THE PERI-IMPLANT HARD AND SOFT-TISSUES AT DIFFERENT IMPLANT SYSTEMS -A COMPARATIVE-STUDY IN THE DOG

The aim of the present experiment was to study the marginal periimplan t tissues at intentionally non-submerged(1-stage implants) and initial ly submerged and subsequently exposed implants (2-stage implants). 5 b eagle dogs, about 1-year-old, were used. 3 months after the extraction of the mandibular premolars, fixtures of the Astra Tech Implants Dent al System(R), the Branemark System(R) and the Bonefit(R)-ITI System we re installed. In each mandibular quadrant, 1 fixture of each implant s ystem was installed in a randomised order. The installation procedure followed the recommendations given in the manuals for each system. Thu s, following installation, the bone crest coincided with the fixture m argin of the Astra Tech Implants Dental System(R) and the Branemark Sy stem(R), whereas the border between the plasma sprayed and the machine d surface of the Bonefit(R)-ITI implant system was positioned at the l evel of the bone crest. Following a healing period of 3 months, abutme nt connection was carried out in the 2-stage systems (the Astra Tech I mplants Dental System(R) and the Branemark system(R)). A 6-month perio d of plaque control was initiated. The animals were sacrificed and bio psies representing each implant region dissected. The tissue samples w ere prepared for light microscopy and exposed to histometric and morph ometric measurements. The mucosal barrier which formed to the titanium surface following 1-stage and 2-stage implant installations comprised an epithelial and a connective tissue component, which for the 3 syst ems studied, had similar dimensions and composition. The amount of lam ellar bone contained in the periimplant region close to the fixture pa rt of the 3-implant systems was almost identical. It is suggested that correctly performed implant installation may ensure proper conditions for both soft and hard tissue healing, and that the geometry of the t itanium implant seems to be of limited importance.