A kinetic approach to the problem of wave propagation in dusty plasmas, which takes into account the variation of the charge of the dust particles due to inelastic collisions with electrons and ions, is utilized as a starting point for the development of a new formulation, which writes the components of the dielectric tensor in terms of a finite and an infinite series, containing all effects of harmonics and Larmor radius. The formulation is quite general and valid for the whole range of frequencies above the plasma frequency of the dust particles, which were assumed motionless. The formulation is employed to the study of electrostatic waves propagating along the direction of the ambient magnetic field, in the case for which ions and electrons are described by Maxwellian distributions. The results obtained in a numerical analysis corroborate previous analysis, about the important role played by the inelastic collisions between electrons and ions and the dust particles, particularly on the imaginary part of the dispersion relation. The numerical analysis also show that additional terms in the components of the dielectric tensor, which are entirely due these inelastic collisions, play a very minor role in the case of electrostatic waves, under the conditions considered in the present analysis.

AIM: To assess the effect of systemic azithromycin as a supplement to scaling and root planing (SRP) in the treatment of aggressive periodontitis (AgP). MATERIAL AND METHODS: Twenty-four individuals (13-26 years old) underwent a plaque control program, and then were treated with SRP. Subjects were assigned randomly into two groups; the test group used 500 mg azithromycin once a day for 3 days, whereas the control group used a placebo. Clinical variables were assessed at baseline, 3, 6, 9, and 12 months. The periodontal status at baseline and 12 months was compared using the Wald test, and adjusting for the effect of clustering of teeth within subjects. RESULTS: There were no significant differences in visible plaque, gingival bleeding, and supragingival calculus between groups throughout the study. Periodontal probing depth (PPD) and clinical attachment level improved significantly from baseline to 12 months in both groups, with the test group showing significantly more reduction in mean PPD compared with controls (2.88 mm versus 1.85 mm, respectively, p=0.025). Subjects administering azithromycin showed a higher percentage of teeth with attachment gain >or=1 mm (81.34 versus 63.63, p=0.037), whereas the controls had higher percentage of teeth with attachment loss >or=1 mm (11.57 versus 2.24, p=0.015). CONCLUSIONS: The adjunctive use of azithromycin has the potential to improve periodontal health of young patients with AgP.

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