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Surface Loss (surface + loss)

Distribution by Scientific Domains

Medical Sciences	55%
Earth and Environmental Science	33%

Selected Abstracts

R1 Effect of brushing on dental erosion

INTERNATIONAL JOURNAL OF PAEDIATRIC DENTISTRY, Issue 2006
A. Z. ABDULLAH
Objectives:, To compare the effect of brushing versus dipping using three different concentrations of fluoridated toothpastes on enamel erosion in vitro using surface profilometry. Methods:, In a randomised, blinded experiment six groups of seven enamel slabs each were cut and mounted into resin blocks, ground and checked for surface flatness using a scanning profilometer (Scantron Proscan 2000). Each slabs' surface was covered with nail varnish except for a small window (1 x 2 mm). Each group was immersed under static conditions for 2 minutes, five times daily in fresh 200 ml aliquots of citric acid 0.3% (pH = 3.6). In addition, three groups were immersed in three different fluoridated toothpastes (0 ppm F, 1100 ppm F, or 1450 ppm F) twice daily morning and evening for 2 minutes each time. The other three groups were brushed using the same toothpastes twice daily for 2 minutes each time. The total cycling period lasted 16 days during which the slabs were incubated overnight and between erosive challenges in artificial saliva at 37oC. A 60-minute gap was left between daytime immersions. Before and after dipping in the erosive solutions the slabs were rinsed with de-ionised water. After the cycling period, the slabs were analysed with the scanning profilometer to measure the amount of surface loss at day 4, 8, 12, and 16. Results:, Surface loss ± SD of enamel at day 16 caused by citric acid combined with dipping using non-fluoridated toothpaste was 61.19 ± 8.50 ,m, 1100 ppm F was 43.44 ± 10.94 ,m or 1450 ppm F was 34.98 ± 4.29 ,m. Surface Loss ± SD of enamel at day 16 caused by citric acid combined with brushing using 0 ppm F, 1100 ppm F, or 1450 ppm F toothpastes was 75.62 ±10.64, 63.51 ± 5.27 and 48.94 ± 13.67 ,m, respectively. Conclusion:, Enamel erosion was increased significantly (CI 95%) using brushing with toothpastes compared to dipping. In addition, enamel erosion showed a dose-response to fluoridated toothpastes. Acknowledgment:, This project was supported by GlaxoSmithKline. [source]

Impact of modified acidic soft drinks on enamel erosion

ORAL DISEASES, Issue 1 2005
T Attin
Objective:, To evaluate the enamel erosive potential of modified acidic soft drinks under controlled conditions in an artificial mouth. Materials and methods:, From each of 144 bovine incisors one enamel sample was prepared. Labial surfaces of the samples were ground flat, polished and covered with adhesive tape, leaving an exposed area. The samples were distributed among four (A,D) groups for treatment with A: Coca-Cola, B: Sprite; C: Sprite light, D: orange juice. Either 1.0 mmol l,1 calcium (Ca) or a combination (comb.) of 0.5 mmol l,1 calcium plus 0.5 mmol l,1 phosphate plus 0.031 mmol l,1 fluoride was added to the beverages. Samples of each group were subdivided into three subgroups (-original; -Ca and -comb.) for treatment with original and modified drinks. De- and remineralization cycles were based on a standard protocol described earlier. Surface loss of the specimens was determined using profilometry after test procedure. Results:, In all subgroups, loss of enamel was observed. The enamel loss recorded for the samples rinsed with original Sprite and original orange juice was significantly higher compared with all other solutions (P = 0.001). Lowest enamel loss was recorded for the original Coca-Cola group (P = 0.001). With the exception of Coca-Cola, demineralization with the modified beverages led to significantly lower losses compared with the respective original solutions. Conclusion:, Modification of the test soft drinks with low concentrations of calcium or a combination of calcium, phosphate and fluoride may exert a significant protective potential with respect to dental erosion. [source]

Periapical lesions and dental wear in the early Maori

INTERNATIONAL JOURNAL OF OSTEOARCHAEOLOGY, Issue 4 2001
J.A. Kieser
Abstract Dental wear and intrabony lesions were evaluated in a sample of 225 skulls (136 male) of pre-contact New Zealand Maoris. The degree and direction of surface wear was scored according to the method of Molnar (Molnar 1971. Human tooth wear, tooth function and cultural variability. American Journal of Physical Anthropology34: 175,190) and revealed severe surface loss in both males and females with horizontal wear being the dominant pattern (62.4% male, 57.5% female). The width of coronal tissue above the pulp chamber, as well as the maximum depth and width of periapical lesions, was measured from both standard radiographs and digital images. The high prevalence of periapical pathology in the Maori underlined the extreme nature of dental wear in these people. It is postulated that this degree of tooth loss may be attributable to a change in diet from large birds to marine-dependence, the introduction of the kumara to New Zealand, dental erosion and finally, to the excessive masticatory forces exerted by a robust facial complex on normally sized teeth. Fenestrated lesions were highly prevalent (83% of skulls) and were centered mostly on the maxilla, with an even distribution among tooth classes. The finding of periapical lesions in teeth with minimal observable wear was attributed to traumatic occlusion. Copyright © 2001 John Wiley & Sons, Ltd. [source]

