Twenty Year Survey of Bacterial Susceptibility to Triclosan

Objective: Triclosan (TCN) is a broad-spectrum antimicrobial agent which is effective against oral biofilm bacteria. Numerous clinical studies have demonstrated the efficacy of triclosan-containing dentifrices on oral health including reduced supragingival plaque, gingivitis and oral malodor. This study evaluated long-term bacterial susceptibility to TCN on human supragingival plaque samples collected from adults over a period of 20 years.  

Materials and Methods: There were 13 separate evaluations over 20 years, with data from 155 assessments presented in this report. Supragingival dental plaque was obtained from adults who had not received dental treatment or antimicrobial therapy in the previous 30 days. Supragingival plaque was collected from the entire dentition at each evaluation and aliquots of the subject's pooled plaque suspension were distributed onto agar media containing 0, 7.5 or 25 µg/ml TCN.  Following incubation at 37^oC for 5-7 days, the number of colony forming units (CFU's) was enumerated.

Results: Without triclosan, large numbers of CFU's were cultivable from all supragingival plaque samples. With triclosan, the number of supragingival plaque bacteria cultivable from the same samples was significantly reduced (p<0.001).  On average, microbial inhibition on 7.5 µg/ml TCN-containing media ranged from 99.1-99.7% and on 25 µg/ml TCN-containing media ranged from 99.9-100%, respectively. For each TCN concentration, regression analyses compared antimicrobial activity at the initial evaluation to the 20-year evaluation. There was no change in antimicrobial susceptibility (p = 0.159 and 0.299 for the 7.5 and 25 µg/ml TCN, respectively) over time discernible by regression analyses.  

Conclusions: This study demonstrates significant in vitro antibacterial activity for triclosan against cultivable supragingival plaque bacteria in samples collected over 20 years.  Changes in antimicrobial susceptibility over this period of time were not detected in any of the samples including those from subject's using triclosan-containing dentifrice.