Linear dimensional changes in plaster die models using different elastomeric materials

Dental impression is an important step in the preparation of prostheses since it provides the reproduction of anatomic and surface details of teeth and adjacent structures. The objective of this study was to evaluate the linear dimensional alterations in gypsum dies obtained with different elastomeric materials, using a resin coping impression technique with individual shells. A master cast made of stainless steel with fixed prosthesis characteristics with two prepared abutment teeth was used to obtain the impressions. References points (A, B, C, D, E and F) were recorded on the occlusal and buccal surfaces of abutments to register the distances. The impressions were obtained using the following materials: polyether, mercaptan-polysulfide, addition silicone, and condensation silicone. The transfer impressions were made with custom trays and an irreversible hydrocolloid material and were poured with type IV gypsum. The distances between identified points in gypsum dies were measured using an optical microscope and the results were statistically analyzed by ANOVA (p < 0.05) and Tukey's test. The mean of the distances were registered as follows: addition silicone (AB = 13.6 ��m, CD=15.0 ��m, EF = 14.6 ��m, GH=15.2 ��m), mercaptan-polysulfide (AB = 36.0 ��m, CD = 36.0 ��m, EF = 39.6 ��m, GH = 40.6 ��m), polyether (AB = 35.2 ��m, CD = 35.6 ��m, EF = 39.4 ��m, GH = 41.4 ��m) and condensation silicone (AB = 69.2 ��m, CD = 71.0 ��m, EF = 80.6 ��m, GH = 81.2 ��m). All of the measurements found in gypsum dies were compared to those of a master cast. The results demonstrated that the addition silicone provides the best stability of the compounds tested, followed by polyether, polysulfide and condensation silicone. No statistical differences were obtained between polyether and mercaptan-polysulfide materials.

Comparison among four commonly used demineralizing agents for root conditioning: a scanning electron microscopy

Dental roots that have been exposed to the oral cavity and periodontal pocket environment present superficial changes, which can prevent connective tissue reattachment. Demineralizing agents have been used as an adjunct to the periodontal treatment aiming at restoring the biocompatibility of roots. OBJECTIVE: This study compared four commonly used demineralizing agents for their capacity of removing smear layer and opening dentin tubules. METHODS: Fifty fragments of human dental roots previously exposed to periodontal disease were scaled and randomly divided into the following groups of treatment: 1) CA: demineralization with citric acid for 3 min; 2) TC-HCl: demineralization with tetracycline-HCl for 3 min; 3) EDTA: demineralization with EDTA for 3 min; 4) PA: demineralization with 37% phosphoric acid for 3 min; 5) Control: rubbing of saline solution for 3 min. Scanning electron microscopy was used to check for the presence of residual smear layer and for measuring the number and area of exposed dentin tubules. RESULTS: Smear layer was present in 100% of the specimens from the groups PA and control; in 80% from EDTA group; in 33.3% from TC-HCl group and 0% from CA group. The mean numbers of exposed dentin tubules in a standardized area were: TC-HCl=43.8��25.2; CA=39.3��37; PA=12.1��16.3; EDTA=4.4��7.5 and Control=2.3��5.7. The comparison showed significant differences between the following pairs of groups: TC-HCl and Control; TC-HCl and EDTA; CA and Control; and CA and EDTA. The mean percentages of area occupied by exposed dentin tubules were: CA=0.12��0.17%; TC-HCl=0.08��0.06%; PA=0.03��0.05%; EDTA=0.01��0.01% and Control=0��0%. The CA group differed significantly from the others except for the TC-HCl group. CONCLUSION: There was a decreasing ability for smear layer removal and dentin tubule widening as follows: AC>TC-HCl>PA>EDTA. This information can be of value as an extra parameter for choosing one of them for root conditioning.

