Bleeding on probing as it relates to smoking status in patients enrolled in supportive periodontal therapy for at least 5 years

AIM To relate the mean percentage of bleeding on probing (BOP) to smoking status in patients enrolled in supportive periodontal therapy (SPT). MATERIALS AND METHODS Retrospective data on BOP from 8'741 SPT visits were related to smoking status among categories of both periodontal disease severity and progression (instability) in patients undergoing dental hygiene treatment at the Medi School of Dental Hygiene (MSDH), Bern, Switzerland 1985-2011. RESULTS A total of 445 patients were identified with 27.2% (n = 121) being smokers, 27.6% (n = 123) former smokers and 45.2% (n = 201) non-smokers. Mean BOP statistically significantly increased with disease severity (p = 0.0001) and periodontal instability (p = 0.0115) irrespective of the smoking status. Periodontally stable smokers (n = 30) categorized with advanced periodontal disease demonstrated a mean BOP of 16.2% compared to unstable smokers (n = 15) with a mean BOP of 22.4% (p = 0.0291). Assessments of BOP in relation to the percentage of sites with periodontal probing depths (PPD) ≥ 4 mm at patient-level yielded a statistically significantly decreased proportion of BOP in smokers compared to non-smokers and former smokers (p = 0.0137). CONCLUSIONS Irrespective of the smoking status, increased mean BOP in SPT patients relates to disease severity and periodontal instability while smokers demonstrate lower mean BOP concomitantly with an increased prevalence of residual PPDs.

Experimental and Theoretical Electron Density Analysis of Copper Pyrazine Nitrate Quasi-Low-Dimensional Quantum Magnets

The accurate electron density distribution and magnetic properties of two metal-organic polymeric magnets, the quasi-one-dimensional (1D) Cu(pyz)(NO3)2 and the quasi-two-dimensional (2D) [Cu(pyz)2(NO3)]NO3·H2O, have been investigated by high-resolution single-crystal X-ray diffraction and density functional theory calculations on the whole periodic systems and on selected fragments. Topological analyses, based on quantum theory of atoms in molecules, enabled the characterization of possible magnetic exchange pathways and the establishment of relationships between the electron (charge and spin) densities and the exchange-coupling constants. In both compounds, the experimentally observed antiferromagnetic coupling can be quantitatively explained by the Cu-Cu superexchange pathway mediated by the pyrazine bridging ligands, via a σ-type interaction. From topological analyses of experimental charge-density data, we show for the first time that the pyrazine tilt angle does not play a role in determining the strength of the magnetic interaction. Taken in combination with molecular orbital analysis and spin density calculations, we find a synergistic relationship between spin delocalization and spin polarization mechanisms and that both determine the bulk magnetic behavior of these Cu(II)-pyz coordination polymers.