Features of physical and mechanical parameters of acrylic plastics after fullerene coating.

OBJECTIVE: The aim of the research is to study the physical and mechanical parameters of the bases in removable laminar dentures after modification of their surface. PATIENTS AND METHODS: Materials and methods: the studied samples were divided into two groups (group I - acrylic plastics, and group II - acrylic plastics with fullerene С60 nanocoating), 50 samples in each group. The coefficients of water absorption, water solubility, microhardness and deformation characteristics of materials were studied. RESULTS: Results and conclusions: The material covered with fullerene С60 has a lower coefficient of water absorption and water solubility, which amounted to 0.55% and 0.23% respectively, from the initial weight of samples, as compared with acrylic plastics without coating (0.71% and 034%, respectively). The strength parameters of samples of group ІІ were higher by 13.5% as compared to group І. The given results of water absorption and water-solubility show that acrylic plastics with fullerene С60 molecules coating has a lower coefficient of water absorption and water solubility, in comparison with acrylic plastics without coating. This indicates a higher degree of resistance to biodegradation of the modified surface material, in turn reducing the washing-out of residual monomer from the denture, which directly improves the strength parameters of the acrylic plastics and can prevent the development of denture stomatitis.

[The reactions of lipid's free radical oxidation, hemocoagulant properties of oral fluid in patients with galvanic currents in the mouth].

OBJECTIVE: Introduction: Oral manifestation of galvanic currents due to the presence of two and more dissimilar metals in dental restorations is rather important in prosthodontics. The aim of our study was to assess the reactions lipid's free radical oxidation and hemocoagulant properties of oral fluid in patients with disorders in oral cavity due to galvanic currents. PATIENTS AND METHODS: Materials and methods: The study had got some groups. The first one consisted of 7 healthy patients without dental prosthesis. The other one included 22 patients with dental prosthesis and they were suffered from short circuiting due dissimilar metallic restorations in oral cavity. This group we were divided into two groups: the second one - for 7 patients were produced metal ceramic fixed dental prosthesis, the third one - for 15 patients were produced whole casted fixed dental prosthesis and pressing brazed fixed dental prosthesis. To assess the process of lipid's free radical oxidation of oral fluid we studied kinetic concentration of malone dialdehyde, activity level of superoxide dismutase and catalase. Also we found out hemocoagulant activity data of oral fluid: thrombin time, prothrombin time, fibrinolytic activity, recalcification time. RESULTS: Results: In our study we observed increasing of lipid's free radical oxidation in patients of the second and third groups, which led to increasing malone dialdehyde data in third group compared with second group. In patients of second and third groups was recorded the increasing of the CAT activity in the oral fluid. Also there is the in fact decreasing in hemocoagulant properties of oral fluid, such as reducing in recalcification time, increasing in prothrombin time in the second and especially in the third groups of patients. It was marked the significant increasing of fibrinolytic activity of oral fluid in the second and third group of patients. CONCLUSION: Conclusions: The oral manifestation of electrochemical interactions due to presence of dissimilar metallic restorations led to shift in oral cavity's homeostasis. This statement we can verify with results of our study. In patients with oral manifestation of galvanic currents were observed the increasing in activity of the reactions of lipid's free radical oxidation in oral fluid, changes in antioxidative enzymes and in local homeostasis of oral fluid.