Influence of different adhesive systems on the pull-out bond strength of glass fiber posts

This in vitro study evaluated the tensile bond strength of glass fiber posts (Reforpost - Angelus-Brazil) cemented to root dentin with a resin cement (RelyX ARC - 3M/ESPE) associated with two different adhesive systems (Adper Single Bond - 3M/ESPE and Adper Scotchbond Multi Purpose (MP) Plus - 3M/ESPE), using the pull-out test. Twenty single-rooted human teeth with standardized root canals were randomly assigned to 2 groups (n=10): G1- etching with 37% phosphoric acid gel (3M/ESPE) + Adper Single Bond + #1 post (Reforpost - Angelus) + four #1 accessory posts (Reforpin - Angelus) + resin cement; G2- etching with 37% phosphoric acid gel + Adper Scotchbond MP Plus + #1 post + four #1 accessory posts + resin cement. The specimens were stored in distilled water at 37��C for 7 days and submitted to the pull-out test in a universal testing machine (EMIC) at a crosshead speed of 0.5 mm/min. The mean values of bond strength (kgf) and standard deviation were: G1- 29.163 �� 7.123; G2- 37.752 ��13.054. Statistical analysis (Student's t-test; a=0.05 showed no statistically significant difference (p<0.05) between the groups. Adhesive bonding failures between resin cement and root canal dentin surface were observed in both groups, with non-polymerized resin cement in the apical portion of the post space when Single Bond was used (G1). The type of adhesive system employed on the fiber post cementation did not influence the pull-out bond strength.

Shear bond strength of self-etch and total-etch bonding systems at different dentin depths

The purpose of this study was to evaluate the dentin shear bond strength of four adhesive systems (Adper Single Bond 2, Adper Prompt L-Pop, Magic Bond DE and Self Etch Bond) in regards to buccal and lingual surfaces and dentin depth. Forty extracted third molars had roots removed and crowns bisected in the mesiodistal direction. The buccal and lingual surfaces were fixed in a PVC/acrylic resin ring and were divided into buccal and lingual groups assigned to each selected adhesive. The same specimens prepared for the evaluation of superficial dentin shear resistance were used to evaluate the different depths of dentin. The specimens were identified and abraded at depths of 0.5, 1.0, 1.5 and 2.0 mm. Each depth was evaluated by ISO TR 11405 using an EMIC-2000 machine regulated at 0.5 mm/min with a 200 Kgf load cell. We performed statistical analyses on the results (ANOVA, Tukey and Scheff�� tests). Data revealed statistical differences (p < 0.01) in the adhesive and depth variation as well as adhesive/depth interactions. The Adper Single Bond 2 demonstrated the highest mean values of shear bond strength. The Prompt L-Pop product, a self-etching adhesive, revealed higher mean values compared with Magic Bond DE and Self Etch Bond adhesives, a total and self-etching adhesive respectively. It may be concluded that the shear bond strength of dentin is dependent on material (adhesive system), substrate depth and adhesive/depth interaction.

A retrospective study of Traumatic Dental Injuries in a Brazilian dental urgency service

Epidemiologic aspects of traumatic dental injuries (TDI) were evaluated in the permanent dentition in a sample of 847 patients treated at the Dental Urgency Service of the Dental School of the Federal University of Goi��s, Brazil, between May 2000 and May 2008. The statistical treatment analyzed data from frequency distribution and chi-square test. The level of significance was set at 5% for all analyses. The results showed a higher incident among males (610; 72.01%) with mean age of 6-10 year-old. Uncomplicated crown fracture (without pulp exposure) (502; 26.95%), avulsion (341; 18.30%) and complicated crown fracture (with pulp exposure) (330; 17.71%) were the most prevalent TDI. The prevalence of trauma throughout the years showed proportionality, being observed a larger number of cases between July and September (249; 29.39%). The most affected teeth were the maxillary central incisors (65.65%), followed by the maxillary left lateral incisors (19.67%). In 311 participants (18.25%), only one tooth was involved, while in most patients (536; 81.75%), TDI occurred in more than one tooth. Significant proportion (82.27%) of traumatized teeth presented completely formed root apex. The main etiologic factors involved in TDI were falls (51.71%), traffic accidents (22.90%) and violence (5.67%). Based on the obtained data, it may be concluded that accurate policies of TDI prevention must be established, capable of stimulating the exposure of appropriate protocols for management of these lesions. The prevalence of TDI in Goi��nia subpopulation is compared to the prevalence reported in epidemiological studies in others populations.

