The Phishing Email Suspicion Test (PEST) a lab-based task for evaluating the cognitive mechanisms of phishing detection.

Phishing emails constitute a major problem, linked to fraud and exploitation as well as subsequent negative health outcomes including depression and suicide. Because of their sheer volume, and because phishing emails are designed to deceive, purely technological solutions can only go so far, leaving human judgment as the last line of defense. However, because it is difficult to phish people in the lab, little is known about the cognitive and neural mechanisms underlying phishing susceptibility. There is therefore a critical need to develop an ecologically valid lab-based measure of phishing susceptibility that will allow evaluation of the cognitive mechanisms involved in phishing detection. Here we present such a measure based on a task, the Phishing Email Suspicion Test (PEST), and a cognitive model to quantify behavior. In PEST, participants rate a series of phishing and non-phishing emails according to their level of suspicion. By comparing suspicion scores for each email to its real-world efficacy, we find initial support for the ecological validity of PEST - phishing emails that were more effective in the real world were more effective at deceiving people in the lab. In the proposed computational model, we quantify behavior in terms of participants' overall level of suspicion of emails, their ability to distinguish phishing from non-phishing emails, and the extent to which emails from the recent past bias their current decision. Together, our task and model provide a framework for studying the cognitive neuroscience of phishing detection.

Immune response in COVID-19: What do we currently know?

In 2002/2003 there was a pandemic denominate SARS (severe acute respiratory syndrome), caused by the SARS-CoV virus that belongs to the genera Betacoranavirus and the family Coronaviridae, generally responsible for influenza infections. In mid of 2019, a new disease by the coronavirus named by COVID-19 (SARS-CoV-2) emerged, both infections have flu symptoms, however they are infections that variable intensity, being medium to severe. In medium infections individuals have the virus and exhibit symptoms, however hospitalization is not necessary, in severe infections, individuals are hospitalized, have high pathology and in some cases progress to death. The virus is formed by simple positive RNA, enveloped, non-segmented, and presenting the largest genome of viruses constituting 32 Kb, consisting of envelope proteins, membrane, nucleocapsid and spike protein, which is essential in the interaction with the host cells. As for the origin of this virus, research has been intensified to determine this paradox and although the similarity with SARS-CoV, this virus did not has necessarily the same place of origin. As for the immune system, it is currently unknown how this new virus interacts. In this brief review, we demonstrate important considerations about the responses to this infection.

Vitamin D receptor FokI and BglI genetic polymorphisms, dental caries, and gingivitis.

BACKGROUND & AIM: To investigate the association between the genetic polymorphisms FokI (rs2228570) and BglI (rs739837) in vitamin D receptor (VDR) with dental caries and gingivitis susceptibility. DESIGN: This study included 353 Brazilian children (8 to 11 years old). Dental caries was assessed using ICDAS (International System for Detection and Assessment of Carious Lesions) and gingival bleeding using Community Periodontal Index (CPI). The presence of visible biofilm was also evaluated. DNA was extracted from saliva, and real-time PCR was used to evaluate genetic polymorphisms in VDR: rs2228570 (FokI, A>G/Met>Thr) and rs739837 (BglI, G>T). Dental caries was evaluated as a continuous data (mean and standard deviation-SD) and was also categorized (ICDAS0 versus ICDAS1-6 or ICDAS1-2 versus ICDAS3-6). Gingivitis was categorized in with and without. One-way ANOVA was used for comparisons of caries among genotypes. Chi-square test, logistic regression, and haplotype analysis were performed (P < .05). RESULTS: Biofilm was associated with dental caries susceptibility and gingivitis (P < .05). The mean distribution of the caries lesions and cavitated caries lesions among FokI and BgII genotypes were not statistically significant (P > .05). Genotype distributions among caries groups (in the two different cut-offs) and among gingivitis and non-gingivitis groups were not statistically significant (P > .05). CONCLUSION: The polymorphisms FokI and BglI in VDR were not associated with dental caries or gingivitis.

