[Antibacterial effect of self-etching adhesive systems on Streptococcus mutans]

Area of Science:

• Dental Materials Science
• Microbiology
• Cariology

Background:

• Streptococcus mutans (S. mutans) is a primary etiological agent in dental caries.
• Self-etching adhesive systems are widely used in dental restorations.
• Investigating the antibacterial properties of dental adhesives is crucial for preventing secondary caries.

Purpose of the Study:

• To evaluate the in vitro antibacterial efficacy of different self-etching adhesive systems against S. mutans.
• To compare the antibacterial effects of adhesive primers and their corresponding adhesives.
• To determine the influence of light-cured polymerization on the antibacterial activity of these systems.

Main Methods:

• Six reagents were tested: Clearfil™ SE Bond primer (SP), Clearfil™ SE Bond adhesive (SA), Clearfil™ Protect Bond primer (PP) with MDPB, Clearfil™ Protect Bond adhesive (PA), chlorhexidine acetate (CHX), and phosphate buffer solution (PBS).
• Antibacterial activity was assessed by colony-forming units (CFU) counts, inhibition zone measurements, and live/dead bacteria ratio using confocal laser scanning microscopy (CLSM) on dentin with artificial caries.
• Reagents were tested before and after light-cured polymerization.

Main Results:

• Both SP and PP exhibited significant antibacterial effects against free S. mutans, surpassing PA, SA, and CHX.
• SP and PP, along with CHX, demonstrated inhibition zones and reduced the live/dead bacteria ratio on dentin.
• Adhesives (SA, PA) showed limited antibacterial effect, and all tested self-etching adhesive systems lost their antibacterial activity after light-cured polymerization.

Conclusions:

• The primers of Clearfil™ SE Bond and Clearfil™ Protect Bond possess significant antibacterial properties against both free and attached S. mutans.
• The antibacterial effect of the adhesive component is limited to the pre-polymerization stage.
• Self-etching adhesive systems, once light-cured, do not retain significant antibacterial activity against S. mutans.