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Dr. Mohammed Alshehri
Saudi Fellowship in Dental Implant
The early causes of crestal bone lossaround dental implant
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The longevity of dental implants is highly dependent on
integration between implant components and oral
tissues, including hard and soft tissues.
Introduction
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Studies have shown that submerged titanium implants
had 0.9 mm to 1.6 mm marginal bone loss from the rstthread by the end of rst year in function, while only 0.05
mm to 0.13 mm bone loss occurred after the rst year.
Adell et al. Int J OralSurg 1981
Jemt et al. Int J Perio Resto Dent 1990Cox et al. Int J Oral Maxillofac Implants1987
Introduction
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The rst report in the literature to quantify the earlycrestal bone loss was a 15-year retrospective study
evaluating implants placed in edentulous jaws.
In this study, Adell et al. reported an average of 1.2 mmmarginal bone loss from the rst thread during healingand the rst year after loading.
In contrast to the bone loss during the rst year, therewas an average of only 0.1 mm bone lost annuallythereafter.
Adell et al. Int J OralSurg 1981
Introduction
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Based on the ndings in sub-merged implants,
Albrektsson et al. andSmith and Zarb proposed criteriafor implant success, including a vertical bone loss less
than 0.2 mm annually following the implants first year of
function.
Albreksson et al. Int J Oral Maxillofac Implants 1986Smith D and Zarb G. J Prosthet Dent 1989
Introduction
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Non-submerged implants also have demonstrated early
crestal bone loss, with greater bone loss in the maxillathan in the mandible, ranging 0.6 mm to 1.1 mm, at the
rst year of function.
Buser et al. Clin Oral Implant Res 1990
Weber et al. Clin Oral Implant Res 1992Brgger et al. Clin Oral Implants Res1998
Introduction
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Heat generated at the time of drilling, elevation of the
periosteal ap, and excessive pressure at the crestal
region during implant placement may contribute to
implant bone loss during the healing period.
Surgical trauma
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Heat generation and excessive pressure
Eriksson and Albrektsson reported that the criticaltemperature for implant site preparation was 47C for 1minute or40C for 7 minutes.
Matthews and Hirsch demonstrated that temperature
elevation was inuencedmore by the force applied thandrill speed.
Eriksson RA, Albrektsson T. J Oral MaxillofacSurg 1984Matthews L, Hirsch C. JBone JointSurg 1972
Surgical trauma
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Heat generation and excessive pressure (Cont)
it was found that when both drill speed and applied force
were increased, no signicant increase in temperature
was observed due to efficient cutting.
Matthews L,H
irsch C. JB
one JointS
urg 1972Brisman DL. Int J Oral Masillofac Implant 1996
Surgical trauma
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Heat generation and excessive pressure (Cont)
Sharawy M. et al. compare the heat generated by thedrills of 4 different implant systems run at speeds of
1225,1667 and 2500rpm. All of the drill systems able to
prepare an 8mm site without the temperature rising more
than 4C (to 41C).
Surgical trauma
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Heat generation and excessive pressure (Cont)
For all drill systems the 1225 rpm drill speed produced
30 to 40% longer drilling times when compared to2500rpm and a 20% to 40% reduction in the timerequired forbone temperature to normalise. With greaterdepth of preparation and insufficient time between drillchanges, detrimental temperatures rise of47C+ may be
reached. The authors recommend that surgeons interruptthe drilling cycle every 5 to 10 seconds to allow irriganttime to cool the osteotomy.
Sharawy M. et al. Journal of Oral and MaxillofacialSurgery 2002
Surgical trauma
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Periosteal flap
The periosteal elevation has been speculated as one of
the possible contributing factors for crestal implant boneloss.
Wilderman et al. reported that the mean horizontal boneloss after osseous surgery with periosteal elevation is
approximately 0.8 mm, and the reparative potential ishighly dependent upon the amount of cancellous bone(not cortical bone) existing underneath the cortical bone.
