dental implants,osseo integration and evaluation of osseointegration success criteria of implant quality scale

1. Implant quality scale :
Osseointegration, success
criteria and basic guides

2. Definitions
Mechanism of
osseointegration
Factors effecting
osseointegration
Methods of evaluation
of osseointegration
Osseointegration
Bone implant
interface
Fibro – osseous
integration
Success criteria
Success Survival,
And failure
Evaluation of
dental Implants

3. HISTORICAL REVIEW
• The concept of osseointegration was developed
and the term was coined by Dr. Per-Ingvar
Branemark, Professor at the institute for Applied
Biotechnology, University of Goteborg, Sweden
.

4. Definitions
“The apparent direct attachment or connection of osseous
tissue to an inert, alloplastic material without intervening
connective tissue”. - GPT 8
Structurally oriented definition
“Direct structural and functional connection between the
ordered, living bone and the surface of load carrying
implants”.
- Branemark and associates (1977)

5. Histologically
Direct anchorage of an implant by the formation of
bone directly on the surface of an implant without
any intervening layer of fibrous tissue.
- Albrektson and Johnson (2001)

6. Clinically
Ankylosis of the implant bone interface.“Functional
ankylosis” -Schroeder and colleagues 1976
“It is a process where by clinically asymptomatic rigid fixation
of alloplastic material is achieved and maintained in bone
during functional loading”
- Zarb and T Albrektson 1991

7. Biomechanically oriented definition
“Attachment resistant to shear as well as tensile forces”
- Steinmann et al (1986).

8. Bone physiology

9. Bone can be classified as
• Compact bone
• Spongy bone

11. Depending on age, developmental age, localization and
function, bone consists of three tissue types that differ in
collagen fibril arrangement and mineral content.
Woven bone
Lamellar bone
Bundle bone

12. Woven bone
• Formed by the osteoprogenitor cells in the vicinity
of blood vessels during prenatal development
,growth and healing .
• Forms 30-50 µm /day
• High cellular osseous tissue
• Low mineral content
• More pliable than mature lamellar bone
• Capable of stabilizing an unloaded implant,woven
bone lacks the strength to resist functional loads .

13. Woven bone

14. Lamellar bone
• Principle load-bearing tissue
• Predominant component of mature cortical and
trabecular bone
• Forms relatively slow (< 1.0µm/day)
• Have highly organized matrix, and are densely
mineralized
• Orientation of the collagen fibrils differs from one
layer to another .

15. Lamellar bone

16. Bundle bone
• Found in the area of ligament and tendon attachment
along the bone-forming surfaces.
• Striation are extension of sharpey’s fibers composed of
collagen bundles from adjacent connective tissue that
insert directly into the bone
• It is formed adjacent to the periodontal ligament of
physiologically drifting teeth.

17. Bundle bone

18. Modelling
• A surface specific activity that produces a net change in
the size and/or shape of bone .
• An uncoupled process, meaning that cell activation(A)
proceeds independently to formation(F) or resorption(R)
• Generalized change in overall dimension of a bone’s
cortex or spongiosa
• Modelling is a fundamental mechanism of growth ,
atrophy and reorientation.

19. Bone Remodeling
• It is the turnover or internal restructuring of previously
existing bone .
• Coupled tissue level phenomenon

20. Bone to implant interface
There are two basic theories
Osseointegration
(Branemark 1985)
Fibro-osseous
integration
Linkow 1976
James 1975
Weiss 1986

21. FIBROINTEGRATION OSSEOINTEGRATION
In 1986, the American Academy of Implant Dentistry (AAID)
“Tissue-to-implant contact with healthy dense collagenous
tissue between the implant and bone”

22. Fibro-osseous integration
 Presence of connective tissue between the implant and
bone
 Collagen fibers functions similarly to Sharpey’s fibers
found in natural dentition.
 The fibers are arranged irregularly, parallel to the implant
body, when forces are applied they are not transmitted
through the fibers

23. Weiss concept
 Collagen fibers at the interface - peri-implant membrane
with an osteogenic effect.
 Collagen fibers invest the implant, originating at the
trabeculae of cancellous bone on one side, weaving
around the implant, and reinserting into a trabeculae on
the other side.
 It was felt that, this membrane gave a cushion effect and
acted as similar as periodontal membrane in natural
dentition.

