Strain driven fast osseointegration of implants.

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ssBioMed CentHead & Face Medicine
Open AcceShort report
Strain driven fast osseointegration of implants
Ulrich Joos†, Andre Büchter†, Hans-Peter Wiesmann† and Ulrich Meyer*
Address: Department of Cranio-Maxillofacial Surgery, University of Münster, Waldeyerstraße 30, D-48129 Münster, Germany
Email: Ulrich Joos - Joos@uni-muenster.de; Andre Büchter - buchtea@uni-muenster.de; Hans-Peter Wiesmann - wiesmap@uni-muenster.de;
Ulrich Meyer* - ulmeyer@uni-muenster.de
* Corresponding author †Equal contributors
Abstract
Background: Although the bone's capability of dental implant osseointegration has clinically been
utilised as early as in the Gallo-Roman population, the specific mechanisms for the emergence and
maintenance of peri-implant bone under functional load have not been identified. Here we show
that under immediate loading of specially designed dental implants with masticatory loads,
osseointegration is rapidly achieved.
Methods: We examined the bone reaction around non- and immediately loaded dental implants
inserted in the mandible of mature minipigs during the presently assumed time for
osseointegration. We used threaded conical titanium implants containing a titanium2+ oxide
surface, allowing direct bone contact after insertion. The external geometry was designed
according to finite element analysis: the calculation showed that physiological amplitudes of strain
(500–3,000 ustrain) generated through mastication were homogenously distributed in peri-implant
bone. The strain-energy density (SED) rate under assessment of a 1 Hz loading cycle was 150 Jm-
3 s-1, peak dislocations were lower then nm.
Results: Bone was in direct contact to the implant surface (bone/implant contact rate 90%) from
day one of implant insertion, as quantified by undecalcified histological sections. This effect was
substantiated by ultrastructural analysis of intimate osteoblast attachment and mature collagen
mineralisation at the titanium surface. We detected no loss in the intimate bone/implant bond
during the experimental period of either control or experimental animals, indicating that immediate
load had no adverse effect on bone structure in peri-implant bone.
Conclusion: In terms of clinical relevance, the load related bone reaction at the implant interface
may in combination with substrate effects be responsible for an immediate osseointegration state.
Findings
Although the bone's capability of dental implant
osseointegration has clinically been utilised as early as in
the Gallo-Roman population [1], the specific mechanisms
for the emergence and maintenance of peri-implant bone
dental implants with masticatory loads, osseointegration
is rapidly achieved. As the osseointegration state is much
faster reached than commonly assumed, osseointegration
is a strain dependant highly dynamic process.
Published: 01 September 2005
Head & Face Medicine 2005, 1:6 doi:10.1186/1746-160X-1-6
Received: 03 May 2005
Accepted: 01 September 2005
This article is available from: http://www.head-face-med.com/content/1/1/6
© 2005 Joos et al; licensee BioMed Central Ltd.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0),
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.Page 1 of 4
(page number not for citation purposes)
under functional load have not been identified. Here we
show that under immediate loading of specially designed
Osseointegration is defined as a direct and stable anchor-
age of an implant by the formation of bony tissue without

Head & Face Medicine 2005, 1:6 http://www.head-face-med.com/content/1/1/6
growth of fibrous tissue at the bone-implant interface [2].
A defining feature of osseointegration is that osteoblasts
and mineralized matrix contacts the implant surface even
when loads are applied. A common perception is that sev-
eral weeks must be given to achieve implant
osseointegration.
We have departed from this time related hypothesis by
proposing that only minimal time (for example few
hours, the time that is necessary for osteoblast adhesion
on artificial substrates [3]) is required for osseointegration
when the peri-implant tissue receives an optimal mechan-
ical environment. We examined the bone reaction around
non- and immediately loaded dental implants inserted in
the mandible of mature minipigs during the presently
assumed time for osseointegration (approved by the Ani-
mal Ethics Committee of the University of Münster under
the reference number G 90/99). We used threaded conical
titanium implants containing a titanium2+ oxide surface,
sis: the calculation showed that physiological amplitudes
of strain (500–3,000µstrain) generated through mastica-
tion were homogenously distributed in peri-implant bone
(Figure 1). The strain-energy density (SED) rate [4] under
assessment of a 1 Hz loading cycle was 150 Jm-3 s-1, peak
dislocations were lower then nm. Eigth male Göttinger
minipigs, 14 to 16 months of age with an average body
weight of 35 kg, were used in this study. At day 3, day 7
and 28 animals were sacrificed with an overdose of T61
given intravenously.
Bone was in direct contact to the implant surface (bone/
implant contact rate 90%) from day one of implant inser-
tion, as quantified by undecalcified histological sections
(Figure 2). This effect was substantiated by ultrastructural
analysis of intimate osteoblast attachment (Figure 3) and
mature collagen mineralisation at the titanium surface.
We detected no loss in the intimate bone/implant bond
during the experimental period of either control or exper-
imental animals, indicating that immediate load had no
adverse effect on bone structure in peri-implant bone (Fig-
ure 4).
Bone response on an implant surface depends on the reac-
tion of cells and matrix towards the material surface as
well as to the mechanical constraints in the vincinity of
the implant. The maintenance of bone and its adaptation
to external loads is based on a complex strain driven reg-
Biomechanics and biology of implant osseointegrationF gure 1
Biomechanics and biology of implant osseointegration.
Finite element model of strain distribution in peri-implant boneigur 2
Finite element model of strain distribution in peri-implant
bone. Bone strains do not exceed physiological values, bone
dislocations are between 0 and 50 nm.Page 2 of 4
(page number not for citation purposes)
allowing direct bone contact after insertion. The external
geometry was designed according to finite element analy-
ulatory process of cells and matrix components [5,6]. Out-
side-in mechanical tension exert direct effects on cell