Wilderman et al. J Periodontol 1970
Surgical trauma
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Periosteal flap (Cont)
The bone loss atstage IIimplant surgery in successfullyosseointegrated implants is generally vertical and noted
only around the implant characterized bysaucerization,
not the surrounding bone even though during the surgery
all the bone was exposed, Therefore, this hypothesis is
not generally supported.
Surgical trauma
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Research has indicated that occlusal overload often
resulted in marginal bone loss or de-osseointegration of
successfully osseointegrated implants.
Adell et al. Int J OralSurg 1981
Cox et al. Int J Oral Maxillofac Implants1987
Lindquist et al. J Prosthet Dent 1988
Block MS, Kent JN. J Oral MaxillofacSurg 1990
Sanz M et al. Clin Oral Implant Res 1991
Quirynen et al. Clin Oral Implant Res 1992
Tonetti MS, Schmid J. Periodontol 2000 1994
IsidorF
. et al. Clin Oral Implant Res 1996IsidorFet al. Clin Oral Implant Res 1997
Occlusal overload
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The crestal bone around dental implants could be a
fulcrum point for lever action when a bending moment is
applied, suggesting that implants could be more
susceptible to crestal bone loss by mechanical force.
Occlusal overload
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Factors associated with increased bending overload indental implants
1. Prostheses supported by 1 or 2 implants in theposterior region.
2. Straight alignment of implants.
3. Signicant deviation of the implant axis from the line
of action.
4. High crown/implant ratio.
5. Excessive cantilever length.
Occlusal overload
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Factors associated with increased bending overload indental implants (Cont)
6. Discrepancy in dimensions between the occlusal table
and implant head.
7. Parafunctional habits.
Rangert et al. Int J Oral Maxillofac Implants 1995
Occlusal overload
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Occlusal overload
Tooth Implant
Connection PDL Osseointgration,
functional ankylosisProprioception Periodontal mechanoreceptor Osseoperception
Tactile sensitivity High Low
Axial mobility 25-100 Q 3-5 Q
Fulcrum to lateral force Apical 3rd of root Crestal bone
Signs of overloading PDL thicking, mobiliy, Screw loosening or fractur wear facets, fremitus, pain abutment fx., bone loss
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The cortical bone is known to be least resisant to shear
force which is signicantly increased by bending
overload
Reilly DT, Burstein AH. JBiomech 1975
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According to VonRecum, when 2 materials of different
modules of elasticity are placed together without
intervening material and one is loaded, a stress contour
increase is observed where the two materials first comeinto contact.
VonRecum A, editor. Handbook ofBiomaterialEvaluation.New York: Macmillan Publishing Co.; 1986.
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Photo-elastic and 3-dimensional nite element analysis
(FE A) studies demonstrated V- or U-shaped stress
patterns with greater magnitude near the point of the rst
contact between implant and photo-elastic block, whichis similar to the early crestal bone loss phenomenon.
Bidez M, McLoughlin S, Lemons JE. FEA investiga-
tions in plate-form dental implant design. In: Lemon JE,
ed. Proceedings of the First World Congress ofBiome-
chanics.San Diego: Society ofBiomechanics; 1990
Occlusal overload
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Misch claimed that the stresses at the crestal bone may
cause micro-fracture or overload, resulting in early
crestal bone loss during the rst year of function, and the
change in bone strength from loading and mineralization
after 1 year alters the stress-strain relationship and
reduces the risk of micro-fracture during the following
years.
Misch CE. Contemporary Implant Dentistry,2nded. St. Louis: Mosby; 1999
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Wiskott andBelser described a lack of osseointegration
attributed to
1. An increased pressure on the osseous bed during
implant placement.
2. Establishment of a physiologic biologic width.
3. Stress shielding.
4. Lack of adequate biomechanical coupling between
the load-bearing implant surface and thesurrounding bone.
