The aim of this study was to determine the antimicrobial capacity, minimum inhibitory concentration (MIC), and cytotoxic effects of a Peganum harmala seed extract in comparison to 5.25% sodium hypochlorite (NaOCl). The oral pathogen Enterococcus faecalis was used to evaluate the antimicrobial capacity, and the MIC values were determined through serial dilution. Inhibition zones were measured in millimeter, and the data were analyzed statistically by analysis of variance and the Tukey HSD test. For cytotoxicity testing, P. harmala seed extract and 5.25% NaOCl solution were incubated with L929 fibroblast cells. After 1, 24, and 72 hr of incubation, cells were stained and the optical density determined with an enzyme-linked immunosorbent assay (ELISA) reader. Data were analyzed with Chi-Square statistical test. The significance level was set at p < .05. There was no significant difference between the antimicrobial capacity of 5.25% NaOCl and the P. harmala extract (p > .05; MIC 4 μg/ml). The Microculture Tetrazolium (MTT) assay test showed that the cytotoxic effects of the P. harmala extract were significantly lower than 5.25% NaOCl (p < .05). The results show that 5.25% NaOCl and P. harmala seed extract have similar antimicrobial activity against Enterococcus faecalis; but P. harmala, which shows reduced cytotoxicity, should be considered for further investigation as a safe, phytotherapeutic, intracanal irrigant.

Background: Accessibility to all sites of root canal and its mechanical and chemical cleaning is mandatory for successful root canal therapy. The presence of isthmus is a major hindrance to complete root canal accessibility. Objectives: The purpose of the present study was to determine the relative frequency and type of isthmuses in the apical region of mesial root of the first mandibular molar extracted in Yazd. Materials and Methods:In this descriptive-laboratory study, 100 mandibular first molar teeth were collected. The mesial roots were excised at the cervical region and three horizontal sections perpendicular to the longitudinal axis of the root were secured with 1-, 3-, and 5-mm distances upwards from apex region of the roots. The incised surfaces were stained using India ink and viewed under stereomicroscope with a magnifying power of ×60 and photographed. The obtained images were studied regarding the presence or absence of isthmuses and the various anatomical forms of isthmuses were recorded based on Hsu and Kim taxonomy. Results: Isthmus was present in 54% of teeth. The greatest frequency of isthmuses was observed in the 5 mm from the apex. The type V isthmus was the most prevalent isthmuses between all levels of roots. Conclusions:The frequency of isthmuses in the mesial root of mandibular first molars was high. The results of clinical and surgical endodontic procedures may be affected by this aspect of root canal anatomy.