Yacón (Smallanthus sonchifolius) prevented inflammation, oxidative stress, and intestinal alterations in an animal model of colorectal carcinogenesis.

BACKGROUND: Yacón (Smallanthus sonchifolius) roots store carbohydrate in the form of prebiotic fructooligosaccharides (FOS), which improve intestinal health. Yacon has the potential to prevent the intestinal barrier alterations associated with colorectal cancer (CRC). This study aimed to investigate the preventive effects of yacón flour (YF) on alterations promoted by CRC induced by 1,2-dimethylhydrazine in rats. RESULTS: CRC increased tumor necrosis factor alpha levels (group CY = 10.2 ± 0.72; group C = 9.6 ± 1.0; group Y = 5.8 ± 0.54; group S = 5.95 ± 0.6 pg mL-1 ) and short-chain fatty acid production, and decreased total antioxidant capacity (group CY = 4.7 ± 0.72; group C = 3.3 ± 0.3; group Y = 4.1 ± 0.47; group S = 6.7 ± 0.78 U mL-1 ). Furthermore, YF treatment reduced intraluminal pH (group CY = 6.45 ± 0.47; group C = 7.65 ± 0.44; group Y = 6.75 ± 0.46; group S = 8.13 ± 0.2), lactulose/mannitol ratio, tumor necrosis factor-alpha (TNF-α)/interleukin (IL)-10 ratio, and increased secretory immunoglobulin A (group CY = 9.48 ± 1.46; group C = 10.95 ± 3.87; group Y = 15.95 ± 7.36; group S = 9.19 ± 1.52), but did not affect IL-10, IL-12, and TNF-α levels nor the IL-12/IL-10 ratio. CONCLUSION: YF as a source of fructooligosaccharides may help to maintain the integrity of intestinal health, which is altered in induced CRC in rats. © 2020 Society of Chemical Industry.

Susceptibility to Spear-Phishing Emails: Effects of Internet User Demographics and Email Content.

Phishing is fundamental to cyber attacks. This research determined the effect of Internet user age and email content such as weapons of influence (persuasive techniques that attackers can use to lure individuals to fall for an attack) and life domains (a specific topic or aspect of an individual's life that attackers can focus an emails on) on spear-phishing (targeted phishing) susceptibility. One-hundred young and 58 older users received, without their knowledge, daily simulated phishing emails over 21 days. A browser plugin recorded their clicking on links in the emails as an indicator of their susceptibility. Forty-three percent of users fell for the simulated phishing emails, with older women showing the highest susceptibility. While susceptibility in young users declined across the study, susceptibility in older users remained stable. The relative effectiveness of the attacks differed by weapons of influence and life domains with age-group variability. In addition, older compared to young users reported lower susceptibility awareness. These findings support effects of Internet user demographics and email content on susceptibility to phishing and emphasize the need for personalization of the next generation of security solutions.

Liquid Redox Probe-Free Plastic Antibody Development for Malaria Biomarker Recognition.

Malaria is a major public health challenge worldwide and requires accurate and efficient diagnostic methods. Traditional diagnostic approaches based on antigen-antibody interactions are associated with ethical and economic concerns. Molecularly imprinted polymers (MIPs) offer a promising alternative by providing a complementary polymer structure capable of selectively binding target molecules. In this study, we developed a liquid, redox-probe-free, MIP-based electrochemical biosensor to detect the Plasmodium falciparum malaria marker histidine-rich protein (HRP2) at the point-of-care (PoC). The imprinting phase consists of the electropolymerization of the monomer methylene blue (MB) in the presence of the target protein HRP2 at the working electrode (WE) of the modified carbon screen printed electrode (C-SPE). Subsequent removal of the protein with proteinase K and oxalic acid yielded the MIP material. The sensor assembly was monitored by cyclic voltammetry (CV), Raman spectroscopy and scanning electron microscopy (SEM). The analytical performance of the biosensor was evaluated by square-wave voltammetry (SWV) using calibration curves in buffer and serum with a detection limit of 0.43 ± 0.026 pg mL-1. Selectivity studies showed minimal interference, indicating a highly selective assay. Overall, our approach to detect the HRP2 infection marker offers simplicity, cost-effectiveness and reliability. In particular, the absence of a redox solution simplifies detection, as the polymer itself is electroactive and exhibits oxidation and reduction peaks.

