In vitro Cariostatic effects of cinnamon water extract on nicotine-induced Streptococcus mutans biofilm

Dental caries is one of the most prevalent chronic oral diseases worldwide. Dental caries is mainly associated with Streptococcus mutans and the Lactobacillus species. A specific relationship was found between nicotine and S. mutans growth as the presence of nicotine increased S. mutans biofilm formation. Nicotine is able to increase the number of S. mutans and extracellular polysaccharide (EPS) synthesis. Among the widely used herbs and spices is cinnamon which demonstrated a strong antibacterial activity against a wide variety of bacteria including S. mutans and showed the ability to inhibit S. mutans biofilm formation. Cinnamon essential oil, obtained from the leaves of C. zeylanicum, has been demonstrated to be effective against S. mutans and Lactobacillus acidophilus, which are partially responsible for dental plaque formation and caries development. The aim of this study was to identify the effects of nicotine exposure on the inhibitory effects of cinnamon water extract on S. mutans biofilm formation.

A 24-h culture of S. mutans UA159 in microtiter plates was treated with varying nicotine concentrations (0-32 mg/ml) in Tryptic Soy broth supplemented with 1% sucrose (TSBS) with or without a standardized concentration (2.5 mg/ml) of cinnamon water extract. A spectrophotometer was used to determine total growth absorbance and planktonic growth. The microtiter plate wells were washed, fixed and stained with crystal violet dye and the absorbance measured to determine biofilm formation.

The presence of 2.5 mg/ml cinnamon water extract inhibits nicotine-induced S. mutans biofilm formation from 34 to 98% at different concentrations of nicotine (0-32 mg/ml).

The results demonstrated nicotine-induced S. mutans biofilm formation is decreased from 34 to 98% in the presence of 2.5 mg/ml cinnamon water extract. This provides further evidence about the biofilm inhibitory properties of cinnamon water extract and reconfirms the harmful effects of nicotine.