Influence of microwave sterilization on the cutting capacity of carbide burs

OBJECTIVE: This study compared the cutting capacity of carbide burs sterilized with microwaves and traditional sterilization methods. MATERIAL AND METHODS: Sixty burs were divided into 5 groups according to the sterilization methods: dry heat (G1), autoclave (G2), microwave irradiation (G3), glutaraldehyde (G4) or control - no sterilization (G5). The burs were used to cut glass plates in a cutting machine set for twelve 2.5-min periods and, after each period, they were sterilized (except G5) following the protocol established for each group. The cutting capacity of the burs was determined by a weight-loss method. Data were analyzed statistically by Kruskal-Wallis and Dunn's test. RESULTS: The means of the cutting amount performed by each group after the 12 periods were G1 = 0.2167 ± 0.0627 g; G2 = 0.2077 ± 0.0231 g; G3 = 0.1980 ± 0.0326 g; G4 = 0.1203 ± 0.0459 g; G5 = 0.2642 ± 0.0359 g. There were statistically significant differences among the groups (

Diametral tensile strength and film thickness of an experimental dental luting agent derived from castor oil

The need to develop new dental luting agents in order to improve the success of treatments has greatly motivated research. Objective: The aim of this study was to evaluate the diametral tensile strength (DTS) and film thickness (FT) of an experimental dental luting agent derived from castor oil (COP) with or without addition of different quantities of filler (calcium carbonate - CaCO3). Material and Methods: Eighty specimens were manufactured (DTS N=40; FT N=40) and divided into 4 groups: Pure COP; COP 10%; COP 50% and zinc phosphate (control). The cements were mixed according to the manufacturers' recommendations and submitted to the tests. The DTS test was performed in the MTS 810 testing machine (10 KN, 0.5 mm/min). For FT test, the cements were sandwiched between two glass plates (2 cm(2)) and a load of 15 kg was applied vertically on the top of the specimen for 10 min. The data were analyzed by means of one-way ANOVA and Tukey's test (alpha=0.05). Results: The values of DTS (MPa) were: Pure COP- 10.94 +/- 1.30; COP 10%- 30.06 +/- 0.64; COP 50%- 29.87 +/- 0.27; zinc phosphate- 4.88 +/- 0.96. The values of FT (pm) were: Pure COP- 31.09 +/- 3.16; COP 10%- 17.05 +/- 4.83; COP 50%- 13.03 +/- 4.83; Zinc Phosphate- 20.00 +/- 0.12. One-way ANOVA showed statistically significant differences among the groups (DTS - p=1.01E-40; FT - p=2.4E-10). Conclusion: The experimental dental luting agent with 50% of filler showed the best diametral tensile strength and film thickness.FAPESP [06/02821-8, 06/00082-3, 07/02441-3]FAPES

Linear models application to categorical data experiments

Pesquisas de diversas áreas corno: Biologia, Medicina, Psicologia, Sociologia, Agricultura etc, apresentam como resultados dados qualitativos o que nos leva a distribuí-los em algumas categorias de respostas, razão principal da denominação de dados categorizados. Nas últimas décadas, dada urna intensa utilização, esse tipo de dados passou a ser objeto de estudo de diversos pesquisadores no intuito de tornar mais flexível as hipóteses a serem testadas, uma vez que as soluções usuais não permitem nenhuma flexibilidade. O objetivo geral do presente trabalho referese ao estudo do método proposto por GRIZZLE et alli (1969) no qual propõe urna teoria utilizando modelos de regressão linear para solucionar problemas envolvendo tabelas de contingência. É objetivo fundamental deste trabalho aplicar o método em um experimento odontológico onde os dados são classificados em cinco fatores subdivididos em dois níveis cada um, e mostrar que as matrizes envolvidas são de fácil construção, após tal construção, o método pode ser processado por um microcomputador através de um programa relativamente simples envolvendo produtos de inversão de matrizes. Pudemos com a teoria de GRIZZLE et alli ajustar uma superfície de resposta ao experimento odontológico com bons resultados e concluir ao final que o método é de fácil aplicação e possibilita uma grande diversificação de hipoteses a serem testadas.Researches of several areas like: Biology, Medicine, Psychology, Sociology, Agriculture, etc, presente like results qualitative data that conducts us to distribute them in some categories of answers, principal reason by denomination of categorical data. ln the last decades, because of a intensive utilization, this type of points passed to be the object of estudy of several searchers in the intent to turn more flexible the hypothesis to be examined, considering that usual solutions do not perrnit any flexibility. General objective of the present work refers to the study of the rnethod proposed by GRIZZLE et alii (1969) in which proposes a theory utilizing models of linear regression to solve problems involving tables of contingency. It is fundamental objective of this work to apply the method in an odontological experiment where the elements are classified in five factors subdivided in two involved matrixes are of easy construction, and following this the method may be prosecuted by a micron computer through a program more or less simple involving products of inversion of matrixes. With the theory by Grizzle, Starmer and Koch we could adjust a response surface to the odontological experiment with good results and we could conclude at the final that the method is of easy application and it makes possible a great diversification of hypothesis to be tested

