Biomedical Engineering Reference
In-Depth Information
acid-etched surface. Some authors have correlated the initial events in bone formation adjacent to
surface with the long-term tissue response to these materials in humans
[70,71]
.
By mimicking the chemical composition of natural bone, HA and CaP coatings on Ti greatly
enhance osseointegration. As shown in
Figure 16.6
, a greater direct bone apposition was observed
on CaP coated than on bare Ti implants. During the bone healing process, calcium and phosphate
ions are released from the CaP coating in the periimplant region and saturate body fluids to precipi-
tate a biological apatite, which serves as a substrate for osteoblastic cells producing bone tissue.
Several authors have shown the benefit of using CaP-coated titanium implants for improving the
osseointegration
[72,73]
. In particular, Le Guehennec et al.
[21]
have studied the osseointegration
of four implant surfaces in the femoral epiphyses of rabbits after 2 and 8 weeks of healing. In this
study, the bone-implant contact and bone growth inside the chambers were compared for four dif-
ferent implant surfaces and it was shown that biomimetic coating method may enhance the bone
apposition onto titanium. In order to prevent coating delamination and implant loosening, the CaP
coating should dissolve or degrade under osteoclastic activity at a similar rate than bone apposition.
The final result should be a direct bone-implant coating without the presence of fibrous tissue.
Another advantage of these CaP coatings is related to their preparation by biomimetic methods at
physiological temperature and pH from simulated body fluids. CaP crystals have characteristics
that resemble bone mineral in terms of size and composition. Furthermore, it is possible to incorpo-
rate biologically active drugs such as antibiotics or growth factors during the precipitation of CaP
coatings on Ti implants
[74]
. These molecules could be locally and gradually released in the peri-
implant region for either preventing bacterial infections or stimulating bone growth.
16.6
Conclusions
Many reports have shown that nanometer-controlled surfaces have a great effect on early events
such as the adsorption of proteins, blood clot formation, and cell behaviors occurring upon implan-
tation of dental implants. These early events have an effective impact on the migration, adhesion,
and differentiation of MSCs. Nanostructured surfaces may control the differentiation pathways into
specific lineages and ultimately direct the nature of periimplant tissues. Despite an active research
in dental implants, the ideal surface for predictive tissue integration remains a challenge.
Acknowledgments
The authors are grateful to Jean-Charles Ricquier for contribution in figures preparation. We acknowledge the
pharmaceutical company SERVIER for allowing us to use some drawings taken from their Web site.
References
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J. Roz
ยด
, S. Babu, A. Saffarzadeh, M. Gayet-Delacroix, A. Hoornaert, P. Layrolle, Correlating implant
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