Intracanal removal and apical extrusion of filling material after retreatment using rotary or reciprocating instruments: A new approach using human cadavers.

AIM: This study compared intracanal removal of filling as well as the frequency and volume of extruded material after retreatment with either HyFlex or Reciproc instruments in mandibular teeth from cadavers. METHODOLOGY: The root canals of 14 pairs of contralateral single-rooted teeth in mandibles of cadavers were instrumented with Reciproc R40 and filled using lateral compaction. The mandibles were scanned in a micro-computed tomographic (micro-CT) device before and after retreatment procedures. The contralateral teeth were assigned to two groups (n = 14) according to the retreatment protocol using either HyFlex or Reciproc instrument systems. In the HyFlex group, the HyFlex Remover instrument was worked 3 mm short of the working length (WL), followed by HyFlex CM 40.04 and 50.04 at the WL. In the Reciproc group, the R50 instrument was worked up at the coronal two thirds, followed by two more cycles until the WL was reached. Pre- and post-operative micro-CT images were analysed for extrusion and intracanal removal of filling material. RESULTS: After retreatment, extrusion of filling material occurred in 11 (78%) and 14 (100%) teeth from HyFlex and Reciproc groups respectively (p > .05). A similar volume of extruded material was observed after retreatment with both systems (p > .05). A significant decrease in the intracanal filling volume was verified after retreatment with both tested systems (p < .05). However, residual filling material was found in all root canals, regardless of the system. The amount of filling material removed (HyFlex = 80.8%; Reciproc = 65.9%) and the operation time was similar between systems (p > .05). CONCLUSIONS: A high frequency of filling material extrusion was observed after retreatment with the two systems in a cadaver model, with no significant difference between them. Both protocols obtained similar efficacy in filling material removal procedures, although none completely cleaned the canals.

Unprepared surface areas, accumulated hard tissue debris, and dentinal crack formation after preparation using reciprocating or rotary instruments: a study in human cadavers.

OBJECTIVES: This study using contralateral teeth from human cadavers assessed the amount of unprepared wall surface areas (USA), accumulated hard tissue debris (AHTD), and dentinal crack formation after root canal preparation using either reciprocating or rotary instruments. MATERIALS AND METHODS: Incisors with a single root canal from 11 human mandibles had their root canals prepared with Reciproc or Mtwo. Each contralateral tooth was treated with one of the test instruments in order to create matched pairs. Micro-CT scans were taken before and after preparation to instrument sizes 40 and 50 in both groups. USA and AHTD were evaluated in the full canal length or the apical portion only. Crack formation was also evaluated in the full root length. RESULTS: After size 40, no significant differences in USA and AHTD were observed in the full canal length (P > .05). Separate analysis of the apical 4-mm canal revealed no difference in AHTD, but significantly more USA with Mtwo than Reciproc (P < .05). After size 50, the amount of USA was similar between groups both in the full canal and in the apical canal (P > .05). More AHTD were observed in the full canal after using Mtwo size 50 (P < .05), but no difference occurred in the apical canal only (P > .05). Intragroup analyses showed a significant decrease of USA and a significant increase of AHTD when preparation size increased from 40 to 50 (P < .05). In teeth without any pre-existing detectable dentinal defect (n = 38), crack formation occurred in 4 teeth, 2 from each preparation system. CLINICAL RELEVANCE: Reciproc instrument size 40 resulted in more prepared areas in the apical canal than Mtwo instrument of the same size. However, the amount of AHTD did not differ between them at this file size. Canal enlargement to size 50 prepared more walls but created more debris. Dentinal defects were produced after preparation with both systems.

Characterization and effect of nanocomplexed fluoride solutions on the inhibition of enamel demineralization created by a multispecies cariogenic biofilm model.

