Effect of the Insertion and Polymerization Technique in Composite Resin Restorations: Analysis of Marginal Gap by Atomic Force Microscopy

This in vitro study evaluated the marginal gap at the composite tooth/resin interface in class V cavities under the influence of two insertion techniques and a curing system by means of atomic force microscopy (AFM). Forty enamel and dentin cavities were prepared on the buccal surface in bovine teeth with quadratic forms measuring 2 mm X 2 mm and depth of 1.5 mm. The teeth were then divided into four groups: group A, 10 cavities were restored in one increment, light cured by halogen light; group B, 10 cavities filled with bulk filling, light cured by the light emitting diodes (LED); group C, 10 cavities were restored by the incremental technique, light cured by halogen light; group D, 10 cavities were restored by the incremental technique, light cured by the LED. The teeth underwent the polishing procedure and were analyzed by AFM for tooth/restoration interface evaluation. The data were compared between groups using the nonparametric Kruskall-Wallis and Mann-Whitney tests (p < 0.05). The results showed a statistically significant difference between groups A and B and groups A and C. It was concluded that no insertion and polymerization technique was able to completely seal the cavity.

Shear bond strength of repairs in porcelain conditioned with laser

The aim of this study was to evaluate the shear bond strength of repairs in porcelain conditioned with laser. Sixty porcelain discs were made and six groups were formed (n = 10): G1: conditioning with laser with potency 760 mW; G2: conditioning with laser with potency 760 mW and application of 37% phosphoric acid for 15 s; G3: conditioning with laser with potency 900 mW; G4: conditioning with laser with potency 900 mW and application of 37% phosphoric acid for 15 s; G5: application of 37% phosphoric acid for 15 s (group control) and G6: application of 10% hydrofluoric acid for 2 min. The composite resin was insert of incremental layers at the porcelain surface aided with a metal matrix, and photoactivation for 20 s each increment. The specimens were submitted to a thermal cycling by 1000 cycles of 30 s in each bath with temperature between 5 and 55 degrees C. After the thermal cycling, specimens were submitted to the shear bond strength. The results were evaluated statistically through analysis of variance and Tukey's tests with 5% significance. The averages and standard deviation founded were: G1, 11.25 (+/- 3.10); G2, 12.32 (+/- 2.65); G3, 14.02 (+/- 2.38); G4, 13.44 (+/- 2,07); G5, 9.91 (-/+ 2,18); G6, 12.74 (+/- 2.67). The results showed that the femtosecond laser produced a shear bond strength of repairs in porcelain equal to the hydrofluoric acid and significantly superior to the use of phosphoric acid. Microsc. Res. Tech., 2012. (C) 2012 Wiley Periodicals, Inc.

Marginal adaptation of Class 2 adhesive restorations

Objective: Control of microleakage represents a challenge for posterior composite restorations. The technique for composite placement may reduce microleakage. The null hypothesis of this in vitro study was that centripetal incremental insertion of composite resin would result in less microleakage than that obtained with the oblique incremental technique or bulk technique. Method and Materials: Standardized Class 2 preparations were made in 60 caries-free extracted third molars and randomly assigned to 3 groups ( n = 20): ( 1) oblique incremental insertion technique ( control), ( 2) centripetal incremental insertion technique, and ( 3) bulk insertion. The teeth were restored with a total-etch adhesive and micro-hybrid composite resin. The specimens were isolated with nail varnish except for a 2-mm-wide area around the restoration and then thermocycled ( 1,000 thermal cycles, 5 degrees C/ 55 degrees C; 30-second dwell time). The specimens were immersed in an aqueous solution of 50% silver nitrate for 24 hours, followed by 8 hours of immersion in a photo-developing solution and subsequently evaluated for leakage. The microleakage scores ( 0 to 4) obtained from the occlusal and cervical walls were analyzed with median nonparametric tests ( P <.05). Results: The null hypothesis was rejected. All techniques attained statistically similar dentin microleakage scores ( P =.15). The centripetal insertion technique displayed significantly less microleakage than the oblique technique at the enamel margins ( P =.04). Conclusion: None of the techniques eliminated marginal microleakage in Class 2 preparations. However, in occlusal areas, the centripetal technique performed significantly better than the other techniques.

