DETERMINATION OF CYCLIC FATIGUE OF A NICKEL-TITANIUM COXO SC PRO FILE USING A SIMULATION ENDODONTIC UNIT.

The use of nickel-titanium instruments during endodontic treatment ensures high-quality treatment of root canals. However, during instrumentation in the curved root canals of nickel-titanium instruments experience cyclic loading, which leads to their breakage. The splinter of the tool in the root canal makes it difficult for high-quality processing and obturation of the root canal, which is a very urgent problem. To carry out instrumental processing in canals with various anatomical and topographic features, the files must have phenomenal flexibility, lack of straightening of the canal, and have a safe non-aggressive tip. And for this reason, one of the most popular nickel-titanium COXO SC PRO tools was selected as a study, which, according to the manufacturer, have all the listed properties. The aim of the study is to determine the limit of resistance to cyclic loading and signs of breakage of the nickel-titanium endodontic instrument COXO SC PRO. Sterilization treatment, which is based on autoclaving, significantly reduces the strength characteristics of COXO SC PRO nickel-titanium files, which limits the use of these tools to one-time use without the risk of their breakage.

[Immunohistochemical study of Ki-67, PHH3, and CK15 protein expression in oral epithelial malignancy]. / Immunogistokhimicheskoe issledovanie ékspressii belkov Ki-67, PHH3 i CK15 pri malignizatsii épiteliia slizistoi obolochki rta.

OBJECTIVE: To investigate the expression of Ki-67, phosphohistone H-3 (PHH3), and cytokeratin 15 (CK15) proteins in the cells of the oral mucosa (OM) according to the degree of its malignant transformation. MATERIAL AND METHODS: OM biopsy specimens from 69 patients diagnosed with focal epithelial hyperplasia, intraepithelial squamous cell neoplasia, cancer in situ, and squamous cell carcinoma were examined. Tissue antigens were determined using mouse Ki-67 monoclonal antibodies, rabbit PHH3 polyclonal antibodies, and mouse CK15 monoclonal antibodies. RESULTS: There was an increase in epithelial proliferative and mitotic activities in squamous cell carcinoma and a sharp decrease in the expression of CK15 in the cytoplasm in cancer in situ and squamous cell carcinoma of the OM. CONCLUSION: The protein CK15 can be used for the differential diagnosis between high-grade dysplasia and OM epithelial malignancy at the stage of carcinoma in situ and squamous cell carcinoma.