Evaluation of αLphav Integrin Role in Mouse Model Induced Periapical Periodontitis

Abstract: Background: alphav (av) integrin is the most common integrin alpha subunit, it is expressed in different cells and involved in many cellular process including adhesion, migration, survival and growth factor signaling. alphav on immune cells has a role in promoting T regulatory (Treg) cells production and differentiation of T helper 17 (Th17) through activating TGF-beta as shown in conditional knockout of alphav in immune cells. Osteopontin (OPN) is a ligand for alphav and involved in modulation of inflammation through its interaction with alphav in immune cells. OPN has been shown to have a protective role in endodontic infection, so we predict alphav to have similar role. The aim of the study is to establish the role of αv integrin in the immune response to endodontic polymicrobial infection, using an established mouse model of endodontic infection Methods: alphavfl/fl mice were mated with mice expressing Cre under the control of the Tie2 promoter, which is expressed in all cells of the hematopoietic lineage as well as in endothelial cells. These mice were subjected to pulp exposure and infection with a mixture of four endodontic pathogens. Bone loss was assessed 0, 7, 14, and 21 days after infection using micro CT. Inflammation and neutrophils enumeration in periapical area evaluated using immunohistochemistry, also osteoclast presence in periapical area examined with TRAP staining. Microarray and qPCR used to investigate cellular and cytokines activity changes. Blood plasma collected from mice during sacrificing was evaluated using ELISA for level of IgG’s and antibody activity against the specific bacteria used for the infection. Results: Lack of alphav expression was confirmed on neutrophils by FACS. Twenty-one days after pulp exposure and infection with oral pathogens, 6 of 16 av-tie2cre KO mice developed swelling and abscesses in the mandible, while no abscesses were observed in control mice. However, the periapical bone resorption was similar in the two groups. Strikingly, ectopic bone formation on the buccal and lingual aspects of the mandibular surface was observed only in the av-tie2cre animals, suggesting a severe disruption of bone turnover caused by the inflammatory process in these animals. Neutrophils showed decrease in number in periapical area and microarray and the observe disseminating infection suggested a B cells defect either in function or migration. Conclusions: Together, these results demonstrate a critical role for the alphav integrin in the suppression of inflammation during the process of endodontic infection

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