Sahar Nouri Gharajalar - Department of Pathobiology, Faculty of Veterinary Medicine, University of Tabriz, Tabriz, Iran.
Mohsen Hassanzadeh - DVM student, Faculty of Veterinary Medicine, University of Tabriz, Tabriz, Iran.
Razzagh Mahmoudi - Medical Microbiology Research Center, Qazvin University of Medical sciences, Qazvin, Iran
Paria Emamverdizadeh - Oral and Maxillofacial Pathology Department, Dentistry Faculty, Tabriz University of Medical Sciences, Tabriz, Iran

Introduction: Mutans Streptococci are significant pathogens isolated from dental plaques. Due to the increasing frequency of antimicrobial resistance among pathogens causing dental caries, more studies have focused on using natural agents against them. This study aimed to evaluate the antibacterial effects of Trachyspermum ammi essential oil against Streptococcus mutans isolated from dental plaques. Methods: Twenty human dental plaque samples were collected, and eight S. mutans isolates were detected using biochemical and molecular tests. The antibiotic susceptibility patterns of the isolates were determined by the disc diffusion method. Also, T. ammi essential oil antibacterial activity was investigated using the disc diffusion method and determining minimum inhibitory concentration (MIC۵۰) and minimum bactericidal concentration (MBC) values. Results: Phenotypic and genotypic characterization identified S. mutans in ۴۰% of the samples. The antibiotic susceptibility assay revealed the highest resistance patterns against cefotaxime (۱۰۰%), ceftriaxone (۱۰۰%), and penicillin (۸۷.۵%). The T. ammi essential oil demonstrated ۲۰ µg/ml MIC and ۸۰µg/ml MBC against S. mutans. Conclusion: The present study revealed a potent antibacterial activity for T. ammi essential oil against S. mutans isolates.

Dental plaque, Streptococcus mutans, Trachyspermum ammi, Essential oil