24. Failure of fibro-osseous theory
 No real evidence
 Forces are not transmitted through the fibers -
remodeling was not expected
 Forces applied resulted in widening fibrous
encapsulation, inflammatory reactions, and gradual bone
resorption there by leading to failure.

25. Natural teeth Implant
Oblique and horizontal
group of fibers
Parallel, irregular,
complete
encapsulation
Uniform distribution of
load (Shock absorber)
Difficult to transmit
the load
Failure : Inability to carry adequate loads -
Infection

26. Osseointegration
American Academy of Implant Dentistry (AAID) defined it as
"contact established without interposition of non-bone tissue
between normal remodeled bone and an implant entailing a
sustained transfer and distribution of load from the implant
to and within the bone tissue"

27. Mechanism of Osseointegration
• Healing process may be primary bone healing or
secondary bone healing.
• In primary bone healing, there is well organized bone
formation with minimal granulation tissue formation -
ideal
• Secondary bone healing may have granulation tissue
formation and infection at the site, prolonging healing
period. Fibrocartilage is sometimes formed instead of
bone - undesirable

28. Blood between the
fixture and bone
Blood clot
Procallus
(contains fibroblast)
Callus (contains
osteoblast)
Bone
Remodelling
Phagocytic
cells
PMNL

30. Mechanism of osseointegration
Phase Timing Specific occurrence
1.Inflammatory
phase
Day 1-10 Adsorption of plasma proteins
Platelet aggregation and
activation
Clotting cascade activation
Cytokine release
Specific cellular inflammatory
response
Macrophage mediated
inflammation.

32. Phase Timing Specific occurrence
2. Proliferative
phase
Day 3 - 42 Neovascularization
Differentiation,
Proliferation and
activation of cells.
Production of immature
connective tissue
matrix.

34. Phase Timing Specific occurrence
3.Maturation
phase
After
Day 28
Remodeling of the
immature bone matrix with
coupled resorption and
deposition of bone.
Bone remodeling in
response to implant loading

36. Bone tissue response
• Distance Osteogenesis
A gradual process of bone healing inward from the edge
of the osteotomy toward the implant. Bone does not
grow directly on the implant surface.

37. • Contact Osteogenesis
The direct migration of bone-building cells through
the clot matrix to the implant surface. Bone is quickly
formed directly on the implant surface.

38. Mechanism of integration: (Davies - 1998)
Contact osteogenesis :
 Early phases of osteogenic cell migration
(Osteoconduction)
 De novo bone formation
 Bone remodeling at discrete sites.

39. Osteoconduction
“Osteoconduction” refers to the migration of differentiating
osteogenic cells to the proposed site.
Migration of the connective tissue cells will occur through
the fibrin that forms during clot resolution.
The migration of cells through a temporary matrix such as
fibrin - retraction of the fibrin scaffold.

40. De novo bone formation
Differentiating osteogenic cells, which reach the implant
surface initially, secrete a collagen-free organic matrix that
provides nucleation sites for calcium phosphate
mineralization
Noncollagenous bone proteins - Osteopontin and bone
Sialoprotein

41. Bone bonding in de novo bone formation
Bonding of de novo bone will occur by the fusion, or
micromechanical interlocking of the biologic cement line
matrix with the surface reactive layer

42. Bone remodeling
During the long-term phase of peri-implant healing, it is
only through those remodeling osteons that actually
impinge on the implant surface that de novo bone
formation will occur at these specific sites on the implant

43. Stages of Osseointegration
According to Misch there are two stages in
osseointegration, each stage been again divided into
two substages. They are:
Surface modeling
Stage 1: Woven callus (0-6 weeks)
Stage 2: Lamellar compaction (6-18 weeks)
Remodeling, Maturation
Stage 3: Interface remodeling (6-18 weeks)
Stage 4: Compact maturation (18-54 weeks)

44. Stage 1: Woven callus
 0-6 weeks of implantation.
 Woven bone is formed at implant site.
 Primitive type of bone tissue and characterized
Random, felt-like orientation of collagen
fibrils
Numerous irregularly shaped osteocytes
Relatively low mineral density

45. Stage 2: Lamellar compaction
 6th week of implantation and continues till 18th week.
 The woven callus matures as it is replaced by lamellar
bone.
 This stage helps in achieving sufficient strength for
loading.