Head & Face Medicine 2005, 1:6 http://www.head-face-med.com/content/1/1/6
behaviour by activating biochemical signalling pathways
and regulating gene expression through focal adhesions
[7]. Frost [8] provided a paradigm for the mechanical con-
trol of cellular bone modelling, the process whereby bone
is laid down onto surfaces without necessarily preceded
the strain related bone modelling process is also regula-
tive for bone tissue formation in healing tissue [9].
Using an atomic force microscope, a molecular mechanis-
tic origin for the remarkably fast recovery of toughness
after bone deformation was found, when deformation of
less then 50 nm at the surface of multivalent ions (as in
the case of Ti-oxide) is present [10]. Our understanding of
osseointegration theorises that bone strengthening
responds to a highly specific mechanical design. Even if
long-term osseointegrated implants show what seems to
be similar bone tissue reactions, osseointegration might
be able to be achieved more rapidly than otherwise
observed. Screw type titanium implants, as used in dental
implantology, have in contrast to orthopaedic implants
not only been convincingly shown very good clinical
long-term success [11], but were also successful when load
transfer is immediately present as seen in traumatology.
In terms of clinical relevance, the load related bone
reaction at the implant interface may in combination with
substrate effects be responsible for an immediate
osseointegration state.
Competing interests
The author(s) declare that they have no competing
interests.
Authors' contributions
UJ designed the study, searched the database, extracted
the data. AB helped with the study design and analysis.
HPW had analysis the histological probes and UJ devel-
oped the implant design.
References
1. Crubezy E, Murail P, Girard L, Bernadou JP: False teeth of the
Roman world. Nature 1998, 391:29.
2. Branemark PI, Adell R, Breine U, Hansson BO, Lindstrom J, Ohlsson
A: Intra-osseous anchorage of dental prostheses. I. Experi-
mental studies. Scand J Plast Reconstr Surg 1969, 3:81-100.
3. Okumura A, Goto M, Goto T, Yoshinari M, Masuko S, Katsuki T, Tan-
aka T: Substrate affects the initial attachment and subse-
quent behavior of human osteoblastic cells (Saos-2).
Biomaterials 2001, 22:2263-2271.
4. Turner CH, Takano Y, Owan I: Aging changes mechanical load-
ing thresholds for bone formation in rats. J Bone Miner Res
1995, 10:1544-1549.
5. Rubin CT, Pratt GW Jr, Porter AL, Lanyon LE, Poss R: Ultrasonic
measurement of immobilization-induced osteopenia: an
experimental study in sheep. Calcif Tissue Int 1988, 42:309-312.
6. Huiskes R, Ruimerman R, van Lenthe GH, Janssen JD: Effects of
mechanical forces on maintenance and adaptation of form in
trabecular bone. Nature 2000, 405:704-706.
7. Chicurel ME, Singer RH, Meyer CJ, Ingber DE: Integrin binding and
mechanical tension induce movement of mRNA and ribos-
omes to focal adhesions. Nature 1998, 392:730-733.
8. Frost HM: The mechanostat: a proposed pathogenic mecha-
nism of osteoporoses and the bone mass effects of mechani-
cal and nonmechanical agents. Bone Miner 1987, 2:73-85.
9. Frost HM: A brief review for orthopaedic surgeons: Fatigue
damage (microdamage in bone (its determinants and clinical
implications). J Orthop Sci 1998, 3:272-281.
Histological picture of implant containing bone one day after inserti nFigure 3
Histological picture of implant containing bone one day after
insertion. Direct contact between bone and the implant is
visible in the scanning electron micrographs.
Immuno-scanning electron microscopy of intimate osteoblast adhesion at the titanium surfa e by fibr nectin mediated focal adhesions (fr ct red specimens, one day under loading)Figure 4
Immuno-scanning electron microscopy of intimate osteoblast
adhesion at the titanium surface by fibronectin mediated
focal adhesions (fractured specimens, one day under loading).Page 3 of 4
(page number not for citation purposes)
by resorption. Recent investigations have indicated that

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10. Thompson JB, Kindt JH, Drake B, Hansma HG, Morse DE, Hansma
PK: Bone indentation recovery time correlates with bond
reforming time. Nature 2001, 13:773-776.
11. Albrektsson T, Johansson : Osteoinduction, osteoconduction
and osseointegration. C Eur Spine J 2001, 10:96-101.yours — you keep the copyright
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