Soft tissue reactions to plaque formation at implant abutments with different surface topography - An experimental study in dogs

Background: The mucosal attachment that forms to titanium implants, uncontaminated by bacterial plaque comprises, independent of the surface characteristics of the abutment, one barrier epithelium and one zone of connective tissue attachment. It was suggested that abutments with a rough surface may accumulate more plaque than abutments with a smooth surface and that such an enhanced rate of plaque build-up may favor the development of inflammatory lesions in the periimplant mucosa. Objectives: The aim of the present experiment was to study some reactions of the periimplant mucosa to plaque accumulation on implant abutments designed with either a rough or a smooth external surface. Material and Methods: In five beagle dogs, four fixtures were placed and submerged in the premolar region. In a second stage procedure performed after 3 months, abutments with two different types of surface topography, one rough, acid-etched (OA) and one smooth, turned abutment (TA), were installed in a random order. After 6 months of undisturbed plaque formation, the animals were sacrificed and biopsies obtained. Tissue samples were prepared for light microscopy and exposed to histometric and morphometric measurements. Results: Six months of plaque accumulation resulted in the establishment of an inflammatory lesion (pl-ICT) in the connective tissue of the periimplant mucosa, the location, size and composition of which did not differ between OA and TA sites. In addition, most OA and TA sites harbored a second inflammatory cell infiltrate in the tissue lateral to the abutment/fixture junction (ab-ICT). While pl-ICT was dominated by plasma cells and lymphocytes, ab-ICT contained a comparatively large number of polymorphonuclear leukocytes. Conclusion: The different surface characteristics of abutment made of c.p. titanium failed to influence plaque formation and the establishment of inflammatory cell lesions in the periimplant mucosa.