46. Stage 3: Interface remodeling
 This stage begins at the same time when woven callus is
completing lamellar compaction.
 During this stage callus starts to resorb, and remodeling
of devitalized interface begins.
 The interface remodeling helps in establishing a viable
interface between the implant and original bone.

47. Stage 4: Compact bone maturation
 This occurs form 18th week of implantation and continues
till the 54th week.
 During this stage compact bone matures by series of
modeling and remodeling processes.
 The callus volume is decreased and interface remodeling
continues.

48. Six different factors known to be important for the
establishment of a reliable, long-term osseous anchorage
of an implanted device
 Implant biocompatibility
 Design characteristics
 Surface characteristics
 State of the host bed
 Surgical technique and
 Loading conditions

49. Implant Biocompatibility
 Chemical interaction determined – properties of surface
oxide
 Commercially pure (c.p.) Titanium and Titanium alloy (Ti
-6AL-4V)
 Documented long term function
 Covered with adherent, self- repairing oxide layer
 Excellent resistance to corrosion – high dielectric
constant
 Load bearing capacity

50. Other metals
 Niobium, tantalum
 Cobalt chrome molybdenum alloys
 Stainless steels
 Ceramics - calcium phosphate hydroxyapatite (HA) and
various types of aluminium oxides
Biocompatible - insufficient documentation and very less
clinical trials - less commonly used.

51. Degree of
Compatibility
Characteristics of Reactions of
Bony Tissue
Materials
Biotolerant Implants separated from
adjacent bone by a soft tissue
layer along most of the
interface: distance
osteogenesis
Stainless steels: CoCrMo
and CoCrMoNi alloys
Bioinert Direct contact to bony tissue
contact osteogenesis
Alumina ceramics, zirconia
ceramics, titanium,
tantalum, niobium, carbon.
Bioactive Bonding to bony tissue:
bonding osteogenesis
Calcium phosphate-
containing glasses, glass-
ceramics, ceramics,
titanium (?)
Grouping of hard tissue replacement materials according to
their compatibility to bony tissue

52. Implant Design (Macrostructure)
Threaded or screw design implants
 Promote osseointegration
 More functional area for stress distribution
than the cylindrical implants.
 Minimal - <0.2 mm/year bone loss
Cylindrical implants
 Press fit root form implants depend on
coating or surface condition to provide
microscopic retention and bonding to the
bone
 Bone saucerization

53. Non threaded
•Tendency for slippage
•Bonding is required
•No slippage tendency
•No bonding is required
Threaded

54. Functional surface area per unit length of implant may be
modified by the three thread geometry parameters
• Thread shape
• Thread pitch
• Thread depth

55. Grooves on the threads of all implants and on the collars,
wherever appropriate.
 Increase surface area
 Increase area for bone-to-implant contact

56. Implant Surface (Microstructure,Surface Topography)
“The extent of bone implant interface is positively
correlated with an increasing roughness of the
implant surface”
Roughened surface

 Greater bone to implant contact at histological level
 Micro irregularities - cellular adhesion.
 High surface energy - improved cellular attachment.

57. • Roughness parameter (Sa)
0.04 –0.4 m - smooth
0.5 – 1.0 m – minimally rough
1.0 –2.0 m – moderately rough
 2.0 m – rough
• Wennerberg (1996) – stated that moderately rough implants
developed the best bone fixation.
Smooth surface < 0.2 m will – soft tissue no bone cell
adhesion  clinical failure.
Moderately rough surface more bone in contact with implant
 better osseointegration.

