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
9. Bone can be classified as
• Compact bone
• Spongy bone
10.
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 .
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 .
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.
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
29.
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.
31.
32. Phase Timing Specific occurrence
2. Proliferative
phase
Day 3 - 42 Neovascularization
Differentiation,
Proliferation and
activation of cells.
Production of immature
connective tissue
matrix.
33.
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
35.
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.
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)
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)
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
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
111. Masuda T, Yliheikkilä PK, Felton DA, Cooper LF.
Generalizations Regarding the Process and
Phenomenon of Osseointegration. Part I. In Vivo Studies.
Int J Oral Maxillofac Implants 1998;13:17–29
Esposito M, Hirsch JM, Lekholm U, Thomsen P,
Biological factors contributing to failures of
osseointegrated oral implants (I). Success criteria and
epidemiology. Eur J Oral Sci 1998; 106: 527–551
Sadhvi KV. Implant surface characteristics – a review –
Part I. Trends in prosthodontics and implantology
2011;2(2):45-48
112. Davies JE. Understanding Peri-Implant Endosseous
Healing. J Dent Edu 2005;67(8):932-949
Pye AD, Lockhart DEA, Dawson MP, Murray CA, Smith AJ.
A review of dental implants and infection. J Hospital
Infection 2009; 72:104-110
López AB, Martínez JB, Pelayo JL, García CC, Diago MP.
Resonance frequency analysis of dental implant stability
during the healing period. Med Oral Patol Oral Cir Bucal.
2008;13(4):E244-7.
113. Palmer R. Introduction to dental implants. Brit Dent J
1999;187(3) 14:127-132
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
Ehrenfest D M D, Coelho P, Kang B, Sul Y and Albrektsson
T.Classification of osseointegrated implant surfaces:
materials, chemistry and topography. Trends in
Biotechnology
Osseointegration.ppt
114. Pjetursson BE et al, Comparison of survival and
complication rates of tooth-supported fixed dental
prostheses (FDPs) and implant-supported FDPs and
single crowns (SCs), Clin. Oral Impl. Res, 2007:97–113
Misch CE et al. Implant Success, Survival, and Failure:
The International Congress of Oral Implantologists
(ICOI) Pisa Consensus Conference. Implant Dent
2008;17:5–15
115. Atsumi M et al, Methods used to Assess implant
stability: current status, Int J Oral Maxillafac
Implants 2007;22:743-54
http://www.ecf.utoronto.ca/~bonehead/
Hinweis der Redaktion
Titanium chamber was surgically inserted into the tibia of a rabbit.
Result revealed that there was a direct
strong bone anchorage of titanium
Elasticity of bone makes contact and connection a functional unit in which contact between implant and bone is maintained.
Diagram showing a wedge of cortical bone and spongy bone. Osteoblast and osteon.
Weak, poorly organised and mineralised
Strong well porganised and minralaised
Fnal attachment of lamellar str to allow attachment of fibres ligaments and tendons
Orientation of collagen fibrils
Remodelling cycle = 17 weeks in humans
Remodelling includes :
Localized changes in individual osteons or trabeculae
Turnover, hypertrophy, atrophy or reorientation
Extensive work by the Swedish orthopaedic surgeon
P.-I. Brånemark led to the discovery that commercially
pure titanium (CPTi), when placed in a suitably
prepared site in the bone, could become fixed in place
due to a close bond that developed between the two
(Fig. 2.1), a phenomenon that he later described as
osseointegration
Weiss concept????
Y did fibrous osseointegration lead to infection
Primary bone healing
Secondary bone healing
The basic science, in brief: Primary bone healing is lead by the formation of a so-called cutting cone (consisting of osteoclasts at the front of the cone to remove bone and trailing osteoblasts to lay down new bone) across the gaps to form a secondary osteon.
