Determination of Antimicrobial Activity of COZ Paste in Oral Pathogens.

Objectives: To evaluate the in vitro antimicrobial activity of COZ paste against Oral Pathogens for use in deciduous molars with pulpal necrosis.
Methods: For this study, bacterial strains of Fusobacterium nucleatum, Prevotella intermedia and Porphyromonas endodontalis were used. The minimum inhibitory concentration (MIC) for chloramphenicol (CHL), oxytetracycline (OTC) and tetracycline (TET) in the bacterial strains was evaluated. Subsequently, the inhibition zone of the individual antibiotics was evaluated for each strain as well as for the COZ paste (CHL, OTC, zinc oxide and eugenol) compared to the CTZ paste (CHL, TET, zinc oxide and eugenol) by disk diffusion test. In addition, the gene expression of adhesin/invasin virulence factor (fadA) of F. nucleatum was evaluated in the presence of non-lethal doses of CHL, OTC and TET by RT-qPCR.
Results: Our results show a MIC value of 1.25 μg/mL for TET and OTC against F. nucleatum and P. endodontalis, while for P. intermedia it was 2.5 μg/mL. For CHL in all bacterial strains its inhibition only occurred at the maximum dose. Regarding the inhibition zone by drug, we obtained the following results: TET 8 ± 0.0 mm, OTC 7 ± 0.0 mm, CHL 12 ± 0.0 mm, CTZ paste 15 ± 0.0 mm while COZ paste was 16 ± 0.0 mm. We observed a statistically signifcant decrease in the expression of the fadA gene of F. nucleatum in the presence of non-lethal doses of OTC (p≤0.001).
Conclusions: The COZ paste could be used favorably in the elimination of oral bacteria that are located in conduits with necrosis in deciduous molars.