this gives a detailed description for the bone density consideration during implant placement. The presentation is available upon request. Mail me at apurvathampi@gmail.com

1. PRESENTED BY:
APURVA THAMPI
BONE DENSITY

2. Contents
•Introduction
•Bone morphology
•Bone physiology
•Influence of bone density on implant
success rates
•Aetiology of various bone density
•Bone classification schemes
•Bone density classification - Misch
•Bone density location
•Radiographic assessment of bone density
•Tactile sense - bone density
•Scientific rationale
•Effect of bone density on surgical
approach and healing
•Case studies
•Conclusion
•References

3. Basic bone biology in
implantology

4. Bone
33% organic67% inorganic
hydroxyapetite
28%
collagen
5% non
collagenous
protiens
2/25/2017
TEXTBOOKOF HUMAN HISTOLOGY , INDERBIR SINGH ;
5TH ED
4

5. There are 4 types of cells in bone
tissue….Osteoprogenitorcells
• Unspecialised
cells
• Develop into
osteoblasts
• Found in
periosteum,
endosteum
and in canals
of vital teeth
Osteoblasts
• Formation of
bone
• Role in
calcification
• Synthesis of
protien
Osteoclasts
• Responsible
for bone
resorption
Osteocytes
• Maintenance
of bone
• Exchange of
calcium
between bone
and ECF
TEXTBOOKOF HUMAN HISTOLOGY , INDERBIR SINGH ;
5TH ED

6. Can be broadly classified into :
Compact
bone
Trabecular
bone
TEXTBOOKOF HUMAN HISTOLOGY , INDERBIR SINGH ;
5TH ED

7. What is lamellar bone?
Structure of adult bone
Made up of layers – lamellae – thin plate of bone consisting
of collagen fibres and mineral salts
Lacunae – between each lamellae
Each lacuna consists of one osteocyte
Canaliculi spread out from each lacuna
A
B
C
Unit of bone - lamellus
Bone acquires thickness by stacking of lamellus
Between adjoining lamellae – spaces called lacunae
- Occupied by osteocytes
TEXTBOOKOF HUMAN HISTOLOGY , INDERBIR SINGH ;
5TH ED

8. What is woven bone?
Osteocyte in lacuna
canaliculi
Collagen fibres present in bundles – at
random
Interlaced – woven bone
All newly formed bone
Abnormal persistence of woven bone – Paget’s
disease

9. Compact bone VS
Trabecular bone

10. Osteon of compact bone
Trabeculae of spongy bone
Haversian canals
Volkmann’s canal
periosteum
osteon
canaliculi
lamellae
Lacunae containing ostecytes

11. Compact bone
Lamellae
arranged in
concentric
circles –
surround -
Haversian
canals
Occupied by
blood vessels
and nerves
Haversian
canal +
lamellae =
osteon or
haversian
system
Between
adjoining
osteons –
interstitial
lamellae
At the surface –
lamellae are
parallel –
circumferential
lamellae
TEXTBOOKOF HUMAN HISTOLOGY , INDERBIR SINGH ;
5TH ED

12. Trabecular bone
Bony plates or rods –
meshwork – trabeculae
Made of number of
lamellae
Enclose wide spaces
filled with bone marrow
– receive nutrition

13. Bone physiology

14. Calcium metabolism

15. Rapid influx
of calcium
from bone
fluid
Short term response
of osteoclasts and
osteoblasts
Long term
control of
bone
turnover
Normal
serum
calcium
levels –
10mg/dL
Low
calcium
level 
tetany and
death
High serum
calcium levels –
kidney stones,
dystrophic
calcification of
soft tissues
CONTEMPORARY IMPLANT DENTISTRY, CARL E MISCH,
3RD EDITION

16. Dec in calcium levels –
transport of ions to
osteocytes
Calciferol enhances
pumping of calcium ions
from cells into ECF
Net flux of Ca ions
PTH + calciferol +
calcitonin
Transiently
suppresses bone
resorption
Profound effect on
skeleton
PTH is the
primary regulator
– mean bone age
Important
determinant of
fragility
Instantaneous
regulation (within
seconds)
Short term
regulation
Long term
regulation
CONTEMPORARY IMPLANT DENTISTRY, CARL E MISCH,
3RD EDITION

17. Calcium conservation
Kidney excretes phophates by minimising loss of calcium
Renal dysfunction – high risk for osseous manipulative procedures –
renal osteodystrophy
Body spends 300mg calcium per day – recovered by absorption from
gut – depends of Vit D
Kidney is the
primary calcium
conservation
organ of the body
CONTEMPORARY IMPLANT DENTISTRY, CARL E MISCH,
3RD EDITION

18. Cortical bone growth and
maturation
Osseous
landmarks
for
superimpos
ition
Anterior
curvature of
the sella
turcica
Cribriform
plate
Internal
curvature of
frontal bone
Most reliable means of
determining post
adolescence growth 
essential for treatment
planning
MELSEN, BIRTE. THE CRANIAL BASE: THE POSTNATAL DEVELOPMENT OF THE CRANIAL BASE STUDIED
HISTOLOGICALLY ON HUMAN AUTOPSY MATERIAL. VOL. 32. ACTA ODONTOLOGICA SCANDINAVICA, 1974.