Secondary bone healing involves the classical stages of injury, hemorrhage inflammation, primary soft callus formation, callus mineralization, and callus remodeling. This method of bone healing closely resembles endochondral ossification (which involves a cartilage template being replaced by bone).
This accumalation of pp on the surface will increase the platelet adhesion
Osseointegration is a biological concept which involves the incorporation of a foreign body to
the living bone (host) with fixation and stability when subjected to functional loads. In order
for dental implant osseointegration to occur, there must be an adherence of the cells to the
surface of the biomaterial. The implant surface characteristics can modulate the adsorption of
proteins, lipids, sugar, and ions present in the tissue fluids. Attachment to a surface is a critical
first step in cell response because it determine which cells will populate the surface and how
many (Boyan et al., 2001). In vitro tests with osteoblastic cells showed that when cell adhesion
occurs, the cells change shape and spread. In this phase, reorganization of cytoskeletal proteins
occurs. At points of contact between cells and biomaterials there is an exchange of information
between cells and the extracellular matrix, leading to activation of specific genes and
remodeling. As the chemical composition of biomaterial induces different reactions of the cells,
the surface properties of biomaterials induce different reaction mechanisms (Anselme &
Bigerelle, 2005). Both the morphology and the surface roughness of biomaterials influence
proliferation, differentiation, extracellular matrix synthesis, production of local factors and
even cell shape
Cytokines and growth fCTORES
the fact that osteoblast cells adhere and spread more easily on rough surfaces than on
smooth ones. Add to surface treatment of implants
Implant stability depends on direct mechanical connection between implant surface and the
surrounding bone and can be divided into primary, secondary and tertiary stability. The
stability obtained immediately after insertion of a dental implant is called primary stability.
The stability obtained after osseointegration is named secondary stability. The tertiary
stability is the maintenance of osseointegration.
During machining of titanium, absorption of O2 molecules occurs. After about 10
nanoseconds, the molecules dissociate and a monolayer of atomic oxygen is deposited. This
oxygen reacts with titanium to form a titanium oxide film with a thickness between 50 and
100 Å (5 a 10 nm).
Bone can be
formed on the adjacent bone surfaces in a phenomenon called distance osteogenesis,
or on the implant surface itself in a phenomenon called contact
osteogenesis [23,24]. In the case of distance osteogenesis, osteogenesis occurs
from the bone toward the implant as the bone surfaces provide a population
of osteogenic cells that deposit a new matrix that approaches the implant. In
the case of contact osteogenesis, osteogenesis occurs in a direction away
from the implant as osteogenic cells are recruited to the implant surface
and begin secreting bone matrix. While both these processes are likely to
occur with implants, their relative significance may depend on the specific
type of implant and its surface characteristics.
migration of differentiating osteogenic cells to the proposed site. These cells are derived at bone remodeling sites from undifferentiated peri-vascular connective tissue cells.
Differentiating osteogenic cells, which reach the implant surface initially, secrete a collagen-free organic matrix that provides nucleation sites for calcium phosphate mineralization. FOLLOWED BY CRYSTAL GROWTH.
because it is the cement
line, secreted as a non-collagenous mineralized matrix by
differentiating osteoblasts, that invaginates, interdigitates
and interlocks with the demineralized collageous matrix
left by the resorbing osteoclast and thus it plays a critical
physical role in the establishment of the interface of new
bone and old bone.
cascade of de novo bone
formation (this term is explained in [7]) at solid surfaces as
a four-stage process (Fig. 1C) comprising: the adsorption
of non-collagenous bone proteins to the solid surface;
the initiation of mineralization by the adsorbed proteins
(Figs. 1D and E); continued mineralization due to crystal
growth; and finally the assembly of a collagenous matrix
overlying the interfacial matrix with mineralization within
the collagenous matrix.