Seasonal development of secondary xylem and phloem in Schizolobium parahyba (Vell.) Blake (Leguminosae : Caesalpinioideae)

The cambial activity and periodicity of secondary xylem and phloem formation have been less studied in tropical tree species than in temperate ones. This paper describes the relationship between seasonal cambial activity, xylem and phloem development, and phenology in Schizolobium parahyba, a fast growing semideciduous seasonal forest tree from southeastern Brazil. From 2002 to 2003, wood samples were collected periodically and phenology and climate were recorded monthly in the same period. S. parahyba forms annual growth increments in wood, delimited by narrow initial parenchyma bands. The reduction of the cambial activity to a minimum correlates to the dry season and leaf fall. The higher cambial activity correlates to the wet season and the presence of mature leaves. In phloem, a larger conductive region was observed in the wet season, when the trees were in full foliage. The secondary phloem did not exhibit any incremental zone marker; however, we found that the axial parenchyma tends to form irregular bands.

Perfil do nível de atividade física na vida diária de pacientes portadores de DPOC no Brasil

Objective: To evaluate characteristics of physical activities in daily life in COPD patients in Brazil, correlating those Characteristics with physiological variables. Methods: Physical activities in daily life were evaluated in 40 COPD patients (18 males; 66 +/- 8 years of age; FEV(1) = 46 +/- 16 % of predicted; body mass index = 27 +/- 6 kg/m(2)) and 30 healthy age- and gender-matched subjects, using a multiaxial accelerometer-based sensor for 12 h/day on two consecutive days. We also assessed maximal and functional exercise capacity, using the incremental exercise test and the six-minute walk test (6MWT), respectively; MIP and MEP; peripheral muscle force, using the one-repetition maximum test and the handgrip test; quality of life, using the Saint George's Respiratory Questionnaire (SGRQ); functional status, using the London Chest Activity of Daily Living questionnaire; and dyspnea sensation, using the Medical Research Council (MRC) scale. Results: Mean walking time/day was shorter for COPD patients than for the controls (55 +/- 33 vs. 80 +/- 28 min/day; p = 0.001), as movement intensity was lower (1.9 +/- 0.4 vs. 2.3 +/- 0.6 m/s(2); p = 0.004). The COPD patients also tended to spend more time seated (294 +/- 114 vs. 246 +/- 122 min/day, p = 0.08). Walking time/day correlated with the 6MWT (r = 0.42; p = 0.007) and maximal workload (r = 0.41; p = 0.009), as well as with age, MRC scale score and SGRQ activity domain score (-0.31 <= r <= -0.43; p <= 0.05 for all). Conclusions: This sample of Brazilian patients with COPD, although more active than those evaluated in studies conducted in Europe, were less active than were the controls. Walking time/day correlated only moderately with maximal and functional exercise capacity.

Máxima fase estável de lactato sanguíneo e potência crítica em ciclistas bem treinados

O principal objetivo deste estudo foi comparar a intensidade correspondente à máxima fase estável de lactato (MLSS) e a potência crítica (PC) durante o ciclismo em indivíduos bem treinados. Seis ciclistas do sexo masculino (25,5 ± 4,4 anos, 68,8 ± 3,0kg, 173,0 ± 4,0cm) realizaram em diferentes dias os seguintes testes: exercício incremental até a exaustão para a determinação do pico de consumo de oxigênio (VO2pico) e sua respectiva intensidade (IVO2pico); cinco a sete testes de carga constante para a determinação da MLSS e da PC; e um exercício até a exaustão na PC. A MLSS foi considerada com a maior intensidade de exercício onde a concentração de lactato não aumentou mais do que 1mM entre o 10º e o 30º min de exercício. Os valores individuais de potência (95, 100 e 110% IVO2pico) e seu respectivo tempo máximo de exercício (Tlim) foram ajustados a partir do modelo hiperbólico de dois parâmetros para a determinação da PC. Embora altamente correlacionadas (r = 0,99; p = 0,0001), a PC (313,5 ± 32,3W) foi significantemente maior do que a MLLS (287,0 ± 37,8W) (p = 0,0002). A diferença percentual da PC em relação à MLSS foi de 9,5 ± 3,1%. No exercício realizado na PC, embora tenha existido componente lento do VO2 (CL = 400,8 ± 267,0 ml.min-1), o VO2pico não foi alcançado (91,1 ± 3,3 %). Com base nesses resultados pode-se concluir que a PC e a MLSS identificam diferentes intensidades de exercício, mesmo em atletas com elevada aptidão aeróbia. Entretanto, o percentual da diferença entre a MLLS e PC (9%) indica que relação entre esses dois índices pode depender da aptidão aeróbia. Durante o exercício realizado até a exaustão na PC, o CL que é desenvolvido não permite que o VO2pico seja alcançado.

