Some confusion exists in the literature whether correlations exist between gingivitis severity and plaque levels as measured by the corresponding indices. The results of a clinical trial and a re‐analysis of literature data indicate that a strong statistical correlation exists between the Löe‐Silness Gingival Index values and both the Löe and the Quigley‐Hein Plaque Index measurements. Furthermore, regression analyses also indicate that Löe‐Silness Gingival Index can be expressed as linear functions of either the Löe Plaque Index or the QuigleyHein Plaque Index and that for each unit increment in the mean plaque index values a half unit increase in the gingival index value can be expected.

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The experiments reported here show how diffusion rates in liquids can be increased by as much as an order of magnitude by use of coupled dBusion fluxes in mixed solvents. Solutes whose diffusion can be accelerated in this way include simple electrolytes, essential oils, dyes, and antibiotics. These increases are primarily caused by thermodynamic interactions and can be estimated from solubilities. E. L. CUSSLER and M. M. BREUERUnilever Resemch Isleworth, Middlesex, England SCOPEThis study aims at sharply increasing diffusion rates in liquids by means of coupled diffusion fluxes. Such increases are important because diffusion in liquids is slow and is often the rate-limiting step of an industrial process. Coupled diffusion fluxes occur when the flux of a solute is altered by the concentration gradient of a second solute. For example, the flux of sodium acetate in aqueous solution can be increased nine times by a gradient of acetone.The feature of this work which distinguishes it from past studies is the large magnitude of the coupled diffusion effects observed. These effects are well understood: most of the theoretical work is over ten years old (1, 2) and the experimental observations go back at least to 1892 (3). But past physical chemical studies have concentrated on the accurate experimental verification of the Onsager reciprocal relations and hence required an emphasis on experimental detail (4). Strongly coupled diffusion fluxes are observed in biological systems, but the interpretation of experimental results in these cases is hindered by the inexact knowledge of the chemical composition of the systems used (5). Engineering studies of coupled diffusion have focused on estimation methods which can avoid the tedious experiments characteristic of exact analysis (6-7).In contrast, this work is not interested in accurately studying small effects but aims at approximately predicting and experimentally discovering greatly accelerated diffusion rates. CONCLUSIONS AND SIGNIFICANCEThere are three conclusions from these experiments:1. The diffusion of simple electrolytes can be accelerated by an order of magnitude by means of coupled fluxes in mixed solvents.2. These increased diffusion rates are primarily caused by thermodynamic interactions and can be estimated from solubilities.3. The diffusion of dyes, antibiotics, and essential oils can also be accelerated several hundred percent, but the increases are generally less than those observed for simple electrolytes. While the experiments reported here all involve increases in diffusion rates, parallel experiments could also achieve decreases in these rates.The accelerated diffusion rates reported here offer a means by which the rate of almost any mass transfer process can be increased. In practice, these increases will be useful if the industrial situation fulfills three requirements:1.. the process is diffusion limited; 2. it involves small amounts of valuable materials; and 3. it is restricted to short process times.Such processes occur most commonly in the photogra...

Supragingival plaque and calculus indices, salivary flow rates, pH, ionic and total calcium concentrations, total phosphate concentration, and the number of cervical restorations and caries lesions were measured in 29 subjects using systemic beta-(beta) blockers and in 28 subjects who were not taking any systemic medication. After 8 weeks of normal oral hygiene following an oral prophylaxis, a second comparison of each of the above quantities was made. With the exception of the calculus indices and the incidence of cervical restorations, no significant differences were found for any of the measured quantities between the medicated and non-medicated groups at either examination. The medicated group showed significantly lower mean calculus values than the non-medicated group at both examinations and a higher incidence of cervical restorations at the baseline examination, suggesting that beta-blockers decrease the rate of mineralization in the oral cavity. Since beta-blockers did not appear to alter stimulated salivary pH, flow rate, phosphate, ionic calcium or total calcium concentrations, their effect on the mineralization processes must be attributed to other mechanisms. Two hypotheses appear plausible: changes in salivary mineralization rates caused by either direct physico-chemical effects of the secreted beta-blockers in the saliva, or by alterations in the salivary protein/glycoprotein composition, enzymes and oral bacterial flora owing to systemic pharmacological effects of beta-blockers.

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