nitrogen-dioxide and Dental-Plaque

To evaluate the effect of nitrogen (N)-doped titanium dioxide (TiO2) coated stainless steel brackets activated with natural visible light and dental operating lights on Streptococcus mutans concentration in the plaque of orthodontic patients at 30 and 60 days.. A total of 30 patients were recruited for this split-mouth study; 60 upper lateral incisor brackets constituted the study sample. A total of 30 brackets (15 right and 15 left) were coated with N-doped TiO2 using the (radio frequency) magnetron sputtering method. Plaque samples were collected at 30 days and 60 days after appliance placement. S mutans concentration was evaluated using real-time polymerase chain reaction.. At both time intervals, the concentration of S mutans in the control group was greater than that in the study group (P = .005). In both the study and the control groups, the S mutans concentrations significantly increased from 30 to 60 days (P = .005).. N-doped TiO2, on exposure to natural visible light and dental operating light, was effective in reducing the plaque concentration of S mutans in orthodontic patients. The efficacy was better at 30 days than at 60 days after placing the orthodontic appliances.

Topics: Dental Plaque; Humans; Nitrogen; Nitrogen Dioxide; Orthodontic Brackets; Stainless Steel; Streptococcus mutans; Surface Properties; Titanium

The pH in dental plaque falls to below 5 after the ingestion of foods, and it may remain low if acid-tolerant bacteria grow in the plaque. Certain nitrate-reducing bacteria in the oral cavity can proliferate in dental plaque at low pH, and nitrite is detected in such plaque. In acidic dental plaque, NO(2) can be produced by self-decomposition of nitrous acid and also by peroxidase-catalyzed oxidation of nitrite, and it may oxidize uric acid, a major antioxidant in the oral cavity. Under experimental conditions that simulate oral cavity, the oxidation of uric acid by nitrite and by nitrite/peroxidase systems was much more rapid at pH 5 than at pH 7, suggesting the more rapid production of NO(2) in dental plaque at lower pH. We propose that if the pH of plaque developed in a dental crevice decreased, NO(2) and other nitrogen oxides produced in the plaque would diffuse into the adjoining gingival tissues. The results of this study seem to contribute to the understanding of the induction of periodontal diseases in the context of nitrite-dependent production of nitrogen oxides in acidic dental plaque.

Topics: Acids; Dental Plaque; Glucose Oxidase; Humans; Hydrogen Peroxide; Hydrogen-Ion Concentration; Mouth; Nitrogen Dioxide; Oxidation-Reduction; Peroxidase; Saliva; Uric Acid