ABSTRACT Objective: To measure enamel thickness at the proximal surfaces of the mandibular incisors, using micro-computed tomography (micro-CT) scans. Material and Methods: Forty-one single-rooted mandibular incisors were selected and analyzed according to anatomical characteristics, to form three groups: Group 1 - central incisors (n = 18); Group 2 - right lateral incisors (n = 10); and Group 3 - left lateral incisors (n = 13). First, enamel thickness at the proximal contact areas of the mandibular incisors was measured. Second, the mesial and distal surfaces of the lateral incisors were compared. Finally, the relationship between the tooth width and the mean enamel thickness was determined. Each tooth was scanned with a micro-CT scanner, and the image was processed with SCANCO micro-CT onboard analysis software. Results: There were no statistically significant differences in mean enamel thickness between the mesial and distal surfaces for each lateral incisor, or between contralateral lateral incisors. In all surfaces analyzed, the upper zones had statistically significantly thinner enamel (0.52 ± 0.10 mm) when compared to the middle and lower zones (0.60 ± 0.08 mm and 0.59 ± 0.08 mm, respectively). There was no correlation (r =0.07) between enamel thickness of the mandibular incisor and the tooth width. Conclusions: The enamel thickness of the mandibular incisors is similar on the mesial and distal surfaces, with the thinnest layer located at the upper zone.

RESUMO Objetivo: Medir a espessura do esmalte nas superfícies proximais dos incisivos inferiores, usando imagens de microtomografia computadorizada (micro-CT). Material e Métodos: Quarenta e um incisivos inferiores com raiz única foram selecionados e analisados de acordo com as características anatômicas, formando três grupos: Grupo 1 - incisivos centrais (n = 18); Grupo 2 - incisivos laterais direitos (n = 10); e Grupo 3 - incisivos laterais esquerdos (n = 13). Primeiro, foi medida a espessura do esmalte nas áreas de contato proximal dos incisivos inferiores. Em segundo lugar, as faces mesial e distal dos incisivos laterais foram comparadas. Por fim, foi determinada a relação entre a largura do dente e a espessura média do esmalte. Cada dente foi escaneado com um scanner micro-CT, e a imagem foi processada com o software de análise SCANCO micro-CT. Resultados: Não houve diferenças estatisticamente significativas na espessura média do esmalte entre as superfícies mesial e distal de cada incisivo lateral, ou entre os incisivos laterais contralaterais. Em todas as superfícies analisadas, as zonas superiores apresentaram esmalte significativamente mais fino (0,52 ± 0,10 mm) quando comparadas às zonas média e inferior (0,60 ± 0,08 mm e 0,59 ± 0,08 mm, respectivamente). Não houve correlação (r = 0,07) entre a espessura do esmalte do incisivo inferior e a largura do dente. Conclusões: A espessura do esmalte dos incisivos inferiores é semelhante nas faces mesial e distal, com a camada mais fina localizada na zona superior.

ABSTRACT Objective: This study was designed to analyze and compare the cusp and apex movements of the maxillary canines and first molars during canine retraction in the first step of extraction space closure, and to evaluate if these teeth follow a curvilinear (acceleration and/or deceleration) movement rate. Material and Methods: Twenty-five patients (23.3 ± 5.1 years of age) were enrolled. The retraction of the maxillary canines was accomplished using nickel-titanium closed coil springs (100gf) on 0.020-in stainless steel archwire. Oblique cephalograms were traced and superimposed on the anatomic best fit of the maxilla (before the retraction [T0], and after one month [T1], three [T3], five [T5] and seven [T7] months). Statistics was based in a normally distributed data. Multilevel procedures were used to derive polynomials for each of the measurements. Student’s t-test and one-way repeated measures ANOVA were conducted. The level of significance of 5% was adopted. Results: Canine cusps and apexes did not follow a quadratic curve regarding horizontal movement (neither accelerate nor decelerate). Canine and molar cusps showed more horizontal movement than apexes (4.80 mm vs. 2.78 mm, and 2.64 mm vs. 2.17 mm, respectively). Conclusions: Canine did not accelerate or decelerate overtime horizontally; the cusps and apexes of the canines and molars showed more horizontal movement and larger rate at the beginning of canine retraction, followed by significantly smaller and constant movement rate after the first month.

