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 peri‐implant tissues at intentionally non‐submerged (1‐stage implants) and initially submerged and subsequently exposed implants (2‐stage implants). 5 beagle dogs, about 1‐year‐old, were used. 3 months after the extraction of the mandibular premolars, fixtures of the Astra Tech Implants Dental System®, the Brånemark System® and the Bonefit®‐ITI System were installed. In each mandibular quadrant, 1 fixture of each implant system was installed in a randomised order. The installation procedure followed the recommendations given in the manuals for each system. Thus, following installation, the bone crest coincided with the fixture margin of the Astra Tech Implants Dental System® and the Brånemark System®, whereas the border between the plasma sprayed and the machined surface of the Bonefit®‐ITI implant system was positioned at the level of the bone crest. Following a healing period of 3 months, abutment connection was carried out in the 2‐stage systems (the Astra Tech Implants Dental System® and the Brånemark system®). A 6‐month period of plaque control was initiated. The animals were sacrificed and biopsies representing each implant region dissected. The tissue samples were prepared for light microscopy and exposed to histometric and morphometric 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 systems studied, had similar dimensions and composition. The amount of lamellar bone contained in the peri‐implant region close to the fixture part 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 titanium implant seems to be of limited importance.