OBJECTIVES: The aim of this study was to assess the in vitro caries preventive effect of nanocomplexed solutions of hydroxypropyl-ß-cyclodextrin and γ-cyclodextrin associated with titanium tetrafluoride (TiF4) after different complexation times (12 or 72 h). MATERIALS AND METHODS: Enamel blocks were randomly distributed in 9 groups (n = 11): negative control, hydroxypropyl-ß-cyclodextrin, γ-cyclodextrin, TiF4, hydroxypropyl-ß-cyclodextrin:TiF4 12 h, hydroxypropyl-ß-cyclodextrin:TiF4 72 h, γ-cyclodextrin:TiF4 12 h, γ-cyclodextrin:TiF4 72 h, and NaF (positive control). The solutions were applied for 1 min and the blocks were exposed to a biofilm model. Nanocompounds were characterized by differential scanning calorimetry and X-ray powder diffraction. The percentage of surface microhardness loss (%SML), mineral density changes (ΔZ), lesion depth, surface morphology (scanning electron microscopy-SEM), and chemical characterization (energy-dispersive spectroscopy-EDS) were assessed. RESULTS: No oxidation was observed, and the formation of the nanocomplexes was evidenced by changes in the melting point compared to pure cyclodextrins and the loss of crystallinity of the materials. Hydroxypropyl-ß-cyclodextrin:TiF4 72 h resulted in lower %SML than negative control, hydroxypropyl-ß-cyclodextrin, γ-cyclodextrin, and TiF4 (p < 0.05). NaF differed from all groups (p < 0.05), except for hydroxypropyl-ß-cyclodextrin:TiF4 72 h (p = 0.83). ΔZ of hydroxypropyl-ß-cyclodextrin:TiF4 72 h was higher than negative control, hydroxypropyl-ß-cyclodextrin, γ-cyclodextrin, γ-cyclodextrin:TiF4 1 2 h, γ-cyclodextrin:TiF4 72 h, and NaF (p < 0.05) and similar to TiF4 and hydroxypropyl-ß-cyclodextrin:TiF4 12 h (p > 0.05). SEM/EDS detected Ti in the blocks subjected to TiF4-products. CONCLUSION: The hydroxypropyl-ß-cyclodextrin:TiF4 72 h solution showed caries preventive effect on the surface and subsurface of the enamel. CLINICAL RELEVANCE: A hydroxypropyl-ß-cyclodextrin nanosystem, in association with TiF4 after 72 h of complexation, may be a promising agent for the prevention of enamel demineralization.

Cranial and endocranial diversity in extant and fossil atelids (Platyrrhini: Atelidae): A geometric morphometric study.

OBJECTIVES: Platyrrhines constitute a diverse clade, with the modern Atelidae exhibiting the most variation in cranial and endocast morphology. The processes responsible for this diversification are not well understood. Here, we present a geometric morphometric study describing variation in cranial and endocranial shape of 14 species of Alouatta, Ateles, Brachyteles, and Lagothrix and two extinct taxa, Cartelles and Caipora. METHODS: We examined cranial and endocranial shape variation among species using images reconstructed from CT scans and geometric morphometric techniques based on three-dimensional landmarks and semilandmarks. Principal components analyses were used to explore variation, including the Procrustes shape coordinates, summing the logarithm of the Centroid Size, the common allometric component, and residual shape components. RESULTS: Differences in endocranial shape are related to a relative increase or decrease in the volume of the neocortex region with respect to brainstem and cerebellum regions. The relative position of the brainstem varies from a posterior position in Alouatta to a more ventral position in Ateles. The shape of both the cranium and endocast of Caipora is within the observed variation of Brachyteles. Cartelles occupies the most differentiated position relative to the extant taxa, especially in regards to its endocranial shape. CONCLUSIONS: The pattern of variation in the extant species in endocranial shape is similar to the variation observed in previous cranial studies, with Alouatta as an outlier. The similarities between Caipora and Brachyteles were unexpected and intriguing given the frugivorous adaptations inferred from the fossil's dentition. Our study shows the importance of considering both extant and fossil species when studying diversification of complex traits.

Brain shape convergence in the adaptive radiation of New World monkeys.

