Bacterial leakage along the implant–abutment interface of premachined or cast components

In recent clinical studies, contamination of the inner parts of dental implants through bacterial penetration along the implant components has been observed. The aim of the present in-vitro study was to investigate leakage of Fusobacterium nucleatum through the interface between implants and premachined or cast abutments. Both premachined (n = 10) and cast (n = 10) implant–abutment assemblies were inoculated with 3.0 μL of microbial inoculum. The assemblies were completely immersed in 5.0 mL of tryptic soy broth culture medium to observe leakage at the implant–abutment interface after 14 days of anaerobic incubation. Bacterial growth in the medium, indicative of microbial leakage, was found only in 1 out of 9 samples (11.1%) in each group. Both premachined and cast abutments connected to external hexagonal implants provide low percentages of bacterial leakage through the interface in in vitro unloaded conditions if the manufacturer's instructions and casting procedures are properly followed.