Mechanism of action of a desensitizing fluoride toothpaste delivering calcium and phosphate ingredients in the treatment of dental hypersensitivity. Part II: comparison with a professional treatment for tooth hypersensitivity.

Tooth hypersensitivity can occur when gum recession causes exposure of dentin. Tiny tubules, which permeate dentin, provide open passageways from the mouth to the intradental nerve in the pulpal cavity. Under such circumstances, stimuli in the mouth can cause pressure on the intradental nerve, leading to pain. Sealing the outside of the tubules with an impermeable substance can effectively treat hypersensitivity. One such clinically proven composition is a professionally applied tooth desensitizer, which has been shown to initially produce a layer of amorphous calcium phosphate (ACP) on the surface of dentin. Under the influence of fluoride, ACP reforms as hydroxyapatite (HAP), which has essentially the same composition as tooth mineral. Three fluoride toothpastes that deliver calcium and phosphate salts to the teeth also have been demonstrated in clinical trials to relieve hypersensitivity. This study compared the mechanism of action of these toothpastes to that of the professional desensitizer. A single application of the professional desensitizer or multiple applications of any of the three toothpastes was shown to reduce dentin permeability. A conventional fluoride toothpaste also was found to inhibit fluid flow through the dentin but to a lesser degree than the other toothpastes. The desensitizer and the three toothpastes were found to occlude the dentinal tubules with a layer of calcium phosphate that had a calcium-to-phosphate ratio consistent with the formation of ACP or HAP. The morphology of the coherent mineral layer formed by Arm & Hammer Enamel Care Sensitive was similar, especially to that produced by the desensitizer. In contrast, the conventional toothpaste left localized areas of surface residue composed of silica particles. The mechanism of action of the three toothpastes that deliver calcium and phosphate salts is the same as that of the professional desensitizer.

Urbanization in India: Population and Urban Classification Grids for 2011.

India is the world's most populous country, yet also one of the least urban. It has long been known that India's official estimates of urban percentages conflict with estimates derived from alternative conceptions of urbanization. To date, however, the detailed spatial and settlement boundary data needed to analyze and reconcile these differences have not been available. This paper presents gridded estimates of population at a resolution of 1 km along with two spatial renderings of urban areas-one based on the official tabulations of population and settlement types (i.e., statutory towns, outgrowths, and census towns) and the other on remotely-sensed measures of built-up land derived from the Global Human Settlement Layer. We also cross-classified the census data and the remotely-sensed data to construct a hybrid representation of the continuum of urban settlement. In their spatial detail, these materials go well beyond what has previously been available in the public domain, and thereby provide an empirical basis for comparison among competing conceptual models of urbanization.

Accessibility Landscapes of Supplemental Nutrition Assistance Program-Authorized Stores.

BACKGROUND: The Supplemental Nutrition Assistance Program (SNAP) is the largest food assistance program in the United States. Participants receive electronic benefits that are redeemable at a variety of food stores. Previous research notes that low-income neighborhoods often lack supermarkets with high-quality, affordable food. OBJECTIVE: The first aim of this study was to explore the number and spatial distribution of SNAP stores by type and to assess how SNAP benefit redemption is linked to store type in North Carolina in 2015. The second aim was to compare the demographics of populations living in areas with a high concentration of SNAP participants vs areas with a lower concentration of SNAP participants. The third aim was to test for disparities in the availability of and access to SNAP-authorized stores in areas with high vs low concentration of SNAP participants stratified by rural/urban status. DESIGN: US Department of Agriculture and US Census data were used to explore the spatial distribution of SNAP stores at the census block group level utilizing a Geographic Information System. PARTICIPANTS: The 9,556 North Carolina SNAP stores in 2015 categorized into full-variety and limited-variety stores. OUTCOME MEASURES: Proximity to limited-variety SNAP food stores and full-variety SNAP food stores within access range (1 mile in urban areas and 10 miles in rural areas). STATISTICAL ANALYSES: Wilcoxon rank sum and χ2 tests are used to compare the distance to and concentration of SNAP stores by rurality and SNAP participant concentration at census block group scale. RESULTS: Among the SNAP stores in North Carolina, 83% are limited-variety stores and 17% are full-variety stores. There are disparities in the demographics of individuals living in census block groups with a high proportion of SNAP participants compared to census block groups with a lower proportion of SNAP participants. More households in higher SNAP participant census block groups were non-white, did not have a car, and had children compared to census block groups with lower SNAP participation. Residents in high SNAP participant census block groups typically had access to 0 full-variety stores and 4 limited-variety stores in urban areas and 3 full-variety stores and 17 limited-variety stores in rural areas. CONCLUSIONS: SNAP participant access to a variety of stores should be considered when approving food stores for SNAP authorization. More research is essential to disentangle the relationship between access to SNAP store type and SNAP food choice and to estimate geographical disparities.