DNA probe indentification of bacteria colonizing internal surfaces of the implant-abutment interface: A preliminary study

Background: Currently, there is limited knowledge concerning the specific genus and species of bacteria that may colonize internal surfaces of the implant-abutment interface (IAI) of two-stage dental implants. The purpose of this study was to use DNA probe analysis to identify those periodontopathic bacteria that may inhabit the internal surfaces and heating abutment screw-threads of the IAI of dental implants in situ. Methods: Following osseointegration, bacterial samples for DNA probe analysis were obtained from 54 two-stage hydroxyapatite plasma spray-coated implants in 32 patients. Using sterile paper points, samples were obtained from the IAI of 43 implants and the screw-threads of heating abutments in the other 11 implants. DNA probes were available to detect the following microbes: Actinobacillus actinomycetemcomitans, Tannerella forsythensis, Campylobacter rectus, Eikenella corrodens, Fusobacterium nucleatum, Porphyromonas gingivalis, Prevotella intermedia, and Treponema denticola. Results: All samples taken from healing abutment screw-threads were negative for all target microbes. The aggregate percentage of positive results for each target microbe for samples from internal surfaces of the IAI were: 41.9%, A. actinomycetemcomitans; 60.5%, T. forsythensis; 44.2%, C. rectus; 60.5%, E. corrodens; 48.8%, F. nucleatum; 46.5%, P. gingivalis; 55.8%, P. intermedia; and 51.2%, T. denticola. In addition, no significant differences were noted between colonization of individual microbial species when comparing anterior to posterior and maxillary to mandibular implant sites. Conclusions: Moderate to high levels of eight different periodontopathic microbes inhabiting the internal surfaces of the IAI of 43 two-stage implants in partially edentulous patients were identified by DNA probe analysis. The microbes colonized these surfaces within 25 days following the second stage surgery and placement of the healing abutment. In contrast, all samples obtained from screw-threads of 11 healing abutments were DNA probe negative. These findings appear to support those of other investigations demonstrating the translocation of bacteria from residual dentition to implants.