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 »  Home  »  Dental Implant 2  »  Experimental Study of Bone Response to a New Surface Treatment of Endosseous Titanium Implants
Experimental Study of Bone Response to a New Surface Treatment of Endosseous Titanium Implants
Introduction - Materials and methods.

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Antonio Sanz R., DDS
Periodontist, Adjunct Professor in Oral Implantology, and Director of the Postgrade in Oral Implantology, Odontology Faculty, University of Chile, Santiago, Chile.

Alejandro Oyarzun, DDS
Biochemical and Oral Biology Unit, Odontology Faculty, University of Chile, Santiago, Chile.

Daniel Farias, DDS, Ivan Diaz, DDS
Specialist in oral implantology, Odontology Faculty, Postgraduate School, University of Chile, Santiago, Chile.

There is a need to find ways of achieving better and more efficient osseointegration in poor bone qualities found in different jaw regions and to attempt to reduce the preload cicatrization period. Success in this area will make possible the placement of implants in sites (such as the posterior areas of the maxilla and the mandible) where it would be difficult or impossible to currently achieve sound osseointegration.
Much of the current research is aimed at finding ways to modify the macrostructure as well as the microstructure of implants. These efforts may include the use of materials that could modify tissue response. The goal of obtaining an implant made with a biomaterial that will allow precise control of the superficial structure, absorption of protein, cellular adhesion, growth, and bone activation is noteworthy.
Different surface treatment of implants to improve their microstructure has been the goal of much experimental and clinical research during the last few years. Studies have demonstrated that the application of hydroxyapatite coatings increases the hardness of the bone-implant interface. Long-term outcomes for implants coated with hydroxyapatite are still under discussion.
Another type of implant surface treatment involves increasing the superficial roughness. Scientific evidence accumulated over the last 10 years suggests that titanium implants with roughened surfaces achieve significantly improved anchorage in the bone than do implants with machined surfaces. The first attempt at increasing surface roughness was made almost two decades ago18 with the application of titanium plasma sprayed onto the surfaces of the implants. Results obtained with this surface have been very satisfactory, as studies have shown.
Other treatments designed to alter the surface morphology of implants include grit blasting with different sized particles of sand, glass, or aluminum oxide to create varying degrees of roughness and acid etching, which produces a uniformly rough texture over the entire implant surface. These techniques have also been used in combination with promising results.
Recently, a new surface treatment called resorbable blast media (RBM) has been developed for application to implants. RBM involves blasting the implant with coarsely ground calcium phosphate (particle size, 180mm 3 425 mm), which gives the implant a coarse surface without leaving any residues. The calcium phosphate is a resorbable material that is not permanently imbedded into the surface of the implant primarily because of the passivation method used. The purpose of this study was to observe the biocompatibility of the RBM surface, analyze bone response, and make a topographical examination of the microstructure.

MATERIALS AND METHODS.
Two one-year-old, white New Zealand rabbits weighing approximately 4 kg each received four commercially manufactured titanium implants (diameter, 4 mm; length, 10 mm) (Restore, Lifecore Biomedical, Chaska, MN) with surfaces treated with RBM. These implants were placed in the mid-face of each tibia (proximal metaphysis). The housing care and experimental protocol were in accordance with guidelines set by the University of Chile Institutional Animal Care and Use Committee. After a 16-week cicatrization period, the rabbits were killed. The implants and all surrounding bone tissue were recovered from the tibial area and fixed in 4% paraformaldehyde in 0.1 mol/L phosphate buffer (pH, 7.4) for seven days. Subsequently, the samples were dehydrated in ascending ethanols, including LR White hard grade resin (London Resin Co., Hants, UK).
For microscopic observation, cuttings were made with diamond discs to a thickness of 100 mm. Their preparation was completed by abrasion to a thickness of 8 to 10 mm based on a method described by Donath.21 The cuttings were stained with methylene blue Azur II– basic fuchsin to observe their histology and take photographs with an Axioscop microscope (Carl Zeiss Inc., Thornwood, NY) on Kodak ASA 100 film (Eastman Kodak, Rochester, NY).
The electron microscopy used to observe the characteristics of the microstructure of the RBM implants and to compare it with the surface of the machined implants was performed on a scanning electron microscope (DSM 940, Carl Zeiss Inc.). Observation of the sample was performed directly and without a gold bath because the implants reflect the ions of the scanning beam.