RESUMO Objetivo: O objetivo deste estudo foi analisar a movimentação das cúspides e dos ápices de caninos e primeiros molares superiores durante a retração de caninos na primeira fase do fechamento do espaço pós-extração, e avaliar se esses dentes apresentam mudança na taxa de movimentação (aceleração e/ou desaceleração). Material e Métodos: Vinte e cinco pacientes (idade = 23,3 ± 5,1 anos) foram incluídos. A retração dos caninos superiores foi realizada com molas helicoidais fechadas de níquel-titânio (100gf) em arco 0,020” de aço inoxidável. Foram feitos traçados cefalométricos de telerradiografias oblíquas e sobrepostos ao melhor ajuste anatômico da maxila (antes da retração [T0]; após um mês [T1], três meses [T3], cinco meses [T5] e sete meses [T7]). A estatística foi baseada em dados com distribuição normal. Procedimentos multiníveis foram usados para derivar polinômios para cada uma das medidas. Teste t de Student e ANOVA de uma via para medidas repetidas foram realizados, adotando-se um nível de significância de 5%. Resultados: As cúspides e os ápices dos caninos não seguiram uma curva quadrática em relação ao movimento horizontal (sem aceleração ou desaceleração). As cúspides dos caninos e molares apresentaram mais movimento horizontal do que os ápices (4,80 mm vs. 2,78 mm e 2,64 mm vs. 2,17mm, respectivamente). Conclusões: A movimentação horizontal dos caninos não acelerou ou desacelerou ao longo do tempo; as cúspides e os ápices dos caninos e molares apresentaram maior movimento horizontal e maior taxa de movimentação no início da retração dos caninos, seguida por uma taxa de movimentação significativamente menor e constante após o primeiro mês.

Abstract Amazon parrots are long-lived birds with highly developed cognitive skills, including vocal learning. Several parrot mitogenomes have been sequenced, but important aspects of their organization and evolution are not fully understood or have limited experimental support. The main aim of the present study was to describe the mitogenome of the blue-fronted Amazon, Amazona aestiva, and compare it to other mitogenomes from the genus Amazona and the order Psittaciformes. We observed that mitogenomes are highly conserved among Amazon parrots, and a detailed analysis of their duplicated control regions revealed conserved blocks. Population level analyses indicated that the specimen analyzed here seems to be close to A. aestiva individuals from Bahia state. Evolutionary relationships of 41 Psittaciformes species and three outgroups were inferred by BEAST. All relationships were retrieved with high support.

The memorization and production of song in songbirds share important parallels with the process of speech acquisition in humans. In songbirds, these processes are dependent on a group of specialized telencephalic nuclei known as the song system: HVC (used as a proper name), RA (robust nucleus of arcopallium), LMAN (lateral magnocellular nucleus of the nidopallium) and striatal Area X. A recent study suggested that the arcopallium of the Sayornis phoebe, a non vocal learner suboscine species, contains a nucleus with some properties similar to those of songbird RA, suggesting that the song system may have been present in the last common ancestor of these groups. Here we report morphological and gene expression evidence that a region with some properties similar to RA is present in another suboscine, the Amazonian endemic Willisornis poecilinotus. Specifically, a discrete domain with a distinct Nissl staining pattern and that expresses the RA marker RGS4 was found in the arcopallium where the oscine RA is localized. Our findings, combined with the previous report on the S. phoebe, suggest that an arcopallial region with some RA-like properties was present in the ancestor of both Suboscines infraorders Tyranni and Furnarii, and is possibly an ancestral feature of Passeriformes.