AN IN-VIVO STUDY OF THE INFLUENCE OF THE SURFACE-ROUGHNESS OF IMPLANTS ON THE MICROBIOLOGY OF SUPRAGINGIVAL AND SUBGINGIVAL PLAQUE

In nine patients with fixed prostheses supported by endosseous titaniu m implants, 2 titanium abutments (transmucosal part of the implant) we re replaced by either an unused standard abutment or a roughened titan ium abutment. After 3 months of habitual oral hygiene, plaque samples were taken for differential phase-contrast microscopy, DNA probe analy sis, and culturing. Supragingivally, rough abutments harbored signific antly fewer coccoid micro-organisms (64 us. 81%), which is indicative of a more mature plaque. Subgingivally, the observations depended on t he sampling procedure. For plaque collected with paper points, only mi nor qualitative and quantitative differences between both substrata co uld be registered. However, when the microbiota adhering to the abutme nt were considered, rough surfaces harbored 25 times more bacteria, wi th a slightly lower density of coccoid organisms. The presence and den sity of periodontal pathogens subgingivally were, however, more relate d to the patient's dental status than to the surface characteristics o f the abutments. These results justify the search for optimal surface smoothness for all intra-oral and intra-sulcular hard surfaces for red uction of bacterial colonization and of periodontal pathogens.