19. Influence of bone
density on implant
success rates

20. Anterior
mandible
Anterior
maxilla
Posterior
mandible
Posterior
maxilla
Position / Arch location
Quality of
bone
dependent on
the position
CONTEMPORARY IMPLANT DENTISTRY, CARL E MISCH,
3RD EDITION

21. •10% greater success rates in anterior mandible as compared to
anterior maxilla (Adell et al)
•Lower success rates in posterior mandible as compared with the
anterior mandible (Schnitman et al)
•Highest clinical failure rates – posterior maxilla – force is greater and
poor bone density
CONTEMPORARY IMPLANT DENTISTRY, CARL E MISCH,
3RD EDITION

22. Quality of bone
CONTEMPORARY IMPLANT DENTISTRY, CARL E MISCH,
3RD EDITION

23. Aetiology of various
bone density

24. Hormones
Vitamins
Mechanical
influences
Duration of
edentulousn
ess
Changes in bone -
adaptability
CONTEMPORARY IMPLANT DENTISTRY, CARL E MISCH,
3RD EDITION

25. “Every change in the form and function of bone or of
its function alone is followed by certain definite
changes in the internal architecture, and equally
definite alteration in its external conformation in
accordance with mathematical laws”
Wolff - 1892

26.  Adaptive phenomena
 Alteration of mechanical forces and strain development within the bone
 density evolves as a result of mechanical deformation from microstrain
MODELLING
Independent sites of formation and
resorption
Results in change in shape and size of
bone
REMODELLING
Resorption and formation at the same
site
Replaces previously existing bone
CONTEMPORARY IMPLANT DENTISTRY, CARL E MISCH,
3RD EDITION

27. The maxilla is a force distribution unit and
mandible is a force absorption unit
CONTEMPORARY IMPLANT DENTISTRY, CARL E MISCH,
3RD EDITION

28. The trabecular bone in dentate mandible is
more coarse compared to the maxilla
CONTEMPORARY IMPLANT DENTISTRY, CARL E MISCH,
3RD EDITION

29. Anterior
mandible
Posterior
maxilla
Density change after tooth
loss.
• Initial density
• Flexure and torsion
• Parafunction before
extraction
NEUFELD JO: CHANGES IN THE TRABECULAR PATTERN OF THE MANDIBLE
FOLLOWING THE LOSS OF TEETH, J PROSTHET DENT 685-697, 1958

30. ORBAN B: ORAL HISTOLOGY AND EMBRYOLOGY, ED 3, ST
LOUIS, 1953, MOSBY

31. Based on Frosts’s mechanostat theory
50 1500 3000 10000+
Acute
Disuse
window
Adapted
window
Mild
Overload
window
Pathologic
Overload
window
Spontaneous
fracture
Stress F/A
Strain O
Strain
Acute disuse window : lowest
microstrain amount
Adapted window : ideal physiologic
loading zone
Mild overload zone : cause
microfracture; triggers an increase in
bone remodelling – more woven bone
Pathologic overload : increased
fatigue fractures, remodelling and
bone resorption
FROST, H. M. "MECHANICAL ADAPTATION. FROST’S MECHANOSTAT THEORY."
STRUCTURE, FUNCTION, AND ADAPTATION OF COMPACT BONE (1989): 179-81.

32. Acute disuse window
•Loses mineral density
•Disuse atrophy – modelling for new bone
inhibited
•Net loss of bone
•Microstrain – 0 – 50
•Cortical bone density decrease – 40% and
trabecular bone density decrease – 12%
CONTEMPORARY IMPLANT DENTISTRY, CARL E MISCH,
3RD EDITION

33. Adapted window phase
•50 – 1500 microstrain
•Equilibrium of modelling and remodelling
•“homeostatic window of health”
•18% trabecular bone and 2-5% cortical bone
•Ideally desired around an endosteal implant