Influence of intracanal post on apical periodontitis identified by cone-beam computed tomography

The determination of the success of endodontic treatment has been often discussed based on outcome obtained by periapical radiography. The aim of this study was to verify the influence of intracanal post on apical periodontitis detected by cone-beam computed tomography (CBCT). A consecutive sample of 1020 images (periapical radiographs and CBCT scans) taken from 619 patients (245 men; mean age, 50.1 years) between February 2008 and September 2009 were used in this study. Presence and intracanal post length (short, medium and long) were associated with apical periodontitis (AP). Chi-square test was used for statistical analyses. Significance level was set at p<0.01. The kappa value was used to assess examiner variability. From a total of 591 intracanal posts, AP was observed in 15.06%, 18.78% and 7.95% using periapical radiographs, into the different lengths, short, medium and long, respectively (p=0.466). Considering the same posts length it was verified AP in 24.20%, 26.40% and 11.84% observed by CBCT scans, respectively (p=0.154). From a total of 1,020 teeth used in this study, AP was detected in 397 (38.92%) by periapical radiography and in 614 (60.19%) by CBCT scans (p<0.001). The distribution of intracanal posts in different dental groups showed higher prevalence in maxillary anterior teeth (54.79%). Intracanal posts lengths did not influenced AP. AP was detected more frequently when CBCT method was used.

Bite force in temporomandibular dysfunction (TMD) and healthy complete denture wearers

The signs and symptoms of temporomandibular dysfunction (TMD) may contribute to reduce bite force and muscular activity. The aims of this study were to compare bite force in complete denture wearers with TMD (TMD group) and without TMD (healthy group).The TMD group consisted of 9 individuals, who had worn a maxillary and a mandibular complete removable denture for more than 10 years. The healthy group consisted of 9 participants who wore dentures and had satisfactory interocclusal and maxillomandibular relationship. Helkimo Index was used to analyze the dysfunction level. Maximum bite force was measured using a digital dynamometer with capacity of 100 kgf and adapted to oral conditions.The TMD group presented smaller mean bite force values than the healthy group, though without statistical significance (p>0.05). This outcome suggests that the TMD signs and symptoms and the structural conditions of the dentures did not affect the maximal bite force of complete denture wearers.

Mechanical properties and porosity of dental glass-ceramics hot-pressed at different temperatures

The objective of this work was to evaluate biaxial-flexural-strength (&#963;f), Vickers hardness (HV), fracture toughness (K Ic), Young's modulus (E), Poisson's ratio (&#957;) and porosity (P) of two commercial glass-ceramics, Empress (E1) and Empress 2 (E2), as a function of the hot-pressing temperature. Ten disks were hot-pressed at 1065, 1070, 1075 and 1080 ��C for E1; and at 910, 915, 920 and 925 ��C for E2. The porosity was measured by an image analyzer software and s f was determined using the piston-on-three-balls method. K Ic and HV were determined by an indentation method. Elastic constants were determined by the pulse-echo method. For E1 samples treated at different temperatures, there were no statistical differences among the values of all evaluated properties. For E2 samples treated at different temperatures, there were no statistical differences among the values of &#963;f, E, and &#957;, however HV and K Ic were significantly higher for 910 and 915 ��C, respectively. Regarding P, the mean value obtained for E2 for 925 ��C was significantly higher compared to other temperatures.

