Colonization of osseointegrated titanium implants in edentulous patients. Early results

The purpose of this investigation was to study the colonization of newly set implants in edentates and to monitor the development of the predominant subgingival microbiota during the first 6 months of wearing the implants in vivo. Microbial samples of the receiving sites were taken one day prior to the insertion with sterile cotton pellets. After implantation, one site per implant was sampled with sterile paperpoints once every week for 2 months, and thereafter in monthly intervals up to 180 days. A total of 114 samples of 9 sites from 5 patients were evaluated using the darkfield microscope and cultured anaerobically on non‐selective and selective media. Representative colonies were identified by atmospheric growth capabilities, Gram‐staining characteristics and biochemical tests. Small amounts of bacteria were collected from the preoperative swabs. On an average 86% of the microorganisms were identified morphologically as coccoid cells and over 80% of the cultivated bacteria were Gram‐positive facultative cocci. After implantation, no significant changes in these proportions could be observed in all but one site. In this particular site a steady decrease of coccoid cells and a simultaneous increase of rods was observed after 21 days. Actinomyces odontolyticus was first detected at Day 21 and Fusobacterium spp. were first detected at Day 42; at Day 120 small spirochetes were found for the first time, pus formation was noted clinically and a pocket probing depth of 6 mm was recorded. None of the other sites showed probing depths of over 3 mm or pus formation. In these clinically successful sites spirochetes were never seen. Fusobacteria could only be detected in 13 of 104 samples. Black‐pigmenting Bacteroides were found infrequently and no trend of increase was apparent in any site over the 180 days of monitoring.