They focused on the signicance of the relationship
between stress and bone homeostasis.
WiskottHW, Belser UC. Clin Oral Im lants Res1999
Occlusal overload
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Based on the previous study byFrost, 5 types of strain
levels interrelated with different load levels in the bone
were described:
1) Disuse, bone resorption.
2) Physiologic load, bone homeostasis.
3) Mild overload, bone mass increase.
4) Pathologic overload, irreversible bone damage.5) fracture.
FrostHM. Angle Orthod1994;64:175-188.
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The concept of "microfracture proposed by Roberts et
al. and concluded that crestal regions around dental
implants are high stress bearingareas.
He also explained that if the crestal region is over-loaded
during bone remodeling, cervical cratering is created
around dental implants. The study also suggests that
axially directedocclusion as well as progressive loading
are recommended to prevent "microfracture" during thebone remodeling periods.
Roberts et al. J Indiana Dent Assoc. 1989
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Progressive loading on dental implants during healing
stages was rst described by Misch in the 1980s to
decrease early implant bone loss and early implant
failure. Based on the concept, progressive loading needs
to be employed to allow the bone to form, remodel, and
mature to resist stress with out detrimental bone loss by
staging application of diet, occlusal contacts, prosthesis
design, and occlusal materials.
Misch CE. Progressive bone loading. In: Misch CE, ed.
Contemporary Implant Dentistry,2nd ed. St. Louis:
Mosb ; 1999
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Appleton et al. reported a decrease in crestal bone loss
was observed in progressively loaded implants,
compared to implants without progressive loading, within
a similar healing and loading period; in addition, digital
radiographs indicated an increase in bone densityin the
crestal 40% of the implant in the progressive loaded
crowns.
Appleton et al. J Dent Res1997
Occlusal overload
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Greater crestal bone loss observed at the rst year of
function compared to following years can be explained
by a reduced occlusal overloador increased resistance
to occlusal overload after the rst year of function
includes a functional adaptation of the oral musculature,wear of the prosthesis material, and/or an increase in
bone densityafter a certain time period
Occlusal overload
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peri-implantitis is one of the two main causative factors
for implant failure in later stages. A correlation between
plaque accumulation and progressive bone loss around
implants has been reported in experimental studies and
clinical studies
Peri-Implantitis
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Tonetti andSchmid reported that peri-implant mucositis
is a reversible inammatory lesion conned to peri-
implant mucosal tissues without bone loss; on the other
hand, peri-implantitis begins with bone loss arounddental implants.
Peri-Implantitis
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Clinical features of peri-implantitis were described by
Mombellias including:
1) Radiographic evidence of vertical destruction of the
crestal bone.
2) Formation of a peri-implantpocketin association with
radiographic bone loss.
3) bleeding after gentle probing, possibly with
suppuration.
4) Mucosalswellingandredness.
5) No pain typically.
Peri-Implantitis
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In an experimental study evaluating the pattern of
ligature-induced breakdown of peri-implant and
periodontal tissues in beagle dogs, signicantly greater
tissue destruction was demonstrated clinically,radiographically, and histomorphometrically at implant
areas than at tooth sites.
It was also found that signicantly fewer vascularstructures existed at implant sites compared to
periodontal tissues.
Peri-Implantitis
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The difference in collagen ber direction (parallel to the
implant surface and perpendicular to tooth surface) and
amount of vascular structure may explain the faster
pattern of tissue destruction in peri-implant tissues thanperiodontal tissues.
Peri-Implantitis
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Literature has shown that peri-implantitis is similar in
nature to periodontitis in that the microbiota of peri-
implantitis resemble the microbiota of periodontitis;
however, there has been no evidence that peri-implantitisinduces crestal bone loss during healing and the rst
year of function at a faster rate than following years.
Peri-Implantitis
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Early crestal bone loss may result in an environment that
is favorable for anaerobic bacterialgrowth, thus possibly
contributing to more bone destruction in following years.