Primates constitute one of the most diverse mammalian clades, and a notable feature of their diversification is the evolution of brain morphology. However, the evolutionary processes and ecological factors behind these changes are largely unknown. In this work, we investigate brain shape diversification of New World monkeys during their adaptive radiation in relation to different ecological dimensions. Our results reveal that brain diversification in this clade can be explained by invoking a model of adaptive peak shifts to unique and shared optima, defined by a multidimensional ecological niche hypothesis. Particularly, we show that the evolution of convergent brain phenotypes may be related to ecological factors associated with group size (e.g., social complexity). Together, our results highlight the complexity of brain evolution and the ecological significance of brain shape changes during the evolutionary diversification of a primate clade.

Osteoderm microstructure of Riostegotherium yanei, the oldest Xenarthra.

Abstract: Riostegotherium yanei from the Itaboraí Basin, Brazil, is the oldest known Xenarthra. This paper aims to describe the internal morphology of the osteoderms of Riostegotherium yanei from the perspective of histology and micro-CT approaches, expanding the available data on cingulate osteoderm microstructure. Seven osteoderms of R. yanei were used for the internal microstructure description and eight of Dasypus novemcinctus for comparison. The osteoderms of Riostegotherium yanei lacks the diploë-like structure typical of glyptodonts but has a three-layered structure composed of two layers of non-Haversian compact bone enclosing a central layer of primary and secondary osteons. This internal organization is distinct from other Astegotheriini of comparable age, but similar to Dasypus. The 3D reconstruction of Riostegotherium yanei revealed two patterns of internal organization. Pattern 1 of movable osteoderm is composed of large remodeled areas at the base and a more compact bone at the tongue; in Pattern 2 (both movable and buckler), the internal cavities are much smaller, more numerous, and more interconnected to each other. In one buckler osteoderm, the cavities are organized somewhat radially with a compact central region (Pattern 1). Pattern 1 of both movable and buckler osteoderms resemble that of Dasypus.

Encephalization and diversification of the cranial base in platyrrhine primates.

The cranial base, composed of the midline and lateral basicranium, is a structurally important region of the skull associated with several key traits, which has been extensively studied in anthropology and primatology. In particular, most studies have focused on the association between midline cranial base flexion and relative brain size, or encephalization. However, variation in lateral basicranial morphology has been studied less thoroughly. Platyrrhines are a group of primates that experienced a major evolutionary radiation accompanied by extensive morphological diversification in Central and South America over a large temporal scale. Previous studies have also suggested that they underwent several evolutionarily independent processes of encephalization. Given these characteristics, platyrrhines present an excellent opportunity to study, on a large phylogenetic scale, the morphological correlates of primate diversification in brain size. In this study we explore the pattern of variation in basicranial morphology and its relationship with phylogenetic branching and with encephalization in platyrrhines. We quantify variation in the 3D shape of the midline and lateral basicranium and endocranial volumes in a large sample of platyrrhine species, employing high-resolution CT-scans and geometric morphometric techniques. We investigate the relationship between basicranial shape and encephalization using phylogenetic regression methods and calculate a measure of phylogenetic signal in the datasets. The results showed that phylogenetic structure is the most important dimension for understanding platyrrhine cranial base diversification; only Aotus species do not show concordance with our molecular phylogeny. Encephalization was only correlated with midline basicranial flexion, and species that exhibit convergence in their relative brain size do not display convergence in lateral basicranial shape. The evolution of basicranial variation in primates is probably more complex than previously believed, and understanding it will require further studies exploring the complex interactions between encephalization, brain shape, cranial base morphology, and ecological dimensions acting along the species divergence process.

Efficacy of WaveOne Gold and ProDesign RT systems in removing filling material: a micro-CT analysis.

The remaining filling material after retreatment can harbor bacteria and organic tissues that can influence the outcome of the therapy. AIM: The aim of this study was to evalúate, by micro-CT, the amount of filling material remaining in the root canal after its removal using WaveOne Gold or ProDesign RT. MATERIAL AND METHOD: Forty human mandibular canines were instrumented with the ProTaper Next system up to the X2 instrument (25.06) and filled with gutta-percha cones and AHPlus. Teeth were divided into 2 groups (n=20): WaveOne Gold 25.07 (WOG) and ProDesign RT 25.08 (PRT) for filling removal, after which they were scanned in a micro-CT device to quantify the volume of remaining filling material. The data were subjected to log 10 transformation, Student 's t-test was performed to account for multiple observationsper sample, significance was set at 5%. RESULTS: Student 's t-test showed that there was no difference between the two systems regarding the volume of remaining filling material in the thirds: apical (p = 0.392), middle (p = 0.065), or cervical (p = 0.918). CONCLUSIÓN: Remaining filling material was present in all groups and both systems were similar in removing root filling material in mandibular canines.