Encapsulation of Citrus sinensis essential oil and R-limonene in lipid nanocarriers: A potential strategy for the treatment of leishmaniasis.

Leishmaniases, a group of neglected tropical diseases caused by an intracellular parasite of the genus Leishmania, have significant impacts on global health. Current treatment options are limited due to drug resistance, toxicity, and high cost. This study aimed to develop nanostructured lipid carriers (NLCs) for delivering Citrus sinensis essential oil (CSEO) and its main constituent, R-limonene, against leishmaniasis. The influence of surface-modified NLCs using chitosan was also examined. The NLCs were prepared using a warm microemulsion method, and surface modification with chitosan was achieved through electrostatic interaction. These nanocarriers were characterized by differential scanning calorimetry (DSC), X-ray diffraction (XRD), transmission electron microscopy, and dynamic light scattering (DLS). In vitro cytotoxicity was assessed in L929 and RAW 264.7 cells, and leishmanicidal activity was evaluated against promastigote and amastigote forms. The NLCs were spherical, with particle sizes ranging from 97.9 nm to 111.3 nm. Chitosan-coated NLCs had a positive surface charge, with zeta potential values ranging from 45.8 mV to 59.0 mV. Exposure of L929 cells to NLCs resulted in over 70 % cell viability. Conversely, surface modification significantly reduced the viability of promastigotes (93 %) compared to free compounds. Moreover, chitosan-coated NLCs presented a better IC50 against the amastigote forms than uncoated NLCs. Taken together, these findings demonstrate the feasibility of using NLCs to overcome the limitations of current leishmaniasis treatments, warranting further research.

Accurate Continuous Prediction of 14 Degrees of Freedom of the Hand from Myoelectrical Signals through Convolutive Deep Learning.

Natural control of assistive devices requires continuous positional encoding and decoding of the user's volition. Human movement is encoded by recruitment and rate coding of spinal motor units. Surface electromyography provides some information on the neural code of movement and is usually decoded into finger joint angles. However, the current approaches to mapping the electrical signal into joint angles are unsatisfactory. There are no methods that allow precise estimation of joint angles during natural hand movements within the large numbers of degrees of freedom of the hand. We propose a framework to train a neural network from digital cameras and high-density surface electromyography from the extrinsic (forearm and wrist) hand muscles. Furthermore, we show that our 3D convolutional neural network optimally predicted 14 functional flexion/extension joints of the hand. We found in our experiments (4 subjects; mean age of 26±2.12 years) that our model can predict individual sinusoidal finger movement at different speeds (0.5 and 1.5 Hz), as well as two and three finger pinching, and hand opening and closing, covering 14 degrees of freedom of the hand. Our deep learning method shows a mean absolute error of 2.78±0.28 degrees with a mean correlation coefficient between predicted and expected joint angles of 0.94, 95% confidence interval (CI) [0.81, 0.98] with simulated real-time inference times lower than 30 milliseconds. These results demonstrate that our approach is capable of predicting the user's volition similar to digital cameras through a non-invasive wearable neural interface. Clinical relevance- This method establishes a viable interface that can be used for both immersive virtual reality medical simulations environments and assistive devices such as exoskeleton and prosthetics.

Nutritional Status is Associated with Permanent Tooth Eruption in a Group of Brazilian School Children.

