Antibacterial activity of fifth-generation dentin bonding systems

Past concepts that the pulp does not become infected until an actual cariou s exposure takes place have been challenged. The antibacterial effects of t he dentin bonding systems Single Bond, Prime&Bond NT, and Excite were evalu ated using the bacteria Streptococcus mutans ATCC 25175, Streptococcus inte rmedius, Lactobacillus acidophilus, Prevotella oris, Prevotella bivia, Prev otella denticola, Porphyromonas gingivalis, Porphyromonas endodontalis, and Clostridium ramosum with a disk diffusion method. Chlorhexidine (0.2%) was used as a positive control. After incubation zones of inhibited bacterial growth were measured. Prime&Bond NT showed growth inhibition for all bacter ial strains. Lactobacillus acidophilus and Streptococcus mutans were remark ably resistant to Single Bond, whereas EX produced no inhibitory effect on Porphyromonas endodontalis, although the adhesive produced the maximum halo inhibition to Streptococcus mutans (15 +/- 1 mm), showing an antibacterial effect closest to chlorhexidine. The variety of results obtained in this s tudy suggest that antibacterial properties of current dentin adhesives may depend on components that are originally incorporated to promote adhesion.