A permanencia de material obturador após o retratamento pode abrigar bactérias e tecidos orgánicos que podem influenciar o resultado da terapia. OBJETIVO: O objetivo deste estudo foi avaliar, por micro-CT, a quantidade de material obturador remanescente no canal radicular após a desobturagdo com WaveOne Gold e ProDesign RT. MATERIAL E MÉTODO: Quarenta caninos inferiores humanos foram instrumentados com o sistema ProTaper Next até o instrumento X2 (25.06) e obturados com cones de guta-percha e AHPlus. Os dentes foram divididos em dois grupos (n=20): WaveOne Gold 25.07 (WOG) e ProDesign RT 25.08 (PRT) e escaneados em micro-CT para quantificagdo do volume de material obturador remanescente. Os dados foram submetidos á transformando log 10, o teste t de Student foi realizado para contabilizar múltiplas observagoes por amostra, a significáncia foi fixada em 5%. RESULTADOS: O teste t de Student mostrou que ndo houve diferenga no volume de material obturador remanescente entre os dois sistemas nos tergos: apical (p = 0,392), médio (p = 0,065) ou cervical (p = 0,918). CONCLUSÃO: O material obturador remanescente estavapresente em todos os grupos e ambos os sistemas foram semelhantes na remogdo do material obturador radicular nos caninos inferiores.

POLYETHYLENE FILTER FOR THE TNF2 THERMAL NEUTRON FACILITY.

The Standard Thermal Neutron Flux Unit, TNF2, in (LNMRI/IRD)(1,  2), was built for neutron detector and survey meter calibrations. The facility's fluence is achieved by moderation of four 241Am-Be with a graphite core and paraffin/graphite blocks surrounding it. Due to the small channel dimensions, it is impossible to calibrate personal dosemeters and survey meters for thermal neutrons. A polyethylene filter construction was carried out to allow the external irradiation of personal dosemeters and neutron survey meters. The polyethylene filter was constructed with 29 stacked discs with diameters ranging from 5 to 34 cm. Different thicknesses were simulated to provide the desired effect. This new irradiation configuration was also experimentally tested and compared with simulation results with MCNPX(3).

Further development of the LNMRI/IRD's TNF2 thermal system for flexible dose rate irradiation.

The 'Inverse Square Law' (ISL)(  1) requires the existence of a point radiation source to be validated, but in some cases where there is more than one source, its use is possible as long as a point is determined where a virtual source can be positioned and from this point the points correspond to the ISL. Ambient dose equivalent rate values were obtained by simulation and measurements at various points along the LNMRI Thermal Neutron Flux 2 (TNF2) central axis front face, determining a function corresponding to the inverse square of the distance and the font position at the virtual point 'y0', so that the ISL is respected. This function will help in the neutron monitors calibration, previously estimating the ambient dose equivalent at a certain distance from the face.

Intraradicular Dentinal Changes Following Fiber Postremoval: Micro-computed Tomography Analysis.

Context: Excessive dentine wear during postremoval can occur due to the adhesion between the cement and the post. Aim: The aim is to evaluate dentine wear and microcrack occurrence following the removal of intraradicular fiberglass posts that were previously cemented with two types of resin cement. Methods: Distal roots (n = 38) of lower molars were instrumented, filled, prepared for intraradicular postinstallation, and divided into two groups according to the cement used for the posts: RelyX ARC or RelyX U200. The posts were removed through abrasion using ultrasonic diamond tips, after which the degrees of dentine wear (volume/mm3) and microcrack formation were assessed using microcomputed tomographic imaging. Statistical Analysis Used: The Mann-Whitney U (P ≤ 0.05) and Chi-squared tests (P ≤ 0.05) were used. Results: After the removal of the posts, no statistically significant difference in root canal volume or microcrack occurrence was observed between the groups (P > 0.05). The procedure produced significant dentine wear regardless of the type of cement used (P < 0.05). Conclusions: The removal of fiberglass posts caused extensive dentine wear but did not influence microcrack occurrence. The type of resin cement used did not affect the dentine loss or microcrack appearance that resulted from fiberglass postremoval.

