Modulation of infection-mediated migration of neutrophils and CXCR2 trafficking by osteopontin.

Osteopontin (OPN) is a pro-inflammatory protein that paradoxically protects against inflammation and bone destruction in a mouse model of endodontic infection. Here we have tested the hypothesis that this effect of OPN is mediated by effects on migration of innate immune cells to the site of infection. Using the air pouch as a model of endodontic infection in mice, we showed that neutrophil accumulation at the site of infection with a mixture of endodontic pathogens is significantly reduced in OPN-deficient mice. Reduced neutrophil accumulation in the absence of OPN was accompanied by an increase in bacterial load. OPN-deficiency did not affect neutrophil survival, CXCR2 ligand expression, or the production of inflammatory cytokines in the air pouch. In vitro, OPN enhanced neutrophil migration to CXCL1, whereas in vivo, inhibition of CXCR2 suppressed cellular infiltration in air pouches of infected wild-type mice by > 50%, but had no effect in OPN-deficient mice. OPN increased cell surface expression of CXCR2 on bone marrow neutrophils in an integrin-αv -dependent manner, and suppressed the internalization of CXCR2 in the absence of ligand. Together, these results support a model where the protective effect of OPN results from enhanced initial neutrophil accumulation at sites of infection resulting in optimal bacterial killing. We describe a novel mechanism for this effect of OPN: integrin-αv -dependent suppression of CXCR2 internalization in neutrophils, which increases the ability of these cells to migrate to sites of infection in response to CXCR2 ligands.

Evaluation of cyclic fatigue behavior of RACE EVO rotary Files: In-vitro comparative study.

Introduction: Comparative evaluation of the newly introduced; RACE EVO file system to the currently well-performing file systems like HyFlex EDM OneFile, Vortex Blue, ProTaper Gold (PTG) with regards to the cyclic fatigue resistance. Materials: &Methods.The endodontic rotary files under evaluation were segregated into four groups as follows:; RACE EVO, PTG, Vortex Blue, and HyFlex EDM OneFile. A detailed physical analysis of the cyclic fatigue resistance was performed in 15 files of each type (n = 60). Under the test conditions of 37 °C the test samples were subjected to continuous motion at the manufacturer recommended speed within an artificial curved canal until it fractured. For all the test samples, with the recording of time of fracture, calculation was done for number of cycles to fracture (NCF). In addition, the length of the fractured segment was determined. The fractured surface was further evaluated with scanning electron microscopic (SEM) images. Results: Highest significance for NCF was seen in HyFlex EDM OneFile followed by the Vortex Blue, PTG, and; RACE EVO (p < 0.05) by analyzing the data statistically. Significant differences among the lengths of the fractured segments were evident among tested files, ranging between 4.73 and 6.3 mm (p < 0.05) with HyFlex EDM OneFile uniquely differentiating from the others showing the fracture at 6.3 mm. The common features of cyclic fatigue failure was further substantiated by SEM images. Conclusions: Compared to the HyFlex EDM OneFile, Vortex Blue, and PTG files; RACE EVO demonstrated significantly lower resistance to cyclic fatigue.

Comparison of bacterial removal from dentinal tubules with different irrigant agitation techniques: An in vitro study.

AIM: This investigation was conducted to assess the ability of various irrigant agitation devices to eradicate Enterococcus faecalis from the dentinal tubules of extracted teeth. METHODOLOGY: Fifty roots of extracted human teeth were instrumented to size 30 k with a 0.04 taper. The roots were autoclaved and then injected with E. faecalis. The canals were assigned to one of four intervention groups and disinfected using (A) standard needle irrigation, (B) EndoUltra® Ultrasonic Activator, (C) the EndoActivator system, or (D) EDDY sonic activation and to two control groups that were (E) treated with saline and (F) not inoculated with any bacteria. The roots were split in half, dyed with a LIVE/DEAD Back Light Bacterial Viability Kit, and then scanned with a confocal laser scanning microscope (CLSM) to identify live/dead bacteria in the dentinal tubules. RESULTS: CLSM images revealed differences among the groups. Both the EndoUltra® Ultrasonic Activator group and the EDDY group had a combination of dead and live bacteria, while the EndoActivator group had mostly dead bacteria, in contrast to single needle irrigation which had mostly live bacteria. Activation of the irrigating solution resulted in more dead bacteria than standard needle irrigation at the coronal, middle, and apical parts of the roots. Overall, the EndoActivator system was superior to all other techniques in reducing live bacteria within the root canal. CONCLUSION: Activation of sodium hypochlorite with sonic and ultrasonic systems dramatically reduced live bacteria contamination in the dentinal tubules of infected root canals.

Evaluation of root canal morphology of mandibular premolars in a Saudi population using cone beam computed tomography: A retrospective study.

OBJECTIVE: To investigate the root canal morphology of mandibular first and second premolars using Cone-Beam Computed Tomography (CBCT) in a Saudi population. METHODS: CBCT images of 707 patients, number of roots and canal configuration were identified and categorized according to Vertucci classification. Bilateral symmetry and association between gender and number of roots, as well as gender and root canal configuration were investigated. RESULTS: Majority of the patients had one root and type I root canal configuration in mandibular first (96.4%) and second premolar (95.6%). All types of canal configurations were observed except Type VII for the mandibular first premolar, and Types VI and VII for the mandibular second premolar. High degree of bilateral symmetry was seen in both mandibular first and second premolars in terms of the number of roots and canal configuration; 93.8% and 97.8%, respectively. There was an association between gender and number of roots (P = 0.04) and gender and root canal configuration in mandibular first premolar (P = 0.030). CONCLUSIONS: Single-root with type I canal configuration was the most prevalent of mandibular premolars in the Saudi population. However, incidence of more than one root with different canal configurations was detected.