An Implant With an Acid-etched Fixture Surface and Internal-hex Collar May Achieve Greater Osseointegration.

Brånemark System® dental implant osseointegration was introduced clinically in 1965 as a novel approach to the replacement of missing teeth. Although this implant's traditional machined screw-shaped surface had excellent, well-documented short- and long-term osseointegration success, newer implant designs were introduced that could enhance biological fusion of the implant to jaw bones, allowing more rapid restoration and function. It was also claimed that such implants could lead to less bone loss with function. One such implant, Screw-Vent®, had a macrostructure very similar to that of the Brånemark implant, except that it's fixture surface was acid-etched which could enhance biological osseointegration. It also had a longer narrower smooth internal-hex interlocking flat collar that could better resist occlusal forces, leading to even less bone loss according to the manufacturer. However, no well-controlled clinical studies existed in 1990 that supported these claims. This study was undertaken, therefore, to first compare the Brånemark implant with another implant, Swede-Vent®, a copy of the Brånemark implant except for its fixture surface that was identically acid-etched as that of Screw-Vent by the same manufacturer. The effect on bone healing could then be compared between Brånemark's machined and Swede-Vent's acid-etched surfaces in the short- and long-terms. Our hypothesis was that the microtextured Swede-Vent fixture would lead to greater bone preservation. Since Screw-Vent's fixture surface was identically acid-etched as that of Swede-Vent by the same manufacturer, we could then evaluate the effect on bone healing of Screw-Vent's collar and the shorter wider machined smooth external-hex flat collar of Swede-Vent (identical to that of Brånemark). All three 2-part platform-matched parallel-wall implants were made of commercially pure titanium, had a very similar fixture macro-design, were approved by the Food and Drug Administration (USA) and Health and Welfare Canada, and were commercially available in North America. Brånemark is still available, but with an oxidized microtextured fixture surface and a shortened machined smooth external-hex flat collar. Screw-Vent is still available with its microtextured fixture surface, but its machined smooth internal-hex flat collar has also been substantially shortened. Swede-Vent is no longer available.