Ontogenetic skull variation in a shovel-headed amphisbaenian species.

Leposternon microcephalum is a species belonging to the Amphisbaenia, a group of burrowing reptiles. Amphisbaenia present various morphological and physiological adaptations that allow them to penetrate the ground and live underground, through a system of galleries and permanent chambers that they build themselves. Among the morphological adaptations in this group, those of the skull stand out as it serves as the main excavation tool. Four basic skull shapes are recognized: rounded, keeled, shovel-shaped, and spade-shaped. The skull of L. microcephalum belongs to this last type, which is considered the most specialized. The species inhabits soils that are highly compacted and difficult to penetrate. Among the species of Leposternon present in South America, L. microcephalum has the widest distribution, being found in all Brazilian biomes and neighboring countries such as Bolivia, Argentina, Paraguay, and Uruguay. The analysis of the skull of this species was carried out using three-dimensional geometric morphometrics (3D-GMM), a technique that allows comparative analysis, through robust statistical methods, of shape and its variations, using Cartesian coordinate data from a configuration of homologous landmarks. The technique allows the size and shape components of a structure to be analyzed separately. From an ontogenetic point of view, this methodology had also been used to investigate variations in Cynisca leucura, a member of the Amphisbaenidae with a rounded head. Our hypothesis is that the patterns of morphological differentiation in the skull, mainly in the intermediate and occipital regions, are similar in different Amphisbaenia species. Therefore, the objective of this study was to analyze cranial morphological variations in an ontogenetic series of L. microcephalum using 3D-GMM. Computed Tomographic scans of 13 specimens were analyzed: juveniles (N = 8) and adults (N = 5), based on 20 landmarks that characterize the skull. Principal components and regression analyses between shape (dependent variable) and size (independent variable) showed a clear difference between the cranial morphological pattern of juvenile individuals and that of adults. For instance, young specimens tend to have a dorsoventrally tall neurocranium, with the tip of the snout more anteriorly oriented and its dorsal border subtly curved. Dorsally, the parietal region is thicker and smoothly dome-shaped in juveniles. As in C. leucura, the variation was strongly correlated with the size change from juvenile to adult, indicating a dominant role for ontogenetic allometry in determining skull shape.

Planned Apical Preparation Using Cone-Beam Computed Tomographic Measures: A Micro-Computed Tomographic Proof of Concept in Human Cadavers.

INTRODUCTION: This study assessed the amount of unprepared surface areas at the apical 4-mm segment of the root canal after a planned preparation based on cone-beam computed tomography (CBCT) measurements. METHODS: Eighteen posterior mandible segments were obtained from cadavers and scanned using CBCT and micro-computed tomographic (micro-CT) imaging. CBCT images were used to measure the largest initial canal diameter from 29 root canals of premolars at 1, 2, 3, and 4 mm short of the apical foramen. Each measurement was used to select a master apical instrument with size/taper that was 1 diameter larger to prepare the apical 4 mm of each particular root canal. A post-preparation micro-CT scan was obtained, and the unprepared canal areas were calculated. RESULTS: A very high amount of surface areas over the apical 4 mm of the root canal was included in the final preparation (mean >90%). The unprepared areas ranged from as low as 3.7% to a maximum of 14.6% (mean and median, 9.2% and 9.1%, respectively). CONCLUSIONS: The proposed planned apical root canal preparation resulted in optimized root canal shaping with a substantial amount of prepared surface areas. The protocol used also resulted in a conservative canal enlargement using final instruments that were 1 size larger than the initial largest canal diameter.