The present study aimed to investigate the association between nutritional status with delayed tooth eruption (DTE). Oral examination was performed in schoolchildren (8-11 years old), and DTE was defined by absence of dental gingival emergence or when primary tooth was still present in the oral cavity after the expected time. BMI z-score of each child were collected and nutritional status was defined. Chi-square test and binary logistic regression adjusted by age and gender were performed. Odds ratio (OR) and 95% Confidence Interval (95% CI) were calculated. The established alpha was 5%. Among 353 included children, 247 were classified as eutrophic, 16 as underweight, 64 as overweight, and 26 as obese. Underweight was associated as a risk factor to DTE (P = .014; OR = 3.5; 95% CI = 1.3-9.8), and underweight girls had more chance to present DTE than eutrophic girls (P = .048; OR = 4.4; 95% CI = 1.1-17.2) in chi square test. In logistic regression, underweight was associated as a risk factor to DTE (OR = 4.21; CI 95% = 1.42-12.43; P = .009). Underweight children have a higher risk of DTE in permanents.

Assessing the Association Between Nutritional Status, Caries, and Gingivitis in Schoolchildren: A Cross-Sectional Study.

Objective. To evaluate if nutritional status is associated with caries and gingivitis in Brazilian schoolchildren. Material and methods. Children of both genders, age ranging from 8 to 11 years old, were included in this study. Caries was diagnosed using ICDAS (International System for Detection and Assessment of Carious Lesions) and gingivitis was diagnosed using the Community Periodontal Index. The nutritional status of each child was defined by BMI Z-score calculation. Data on oral health behavior and dietary habit were collected through parent's questionnaires. Parametric analyzes were performed to compare the groups. The established alpha was 5%. Results. The sample consisted of 353 schoolchildren: 16 underweight children, 247 eutrophic children, 64 overweight children, and 26 were obese children. Overweight, Obese and Overweight + Obese children presented less cavitated caries lesion than Eutrophic children (P < .05). Gingivitis was not associated with nutritional status (P > .05). Conclusion. Caries was associated with overweight and obesity in Brazilian schoolchildren.

Uncovering Susceptibility Risk to Online Deception in Aging.

OBJECTIVES: Fraud in the aged is an emerging public health problem. An increasingly common form of deception is conducted online. However, identification of cognitive and socioemotional risk factors has not been undertaken yet. In this endeavor, this study extended previous work suggesting age effects on susceptibility to online deception. METHODS: Susceptibility was operationalized as clicking on the link in simulated spear-phishing emails that young (18-37 years), young-old (62-74 years), and middle-old (75-89 years) Internet users received, without knowing that the emails were part of the study. Participants also indicated for a set of spear-phishing emails how likely they would click on the embedded link (susceptibility awareness) and completed cognitive and socioemotional measures to determine susceptibility risk profiles. RESULTS: Higher susceptibility was associated with lower short-term episodic memory in middle-old users and with lower positive affect in young-old and middle-old users. Greater susceptibility awareness was associated with better verbal fluency in middle-old users and with greater positive affect in young and middle-old users. DISCUSSION: Short-term memory, verbal fluency, and positive affect in middle-old age may contribute to resilience against online spear-phishing attacks. These results inform mechanisms of online fraud susceptibility and real-life decision-supportive interventions toward fraud risk reduction in aging.

Use of a clinical-laboratory score to guide treatment of gestational diabetes.

OBJECTIVE: To assess the outcomes of implementing a clinical-laboratory score in the treatment of pregnant women with gestational diabetes. METHODS: A retrospective before-and-after implementation analysis was undertaken using data and neonatal outcomes for pregnant women with gestational diabetes treated before (January 2011-December 2012; control group) and after (January 2013-December 2014; score group) introduction of a newly developed score. To evaluate the effects of score adoption, odds ratios with 95% confidence intervals were calculated after adjustment for confounding factors. RESULTS: The control group included a greater proportion of women treated with diet alone (170/312 [54.5%]) than the study group did (122/391 [31.2%]; P<0.001). By contrast, more women in the study group received metformin (172 [44.0%] vs 77 [24.7%]; P<0.001). The neonatal outcomes, including low Apgar scores at 1 minute and at 5 minutes and neonatal intensive care unit admission, were similar in both groups. Multivariate logistic regression analysis showed that the adoption of the score did not significantly affect the choice of treatment or the birth weight rating. CONCLUSION: The score served well as an orientation tool in therapeutic decision making and had no negative effect on the treatment choice and perinatal outcomes.

