Biased-corrected richness estimates for the Amazonian tree flora

Amazonian forests are extraordinarily diverse, but the estimated species richness is very much debated. Here, we apply an ensemble of parametric estimators and a novel technique that includes conspecific spatial aggregation to an extended database of forest plots with up-to-date taxonomy. We show that the species abundance distribution of Amazonia is best approximated by a logseries with aggregated individuals, where aggregation increases with rarity. By averaging several methods to estimate total richness, we confirm that over 15,000 tree species are expected to occur in Amazonia. We also show that using ten times the number of plots would result in an increase to just ~50% of those 15,000 estimated species. To get a more complete sample of all tree species, rigorous field campaigns may be needed but the number of trees in Amazonia will remain an estimate for years to come

Amazon tree dominance across forest strata

The forests of Amazonia are among the most biodiverse plant communities on Earth. Given the immediate threats posed by climate and land-use change, an improved understanding of how this extraordinary biodiversity is spatially organized is urgently required to develop effective conservation strategies. Most Amazonian tree species are extremely rare but a few are common across the region. Indeed, just 227 ‘hyperdominant’ species account for >50% of all individuals >10 cm diameter at 1.3 m in height. Yet, the degree to which the phenomenon of hyperdominance is sensitive to tree size, the extent to which the composition of dominant species changes with size class and how evolutionary history constrains tree hyperdominance, all remain unknown. Here, we use a large floristic dataset to show that, while hyperdominance is a universal phenomenon across forest strata, different species dominate the forest understory, midstory and canopy. We further find that, although species belonging to a range of phylogenetically dispersed lineages have become hyperdominant in small size classes, hyperdominants in large size classes are restricted to a few lineages. Our results demonstrate that it is essential to consider all forest strata to understand regional patterns of dominance and composition in Amazonia. More generally, through the lens of 654 hyperdominant species, we outline a tractable pathway for understanding the functioning of half of Amazonian forests across vertical strata and geographical locations

Análise de dentição mista: tomografia versus predição e medida radiográfica Mixed-dentition analysis: tomography versus radiographic prediction and measurement

OBJETIVO: o objetivo dos autores desse estudo foi comparar o método de análise de dentição mista que utiliza tomografia computadorizada de feixe cônico para avaliar os diâmetros dos dentes intraósseos com os métodos de Moyers, Tanaka-Johnston e radiografias oblíquas em 45º. MÉTODOS: foram realizadas medidas, na arcada inferior, dos diâmetros mesiodistais dos incisivos permanentes irrompidos, nos modelos de gesso com auxílio de paquímetro digital e estimativa do tamanho de pré-molares e caninos permanentes ainda não irrompidos utilizando-se a tabela de Moyers e a fórmula de predição de Tanaka-Johnston. Nas radiografias oblíquas em 45º, caninos e pré-molares foram medidos utilizando-se o mesmo instrumento. Nas tomografias, as mesmas unidades dentárias foram aferidas por meio de ferramentas do programa Dolphin. RESULTADOS: a análise estatística revelou elevada concordância entre o método tomográfico e o radiográfico, e baixa concordância entre o tomográfico e os demais avaliados. CONCLUSÃO: a tomografia computadorizada de feixe cônico mostrou-se confiável para análise da dentição mista e apresenta algumas vantagens em relação aos métodos comparados: a observação e mensuração dos dentes intraósseos individualmente, com a possibilidade, contudo, de visualizá-los sob diferentes perspectivas e sem superposição de estruturas anatômicas.<br>OBJECTIVE: The aim of this study was to evaluate the method for mixed-dentition analysis using Cone-Beam Computed Tomography for assessing the diameter of intra-osseous teeth and compare the results with those obtained by Moyers, Tanaka-Johnston, and 45-degree oblique radiographs. METHODS: Measurements of mesial-distal diameters of erupted lower permanent incisors were made on plaster cast models by using a digital calliper, whereas assessment of the size of non-erupted permanent pre-molars and canines was performed by using Moyer's table and Tanaka-Johnston's prediction formula. For 45-degree oblique radiographs, both canines and pre-molars were measured by using the same instrument. For tomographs, the same dental units were gauged by means of Dolphin software resources. RESULTS: Statistic analysis revealed high agreement between tomographic and radiographic methods, and low agreement between tomographs and other methods being evaluated. CONCLUSION: Cone-Beam Computed Tomography was accurate for mixed-dentition analysis in addition to presenting some advantages over compared measurement methods: observation and measurement of intra-osseous teeth individually with the possibility, however, to view them from different prospects and without superimposition of anatomical structures

Asymmetric extractions in orthodontics

INTRODUCTION: Extraction decisions are extremely important in during treatment planning. In addition to the extraction decision orthodontists have to choose what tooth should be extracted for the best solution of the problem and the esthetic/functional benefit of the patient. OBJECTIVE: This article aims at reviewing the literature relating the advantages, disadvantages and clinical implications of asymmetric extractions to orthodontics. METHODS: Keywords were selected in English and Portuguese and the EndNote 9 program was used for data base search in PubMed, Web of Science (WSc) and LILACS. The selected articles were case reports, original articles and prospective or retrospective case-control studies concerning asymmetrical extractions of permanent teeth for the treatment of malocclusions. CONCLUSION: According to the literature reviewed asymmetric extractions can make some specific treatment mechanics easier. Cases finished with first permanent molars in Class II or III relationship in one or both sides seem not to cause esthetic or functional problems. However, diagnosis knowledge and mechanics control are essential for treatment success