Optimal theranostic SPECT imaging protocol for 223radium dichloride therapy.

223Radium dichloride image-based individual dosimetry requires an optimal acquisition and reconstruction protocol and proper image correction methods for theranostic applications. To assess this problem, radium-223 dichloride SPECT images were acquired from a Jaszczak simulator with a dual-headed gamma camera, LEHR collimator, 128 × 128 matrix, and total time of 32 minutes. A cylindrical PMMA phantom was used to calibrate the measurements performed with Jaszczak. The image quality parameters (noise coefficient, contrast, contrast-to-noise ratio and recovery coefficient) and septal penetration correction were calculated by MATLAB®. The best results for the investigated image quality parameters were obtained with an 89 keV energy window (24% wide) produced together with OSEM/MLEM reconstruction (8 subsets and 4 iterations) applying a Butterworth filter (order 10 and cutoff frequency of 0.48 cycles·cm-1). The successfully performed recovery coefficient parameter evaluation allows uptake correction for future patient dosimetry applications.

The effectiveness of passive ultrasonic irrigation and the easy-clean instrument for removing remnants of filling material.

OBJECTIVE: This study aimed to evaluate the efficacy of passive ultrasonic irrigation (PUI) and the easy clean instrument by micro-computed tomography (CT) for removing remnant filling materials during endodontic retreatment. MATERIALS AND METHODS: Forty mesial roots of mandibular molars were divided into four groups (n = 10) according to the agitation system and sealer used: Group 1: PUI/AH Plus; Group 2: PUI/TotalFill; Group 3: Easy Clean/AH Plus; and Group 4: Easy Clean/TotalFill. The groups were compared by micro-CT analysis according to the volumes of the obturation and the remaining material before and after the agitation systems were used. RESULTS: There was no difference between the groups for total filling volume and initial and final remaining filling volume (P > 0.05). CONCLUSIONS: Both the PUI and easy-clean instrument are effective for removing remnants of filling material with no difference between the groups.

Efficacy of an arrow-shaped ultrasonic tip for the removal of residual root canal filling materials.

This study aimed to evaluate the efficacy of supplementary methods to remove the remaining root filling material from root canals. Twenty mandibular single-rooted teeth were instrumented with Reciproc 25/0.08 and filled with gutta-percha and AH-Plus sealer, followed by a micro-CT scanning. The retreatment procedures were performed, the samples were rescanned and divided into two groups (n = 10) according to the supplementary method: XP-endo Finisher R and Clearsonic tip. The samples were rescanned and the volume of remaining root filling material was quantified. Data were analysed statistically (P < 0.05). The amount of filling material removed after supplementary methods was higher compared with retreatment procedure (P < 0.05). XP-endo Finisher R promoted a greater percentage of filling materials reduction in the entire root canal and apical third compared with Clearsonic tip (P < 0.05). Supplementary methods were effective in the reduction of root filling materials. XP-endo Finisher R removed more root filling material than Clearsonic tip.

Accuracy of Microcomputed Tomography in Detecting Dentinal Cracks: A Correlative Study with Scanning Electron and Operative Microscopy.

The aim of the study was to evaluate the accuracy of microcomputed tomography (mCT) to detect dentinal cracks when compared with scanning electron microscopy (SEM) and operating microscopy (OM). Different conditions of pixel size (10 or 17 µm), sample moisture (dry/moist), and transillumination (with/without) were evaluated. Additionally, the influence of the dentinal defect width on its detection was analyzed. The root canals of human mandibular incisors were prepared with the Reciproc R40 instrument (VDW, Munich, Germany). The roots were sectioned 5 and 10 mm from the apex, and mCT scans of middle and apical segments were performed at two pixel sizes: 10 µm and 17 µm, under dry and moist conditions (groups: 10dry, 10moist, 17dry, and 17moist). The operating microscope was used with and without transillumination (groups: OMTrans and OM). Findings showed that accuracy was moderate for the 10dry, 10moist, and OMTrans groups, poor for OM and very poor for 17dry and 17moist. The thickness of the dentin crack significantly influenced its detection by mCT using the resolution of 10 µm in both dry and wet conditions (P = .002), 17 µm in the dry condition (P = .002), and by the operating microscope using transillumination (P = .009). Some cracks visualized in SEM were not detected by mCT and an operating microscope. Not only the mCT resolution but also the sample moisture condition and the dentinal crack width can significantly influence its detection.