Cross-sectional relationships between sedentary behavior and frailty in older adults.

BACKGROUND: The aim of this study was to analyze the association between frailty and sedentary behavior and to examine the discriminative ability of sedentary behavior in screening frailty in older adults. METHODS: This was a cross-sectional study based on data from an epidemiologic population-based household survey involving 316 community-dwelling older adults (≥60 years) of both sexes (173 women and 143 men). The frailty was measured from an adapted version of the criteria proposed by Fried et al. in 2001, which is based on the presence of three or more of the following components: shrinking, weakness, poor endurance/exhaustion, slowness and low activity. Sedentary behavior was determined by the International Physical Activity Questionnaire (long version). RESULTS: The prevalence of frailty was 23.8%, and the average time in sedentary behavior was 6.1±3.2 h/day. Sedentary behavior was independently and positively associated with frailty (PR=1.10; 95% CI: 1.02-1.19; P=0.013). The ROC curve showed that the sedentary behavior could discriminate frail older adults (AUC=0.66; 95% CI: 0.61-0.72), and the best cutoff point was 7 h/day (sensitivity =54% and specificity =75%). CONCLUSIONS: Frailty is strongly associated with sedentary behavior. Sedentary behavior can be a potential marker in screening of frailty in community-dwelling older adults. Our findings suggest that reducing the time with sedentary behavior and increasing the time with physical activity may prevent frailty syndrome.

Neonatal outcomes according to different therapies for gestational diabetes mellitus.

OBJECTIVES: To compare different neonatal outcomes according to the different types of treatments used in the management of gestational diabetes mellitus. METHODS: This was a retrospective cohort study. The study population comprised pregnant women with gestational diabetes treated at a public maternity hospital from July 2010 to August 2014. The study included women aged at least 18 years, with a singleton pregnancy, who met the criteria for gestational diabetes mellitus. Blood glucose levels, fetal abdominal circumference, body mass index and gestational age were considered for treatment decision-making. The evaluated neonatal outcomes were: type of delivery, prematurity, weight in relation to gestational age, Apgar at 1 and 5min, and need for intensive care unit admission. RESULTS: The sample consisted of 705 pregnant women. The neonatal outcomes were analyzed based on the treatment received. Women treated with metformin were less likely to have children who were small for gestational age (95% CI: 0.09-0.66) and more likely to have a newborn adequate for gestational age (95% CI: 1.12-3.94). Those women treated with insulin had a lower chance of having a preterm child (95% CI: 0.02-0.78). The combined treatment with insulin and metformin resulted in higher chance for a neonate to be born large for gestational age (95% CI: 1.14-11.15) and lower chance to be born preterm (95% CI: 0.01-0.71). The type of treatment did not affect the mode of delivery, Apgar score, and intensive care unit admission. CONCLUSIONS: The pediatrician in the delivery room can expect different outcomes for diabetic mothers based on the treatment received.

Resin luting materials: Tissue response in dog's teeth.

