Efeito de verniz de própolis em Streptococcus mutans e em modelo experimental de cárie

Abstract

Natural products are sources of effective and innovative therapeutic agents, offering various active principles to be tested, enabling the discovery and development of new products. Propolis has proven antimicrobial effect on cariogenic bacteria, attracting many studies for this purpose. This work evaluated the effect of the experimental propolis varnish in a caries experimental model and in the reduction of Streptococcus mutans (SM) in saliva and in biofilm of children from 8 to 11 years using a single application of the product. In the experimentwith animal model under high cariogenic challenge, fifty-six female SPF wistar rats, previously infected with SM, were assigned to 4 groups (n=14) and treated as follows: G1 - propolis varnish; G2 - chitosan varnish/vehicle; G3 - Duraphat and G4 - no treatment. Animals received a single varnish application on their molars and were then submitted to a high cariogenic challenge (Diet 2000, 56% sucrose, ad libitum) for 4 weeks. After this period, animals were euthanized by CO2 asphyxiation and their jaws removed to quantify the total cultivable microbiota, recovered S. mutans, and caries lesions. Data were analyzed usingthe Tukey-Kramer HSD test. Total microbiota and the percentage of SM were not different between the experimental groups (p<0.05). There was no statistical difference in total smooth surface caries lesions between G1 and G3 (p <0.05). However, in more severe caries lesions, G1 did not differ statistically from G4. In sulcal caries, Duraphat® had better results, showing statistical differences in all severity indexes among all groups (p <0.05). The clinical study followed the single application protocol at the beginning of treatment (baseline), following with daily collections until the 5th day and on the 10th, 15th and 30th day after applying the varnish. The colonies with typical morphology were counted and the number of CFU/ml was compared using the t test for independent samples with 5%significance level. There was no statistically significant difference between the baseline and the 2nd day and between 2nd day and 30th day, but there was no difference from 4th day forward. We conclude that propolis varnish had effect in superficial caries lesions with a single application in animal model and suppressed the number of salivary SM for 3 days in children. The possibility of these results have an impact on the incidence of caries needs to be confirmed.