Inhibitory effects of citrus lemon oil and limonene on Streptococcus sobrinus - Induced dental caries in rats.

Objective: This study aimed to examine and compare the anti-caries effects of citrus lemon oil (CLO) and limonene in rats.

Methods: The minimal inhibitory concentrations of CLO and limonene were measured using the disk diffusion method. The rats were infected with Streptococcus sobrinus and assigned into four groups: (1) Chlorhexidine, (2) CLO, (3) limonene, and (4) distilled water (HO). The total cultivable microbiota and Streptococcus sobrinus in the mouth of the rats were counted, and the caries lesions were measured by Keyes' scoring and DIAGNOdent examination.

Results: The minimal inhibitory concentrations of CLO and limonene against Streptococcus sobrinus were 4.50 and 21.00 mg/mL, respectively. The chlorhexidine group had the lowest total microbiota counts (p < 0.05), while there were no significant differences among the CLO, limonene and HO groups (p > 0.05). The proliferation of Streptococcus sobrinus was remarkably inhibited by chlorhexidine, limonene and CLO (p < 0.05). The Keyes' scoring and DIAGNOdent results indicated that the caries lesions were reduced in the CLO and limonene groups compared to that of the vehicle control group (p < 0.05). There was no significant difference between CLO and limonene (p > 0.05).

Conclusion: Limonene and CLO have similar anti-caries abilities in a bacteriostatic manner in vivo.