The aim of this study was to evaluate radiographically and histologically the pulpal and periapical response to self-adhesive (Rely X™ Unicem) and self-etching and self-curing (Multilink(®)) resin-based luting materials in deep cavities in dogs' teeth. Deep class V cavities (0.5-mm-thick dentin) were prepared in 60 canine premolars and the following materials were applied on cavity floor: Groups I/V-RelyX™ Unicem; Groups II/VI-Multilink(®); Groups III/VII-zinc phosphate cement (control) and; Groups IV/VIII-gutta-percha (control). Cavities were restored with silver amalgam. Animals were euthanized after 10 days (groups I-IV) and 90 days (groups V-VIII). Tooth/bone blocks were radiographed and processed for histopathological evaluation of pulp and periapical tissue response to the materials. All materials presented similar histopathological features and radiographic findings at both periods. The pulp tissue was intact. The apical and periapical regions and periodontal ligament thickness were normal. No inflammatory cells, resorption of mineralized tissue (dentin, cementum, and alveolar bone) or bacteria were observed. The lamina dura was intact and no areas of periapical bone rarefaction or internal/external root resorption were observed radiographically. It can be concluded that Rely X™ Unicem and Multilink(®) caused no adverse tissue reactions and may be indicated for cementation of indirect restorations in deep dentin cavities without pulp exposure.

Neonatal outcomes according to different therapies for gestational diabetes mellitus / Desfechos neonatais de acordo com diferentes terapêuticas do diabetes mellitus gestacional

Abstract: Objectives: To compare different neonatal outcomes according to the different types of treatments used in the management of gestational diabetes mellitus. Methods: This was a retrospective cohort study. The study population comprised pregnant women with gestational diabetes treated at a public maternity hospital from July 2010 to August 2014. The study included women aged at least 18 years, with a singleton pregnancy, who met the criteria for gestational diabetes mellitus. Blood glucose levels, fetal abdominal circumference, body mass index and gestational age were considered for treatment decision-making. The evaluated neonatal outcomes were: type of delivery, prematurity, weight in relation to gestational age, Apgar at 1 and 5 min, and need for intensive care unit admission. Results: The sample consisted of 705 pregnant women. The neonatal outcomes were analyzed based on the treatment received. Women treated with metformin were less likely to have children who were small for gestational age (95% CI: 0.09-0.66) and more likely to have a newborn adequate for gestational age (95% CI: 1.12-3.94). Those women treated with insulin had a lower chance of having a preterm child (95% CI: 0.02-0.78). The combined treatment with insulin and metformin resulted in higher chance for a neonate to be born large for gestational age (95% CI: 1.14-11.15) and lower chance to be born preterm (95% CI: 0.01-0.71). The type of treatment did not affect the mode of delivery, Apgar score, and intensive care unit admission. Conclusions: The pediatrician in the delivery room can expect different outcomes for diabetic mothers based on the treatment received.

Resumo: Objetivos: Comparar diferentes desfechos neonatais de acordo com as diferentes modalidades de tratamento do diabetes mellitus gestacional. Métodos: Trata-se de uma coorte retrospectiva. A população do estudo foi composta por gestantes com diabetes gestacional atendidas em uma maternidade pública de julho de 2010 a agosto de 2014. Foram incluídas mulheres com idade mínima de 18 anos, gestação única e com critérios para diabetes mellitus gestacional. Para decisão terapêutica foram considerados glicemias, circunferência abdominal fetal, índice de massa corporal e idade gestacional. Os desfechos neonatais avaliados foram: via de parto, prematuridade, relação do peso com idade gestacional, Apgar no 1º e 5º minuto e necessidade de internação em unidade de terapia intensiva. Resultados: A amostra foi composta por 705 gestantes. Os desfechos neonatais foram analisados com base na terapêutica recebida. Mulheres tratadas com metformina tiveram menor chance de ter filhos pequenos para a idade gestacional (IC 95%: 0,09-0,66) e maior chance de ter um filho adequado para a idade gestacional (IC 95%: 1,12-3,94). A gestante tratada com insulina teve menor chance de ter um filho prematuro (IC 95%: 0,02-0,78). O tratamento feito com a associação de insulina e metformina resultou em maior chance de um recém-nascido grande para a idade gestacional (IC 95%: 1,14-11,15) e menor chance de prematuridade (IC 95%: 0,01-0,71). A modalidade de tratamento não interferiu na via de parto, Apgar e internação em terapia intensiva. Conclusões: O pediatra na sala de parto pode esperar diferentes desfechos para o filho de mãe diabética, com base no tratamento recebido.