Flexural strength and hardness of direct and indirect composites

The objective of this study was to evaluate the flexural strength (&#963;f) and hardness (H) of direct and indirect composites, testing the hypotheses that direct resin composites produce higher &#963;f and H values than indirect composites and that these properties are positively related. Ten bar-shaped specimens (25 mm x 2 mm x 2 mm) were fabricated for each direct [D250 - Filtek Z250 (3M-Espe) and D350 - Filtek Z350 (3M-Espe)] and indirect [ISin - Sinfony (3M-Espe) and IVM - VitaVM LC (Vita Zahnfabrik)] materials, according to the manufacturer's instructions and ISO4049 specifications. The &#963;f was tested in three-point bending using a universal testing machine (EMIC DL 2000) at a crosshead speed of 0.5 mm/min (ISO4049). Knoop hardness (H) was measured on the specimens' fragments resultant from the &#963;f test and calculated as H = 14.2P/l��, where P is the applied load (0.1 kg; dwell time = 15 s) and l is the longest diagonal of the diamond shaped indent (ASTM E384). The data were statistically analyzed using Anova and Tukey tests (&#945; = 0.05). The mean &#963;f and standard deviation values (MPa) and statistical grouping were: D250 - 135.4 �� 17.6a; D350 - 123.7 �� 11.1b; ISin - 98.4 �� 6.4c; IVM - 73.1 �� 4.9d. The mean H and standard deviation values (kg/mm��) and statistical grouping were: D250 - 98.12 �� 1.8a; D350 - 86.5 �� 1.9b; ISin - 28.3 �� 0.9c; IVM - 30.8 �� 1.0c. The direct composite systems examined produce higher mean &#963;f and H values than the indirect composites, and the mean values of these properties were positively correlated (r = 0.91), confirming the study hypotheses.

Caracter��sticas de carca��a de su��nos de tr��s linhagens gen��ticas em diferentes idades ao abate

O objetivo deste trabalho foi estudar as caracter��sticas da carca��a de su��nos de diferentes linhagens gen��ticas, em diferentes idades ao abate. Foram utilizados 88 su��nos por linhagem, f��meas e machos castrados, com idade e peso m��dio iniciais de 74 dias e 30kg, respectivamente, pertencentes a tr��s linhagens gen��ticas distintas, designadas de AgroceresPic, Dalland e Seghers. A etapa experimental foi dividida em quatro fases (Crescimento I, Crescimento II, Termina����o I e Termina����o II). Ao final de cada etapa, foram abatidos 60 animais (10 por linhagem/sexo), para as caracteriza����es: Peso (PCQ) e Rendimento de Carca��a Quente (RCQ), ��rea de Olho de Lombo (AOL) e Espessura de Toucinho (ET). Na an��lise dos resultados foi utilizado um delineamento inteiramente casualizado com desdobramento dos graus de liberdade em esquema fatorial 4 x 3 x 2, sendo quatro idades ao abate (90, 119, 150 e 186 dias), tr��s linhagens (AgroceresPic, Dalland e Seghers) e dois sexos (f��mea e macho castrado), com 10 repeti����es por tratamento, sendo utilizado o pacote PROC MIXED do Softwear SAS. Os valores m��dios de peso vivo apresentaram diferen��a entre as linhagens e intera����o entre fase e linhagem (P<0,05). Os valores m��dios das demais vari��veis estudadas apresentaram diferen��a e a intera����o (P<0,05) entre fase, linhagem e sexo, sendo que de maneira geral as principais diferen��as ocorreram a partir da fase de Termina����o I, em que as f��meas das linhagens AgroceresPic e Dalland apresentaram melhores resultados (P<0,05) de RCQ (80,4 e 80,7%, respectivamente) em compara����o com os machos (78,8 e 78,7%, respectivamente) e al��m disso as f��meas Dalland apresentaram valores superiores (P<0,01) de AOL e ET (45,7cm�� e 11,4mm x 38,3cm�� e 18,3mm). Conclui-se que as linhagens gen��ticas avaliadas apresentaram caracter��sticas de carca��a muito interessantes para o mercado atual e que as f��meas su��nas podem ser utilizadas em programas que visem o abate de animais mais pesados.

Efeitos da administra����o di��ria da associa����o estavudina/nelfinavir sobre os fetos e placentas da rata albina