Shaping ability of reciprocating and rotary systems in oval-shaped root canals: a microcomputed tomography study.

This study compared the shaping ability of single-file reciprocating (WaveOne Gold) and multifile rotary (Mtwo) systems on mandibular oval-shaped canine root canals, using microcomputed tomography (micro-CT). Thirty mandibular canines were scanned by micro-CT and assigned to one of two groups (n=15) according to the system used for root canal preparation: WaveOne Gold or Mtwo. After preparation, the teeth were rescanned, and the percentage of untouched canal area, apical transportation and centering ability were analyzed. The data was evaluated using Kruskal and Mann- Whitney tests (p<0.05). No difference was found in percentage of unprepared canal area between groups in the entire root canal or the apical third, or in centering ability (p>0.05). WaveOne gold had less canal transportation than MTwo at the 5 mm section (p<0.05). WOG and Mtwo systems presented similar shaping ability and centering ability in oval-shaped canals. However, WOG presented less transportation than Mtwo at 5 mm from the apex.

Este estudo comparou a capacidade de modelagem dos sistemas reciprocante de lima única (WaveOne Gold) e rotatórios com múltiplas limas (Mtwo) em caninos ovais inferiores, usando microtomografia computadorizada (micro-CT). Trinta caninos inferiores foram escaneados por micro-CT e divididos em dois grupos (n = 15) de acordo com o sistema usado durante o preparo do canal radicular: WaveOne Gold (WOG) e Mtwo. Os dentes foram reeescaneados e a porcentagem de área do canal não preparada, transporte apical e capacidade de centralização foram analisados. Os dados foram avaliados pelos testes de Kruskal Wallis e Mann-Whitney (p<0,05). Nenhuma diferença foi encontrada na porcentagem de área não preparada entre os grupos em todo o canal radicular e no terço apical e na capacidade de centralização (p>0,05). O sistema WOG promoveu menor transporte do canal do que o sistema Mtwo na região de 5mm aquém do ápice (p<0,05). Os sistemas WOG e Mtwo apresentaram capacidade de modelagem e capacidade de centralização semelhantes em canais ovais. No entanto, WOG promoveu menor transporte do que Mtwo a 5 mm do ápice.

Skull diversity and evolution in miniaturized amphibians, genus Brachycephalus (Anura: Brachycephalidae).

Miniaturized amphibians of the genus Brachycephalus are phenotypically diverse. The species of Brachycephalus have bufoniform or leptodactyliform Baupläne and any of three skeletal states: nonhyperossified, hyperossified without dorsal shield, and hyperossified with dorsal shield. We integrate high-resolution microcomputed tomography, geometric morphometrics, and an estimate of molecular phylogenetic relationships to investigate skull diversity in shape and size-shape space in selected species of Brachycephalus. Skull diversity amongst species of Brachycephalus can be partitioned into shape and size-shape space according to the four conditions of skeletal states-Baupläne, namely, nonhyperossified leptodactyliform, nonhyperossified bufoniform, hyperossified bufoniform without dorsal shield, and hyperossified bufoniform with dorsal shield. Skull diversity in shape and size-shape space in nonhyperossified leptodactyliform species of Brachycephalus is markedly larger, when compared to skull diversity in species of the three other conditions of skeletal states-Baupläne. Variation in skull shape scales with size across Brachycephalus and, therefore, can be explained by allometry. Skull diversity, Baupläne, and skeletal states covary to a large extent with monophyletic lineages of Brachycephalus, as revealed by a mitochondrial DNA species tree. Nonhyperossified bufoniform species and hyperossified bufoniform species with or without dorsal shield are monophyletic lineages, as inferred from a mitochondrial DNA species tree. Nonhyperossified leptodactyliform species of Brachycephalus do not share, however, a most recent common ancestor. The nonhyperossified leptodactyliform species of Brachycephalus, due to their marked skull diversity and lack of monophyly, emerge as evolutionarily complex. Therefore, further sampling of the nonhyperossified leptodactyliform condition of skeletal states-Baupläne will be necessary to further understand the evolutionary history of Brachycephalus.

