The aim of this study was to evaluate the inhibitory effect of copaiba oil and its resinous and volatile fractions against 20 bacterial isolates from dental plaque of dogs. The antimicrobial activities of the oil and its fractions were evaluated by the agar diffusion test with solutions at 10% concentration. The results showed antimicrobial activity for the copaiba oil solution on 16 isolates. The volatile fraction was considered statistically similar (P>0.05) to copaiba oil intact on the size of inhibition zones inhibiting 17 isolates. The resinous fraction inhibited only eight isolates, with smaller haloes when compared with those of the volatile fraction and intact oil (P<0.05). It is concluded from these results that copaiba oil is a potential phytotherapic to be used in dental plaque antimicrobial therapy of dogs and suggests that its activity is due to sesquiterpenes of the volatile fraction.

Key words: Copaiba, Dogs, Medicinal plants, Periodontal disease, Plaque inhibition