Histopathological evaluation of root canal filling materials for primary teeth.

This study aimed to assess the response of apical and periapical tissues of dogs' teeth after root canal filling with different materials. Forty roots from dogs' premolars were prepared biomechanically and assigned to 4 groups filled with: Group I: commercial calcium hydroxide and polyethylene glycol-based paste (Calen) thickened with zinc oxide; Group II: paste composed of iodoform, Rifocort and camphorated paramonochlorophenol; Group III: zinc oxide-eugenol cement; Group IV: sterile saline. After 30 days, the samples were subjected to histological processing. The histopathological findings revealed that in Groups I and IV the apical and periapical regions exhibited normal appearance, with large number of fibers and cells and no resorption of mineralized tissues. In Group II, mild inflammatory infiltrate and mild edema were observed, with discrete fibrogenesis and bone resorption. Group III showed altered periapical region and thickened periodontal ligament with presence of inflammatory cells and edema. It may be concluded that the Calen paste thickened with zinc oxide yielded the best tissue response, being the most indicated material for root canal filling of primary teeth with pulp vitality.

Histopathological evaluation of root canal filling materials for primary teeth

This study aimed to assess the response of apical and periapical tissues of dogs' teeth after root canal filling with different materials. Forty roots from dogs' premolars were prepared biomechanically and assigned to 4 groups filled with: Group I: commercial calcium hydroxide and polyethylene glycol-based paste (Calen®) thickened with zinc oxide; Group II: paste composed of iodoform, Rifocort® and camphorated paramonochlorophenol; Group III: zinc oxide-eugenol cement; Group IV: sterile saline. After 30 days, the samples were subjected to histological processing. The histopathological findings revealed that in Groups I and IV the apical and periapical regions exhibited normal appearance, with large number of fibers and cells and no resorption of mineralized tissues. In Group II, mild inflammatory infiltrate and mild edema were observed, with discrete fibrogenesis and bone resorption. Group III showed altered periapical region and thickened periodontal ligament with presence of inflammatory cells and edema. It may be concluded that the Calen paste thickened with zinc oxide yielded the best tissue response, being the most indicated material for root canal filling of primary teeth with pulp vitality.

O objetivo deste estudo foi avaliar a resposta dos tecidos apicais e periapicais de dentes de cães, após obturação dos canais radiculares com diferentes materiais indicados para dentes decíduos. Foram utilizados pré-molares de cães, totalizando 40 raízes que, após pulpectomia e preparo biomecânico, foram divididas em 4 grupos, nos quais os canais radiculares foram obturados com os seguintes materiais: Grupo I - pasta comercial composta de hidróxido de cálcio e polietileno glicol 400 (Calen®) espessada com óxido de zinco; Grupo II - pasta composta de iodofórmio, Rifocort® e paramonoclorofenol canforado; Grupo III - cimento de óxido de zinco e eugenol; e Grupo IV - solução salina. Decorridos 30 dias, as peças foram submetidas ao processamento histológico. De acordo com os resultados da análise histopatológica observou-se que nos Grupos I e IV as regiões apical e periapical apresentaram aspecto de normalidade, com grande número de fibras e células e ausência de reabsorção dos tecidos mineralizados. No Grupo II observou-se infiltrado inflamatório e edema leves, com discreta fibrogênese e reabsorção óssea. O Grupo III apresentou alteração na região periapical e ligamento periodontal ampliado, com presença de células inflamatórias e edema. Os resultados obtidos permitiram concluir que a pasta Calen espessada com óxido de zinco apresentou a melhor resposta tecidual, sendo a mais indicada para a obturação de canais radiculares de dentes decíduos com vitalidade pulpar.