Impact of different fluoride concentrations and pH of dentifrices on tooth erosion/abrasion in vitro

Background: This in vitro study analysed the effect of different fluoride concentrations in acidic or neutral liquid dentifrices in protecting enamel and dentine from erosive and abrasive wear. Methods: Bovine enamel and dentine specimens (n = 132) were randomly allocated to 11 groups (each n = 12): experimental liquid dentifrices with 550 ppm F, 1100 ppm F, 5000 ppm F or 0 ppm F/placebo (each at pH 4.5 and pH 7.0); and commercial dentifrices with 550 ppm F (Colgate Baby, pH 7.0), 1100 ppm F (Crest, pH 7.0) and 5000 ppm F (Duraphat, pH 7.0). The specimens were subjected to erosion for 90 seconds, 4 times/day, over 7 days. Immediately after the first and last erosion, the specimens were brushed for 15 seconds using one of the dentifrices. Tooth wear was measured profilometrically (lm) and analysed by ANOVA (p < 0.05). Results: All fluoridated liquid dentifrices significantly reduced enamel wear compared to the placebo and commercial dentifrices. Only liquid dentifrices with 1100 and 5000 ppm F significantly reduced dentine wear compared to placebo dentifrice. The pH had no effect, but the consistency had a significant impact on the effect of dentifrices. Conclusions: Liquid dentifrices with high F concentration appear to be a good option to prevent tooth wear

Saliva and dental erosion

Dental erosion is a multifactorial condition. The consideration of chemical, biological and behavioral factors is fundamental for its prevention and therapy. Among the biological factors, saliva is one of the most important parameters in the protection against erosive wear. Objective: This review discusses the role of salivary factors on the development of dental erosion. Material and Methods: A search was undertaken on MeDLINe website for papers from 1969 to 2010. The keywords used in the research were "saliva", "acquired pellicle", "salivary flow", "salivary buffering capacity" and "dental erosion". Inclusion of studies, data extraction and quality assessment were undertaken independently and in duplicate by two members of the review team. Disagreements were solved by discussion and consensus or by a third party. Results: Several characteristics and properties of saliva play an important role in dental erosion. Salivary clearance gradually eliminates the acids through swallowing and saliva presents buffering capacity causing neutralization and buffering of dietary acids. Salivary flow allows dilution of the acids. In addition, saliva is supersaturated with respect to tooth mineral, providing calcium, phosphate and fluoride necessary for remineralization after an erosive challenge. Furthermore, many proteins present in saliva and acquired pellicle play an important role in dental erosion. Conclusions: Saliva is the most important biological factor affecting the progression of dental erosion. Knowledge of its components and properties involved in this protective role can drive the development of preventive measures targeting to enhance its known beneficial effects.

Brazilian sandy beach macrofauna production: a review

The state of the art of the studies on the production of Brazilian sandy beach macrofauna was analyzed on the basis of the data available in the literature. For this purpose, the representativeness of the production dataset was examined by latitudinal distribution, degree of exposure and morphodynamic state of beaches, taxonomic groups, and methods employed. A descriptive analysis was, further, made to investigate the trends in production of the more representative taxonomic groups and species of sandy beach macrofauna. A total of 69 macrofauna annual production estimates were obtained for 38 populations from 25 studies carried out between 22º56'S and 32º20'S. Production estimates were restricted to populations on beaches located on the southern and southeastern Brazilian coast. Most of the populations in the dataset inhabit exposed dissipative sandy beaches and are mainly represented by mollusks and crustaceans, with a smaller number of polychaetes. The trends in production among taxonomic groups follow a similar pattern to that observed on beaches throughout the world, with high values for bivalves and decapods. The high turnover rate (P/B ratio) of the latter was due to the presence of several populations of the mole crab Emerita brasiliensis, which can attain high values of productivity, in the dataset. Most of the studies focus on the comparison of production and, especially, of P/B ratio according to life history traits in populations of the same species/taxonomic group. Despite the importance of life history-production studies, other approaches, such as the effect of man-induce disturbances on the macrofauna, should be undertaken in these threatened environments.

A new method to evaluate glenoid erosion in instable shoulder

Background: We aimed to establish values and parameters using multislice reconstruction in axial computerized tomography (CT) in order to quantify the erosion of the glenoid cavity in cases of shoulder instability. Methods: We studied two groups using CT. Group I had normal subjects and Group II had patients with shoulder instability. We measured values of the vertical segment, the superior horizontal, medial and inferior segments, and also calculated the ratio of the horizontal superior and inferior segments of the glenoid cavity in both normal subjects and those with shoulder instability. These variables were recorded during arthroscopy for cases with shoulder instability. Results The mean values were 40.87 mm, 17.86 mm, 26.50 mm, 22.86 mm and 0.79 for vertical segment, the superior horizontal, medial and inferior segments, and the ratio between horizontal superior and inferior segments of the glenoid cavity respectively, in normal subjects. For subjects with unstable shoulders the mean values were 37.33 mm, 20.83 mm, 23.07 mm and 0.91 respectively. Arthroscopic measurements yielded an inferior segment value of 24.48 mm with a loss of 2.39 mm (17.57%). The ratio between the superior and inferior segments of the glenoid cavity was 0.79. This value can be used as a normative value for evaluating degree of erosion of the anterior border of the glenoid cavity. However, values found using CT should not be used on a comparative basis with values found during arthroscopy. Conclusions: Computerized tomographic measurements of the glenoid cavity yielded reliable values consistent with those in the literature.

