Western Society of Periodontics

Clinical Studies

Volume Number 3, 1995

Antimicrobial susceptibility of periodontopathic bacteria associated with failing implants

The aim of this study was to examine subgingival microflora associated with unsuccessful implants and to determine their susceptibility to the most commonly used antibiotics in periodontal therapy. The investigators took 13 partially edentulous patients for a total of 19 failing implants. Their criteria of failing was an implant that exhibited three or more of the following: deep pockets, bleeding suppuration, attachment loss of 2 mm every year, mobility, and pert-implant radiolucency. They looked at clinical parameters and did microbiological testing. Their results showed that the mean GI was 2.3; mean PI, 1.7; and mean pocket depth, 6.35. Moreover, 80% of the implants exhibited mobility and those that had no mobility were part of a bridge. The prevalent periodontal pathogens isolated were Porphyromonas gingivalis, 6.5 %; Prevotella intermedia, 8.5 %; and Fusobacterium nucleatum, 10.4%. Actinobacillus actinomycetemcomitans and Eickenella corrodens were not detected. The composition of bacterial morphotypes was as follows: spirochetes, 5.6%; motile rods, 12.3%; rods, 31.7%; cocci 42.1%; and fusiform, 8.3%. There was 50% of anaerobic Gm(-) rods. The antibiotic susceptibility showed that for P.g., Pen G and amoxicillin were the most effective. Tetracycline inhibited 90% of isolates at high concentration (12 ug/ml), and erythromycin and metronidazole were not able to inhibit 90% of P.g. For P.i., Pen G and amoxicillin were the most potent; P.i. was resistant to erythromycin and was susceptible to high concentrations of metronidazole. The authors recommend that every partially edentulous patient scheduled for implant undergo a complete periodontal evaluation followed by, if necessary, appropriate antimicrobial therapy. [M.C.R.]