Os anfíbios miniaturizados do gênero Brachycephalus são fenotipicamente diversos. As espécies de Brachycephalus têm o plano corporal bufoniforme ou leptodactyliforme e três estados esqueléticos: não-hiperossificado, hiperossificado sem placa dorsal e hiperossificado com placa dorsal. Neste trabalho nós integramos tomografia micro-computadorizada de alta resolução, morfometria geométrica e uma estimativa de relações filogenéticas moleculares para investigar diversidade craniana nos espaços de forma e tamanho-forma em determinadas espécies de Brachycephalus. A diversidade craniana entre espécies de Brachycephalus pode ser dividida no espaço de forma e tamanho-forma segundo as quatro condições de plano corporal-esqueleto, a saber, leptodactiliforme não-hiperossificado, bufoniforme não-hiperossificado, bufoniforme hiperossificado sem placa dorsal e bufoniforme hiperossificado com placa dorsal. A diversidade craniana nos espaços de forma e tamanho-forma nas espécies de Brachycephalus leptodactiliformes não-hiperossificadas é pronunciadamente maior quando comparada àquela das espécies nas outras trcs condições de plano corporal-esqueleto. A variação na forma craniana aumenta com o tamanho craniano em Brachycephalus e, portanto, pode ser explicada por alometria. Diversidade craniana, plano corporal e estados esqueléticos covariam consideravelmente com as linhagens monofiléticas de Brachycephalus, como estimado pela filogenia mitocondrial. As espécies de Brachycephalus leptodactiliformes não-hiperossificadas e bufoniformes hiperossificadas com ou sem placa dorsal são linhagens monofiléticas, como estimado pela filogenia mitocondrial. As espécies leptodactiliformes não-hiperossificadas não compartilham, todavia, um ancestral comum mais recente. As espécies de Brachycephalus leptodactiliformes não-hiperossificadas devido a sua pronunciada diversidade e não-monofilia emergem claramente como entidades evolutivamente complexas. Por conseguinte, a amostragem adicional de populações leptodactiliformes não-hiperossificadas será necessária para uma melhor compreensão da história evolutiva do gênero Brachycephalus.

A cell-based dosimetry model for radium-223 dichloride therapy using bone micro-CT images and GATE simulations.

Dosimetry at the cellular level has outperformed macrodosimetry in terms of agreement with toxicity effects in clinical studies. This fact has encouraged dosimetry studies aiming to quantify the absorbed doses needed to reach radiotoxicity at the cellular level and to inform recommendations on the administration of radium-223. The aim of this work is to qualitatively and quantitatively evaluate the absorbed doses of radium-223 and the interactions of the doses at the cellular level. The analysis was performed by Monte Carlo simulations in GATE using micro-CT image of a mouse. Two physics lists available in the GATE code were tested. The influence of single and multiple scattering models on the absorbed dose distribution and number of particle hits was also studied. In addition, the fuzzy c-means clustering method was used for data segmentation. The segmentation method was suitable for these analyses, particularly given that it was unsupervised. There was no significant difference in the estimated absorbed dose between the two proposed physics lists. The absorbed dose values were not significantly influenced by scattering, although single scattering resulted in twice as many interactions as multiple scattering. The absorbed dose histogram at the voxel level shows heterogeneous absorbed dose values within each shell, but the observations from the graph of the medians were comparable to those in the literature. The interaction histogram indicates 104 events, although some voxels had no interactions with alpha particles. However, the voxels did not show absorbed doses capable of deterministic effects in the deepest part of the bone marrow. The absorbed dose distribution in images of mouse trabecular bone was compatible with simple geometric models, with absorbed doses capable of deterministic effects near the bone surface. The interaction distributions need to be correlated with in vivo studies for better interpretation.