Nonetheless, in the majority of implants the bone loss isdramatically reduced after the rst year of prosthesis
loading. Therefore, it may not be justied that peri-
implantitis is the main causative factor for early implant
bone loss.
Peri-Implantitis
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Many implant systems have an abutments used with
conventional implant types which are flush with the
implant shoulder in the contact zone. This results in the
formation of microcracks between the implant and theabutment.
Microgap and The platform-switching concept
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Numerous studies have shown that bacterial
contamination of the gap between the implant and the
abutment adverselyaffects the stability of the periimplant
tissue. If above-average axial forces are exerted on the
implant, a pumpingeffect may ensue (depending on the
positive internal / external connection at the interface)
that may then result in a flow of bacteria from the gap,
provoking the formation of inflammatory connective
tissue in the region of the implant neck.
Hermann et al. J Periodontol. 2001
Todescan et al. Int J Oral Maxillofac Implants. 2002
Dibart et al. J Oral MaxillofacSurgery. 2005
Microgap and The platform-switching concept
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Berglundh et al. and Lindhe et al. also evaluated the
microgap of the Brnemark 2-stage implant and found
inamed connective tissue existed 0.5 mm above andbelow the abutment-implant connection, which resulted
in 0.5 mm bone loss within 2 weeks after the abutment
was connected to the implant.
Lindhe et al. Clin Oral Implant Res1992;3:9-16.
Microgap and The platform-switching concept
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Ericsson et al. coined the term distance-sleeve-associated infiltrated connective tissue to describe this
phenomenon. They interpreted this to be a biologicalprotective mechanism against the bacteria residing in themicrocrack, explaining the plaque independent bone lossof approximately 1 mm during the first year. This boneloss may result in a reduction of the marginal bone levelin both the vertical and the horizontaldimensions.
Ericsson et al. J Clin Periodontol. 1995
Microgap and The platform-switching concept
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If the microcrack is located close to the bone, thecreation of the biologic width will occur at the expense ofthe bone.
The platform switching effect was first observed in themid-1980s. At the time, larger-diameter implants wereoften restored with narrower abutments (AnkylosDensply, Friadent, Germany; Astra-Zeneca, Sweden;Bicon, Boston), as congruent abutments were often still
unavailable. As it later turned out, this was a remarkablecoincidence.
Lazzara RJ, PorterSS. Int J Periodontics Restorative Dent. 2006
Microgap and The platform-switching concept
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platform-switching concept requires that this microcrack
be placed away from the implant shoulder and closer
toward the axis in order to increase the distance of this
microcrack from the bone as a protective measure.
Microgap and The platform-switching concept
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The clinical term biologic width denotes the dimensions
of periodontal and periimplant soft-tissue structures such
as the gingival sulcus, the junctional epithelium, and the
supracrestal connective tissues.
Biologic width
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According to measurements conducted byGargiulo et al,
the average biologic width (from the base of the sulcus to
the alveolar bone margin) is 2.04 mm, of which 0.97 mmis epithelial attachment and1.07 mm is connective tissue
attachment. These dimensions, however, are in no way
static but subject to interindividual variation (from tooth to
tooth and from patient to patient) and will also vary
according to gingival type and implant concepts.
Gargiulo et al. J Periodontol.1961Cohen DW. Biologic width. Washington,DC. Presented at Walter ReedArmy Medical Center; 1962.
Biologic width
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Biologic width
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Numerous studies have shown that bone resorption
around the implant neckdoes not startuntil the implant is
uncovered and exposed to the oral cavity. This invariablyleads to bacterial contamination of the gap between the
implant and the superstructure. Bone remodeling will
progress until the biologic width has been created and
stabilized.
Quirynen M, Van Steenberghe D. Clin Oral Implants Res. 1994
Quirynen et al. Clin Oral Implants Res. 1994
Ericsson et al. J Clin Periodontol. 1995Persson et al. Clin Oral Im lants Res. 1996.