34. Mild overload zone
•1500 – 3000 microstrain
•Greater rate of fatigue microfracture
•Bone strength and density decreases
•State of bone when endosteal implant is
overloaded
•Repair – woven bone is weaker than lamellar –
“safety range” for bone strength is reduced
CONTEMPORARY IMPLANT DENTISTRY, CARL E MISCH,
3RD EDITION

35. Pathologic overload zone
•Microstrains <3000 units
•Physical fracture of cortical bone
•Formation of fibrous tissue
•Marginal bone loss in implant overloading –
implant failure

36. Bone classification
schemes in implant
dentistry

37. Linkow in 1970 :
Class I
• Ideal
• Evenly spaced
trabeculae
with small
cancellated
spaces
Class II
• Less
uniformity
• Larger
cancellated
spaces
• Large marrow
filled spaces
exist
CONTEMPORARY IMPLANT DENTISTRY, CARL E MISCH,
3RD EDITION

38. Lekholm and Zarb in 1985:
Quality 1
•Homogenous
compact bone
Quality 2
•Thick layer of
compact bone
around a core of
dense
trabecular bone
Quality 3
•Thin layer of
cortical bone
around dense
trabecular bone
•Favorable
strength
Quality 4
•Thin layer of
cortical bone
around a coreof
low density
trabecular bone
CONTEMPORARY IMPLANT DENTISTRY, CARL E MISCH,
3RD EDITION

39. Misch in 1988
Bone density Description Tactile analogue Typical anatomic
location
D1 Dense cortical Oak / maple wood Anterior mandible
D2 Porous cortical and
coarse trabecular
White pine or spruce
wood
Anterior mandible
Posterior mandible
Anterior maxilla
D3 Porous cortical (thin)
and fine
Balsa wood Anterior maxilla
Posterior maxilla
Posterior mandible
D4 Fine trabecular Styrofoam Posterior maxilla

40. D5 type of bone exists
– most immature
bone – found in a
developing sinus
graft.
CONTEMPORARY IMPLANT DENTISTRY, CARL E MISCH,
3RD EDITION

41. To be continued…

42. Bone density
location

43. Location of bone density types (%
occurance)
Bone Anterior maxilla Posterior maxilla Anterior
mandible
Posterior
mandible
D1 0 0 6 3
D2 25 10 66 50
D3 65 50 25 46
D4 10 40 3 1
CONTEMPORARY IMPLANT DENTISTRY, CARL E MISCH,
3RD EDITION

44. CONTEMPORARY IMPLANT DENTISTRY, CARL E MISCH,
3RD EDITION

45. D1 Bone
•Incresed torsion / flexure
•Div A Kennedy’s class IV
•Antr/postr mandible – lingual cortex
D2 Bone
•Partially edentulous antr/postr
mandible (premolar)
•Single tooth or 2 teeth missing
D3 Bone
•Most common in maxilla
•Also present in posterior mandible
D4 Bone
•Softest bone
•Posterior maxilla – after sinus
augmentation or iliac crest bone graft
CONTEMPORARY IMPLANT DENTISTRY, CARL E MISCH,
3RD EDITION

46. • First way to identify bone density in implant site
◦ Anterior maxilla – D3
◦ Posterior maxilla - D4
◦ Anterior mandible - D2
◦ Posterior mandible – D3
D2
D3 D4
CONTEMPORARY IMPLANT DENTISTRY, CARL E MISCH,
3RD EDITION

47. Radiographic bone
density

48. IOPAR
OPGs
• Lateral cortical plates
obscure the trabecular
bone density
• More subtle changes
cannot be qualified

49. Correlation between Misch bone density classification
and Hounsfield units….
Type of
bone
Hounsfield units
D1 >1250 HU
D2 850 – 1250 HU
D3 350 - 850 HU
D4 150 – 350 HU
D5 <150 HU
SOGO, MOTOFUMI, ET AL. "ASSESSMENT OF BONE DENSITY IN THE POSTERIOR MAXILLA BASED ON HOUNSFIELD UNITS TO
ENHANCE THE INITIAL STABILITY OF IMPLANTS." CLINICAL IMPLANT DENTISTRY AND RELATED RESEARCH 14.S1 (2012): E183-E187.

50. Correlation between Lekholm and Zarb’s bone density
classification and bone density…
NORTON, MICHAEL R., AND CAROLE GAMBLE. "BONE CLASSIFICATION: AN OBJECTIVE SCALE OF BONE DENSITY USING THE
COMPUTERIZED TOMOGRAPHY SCAN." CLINICAL ORAL IMPLANTS RESEARCH 12.1 (2001): 79-84.

