Does addition of a novel antimicrobial agent chitosan into dental resin composites make the difference ? An in-vitro study

Objectives: To assess antibacterial activity of flowable and universal resin based composites (RBCs) containing different weight percent’s of chitosan (CS) (0, 0.25, 0.5 and 1% ) against cariogenic bacteria.
Methods: The direct contact test (DCT) was used to investigate antibacterial activity. Streptococcus mutans (ATCC# 25175) was inoculated on mitis salivarius (MS) agar and incubated at 37 ⁰C for 48 hours in 5 % CO₂ Incubator. The bacteria grown on agar were transferred to brain heart infusion (BHI) broth and incubated overnight. That broth was cetrifuged to make bacterial suspensions in phosphate buffer saline and its turbidity was adjusted to 0.5 McFarland standard. Five disc shaped specimens (5 mm × 2mm) of each universal (Filtek Z350 XT 3M ESPE) and flowable RBCs (Filtek Z350 3M ESPE­) were prepared, disinfected and fit into bottom of 1.5 ml sterile eppendorf tube. Then 10 µl of bacterial suspension was placed onto specimen followed by 300 µl of BHI broth and incubated for 48 hours. Then the same BHI broth was tenfold serially diluted and inoculated onto MS agar for colony forming unit count using Miles and Misra technique.
Results: Colony forming unit count of streptococcus mutans was comparable among the experimental and control RBCs.
Conclusions: Within the limitations of current study it may be concluded that addition of upto 1 % CS w/w into RBCs have no effect on its antibacterial activity against streptococcus mutans.