OBJETIVO: avaliar o efeito da administra����o da associa����o estavudina/nelfinavir durante toda a prenhez da rata, avaliando seu peso e dos conceptos, bem como o n��mero de implanta����es, fetos, placentas, reabsor����es e mortalidades materna e fetal. M��TODOS: quarenta ratas albinas EPM-1 Wistar, prenhes, foram aleatoriamente divididas em quatro grupos: GCtrl (controle do ve��culo) e tr��s experimentais, ExpI, ExpII e ExpIII, que receberam, respectivamente, 1/40, 3/120 e 9/360 mg/kg por dia de estavudina/nelfinavir por via oral. As drogas e o ve��culo (��gua destilada) foram administrados por gavagem em duas tomadas di��rias (12/12 horas), desde o dia 0 at�� o 20�� dia da prenhez. No ��ltimo dia do experimento, todos os animais foram anestesiados e eutanasiados. Foram avaliados a evolu����o do peso materno no 7��, 14�� e 20�� dias, n��mero de fetos, placentas, implanta����es, reabsor����es, ��bitos intrauterinos, malforma����es maiores e o peso dos fetos e das placentas. A an��lise estat��stica foi realizada por an��lise de vari��ncia (ANOVA), complementada pelo teste de Kruskal-Wallis (p<0,05). RESULTADOS: em rela����o ao peso corporal das ratas, houve ganho gradual e progressivo durante o decorrer da prenhez em todos os grupos, sendo este ganho mais evidente no per��odo final; por��m n��o foram constatadas diferen��as estatisticamente significantes entre eles. O n��mero de fetos, placentas, implanta����es, assim como os pesos fetais e placent��rios tamb��m n��o mostraram diferen��as estatisticamente significantes entre os grupos analisados. N��o foram observadas, tamb��m nos grupos experimentais, reabsor����es e malforma����es fetais maiores externas, no entanto, observamos entre o 8�� e o 14�� dias de gesta����o um caso de morte materna em cada grupo experimental. CONCLUS��ES: a administra����o da associa����o estavudina/nelfinavir n��o mostrou efeitos delet��rios sobre os conceptos.

Previs��es clim��ticas sazonais sobre o Brasil: avalia����o do RegCM3 aninhado no modelo global CPTEC/COLA

Este trabalho avalia o desempenho de previs��es sazonais do modelo clim��tico regional RegCM3, aninhado ao modelo global CPTEC/COLA. As previs��es com o RegCM3 utilizaram 60 km de resolu����o horizontal num dom��nio que inclui grande parte da Am��rica do Sul. As previs��es do RegCM3 e CPTEC/COLA foram avaliadas utilizando as an��lises de chuva e temperatura do ar do Climate Prediction Center (CPC) e National Centers for Enviromental Prediction (NCEP), respectivamente. Entre maio de 2005 e julho de 2007, 27 previs��es sazonais de chuva e temperatura do ar (exceto a temperatura do CPTEC/COLA, que possui 26 previs��es) foram avaliadas em tr��s regi��es do Brasil: Nordeste (NDE), Sudeste (SDE) e Sul (SUL). As previs��es do RegCM3 tamb��m foram comparadas com as climatologias das an��lises. De acordo com os ��ndices estat��sticos (bias, coeficiente de correla����o, raiz quadrada do erro m��dio quadr��tico e coeficiente de efici��ncia), nas tr��s regi��es (NDE, SDE e SUL) a chuva sazonal prevista pelo RegCM3 �� mais pr��xima da observada do que a prevista pelo CPTEC/COLA. Al��m disto, o RegCM3 tamb��m �� melhor previsor da chuva sazonal do que da m��dia das observa����es nas tr��s regi��es. Para temperatura, as previs��es do RegCM3 s��o superiores ��s do CPTEC/COLA nas ��reas NDE e SUL, enquanto o CPTEC/COLA �� superior no SDE. Finalmente, as previs��es de chuva e temperatura do RegCM3 s��o mais pr��ximas das observa����es do que a climatologia observada. Estes resultados indicam o potencial de utiliza����o do RegCM3 para previs��o sazonal, que futuramente dever�� ser explorado atrav��s de previs��o por conjunto.

Epidemiologia da leishmaniose tegumentar americana no Estado do Acre, Amaz��nia brasileira

Efetuou-se estudo estat��stico descritivo em 8.516 casos de leishmaniose tegumentar americana no Estado do Acre, Brasil, no per��odo de 2001 a 2006 (segundo per��odo), comparando-se com os resultados de publica����o anterior com dados no mesmo estado entre 1992 e 1997 (primeiro per��odo). A preval��ncia no estado mais que dobrou entre os dois momentos (55,7/10 mil habitantes de 1992 a 1997 e 128,5/10 mil habitantes entre 2001 e 2006. O sexo masculino foi o mais acometido (68,8%, n = 5.860) no segundo per��odo. A m��dia das idades foi de 26,3 anos, valor discretamente menor do que o do primeiro per��odo. Pacientes com baixa escolaridade foram os mais acometidos pela doen��a. As demais vari��veis avaliadas foram zona de resid��ncia, ocupa����o, crit��rio de diagn��stico, forma cl��nica, tratamento, recidiva, tempo para procurar tratamento e evolu����o da doen��a. Conclui-se que houve piora nos indicadores epidemiol��gicos da leishmaniose tegumentar americana avaliados no estado entre os per��odos estudados.