51. Failure in
mandible –
higher
Hounsfield
units
• Lack of
vascularisation
• Overheating
ROTHMAN, STEPHEN LG, MELVYN S. SCHWARZ, AND NEIL I. CHAFETZ. "HIGH-RESOLUTION COMPUTERIZED TOMOGRAPHY AND NUCLEAR BONE
SCANNING IN THE DIAGNOSIS OF POSTOPERATIVE STRESS FRACTURES OF THE MANDIBLE: A CLINICAL REPORT." INTERNATIONAL JOURNAL OF

52. Bone density –
tactile sense

53. Bone density Description Tactile analogue Typical anatomic
location
D1 Dense cortical Oak / maple wood Anterior mandible
D2 Porous cortical and
coarse trabecular
White pine or spruce
wood
Anterior mandible
Posterior mandible
Anterior maxilla
D3 Porous cortical (thin)
and fine
Balsa wood Anterior maxilla
Posterior maxilla
Posterior mandible
D4 Fine trabecular Styrofoam Posterior maxilla

54. Scientific rationale for
a bone density - based
treatment plan

55. Bone strength
and density
Bone elastic
modulus and
density
Bone density
and implant
bone contact
interface
Bone density
and stress
transfer

56. Bone density and strength
Bone density is
directly related
to the strength
of bone before
microfracture
CONTEMPORARY IMPLANT DENTISTRY, CARL E MISCH,
3RD EDITION
1 2 43 5 6 7 8 9 10
D1D2D3D4

57. MISCH, C. E., AND M. W. BIDEZ. "IMPLANT-PROTECTED OCCLUSION: A BIOMECHANICAL RATIONALE." COMPENDIUM
(NEWTOWN, PA.) 15.11 (1994): 1330-1332.

58. Elastic modulus and density
Directly related to the density of bone
Relates to the stiffness of the material
Amount of
strain as a
result of a
particular
amount of
stress
EM of
bone more
flexible
than Ti
Pathologic
overload
Stresses
minimized
– adapted
window
zone
Lamellar
bone at
the
interface
MISCH, C. E., AND M. W. BIDEZ. "IMPLANT-PROTECTED OCCLUSION: A BIOMECHANICAL RATIONALE." COMPENDIUM
(NEWTOWN, PA.) 15.11 (1994): 1330-1332.

59. Ti - D1 bone
interface –
very little
microstrain
Ti – D4 bone
interface –
pathologic
overload
MISCH, C. E., AND M. W. BIDEZ. "IMPLANT-PROTECTED OCCLUSION: A BIOMECHANICAL RATIONALE." COMPENDIUM
(NEWTOWN, PA.) 15.11 (1994): 1330-1332.

60. Bone density and bone-implant
contact percentage Area  less area = greater stress
D1 bone has greatest BIC
D2 has 65 – 75% BIC
D3 bone has 40 – 50% BIC
D5 bone has 30% BIC
CONTEMPORARY IMPLANT DENTISTRY, CARL E MISCH,
3RD EDITION

61. Bone density and stress transfer
Different stress contours
for different types of bone
Bone
implant
contact
Bone
density
Elastic
modulus
Crestal
bone loss
and early
implant
failure due
to increased
stress
D1 bone
Stress is of
lesser
magnitude
Highest
strains near the
crest
D2 bone
Sustains
greater strain
 intensity of
stress extends
farther apically
D4 bone
Greatest crestal
strain 
magnitude of
strain is further
apical
Adapted
window
Mild overload Implant failure
CONTEMPORARY IMPLANT DENTISTRY, CARL E MISCH,
3RD EDITION

62. A nutshell….
Each bone density has different strengths
Bone density affects elastic modulus
Density differences result in difference in BIC
Different stress-strain distribution at a B-I interface
CONTEMPORARY IMPLANT DENTISTRY, CARL E MISCH,
3RD EDITION

63. Effect of bone
density on treatment
planning

64. Modifications in treatment
plan
Prosthetic
factors
Implant
surface
condition
Implant
number
Need of
progressive
loading
Implant
design
Implant
size
CONTEMPORARY IMPLANT DENTISTRY, CARL E MISCH,
3RD EDITION
Aim : decrease strain in the bone thereby decrease microfracture  increase SA

65. Dense cortical D1 Bone
Analogous to oak or
maple wood
Almost all dense cortical
bone
Mostly seen in anterior
mandible and sometimes
in posterior mandible

66. Advantages/disadvantages of D1
bone
Highly mineralized
Excellent bone
strength
Best implant bone
contact
Less force
transmission to apical
thirds
Implant crown ratio>1
Less blood supply – not
regenerative
Easily overheated
Implant height limited
to less than 12mm