R1 Effect of brushing on dental erosion

Erosive potential of beverages sold in Australian schools

AUSTRALIAN DENTAL JOURNAL, Issue 3 2009
NJ Cochrane
Abstract Background:, Dental erosion is an increasingly prevalent problem in Australia. The aim of this study was to analyse the composition and erosive potential of beverages sold for consumption in Victorian schools. Methods:, Fifteen drinks were selected and analysed to determine their pH, titratable acidity and ionic composition (calcium, fluoride and inorganic phosphate). The erosive potential of the beverages was measured by analysing weight loss, surface loss and the release of calcium ions from human enamel following a 30-minute or 24-hour exposure. The association of the chemical parameters with the measures of erosion was determined using Spearman's rank correlation. Results:, All beverages tested except the milks and the bottled water produced significant dental erosion in vitro. The only chemical parameter that correlated significantly with all measures of erosion was the initial pH of the beverage (p < 0.01). Levels of fluoride similar to those of Australian reticulated water were found in the carbonated beverages. Conclusions:, The majority of the tested beverages sold from school canteens exhibited erosive potential. [source]

Edge-roundness of boulders of Torridonian Sandstone (northwest Scotland): applications for relative dating and implications for warm and cold climate weathering rates

BOREAS, Issue 2 2010
MARTIN P. KIRKBRIDE
Kirkbride, M.P. & Bell, C.M. 2009: Edge-roundness of boulders of Torridonian Sandstone (northwest Scotland): applications for relative dating and implications for warm and cold climate weathering rates. Boreas, 10.1111/j. 1502-3885.2009.00131.x. ISSN 0300-9483. The relative ages of late Quaternary morainic and rock avalanche deposits on Late Precambrian Torridonian Sandstone are determined from the characteristic edge-roundness of constituent boulders. Because weathering of sandstone is manifest as edge-rounding by granular disintegration, a relative chronology can be derived by measuring the effective radii of curvature of a sample of boulder edges. Thirteen samples totalling 597 individual boulder edges fall into two statistically distinct groups. Moraines of inferred Younger Dryas age (12.9,11.5 kyr BP) are distinguished from moraines of the Wester Ross Re-advance (,14.0 kyr BP). One moraine previously assumed to be of Younger Dryas age is reassigned to the older group. The method allows spatial extrapolation of deposit ages from dated sites where lithological and sampling criteria are met. Calculated rates of edge-rounding imply that granular disintegration was several times more rapid during cold stadial climates than during the Holocene. Used as a proxy for boulder ,erosion rate', this indicates that surface loss of grains in glacial climates exceeds that during interglacials by a factor of 2,5, with implications for the calculation of exposure ages from cosmogenic nuclides. [source]

Kinks and rotations in long Josephson junctions

MATHEMATICAL METHODS IN THE APPLIED SCIENCES, Issue 15 2001
Wolfgang Hauck
Abstract Kinks and rotations are studied in long Josephson junctions for small and large surface losses. Geometric singular perturbation theory is used to prove existence for small surface losses, while numerical continuation is necessary to handle large surface losses. A survey of the system behaviour in terms of dissipation parameters and bias current is given. Linear orbital stability for kinks is proved for small surface losses by calculating the spectrum of the linearized problem. The spectrum is split into essential spectrum and discrete spectrum. For the determination of the discrete spectrum, robustness of exponential dichotomies is used. Puiseux series together with perturbation theory for linear operators are an essential tool. In a final step, a smooth Evans function together with geometric singular perturbation theory is used to count eigenvalues. For kinks, non-linear orbital stability is shown. For this purpose, the asymptotic behaviour of a semigroup is given and the theory of centre and stable manifolds is applied. Copyright © 2001 John Wiley & Sons, Ltd. [source]

Comparison of ozone fluxes over grassland by gradient and eddy covariance technique

ATMOSPHERIC SCIENCE LETTERS, Issue 3 2009
Jennifer B. A. Muller
Abstract Ozone flux measurements over vegetation are important to estimate surface losses and ozone uptake by plants. The gradient and eddy covariance flux technique were used for measurements over grassland at a flux-monitoring site in southern Scotland during August 2007. The comparison of the two methods shows that the aerodynamic flux-gradient method provides very similar long-term average fluxes of ozone as the eddy covariance method. The eddy covariance technique is better at capturing diurnal cycles and short-term changes, but the comparison of two fast analysers illustrate that there can be considerable measurement uncertainty. Copyright © 2009 Royal Meteorological Society [source]