Precis��o experimental em ensaios com a cultura do feij��o

A avalia����o do coeficiente de varia����o (CV) como medida da precis��o dos experimentos tem sido feita com diversas culturas, esp��cies animais e forrageiras por meio de trabalhos sugerindo faixas de classifica����o dos valores, considerando-se a m��dia, o desvio padr��o e a distribui����o dos valores de CV das diversas vari��veis respostas envolvidas nos experimentos. Neste trabalho, objetivouse estudar a distribui����o dos valores de CV de experimentos com a cultura do feij��o, propondo faixas que orientem os pesquisadores na avalia����o de seus estudos com cada vari��vel. Os dados utilizados foram obtidos de revis��o em revistas que publicam artigos cient��ficos com a cultura do feij��o. Foram consideradas as vari��veis: rendimento, n��mero de vagens por planta, n��mero de gr��os por vagem, peso de 100 gr��os, estande final, altura de plantas e ��ndice de colheita. Foram obtidas faixas de valores de CV para cada vari��vel tomando como base a distribui����o normal, utilizando-se tamb��m a distribui����o dos quantis amostrais e a mediana e o pseudo-sigma, classificando-os como baixo, m��dio, alto e muito alto. Os c��lculos estat��sticos para verifica����o da normalidade dos dados foram implementados por meio de uma fun����o no software estat��stico livre R. Os resultados obtidos indicaram que faixas de valores de CV diferiram entre as diversas vari��veis apresentando ampla varia����o justificando a necessidade de utilizar faixa de avalia����o espec��fica para cada vari��vel.

Confiabilidade do question��rio Lista de Atividades F��sicas em crian��as

OBJETIVO: Avaliar a confiabilidade do question��rio Lista de Atividades F��sicas em crian��as. M��TODOS: O estudo �� parte da adapta����o transcultural do question��rio, realizado com 83 escolares de sete a dez anos, matriculados do segundo ao quinto ano do ensino fundamental da cidade de S��o Paulo, SP, em 2008. O question��rio foi respondido pela crian��a por meio de entrevista individual, apresenta lista com 21 atividades f��sicas moderadas a vigorosas realizadas no dia anterior, �� dividido em per��odos (antes, durante e ap��s a escola) e possui se����o de avalia����o da entrevista. O question��rio permite quantificar: tempo em atividades f��sicas e sedent��rias; e custos metab��licos total e ponderado. A confiabilidade foi avaliada comparando-se duas entrevistas realizadas com intervalo m��dio de tr��s horas. Para a se����o C (avalia����o da entrevista), compararam-se dados da primeira entrevista e de um avaliador externo. Utilizaram-se a proposta de Bland & Altman e os coeficientes de correla����o intraclasse e de correla����o de concord��ncia de Lin na avalia����o da confiabilidade. RESULTADOS: Os limites inferiores dos coeficientes de correla����o intraclasse para os desfechos analisados variaram de 0,84 a 0,96. A precis��o e concord��ncia variaram, respectivamente, de 0,83 a 0,97 e de 0,99 a 1. A reta estimada a partir de pares de valores obtidos nas duas aplica����es para atividade f��sica indica elevada precis��o dos dados. O item da entrevista com pior resultado foi a habilidade em estimar tempo (regular em 27,7% das entrevistas). Os itens da se����o C apresentaram coeficientes de correla����o intraclasse entre 0,60 e 0,70, exceto o n��vel de coopera����o (0,46). CONCLUS��ES: A Lista de Atividades F��sicas apresenta alta confiabilidade para aferir atividade f��sica e sedent��ria do dia anterior em crian��as.