67. Prior to osteotomy…
Amount of heat generated by each drill is directly
related to the bone removal by each drill
First drill – 2mm diameter
Rotational speed – 2000rpm
Intermittent pressure  “bone dances”

68. Osteotomy preparation in D1 bone
•Ext/Int irrigation
•Intermittent pressure
•Pause 3-5mins
•New drills
•Incremental drill
sequence
Overheating
•Primarily from
periosteum
•Minimal reflection
•Precise approximation
Blood supply
•Greater width
•Greater height
•Slower speed used
Final
osteotomy drill

69. •Short of full osteotomy
depth
•Allows passive implant
fit
•Removed drill
remnants
Bone tap
•Unthread ½ turn to
relieve internal
stresses
Final implant
placement •Slower healing rate
•5 months to achieve
mature interface
healing
•3-4 months
•May use immediate
loading
Stage II
recovery

70. D2 bone Dense-to-thick porpus cortical
and carse trabeculae
Hounsfield values – 750-1250
units
Analogous to spruce or white pine
wood
Occurs mostly in anterior
mandible and posterior mandible
Ideal implant dimension – 4mm
diameter ; 12 mm height

71. Advantages/disadvantages
Excellent implant
surface healing
Secure initial
rigid interface
Intrabony blood
supply

72. Osteotomy preparation in D2 bone
Rotation of drill – 2500 rpm
Ext/int irrigation used
Pause every 5-10 seconds – pumping motion
Drill sequence similar to D1 bone
Crestal bone drills should be used – reduce mechanical trauma
Bone tap – engages lateral or apical cortical bone

73. Healing
Excellent
blood supply
Initial rigid
fixation
Lamellar
bone interface
< 60% - 4
months
healing
interval
Abutment
placement
may
commence

74. D3 bone
Thinner porous cortical bone
Hounsfield values – 375 – 750 HU
Analogous to balsa wood
Found in anterior maxilla and anterior mandible/maxilla
Ideal implant dimension – 4X12
Roughened implant body – acid etched or resorbable blast media

75. Advantages/ disadvantages
Time and difficulty
for preparation is
minimal
Blood supply is
excellent
Highest survival
rate

76. Disadvantages of D3 bone
Bone anatomy
• Anterior maxilla is narrow
Osteotomy
• Lateral perforation
• Oversize by mistake
• Apical perforation
BIC
• 50%
Implant placement
• One time
• In level with crestal bone
Implant design
•TPS or Hydroxyapatite coated
•Costly
•Threaded
•Greater SA
•Press fit
Healing
•6 months
•Progressive loading more important than D1 or D2

77. D4 bone
Least density – no
cortical crestal bone
Found in posterior
molar region
Analogous to stiff
Styrofoam
Ideal Implant height –
14 mm (min 12 mm)

79. Disadvantages
Difficult to obtain rigid fixation
Rotating drills not to be used apart from pilot drill
Osteotomes may be used to compress osteotomy site
Cortical bone in the opposite landmark to be engaged (if any)
Increase number of implants to improve load distribution
No cantilever advocated

80. Summary
Densities vary depending of the location of edentulous ridge and the period of
edentulousness
D1 is the strongest bone - 10 times greater than D4
Minimum of 12mm height of implant required for initial stability
Additional bone healing and incremental loading will improve bone density

81. Conclusion
Bone remodels in relationto the forces excerted upon it – density varies

82. References
Textbookof human histology , Inderbir Singh ; 5th ed
Contemporary implant dentistry, Carl E Misch, 3rd edition
Orban B: Oral histology and embryology, ed 3, St Louis, 1953, Mosby
Melsen, Birte. The cranial base: the postnatal development of the cranial base
studied histologically on human autopsy material. Vol. 32. Acta Odontologica
Scandinavica, 1974.
Neufeld JO: changes in the trabecular pattern of the mandible following the loss of
teeth, J Prosthet Dent 685-697, 1958
Frost, H. M. "Mechanical adaptation. Frost’s mechanostat theory." Structure,
function, and adaptation of compact bone (1989): 179-81

83. Sogo, Motofumi, et al. "Assessment of bone density in the posterior maxilla based on
Hounsfield units to enhance the initial stability of implants." Clinical implant
dentistry and related research 14.s1 (2012): e183-e187.
Norton, Michael R., and Carole Gamble. "Bone classification: an objective scale of
bone density using the computerized tomography scan." Clinical oral implants
research 12.1 (2001): 79-84.
Misch, C. E., and M. W. Bidez. "Implant-protected occlusion: a biomechanical
rationale." Compendium (Newtown, Pa.) 15.11 (1994): 1330-1332.