58. Surface treatments
 Turned surface
 Sandblasted surface
 Acid etched surface
 Titanium plasma spray
 Sandblasting and surface etching
 Hydroxyapatite coatings
 Anodized surface

59. Bone – implant contact area
Surface treatment 1 month 3 months 6 months
Machined/ truned 42% 44%
Machined/ sandblasted 54%
Machined/ acid etched 42% 51% 49%
Sandblasted
and acid etched
58%
72%
52%
68%
Oxidized 35% 43%
Titanium plasma-sprayed 52% 78%
Hydroxyapaptite 79%
Ion implantation 68% 61%
Laser treated 38%

60. State of the host bed
Ideal host bed
Healthy and with an adequate bone stock
 Bone height
 Bone width
 Bone length
 Bone density
Undesirable host bed states for implantation
 Previous irradiation
 Ridge height resorption
 Osteoporosis

61. Implant bed - Bone Quality
According to Lekholm and Zarb,1985
• Quality I
composed of homogenous compact
bone found in the lower anterior
• Quality II
Thick layer of cortical bone surrounding
dense trabecular bone found in the lower
posterior

62.  Quality III
Thin layer of cortical bone surrounding
dense
trabecular bone – upper anterior and
upper &
lower posterior region
 Quality IV
Very thin layer of cortical bone surrounding
a core of low-density trabecular bone
- very soft bone found in the
upper anterior and posterior

63.  Branemark system (5 year documentation)
 Mandible – 95% success
 Maxilla – 85-90% success
According to Branemark and Misch
 D1 and D2 bone  initial stability / better osseointegration
 D3 and D4  poor prognosis
 D1 bone – least risk
 D4 bone - most at risk
Selection of implant
 D1 and D2 – conventional threaded implants
 D3 and D4 – HA coated or Titanium plasma coated implants

64. Surgical Considerations
 Promote regenerative type of the bone healing rather than
reparative type of the bone healing.
 The critical time/ temperature - bone tissue necrosis - 47°
for one minute.

65. Recommendations
 Slow speed
 Graded series
 Adequate cooling
 Bone cutting speed of less than 2000 rpm
 Tapping at a speed of 15 rpm with irrigation
 Using sharp drills
 The optimal torque threshold – 35 N/cm.
 Implant should gently engage the bone in order to avoid
too much pressure at the bone interface which could
jeopardize healing
 Surgical skill / technical excellence

66. Progressive or two stage loading
Branemark et al to accomplish osseointegration
considered the following prerequisites
 Countersinking the implant below the crestal bone
 Obtaining and maintaining a soft tissue covering over
the implant for 3 to 6 months
 Maintaining a non loaded implant environment for 3 to
6 months

67.  Delayed loading:
- Two-stage surgical protocol
- One-stage surgical protocol
 Immediate loading:
1. Immediate occlusal loading (placed within 48 hours)
2. Immediate non-occlusal loading (in single-tooth or
short-span applications)
3. Early loading (within two months)

68. Frost’s mechanostat theory

69. Systemic factors
 Active chemotherapy
 Type 2 (late-onset) diabetes: This is especially the
case where this is not well controlled
 Treatment by an operator with limited surgical
experience.

70.  Patients who were smokers at the time of implant
surgery had a significantly higher implant failure rate
(23.08%) than non-smokers (13.33%)
 Short implants and implant placement in the maxilla
were additional independent risk factors for implant
failure.
DeLuca S, Habsha E, Zarb GA. The effect of smoking on
osseointegrated dental implants. Part I: implant survival. Int J
Prosthodont 2006;19(5):491-8

71. Subjective criteria
 Adequate function
 Absence of discomfort
 Improved aesthetics
 Improved emotional and psychological wellbeing
Harvard success criteria
The dental implant must provide functional service
for 5 years in 75% of cases

72. Objective criteria
 Bone loss no greater than 33% of vertical length of implant
 Gingival inflammation amenable to treatment
 Mobility of less than 1mm in any direction
 Absence of symptoms of infection
 Absence of damage to surrounding structure
 Healthy connective tissues

73. Possible criteria for success
 Mobility
 Peri-implant radiolucency
 Marginal bone loss
 Sulcus depth
 Gingival status
 Damage to adjacent teeth
 Violation of maxillary sinus , mandibular canal
or floor of nasal cavity
 Appearance
 Length of service

74. Condition for application of criteria
 Only osseointegrated implants should be
evaluated with these criteria.
 The criteria apply to individual endosseous
implants.
 At the time of testing, the implants must have
been under a functional load.

