Scientific Abstracts

Compiled by Dr. Juan José Gersberg
1731 Billinghurst St. # 1º A (1425)
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Buenos Aires – Argentina

Buser D, Nydegger T, Hirt HP, Cochran DL, Nolte LP.
Int J Oral Maxillofac Implants. 1998 Sep-Oct;13(5):611-9.
Department of Oral Surgery, School of Dental Medicine, University of Berne, Switzerland.

The purpose of this study was to compare side-by-side two different titanium screw-type implants in the maxillae of miniature pigs. The test implants had a machined and acid-etched surface (Osseotite) whereas the control implants were sandblasted and acid-etched (SLA). After 4, 8, and 12 weeks of healing, removal torque testing was performed to evaluate the shear strength of the bone-implant interface for both implant types. The results demonstrated significant differences between both implant types (P < .01). Osseotite implants revealed mean removal torque values (RTV) of 62.5 Ncm at 4 weeks, 87.6 Ncm at 8 weeks, and 95.7 Ncm at 12 weeks of healing. In contrast, the SLA implants demonstrated mean RTV of 109.6 Ncm, 196.7 Ncm, and 186.8 Ncm at corresponding healing periods. The mean RTV for SLA implants was 75% to 125% higher than for Osseotite implants up to 3 months of healing.

Buser D, Nydegger T, Oxland T, Cochran DL, Schenk RK, Hirt HP, Snetivy D, Nolte LP.
J Biomed Mater Res. 1999 May;45(2):75-83.
Department of Oral Surgery, School of Dental Medicine, University of Berne, Freiburgstrasse 7, CH-3010 Berne, Switzerland.

The purpose of the present study was to evaluate the interface shear strength of unloaded titanium implants with a sandblasted and acid-etched (SLA) surface in the maxilla of miniature pigs. The two best documented surfaces in implant dentistry, the machined and the titanium plasma-sprayed (TPS) surfaces served as controls. After 4, 8, and 12 weeks of healing, removal torque testing was performed to evaluate the interface shear strength of each implant type. The results revealed statistically significant differences between the machined and the two rough titanium surfaces (p <.00001). The machined surface demonstrated mean removal torque values (RTV) between 0.13 and 0.26 Nm, whereas the RTV of the two rough surfaces ranged between 1.14 and 1.56 Nm. At 4 weeks of healing, the SLA implants yielded a higher mean RTV than the TPS implants (1.39 vs. 1. 14 Nm) without reaching statistical significance. At 8 and 12 weeks of healing, the two rough surfaces showed similar mean RTVs. The implant position also had a significant influence on removal torques for each implant type primarily owing to differences in density in the periimplant bone structure. It can be concluded that the interface shear strength of titanium implants is significantly influenced by their surface characteristics, since the machined titanium surface demonstrated significantly lower RTV in the maxilla of miniature pigs compared with the TPS and SLA surfaces.

Brunette DM, Chehroudi B.
J. Biomech Eng. 1999 Feb;121(1):49-57.
Department of Oral Biological and Medical Sciences, Faculty of Dentistry, University of British Columbia, Vancouver, Canada.

Surface properties, including topography and chemistry, are of prime importance in establishing the response of tissues to biomaterials. Microfabrication techniques have enabled the production of precisely controlled surface topographies that have been used as substrata for cells in culture and on devices implanted in vivo. This article reviews aspects of cell behavior involved in tissue response to implants with an emphasis on the effects of topography. Microfabricated grooved surfaces produce orientation and directed locomotion of epithelial cells in vitro and can inhibit epithelial downgrowth on implants. The effects depend on the groove dimensions and they are modified by epithelial cell-cell interactions. Fibroblasts similarly exhibit contact guidance on grooved surfaces, but fibroblast shape in vitro differs markedly from that found in vivo. Surface topography is important in establishing tissue organization adjacent to implants, with smooth surfaces generally being associated with fibrous tissue encapsulation. Grooved topographies appear to have promise in reducing encapsulation in the short term, but additional studies employing three-dimensional reconstruction and diverse topographies are needed to understand better the process of connective-tissue organization adjacent to implants. Microfabricated surfaces can increase the frequency of mineralized bone-like tissue nodules adjacent to subcutaneously implanted surfaces in rats. Orientation of these nodules with grooves occurs both in culture and on implants. Detailed comparisons of cell behavior on micromachined substrata in vitro and in vivo are difficult because of the number and complexity of factors, such as population density and micromotion, that can differ between these conditions.