Abstract This study evaluated the interference of enamel and coronal dentin thickness and ambient light in pulse oximetry interpretation, using SaO2the human finger as a reference. Forty-two intact human permanent mandibular molars were sectioned mesiodistally in the central portion. Buccal and lingual dentin surfaces were drilled, and 4 mm, 3 mm and 2 mm enamel/dentin thicknesses were interposed between finger and device, after which SaO2 levels were measured by finger pulse oximetry. A reference device was designed to align pulse oximeter light-emitting diode, buccal surface of tooth, little finger, lingual surface of tooth and photodiode. Variables were described as means and standard deviation, and the confidence interval was reported. Repeated measures analysis of variance (ANOVA) was used to compare the groups, followed by Bonferroni correction. Student t test for paired samples was used to determine presence of ambient light (α = 0.05). Mean SaO2 level was lower at 4.0 ± 0.2 mm thickness, regardless of presence or absence of ambient light (92.7% and 89.3%). The other thicknesses yielded values of 95.5% and 94.5% at 3.0 ± 0.2 mm, and 96.4% and 96.0% at 2.0 ± 0.2 mm (p < 0.001). There were significant differences between SaO2 values at 4.0 ± 0.2 mm, 3.0 ± 0.2 mm and 2.0 ± 0.2 mm thicknesses, in the presence of ambient light. Mean SaO2 level in positive control was 96.3%, and mean pulse rate was 69.5 bpm in presence of ambient light; in the absence of light, these values were 96% and 70.5 bpm. Enamel and dentin thickness interfere with SaO2, regardless of presence or absence of ambient light. The lowest SaO2 levels were found for the thickest tooth samples.

RESUMO Tem-se como objetivo no presente artigo analisar a chegada dos Vikings na costa do rio Tejo, colocando em destaque os impactos das navegações no período do VIII ao IX século d.C.Para interpretar tal episódio serão utilizadas fontes textuais e arqueológicas além da construção de uma contextualização acerca do período abordado. Será possível observar que a chegada dos vikings ou normandos é um momento chave para a história da região em redor de Lisboa. De região esquecida e lateral, na perspectiva dos poderes estabelecidos em Córdova, o litoral do Gharb al-Andalus, o futuro litoral português central, passará por uma fase de surpresa, de ataques mas também, de revitalização e de novos desafios.

ABSTRACT The goal of this article is to analyze the Vikings' arrival at the coast of the Tagus, highlighting the impacts of the sailings in the period from the VII to the IX century A.D. To interpret such episode, textual and archeological sources will be used, as well as the construction of a contextualization regarding the addressed period. It will be possible to observe that the Vikings' or the Normans' arrival is a key moment for the history of the region around Lisbon. From a forgotten and lateral region, in the perspective of the established powers in Cordoba, the coast of Gharb al-Andalus, the future central Portuguese coast, will undergo a phase of surprise, of attacks, but also, of renovations and of new challenges.