75.  Implants that are beneath the mucosa and in a
state of health in relation to the surrounding
bone should preferably not be included in the
evaluations but reported as complications.
 Complications of an iatrogenic nature that are
not attributable to a problem with material or
design should be considered separately when
computing the percentage of success

76. Revised criteria - Albrektsson
 Individual implant is immobile clinically
 No evidence of peri-implant radiolucency is
present as assessed on an undistorted
radiograph.
 Mean vertical bone loss is less than 0.2 mm
annually after the first year of service.

77.  No persistent pain, discomfort, or infection is
attributable to the implant.
 Implant design does not preclude placement of
a crown or prosthesis with an appearance that is
satisfactory to the patient and dentist.
 By these criteria, a success rate of 85% at the
end of a 5-year observation period and 80% at
the end of a 10 year period are minimum levels
for success.

78.  Drago et al
anterior maxilla-89.1%
posterior maxilla-71.4%
anterior mandible-96.7%
posterior mandible-98.7%
Success rate

79. Moy et al –
maxilla-91.8% mandible-95.1%
Bass et al –
maxilla-93.4% mandible-97.2%

80. 5-year survival
 conventional tooth-supported FDPs of 93.8%
 cantilever FDPs of 91.4%
 solely implant supported FDPs of 95.2%
 combined tooth-implant-supported FDPs of 95.5%
 implant supported SCs of 94.5%
FDP vs Implants

81. After 10 years of function –
 89.2% -conventional FDPs
 80.3% -cantilever FDPs
 86.7%- implant-supported FDPs
 77.8% - combined tooth-implant-supported FDPs
 89.4% - implant-supported SCs
 Technical complications were (fractures of the veneer
material, abutment or screw loosening and loss of
retention)

82. Methods of evaluation of
Osseointegration

83.  Stability is a requisite characteristic of
osseointegration.
 Initial stability is a function of the
Bone quality,
Implant design and
Surgical technique.
 During the osseointegration healing and
maturation process , the initial stability changes
with increases in bone- to –implant contact and
osseous remodeling.

84. Invasive Methods
 Histological sections (10 microns sections)
 Histomorphometric – To know the percentage of bone
contact
 Transmission electron microscopy
 By using Torque gauges

85. Non-Invasive Methods
 Percussion test
 Tapping with a metallic instruments
Ringing sound- osseointegrated.
Dull sound - fibrous integration.
 Radiographs

86.  Reliable method to determine implant stability
 Emg driven and electronically controlled
tapping head that hammers an object at a
rate of 4 times/sec
Periotest

87.  Response to striking is measured by a small
accelerometer present in head
 Signals converted to periotest value
 Depends on damping characteristic of tissues
surrounding teeth or implant

88.  Developed by Aoki and Hirakawa
 Mech is similar to periotest
 Microphone used as receiver and signals
transferred is processed by FFT for analysis
Dental mobility checker

89.  Non invasive can be performed at any stage of
healing
 Bite wing-measure crestal bone level
 1.5 mm of CBL can be expected in the Ist year
of loading with 0.1 mm of subsequent annual
bone loss
Radiographic evaluation

90.  Problems
Difficult for clinician to detect changes at 0.1mm
resolution
Can be measured when central ray of x-ray is
perfectly ll with the structure of interest

91.  Excellent method to assess health of natural teeth
 In implants little diagnostic value unless accompanied by
signs & symptoms
 Stable implants pocket depth- 2-6mm
 Indicate bone loss but not necessarily disease
 Sulcus depth greater than 5-6 mm-risk of anaerobic
bacterial infection
Probing depth