Biologic width
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This width progress not only apically, along the vertical
axis, but according to studies conducted by Tarnow et al,
there is also a horizontal componentamounting to 11.5mm. This is the reason to maintain a minimum distance
of 3 mm between 2 implants and platform switching in
the esthetic reconstruction zone in order to obtain intact
papillae and stable inter-implant bone.
Tarnow et al. J Periodontol. 2000
Tarnow et al.. J Periodontol. 1992Tarnow et al. J Periodontol. 2003
Biologic width
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Biologic width
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This width progress not only apically, along the vertical
axis, but according to studies conducted by Tarnow et al,
there is also a horizontal componentamounting to 11.5mm. This is the reason to maintain a minimum distance
of 3 mm between 2 implants and platform switching in
the esthetic reconstruction zone in order to obtain intact
papillae and stable inter-implant bone.
Biologic width
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bone volume/bone qualityMisch CE. Contemporary Implant
Dentistry. 2nd ed. Mosby; 1999
Summary and additional parameters on the
functional and esthetic long-term results
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Mucosal quality: type/thicknessKois JC. Compend Contin Educ Dent. 2001
Kois JC. JEsthet Dent. 1994;6:3-9.
Summary and additional parameters on the
functional and esthetic long-term results
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Condition of the adjacent teethPalacci P. Esthetic Implant Dentistry.
Quintessence; 2001.
Summary and additional parameters on the
functional and esthetic long-term results
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Distances to the adjacent teethTarnow et al. J Periodontol. 2000
Tarnow et al.. J Periodontol. 1992
Tarnow et al. J Periodontol. 2003
Summary and additional parameters on the
functional and esthetic long-term results
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Biologic width and the platform switchingconcept
Nentwig J Oral Implantol. 2004
Nentwig ckenversorgungen mit dem NMSystem. 1992
Blake A. WhatEveryEngineerShould Know about ThreadedFasteners Materials and Design.
New York, NY: Lawrence Livermore Laboratories, Marcel Dekker, Inc; 1986.
Driskell DriskellBioengineering; 1985.
Summary and additional parameters on the
functional and esthetic long-term results
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Implant design: macro-/micro-/nanoleveldesign and implant dimensions
Davies JE. Int J Prosthodont. 1998
Summary and additional parameters on the
functional and esthetic long-term results
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Abutment design: macro-/micro-/nanolevelDaftaryF. Int J DentSymp. 1995
Summary and additional parameters on the
functional and esthetic long-term results
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Augmentation procedures: type/materials/membranes
Buser et al. Int J Oral Maxillofac Implants 1995
Summary and additional parameters on the
functional and esthetic long-term results
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Surgical procedure: soft-tissue
management/ton of insertionBranemark et al. Scand J Plast ReconstrSurg. 1969
Adell R et al. Int J Oral MaxillofacSurgery. 1986
Cochran et al. J Periodontol. 1997
Summary and additional parameters on the
functional and esthetic long-term results
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implant insertion depth
time of loading/time of restoration
Summary and additional parameters on the
functional and esthetic long-term results
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Prosthetic procedure: frequency of
secondary-component replacementAbrahamsson J Clin Periodontol.1997
Summary and additional parameters on the
functional and esthetic long-term results
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Suturing techniques: materials
Summary and additional parameters on the
functional and esthetic long-term results
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Provisional restorations: abutmentmaterials/abutment shapes; crown
materials/crown shapes
Summary and additional parameters on the
functional and esthetic long-term results
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Definitive restorations: abutment
materials/abutment shapes; crown
materials/crown shapes
Summary and additional parameters on the
functional and esthetic long-term results
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Patient compliance: oral hygiene/
smoking/nutrition/recall intervals
Summary and additional parameters on the
functional and esthetic long-term results
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Thank you