Efeitos do estado e especificidade do treinamento aeróbio na relação %VO2max versus %FCmax durante o ciclismo

OBJETIVO: Determinar os efeitos do estado e especificidade de treinamento aeróbio na relação entre o percentual do consumo máximo de oxigênio (%VO2max) e o percentual da frequência cardíaca máxima (%FCmax) durante o exercício incremental realizado no cicloergômetro. MÉTODOS: Sete corredores, 9 ciclistas, 11 triatletas e 12 sedentários, todos do sexo masculino e aparentemente saudáveis, foram submetidos a um teste incremental até a exaustão no cicloergômetro. Regressões lineares entre %VO2max e %FCmax foram determinadas para cada indivíduo. Com base nessas regressões, foram calculados %FCmax correspondentes a determinados %VO2max (50, 60, 70, 80 e 90%) de cada participante. RESULTADOS: Não foram encontradas diferenças significantes entre todos os grupos nos %FCmax para cada um dos %VO2max avaliados. Analisando-se os voluntários como um único grupo, as médias dos %FCmax correspondentes a 50, 60, 70, 80 e 90% %VO2max foram 67, 73, 80, 87, e 93%, respectivamente. CONCLUSÃO: Nos grupos analisados, a relação entre o %VO2max e %FCmax durante o exercício incremental no ciclismo não é dependente do estado e especificidade do treinamento aeróbio.

Effect of the aerobic capacity on the validity of the anaerobic threshold for determination of the maximal lactate steady state in cycling

The maximal lactate steady state (MLSS) is the highest blood lactate concentration that can be identified as maintaining a steady state during a prolonged submaximal constant workload. The objective of the present study was to analyze the influence of the aerobic capacity on the validity of anaerobic threshold (AT) to estimate the exercise intensity at MLSS (MLSS intensity) during cycling. Ten untrained males (UC) and 9 male endurance cyclists (EC) matched for age, weight and height performed one incremental maximal load test to determine AT and two to four 30-min constant submaximal load tests on a mechanically braked cycle ergometer to determine MLSS and MLSS intensity. AT was determined as the intensity corresponding to 3.5 mM blood lactate. MLSS intensity was defined as the highest workload at which blood lactate concentration did not increase by more than 1 mM between minutes 10 and 30 of the constant workload. MLSS intensity (EC = 282.1 ± 23.8 W; UC = 180.2 ± 24.5 W) and AT (EC = 274.8 ± 24.9 W; UC = 187.2 ± 28.0 W) were significantly higher in trained group. However, there was no significant difference in MLSS between EC (5.0 ± 1.2 mM) and UC (4.9 ± 1.7 mM). The MLSS intensity and AT were not different and significantly correlated in both groups (EC: r = 0.77; UC: r = 0.81). We conclude that MLSS and the validity of AT to estimate MLSS intensity during cycling, analyzed in a cross-sectional design (trained x sedentary), do not depend on the aerobic capacity.

Comparação entre a utilização de saliva e sangue para determinação do lactato mínimo em cicloergômetro e ergômetro de braço em mesa-tenistas

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Determination of anaerobic threshold in rats using the lactate minimum test

The break point of the curve of blood lactate vs exercise load has been called anaerobic threshold (AT) and is considered to be an important indicator of endurance exercise capacity in human subjects. There are few studies of AT determination in animals. We describe a protocol for AT determination by the lactate minimum test in rats during swimming exercise. The test is based on the premise that during an incremental exercise test, and after a bout of maximal exercise, blood lactate decreases to a minimum and then increases again. This minimum value indicates the intensity of the AT. Adult male (90 days) Wistar rats adapted to swimming for 2 weeks were used. The initial state of lactic acidosis was obtained by making the animals jump into the water and swim while carrying a load equivalent to 50% of body weight for 6 min (30-s exercise interrupted by a 30-s rest). After a 9-min rest, blood was collected and the incremental swimming test was started. The test consisted of swimming while supporting loads of 4.5, 5.0, 5.5, 6.0 and 7.0% of body weight. Each exercise load lasted 5 min and was followed by a 30-s rest during which blood samples were taken. The blood lactate minimum was determined from a zero-gradient tangent to a spline function fitting the blood lactate vs workload curve. AT was estimated to be 4.95 ± 0.10% of body weight while interpolated blood lactate was 7.17 ± 0.16 mmol/l. These results suggest the application of AT determination in animal studies concerning metabolism during exercise.