The village that vanished : The roots of erosion in a Tanzanian village

In the village'of Citing in the northern highlands of Tanzania, the factors: social stratification, land tenure, production strategies, investment patterns and the economic uncertainties of society are studied and their relationship to land degradation is examined. The main assumption of the study is that the causes of land degradation are so complex that a methodology that emphasises contextualisation has to be used. A methodological framework that considers inter-linkages between all these factors is developed and tested. The result of the test shows that contextualisation gives a more in-depth and complex explanation than conventional, positivist research. The study gives a detailed account of the relationship that various wealth groups have to land and land degradation in the village. It is found that all wealth groups are destructive to the land but in varying ways. The rich farmers are over-cultivating land marginal to agriculture, the middle peasants have too many cattle in the village while the poor peasants are so marginalised socially that they hardly influence land management. Those identified as having economic as well as social incentives to maintain soil fertility are the middle peasants, while the rich farmers are shown to be consciously soil-mining the former grazing areas.

Characterization of sands in the beach-dune systems of the Eastern Canary Islands.

Characterization of sands in the beach-dune systems of the Eastern Canary Islands.

Problemática ambiental en la isla de La Graciosa: ¿Hay déficit de arena actual en sistemas playa-duna?

[ES] La isla La Graciosa está situada al noroeste de Lanzarote y tiene una extensión de 27,05 km2. Se trata de un área que presenta un alto valor ecológico pues está protegida a través de diferentes figuras tales como: Parque Natural y Reserva Marina del Archipiélago Chinijo, Reserva de la Biosfera de Lanzarote, Zona de Especial Protección de aves (ZEPA) y Zona de Especial Conservación (ZEC), entre otras. En la isla hay varios sistemas playa-duna tanto en la mitad nororiental de la isla (Las Conchas, Lambra y El Jablillo) como en su parte meridional (Barranco de Los Conejos, Las Caletas, El Salado y Francesa). Algunas de las playas muestran evidencias de un déficit sedimentario pues tienen una reducida o nula entrada de sedimentos arenosos al sistema y/o muestran procesos erosivos que hacen aparecer el substrato rocoso. Además, se observa en el interior de la isla la estabilización de los mantos eólicos por la vegetación. Estos ambientes eólicos costeros son esenciales, tanto para la preservación de los ecosistemas protegidos, como para la actividad turística insular. En este contexto se están desarrollando investigaciones multidisciplinares para elaborar un diagnóstico científico de esta problemática ambiental, determinando si las causas de este déficit sedimentario son naturales o antrópicas, y proponer soluciones al respecto.

A pocket beach that reaches equilibrium after becoming disconnected from a large system of beaches. Playa Barca (Fuerteventura)

[EN] Playa Barca is a 370 m long beach located within the system of the Leeward beaches on the Jandía peninsula, Fuerteventura. This system of beaches represents one of the major sources of economic income to the island, both because of its natural landscape that attract a specific type of tourism, and because of its particular climate conditions that make these beaches ideal for practicing wind-water sports. Nevertheless, in the past decades, this area has suffered from a significant and worrying coastline retreat. In order to look for an explanation to this retreat, five topographic surveys were carried out in October 1999, February 2001, February 2002, February 2003 and February 2013 to track the beach behavior in the last 15 years. A total station Topcon GTS-303D was used for this purpose. Surveys were carried out during low spring tides, so that the outer limit was the furthest possible depending on wave conditions. The inner limit covered part of the dunes in the backshore. From these topographic data both coastline changes and the sedimentary balance have been obtained.

Beach Profiles: Complying with the EU Directive

Interpretación realizada por las alumnas en prácticas de la Facultad de Traducción e Interpretación, Danaide Rodríguez Hernández, Esther Ramírez Millares y Estíbaliz López-Leiton Trujillo, ,

Sedimentary budget on Las Canteras Beach, Gran Canaria (Canary Islands, Spain)

[EN]This paper deals with sedimentary balances and how the sediments move in function of the waves in a beach with special boundary conditions. For this purpose, the topography of the beach was done with a total station and two prism. Topography data were analyzed with SIG software. Wave data were taken from deepwater buoys. Two parameters were calculated, the Dean’s parameter and Larson’s (1988) parameter, to know the type of the beach. Balances show an accretion of sand on the beach even though in some periods there were big losses of sand on the beach. The parameters calculated are not good to estimate the type of the beach due to the boundary conditions of this particular beach