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External cervical tooth root resorption is one of the most aggressive types of pathological resorption. Due to the uncontrolled growth of resorptive tissue, irreversible loss of dentin and cement occurs. To date, there is no common position regarding the etiological factor and pathogenesis of invasive cervical resorption. The histological picture is similar to some fibro-bone lesions. The treatment outcome of the pathology is difficult to predict because elimination of the causative factor is often not sufficient for resorption arrest. Only the complete elimination of resorptive tissue helps to stop the process. The report describes a clinical case of a successful treatment of invasive cervical resorption of dental hard tissues.

The aim of the study was to assess root canal dentinal walls structure after photodynamic exposure with the use of 0.5% photoditazine. A root canal dentin of 46 single root intact teeth removed for orthodontic indications was examined by scanning electron microscope JEOL JSM-6510 (Japan). Microphotographs of the root canal wall were obtained in the orifice, central and apical parts under×2000 magnification. It was found that photoactivation of 0.5% gel photoditazine by a light source, laser or diode, with a wavelength of 635-660 nm and a power of 150-200 mW is an effective technique for removing the smear layer of the root canal wall, which facilitates the maximum opening of the dentinal tubules to a depth of 2-3 μm. The best result (the maximum number of open dentinal tubules, the absence of a smear layer) is observed with 3 min photoditazine exposure and 2 min of laser exposure. The method can be proposed as an alternative supplement to the conventional root canals irrigation.

Lethal and mutagenic effects of N-nitrosomethyl biuret on the organism producing a complex of proteolytic enzymes i. e. Acremonium chrysogenum were studied. It was shown that methionine inhibited production of the protease complex in the induced prototrophic mutants. The selected mutants were classified according to the level of enzyme biosynthesis induction by methionine.

Protein spectra of 19 strains of typical and atypical mycobacteria were studied. The advantage of protein extracts obtained from the living cells destroyed by press was shown in experiments of fractionation in polyacrylamide gel. On the basis of similarity indices of the protein spectra a conditioned scheme reflecting the extent of similarity of the cultures under study was drawn. there were revealed protein fractions common for the majority of the cultures studied; It was impossible to isolate the fractions strictly specific of individual groups.