92.  Suggested by James, modified by Misch
 Group I
 Group II
 Group III
 Group IV
Misch CE, Perel ML, Wang HL, et al. Implant success, survival, and failure: The
International Congress of Oral Implantologists (ICOI) Pisa Consens Conference.
Implant Dent 2008;17:5-15.
Implant quality of health scale

93.  No pain or tenderness upon function
 0 Mobility
 Less than 2.0 mm crestal bone loss from initial
surgery
 No history of exudate
Group I (Success)

94.  No pain on function
 0 mobility
 Crestal bone loss – 2 to 4 mm
 No history of transient exudate
 Prognosis good to very good
Group II
(survival-satisfactory health)

95.  Slight to moderate peri-implantitis
 Sensitivity on function
 Radiographic bone loss > 4 mm (<1/2 of implant
body)
 No mobility (IM-O)
 Probing depth >7 mm
 May have exudates history
Group III
(Survival-compromised health)

96.  Implant removed
 Pain
 mobility
 Uncontrolled progressive bone loss;
 Uncontrolled exudate
 50% bone loss
 surgically removed/ exfoliated
Group IV
(clinical or absolute failure)

97. Rigid fixation
Scale Description
0 Absence of clinical mobility with 500g in any
direction
1 Slight detectable horizontal movement
2 Moderate visible horizontal mobility up to
0.5 mm
3 Sever horizontal movement greater than 0.5
mm
4 Visible moderate to sever horizontal and any
visible vertical movement

98.  Cutting Torque resistance analysis (CRA)
 Reverse Torque test (RTV)
 Resonance Frequency analysis (RFA)
Other methods

99.  Johansson and strid and improved by Friberg et
al
 Energy required for a current fed electric motor
in cutting off a unit volume of bone during
surgery is measured.
 Energy is correlated with bone density which
influences the implant stability
Cutting Torque resistance analysis (CRA)

100.  Torque guage-in drilling unit measures the
insertion torque in Ncm, gives idea about the
bone quality
 Gives more objective assessment than clinician
dependent evaluation

101. Advantages
a. Detect bone density
b. Identify bone density during surgery
c. Can be used in daily practice
Disadvantages
a. can only be used during surgery
b. longitudinal data cannot be collected to assess
bone quality changes after implant placement

102.  Measures the ‘critical’ torque threshold where
bone-implant contact (BIC) was destroyed
 Removal Torque value (RTV)-indirect
measurement of BIC/clinical osseointegration
Reverse Torque test (RTV)

103.  Ranges from 45-48 Ncm
 RTV >20 Ncm accepted as criteria for
successful osseointegration
 Varies depending on bone quality & quantity

104. Disadvantages
a. RTV only provide information as to “all or
none” outcome
b. Mainly used in experiments

105.  Non invasive method that measures implant stability
& bone density at various time points
 RFA utilizes a small L-shaped transducer that is
tightened to implant or abutment
Resonance Frequency analysis (RFA)

106.  Transducer comprises of 2 piezoceramic
elements
 One for vibration, and other serves as a receptor
for the signal
 Resonance peaks from the received signal
indicates the first RF of the measured object

107.  Earlier hertz was used as measurement unit
now implant stability quotient (ISQ)
 RF values ranging from 3500-8500 Hz
translated into ISQ of 0-100

108.  Higher value-greater stability
 Low value-instability
 Successful implant-ISQ >65
 ISQ <50 indicates potential failure/increased risk
of failure

109.  RFA can only give information regarding success
cannot provide information with respect to survival
or failure.
 ISQ is fairly reliable when implant has achieved
osseointegration & the B-I interface is rigid.
 ISQ tends to fluctuate when the interface is not rigid

110. References
 Misch CE. Contemporary implant dentistry, 3rd edition,
Mosby Elsevier publication, St Louis, 2008, pp:27, 70,
621
 Hobkirk JA, Watson RM, Searson LJ. Introducing dental
implants, 1st edition, Churchill Livingstone, London, 2003
pp:3 – 18
 Smith DE, Zarb GA, Criteria for success of
osseointegrated endosseous implants, J Prosthet Dent
1989;62:567-72

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