Adaptação da máscara do analisador de gases VO2000 para mensuração de parâmetros cardiorrespiratórios em natação

O objetivo do presente estudo foi desenvolver um snorquel (SNQ) de baixo custo para mensuração de parâmetros cardiorrespiratórios em natação. Para isso, a máscara do analisador de gases VO2000 (MASC) foi adaptada a um SNQ desenvolvido artesanalmente com espaço morto de 250ml. Oito participantes foram submetidos a dois testes incrementais (TI) em cicloergômetro utilizando a MASC e o SNQ. Os TI foram realizados até a exaustão voluntária e foram compostos por estágios de 3min com carga inicial e incrementos de 35W. em ambas as situações, amostras gasosas foram coletadas em intervalos de 10s para determinação dos volumes de oxigênio (VO2), gás carbônico (VCO2), ventilatório (VE) e mensuração da freqüência cardíaca (FC). A comparação dos parâmetros cardiorrespiratórios (VO2, VE, VCO2 e FC) mensurados com o SNQ e a MASC foi realizada com o teste t de Student para amostras dependentes, enquanto que o teste de correlação de Pearson e a análise gráfica de Bland e Altman foram utilizados para verificar as associações e concordância entre parâmetros. em todos os casos, o nível de significância foi de P < 0,05. A adequação das equações de correção para os valores provenientes do SNQ foi verificada pelos erros sistemáticos (bias), aleatórios (precisão) e acurácia (ac). Não foram observadas diferenças significativas entre os valores de VO2, VCO2 e FC obtidos com a MASC e SNQ. Os valores de VE mensurados com o SNQ foram significativamente superiores aos obtidos com a MASC. No entanto, todos os parâmetros apresentaram elevada concordância e coeficiente de correlação (0,88 a 0,97). Além disso, foram verificados reduzidos valores de bias (VO2 = 0,11L/min; VE = 4,11L/min; VCO2 = 0,54L/min; 8,87bpm), precisão (VO2 = 0,24L/min; VE = 11,02L/ min; VCO2 = 0,18L/min; 7,42bpm) e ac (VO2 = 0,27L/min; VE = 11,76L/min; VCO2 = 0,56L/min; 11,56bpm). Desse modo, pode-se concluir que o SNQ desenvolvido neste estudo possibilita a mensuração válida de parâmetros cardiorrespiratórios em natação.

Força crítica em nado atado para avaliação da capacidade aeróbia e predição de performances em nado livre

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Predicting MAOD Using Only a Supramaximal Exhaustive Test

The objective of this study was to propose an alternative method (MAOD(ALT)) to estimate the maximal accumulated oxygen deficit (MAOD) using only one supramaximal exhaustive test. Nine participants performed the following tests: (a) a maximal incremental exercise test, (b) six submaximal constant workload tests, and (c) a supramaximal constant workload test. Traditional MAOD was determined by calculating the difference between predicted O(2) demand and accumulated O(2) uptake during the supramaximal test. MAOD(ALT) was established by summing the fast component of excess post-exercise oxygen consumption and the O(2) equivalent for energy provided by blood lactate accumulation, both of which were measured during the supramaximal test. There was no significant difference between MAOD (2.82 +/- 0.45 L) and MAOD(ALT) (2.77 +/- 0.37 L) (p = 0.60). The correlation between MAOD and MAOD(ALT) was also high (r = 0.78; p = 0.014). These data indicate that the MAOD(ALT) can be used to estimate the MAOD.

Effect of aerobic training status on both maximal lactate steady state and critical power

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effect of a previous high intensity running exercise on isokinetic muscular strength in individuals with different training backgrounds

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)