When osteoclasts resorb bone, which is known to be a
two phase process of both the dissolution of the inorganic
matrix and enzymatic degradation of the organic components,
the result is the creation of a demineralized bone
matrix which becomes the recipient surface for new bone
formation.
morphological
feature of the resorbed bone matrix is important because
it presents a surface of three-dimensional complexity, at the
sub-micron scale range, into which the matrix of the
cement line can be deposited to form an anchoring
mechanism of new bone to old. Thus, in normal bone
remodeling, the resorption surface of old bone provides a
highly topographically complex surface into which new
bone matrix will be deposited, and with which the latter
can interdigitate and interlock.
The thickness of the oxide layer
increases with time and incorporates ions of Ca, P and S from the physiological environment.
The surface properties of implants, such as morphology, roughness, thickness of the oxide
layer, impurity level and types of oxide depend on the treatment to which the material was
submitted. It is important to remember that contact between the implant and the body
established through a titanium oxide film; there is no contact between metallic titanium and
the body.
This term refers to calcium phospate and bioactive glasses which undergo reactions that lead to chemical bonding.
OSSEOCOALESCENCE=The term applies to surface
reactive materials, such as calcium phosphates and bioactive glasses,
which undergo reactions that lead to chemical bonding between bone and
biomaterial. An example of qualitative evidence for chemical bonding is when
fracture lines propagate through either the implant or the tissue but not
along the interface
Biocompatibility is attributed to the
stable oxide layer, primarily titanium dioxide (TiO2), that spontaneously
forms when titanium is exposed to oxygen.
Calciumphosphate hydroxyapatite, Al2O3, Tricalcium phosphate)
Develop a chemical bond of a cohesive nature
Makeup the entire implant
Applied in the form of coating onto the metallic core.
Bone saucerisation???
Reverse buttress
Thread pitch of implant
Crest – The outermost surface joining the two sides of the thread.
Root – The innermost surface joining the two sides of the thread.
Helix angle – The angle formed by a point on the side and the plane perpendicular to the axis of the screw thread.
Pitch – The distance from a point on one thread to a corresponding point on the adjacent thread, measured parallel to the axis.
Lead – The axial distance that the implant advances in one complete turn.
Buttress threads are the strongest thread form for a given size because of their larger base cross-section, and because they minimize shear forces in a manner similar to square threads. They combine excellent primary stability with the best features of both V- and square-thread forms.
V , TRAPEZOID, SQUARE AND BUTTRESS
In the past, implants coated with hydroxyapatite (HA) were widely used. They are no
longer used due to the huge number of periimplantitis observed. However, HA-coated
implants had a larger amount of bone overlying the surface compared to uncoated implants.
In these implants the number of gaps between the HA coating and bone was lower and the
formation of mineralized nodules was more pronounced.
REFER INTECH FACTORS AFFECTING SUCCESS OF DENTAL IMPLANTS
During machining of titanium, absorption of O2 molecules occurs. After about 10
nanoseconds, the molecules dissociate and a monolayer of atomic oxygen is deposited. This
oxygen reacts with titanium to form a titanium oxide film with a thickness between 50 and
100 Å (5 a 10 nm). It is important to remember that contact between the implant and the body
established through a titanium oxide film; there is no contact between metallic titanium and
the body.
Clinical results indicate that when the dental implant insertion torque is
higher than 40 N.cm, the success rate increases
Countersinking done to
To reduce and minimize the bacterial
infection.
ii. To prevent the apical migration of oral
epithelium along the body of implant.
iii. To reduce and minimize the risk of early
implant loading during bone remodelling.
The marginal bone around the implant
crestal region is usually a significant
indicator of implant health
Of
course, conventional radiographics
only monitor the mesial or distal aspect
of bone loss around the implant
Presence of deep pockets ws not accompanied by accelerated marginal bone loss
Probing not only measures
pocket depth, but also reveals tissue
consistency, bleeding, and the presence
of exudate
It is of benefit to probe and establish
a baseline measurement after the
initial soft tissue healing around the
permucosal aspect of the implant. Increases
in this baseline measurement
over time most often represents marginal
bone loss.