maxilla
following injuries or after implantation.
β’ In tooth extraction and periodontal diseases it can hasten the ridge resorption,
because RAP increases regional remodeling and hence increased bone to marrow.
Frost hm. Wolff's law and bone's structural adaptations to mechanical usage: an overview for clinicians. The angle
orthodontist. 1994 jun;64(3):175-88
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31. MICRODAMAGE AND ITS THRESHOLD
ο± Mechanical fatigue damage normally occurs in bone in life.
ο± Remodeling BMUβs usually repair the damage and keep it from accumulating.
ο± This is done by removing and replacing the damaged bone with new bone.
ο± Overloading bone can increase the microdamage.
ο± The largest normally allowed peak bone strains lies in 1500 microstrain range.
ο± In between 2000 -4000 microstrain increases microdamage.
ο± This can loosen dental and orthopaedic bone implants.
Frost hm. Wolff's law and bone's structural adaptations to mechanical usage: an overview for clinicians. The angle
orthodontist. 1994 jun;64(3):175-88
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36. REFERENCES
ο K Sembulingam, essentials of medical physiology, 6th edition
ο Graber Vanarsdall, orthodontics current principles and techniques, 6th
edition
ο W R Proffit & H W Fields jr.- Contemporary orthodontics,4th edition
ο IB Singh - textbook of human histology, 6th edition.....
ο Sridhar Premkumar . textbook of craniofacial growth, first edition,2011
ο Frost hm. Wolff's law and bone's structural adaptations to mechanical
usage: an overview for clinicians. The angle orthodontist. 1994
jun;64(3):175-88.
ο Hill pa. Bone Remodelling. British journal of orthodontics. 1998
may;25(2):101-7.
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