BackgroundDebridement and disinfection of the root canal system is a crucial step in endodontic procedures. The effectiveness of irrigation relies on both the mechanical flushing action and the ability of irrigants to dissolve tissue and kill bacteria. The objective of the present study is to evaluate and compare the cytotoxicity of QMix™ root canal irrigating solution on immortalized human bone marrow mesenchymal stem cells (hTERT-MSC-C1) and to compare it with that of sodium hypochlorite (NaOCl).MethodsImmortalized human bone marrow mesenchymal stem cells (hTERT-MSCs) were exposed to QMix™ and NaOCl. Cell viability was assessed by 3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and alamarBlue assays. The cell morphology was studied after two hours of exposure to QMix™ and NaOCl. Scanning electron microscopy (SEM) analyses were performed after 2- and 4-hour incubation periods. Finally, ethidium bromide/acridine orange (EB/AO) fluorescent stain was applied to the cells in the 8-chamber slides after they were incubated with the testing agents for 2 hours to detect live and dead cells. The observations were tabulated and analyzed statistically.ResultsQMix™ exposure resulted in a significantly higher percentage of cell viability than NaOCl in the MTT and alamarBlue assays at three time points compared to the control. The SEM analysis demonstrated minimal morphological changes associated with cells that were exposed to the QMix™ solution, with little shrinkage and fragmentation of the cell wall. The live/dead analysis showed that the number of live cells after exposure to QMix™ was similar to that of the untreated control. No cell structure could be observed with the NaOCl group, indicating cell lysis.ConclusionBoth the QMix™ and NaOCl solutions were toxic to human bone marrow MSCs. Each solution might have induced cell death in a different way as evidenced in the cell viability, SEM and fluorescent studies. The slower cell death induced by QMix™ might therefore be less aggressive and more acceptable to living tissues.

Aim. To evaluate dentinal microcrack formation on root canals instrumented, continuously in the body temperature, with XPendo shaper (XPES) and ProTaper Universal (PTU), by means of microcomputed tomographic (micro-CT) analysis. Methodology. Nineteen mesial roots with two separate canals (Vertucci Type IV) of extracted mandibular molars were used in this study. e root canals (N � 38) were divided into 2 groups. Group 1 (n � 19): all MB canals were instrumented with XPES. Group 2 (n � 19): all ML canals were instrumented with PTU. All roots were scanned with micro-CT before and after instrumentation. Two precalibrated examiners evaluated the cross-sectional images of each sample with DataViewer program. e dentinal microcracks (complete and incomplete) were counted in each third of the root for the preinstrumentation and the postinstrumentation images. Wilcoxin signed-rank and Mann-Whitney U tests were used for statistical analysis at a significance level of P < 0.05. Results. e number of microcracks increased significantly (P < 0.05) after instrumentation with XPES in the middle and cervical thirds. e number of microcracks increased significantly (P < 0.05) after instrumentation with PTU in the cervical third only. ere was no significant difference between the groups in the cervical and apical thirds. In the middle third, the XPES induced more incomplete microcracks than PTU (P < 0.05). Conclusion. Within the limitations of this study, there was no significant difference in the dentinal microcrack formation between XPES and PTU in the apical and cervical thirds of the root. However, XPES instrumentation induced more incomplete microcracks than PTU in the middle third of human roots.

Background The radicular groove (RG) is one of the developmental anomalies that is commonly found in maxillary incisors. The formation of radicular groove is initiated around the cingulum and can reach the root at different levels. The incidence of radicular grooves was reported in different countries but there was no published data about the incidence of RG in Saudi Arabia. Therefore, this study aimed to evaluate the incidence of radicular grooves on maxillary lateral incisors in the Saudi population using cone-beam computed tomography (CBCT). Methods The dental records of 490 patients (N = 490) with CBCT images of maxillary anterior teeth were screened for inclusion criteria. Then 264 included cases were evaluated independently by two Endodontists. The evaluation was performed on CBCT images in the axial, sagittal, and coronal sections using Planmeca Romexis® software. The following data were recorded for each patient: Patients’ age and gender, radicular groove presence or absence, and if it is bilateral or unilateral. The type of radicular groove was recorded according to Gu’s classification (type I, II, or III). Results The incidence rate of radicular grooves in maxillary lateral incisors was 4.9%. RG was found to be unilateral in 61.5% and bilateral in 38.5%. The majority of RG were classified as type I in 69.2%, followed by type II in 15.4%, and type III was found in 15.4%. Conclusion 4.9% of the Saudi population has RG in the upper lateral incisor. This anatomical variation is mostly present as type I on one side only (unilateral).

Within the limitations of this in vitro study it can be concluded that NaOCl is toxic to the human bone marrow MSCs. The cell lysis was evident with higher concentration of sodium hypochlorite. From the observations, it can be concluded that a lower concentration of NaOCl may be used as endodontic irrigant due to its cytotoxic properties. Further studies are mandatory to evolve a consensus on the optimal concentration of sodium hypochlorite to be used as endodontic irrigant.

The Knowledge of the root canal morphology is essential for the success of the endodontic treatment. The most common anatomical configuration in mandibular canines is to have one root with one canal. However, previous studies reported 4.6 to 15% of the cases to have a second canal. In order to increase the knowledge about root canal morphology in Saudi population, we reported a clinical case about successful endodontic management of mandibular canine with two joined canals (Vertucci type II) in Saudi female.