Análise sensorial: um estudo sobre procedimentos estatísticos e número mínimo de julgadores

A partir do início dos anos 70, ficou estabelecido que a qualidade sensorial é o resultado da interação entre o alimento e o homem, portanto varia de forma subjetiva. Diferentes escalas foram então associadas às análises sensoriais, surgindo como conseqüência procedimentos estatísticos específicos nesta área. Os experimentos envolvendo análise sensorial iniciaram assim a discussão quanto ao número necessário de julgadores, ao seu treinamento e aos procedimentos apropriados à análise dos dados extraídos dessas escalas ordenadas. Este trabalho foi baseado em um teste sensorial de aceitação do atributo “Impressão Global” de quatro amostras de cachaças avaliadas por 120 julgadores. O objetivo fundamental foi realizar comparações entre os procedimentos estatísticos, paramétricos ou não-paramétricos, com vistas a compará-los e estabelecer o número mínimo de julgadores. Com base nos dados dos testes sensoriais foram criadas 5400 amostras sistemáticas com números diferentes de julgadores, sobre as quais foram aplicados os procedimentos estatísticos estabelecidos. Os resultados assim obtidos mostraram ser possível a utilização de um número menor de julgadores. Revelaram ainda que, na maioria dos casos, o índice de concordância é o fator mais importante na determinação do número mínimo de julgadores, sendo que, para valores de concordância de Kendall maior ou igual a 0,18, o número de 60 julgadores mostrou-se suficiente.Since begin of 1970s, it was well established that the sensory quality of a food was a result of the interaction between the food and humans, thus varying subjectively. This led to the creation of scales associated to sensory analyses, end as a consequence, specific statistical procedures in this area. The experiments related to sensory analysis started the discussion about the number of judges required, their training, and the appropriate procedures for the analysis of data extracted from these ordered scales. The present work was based on a sensory acceptance test of the attribute “Global Impression” cachaça samples evaluated by 120 judges. The basic objective was to compare the standard statistical procedures, parametric and nonparametric, in order to determine the minimum number of judges necessary. From the initial data, 5400 systematic samples with different numbers of judges were created, and the standard statistical procedures were applied. Bored on the obtained data it was evaluated if the base experiment could be reproduced with fewer judges. The results indicated that, in most cases, the index of agreement is the most important factor to determine the necessary number of judges. In this case, if the Kendall concordance value among judges is ≥ 0,18, the total number of judges could be only 60.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

Teste de aceitação em amostras de cachaça: avaliação de métodos estatísticos e de número mínimo de julgadores

Based on data of global impression acceptance tests of 4 cachaças samples, sensory evaluated by 120 judges, statistical parametric and non-parametric proceedings were compared. In this way, based on the sensory acceptance obtained data, 5400 systematic samples were created with different judges numbers and submitted to the established statistical proceedings. The obtained results showed that ANOVA, with two factors and Friedman tests, were equivalent to determine signifi cant differences among the cachaça samples, and in relation to the number of judges, the results pointed out 45 as the minimum necessary to detect signifi cative differences.A partir de dados obtidos em testes de aceitação em relação ao atributo “Impressão Global” de quatro cachaças avaliadas por 120 julgadores, foram realizadas comparações entre procedimentos estatísticos, paramétricos e não-paramétricos. A partir dos dados obtidos conforme descrito acima, foram criadas 5400 amostras sistemáticas com diferentes números de julgadores e sobre as quais, aplicados os diferentes procedimentos estatísticos. Os resultados obtidos mostraram que, a ANOVA de dois fatores e o teste de Friedman são equivalentes para determinar diferenças signifi cativas entre as amostras de cachaça e em relação ao número de julgadores os resultados apontaram 45 como número o mínimo necessário para detectar diferenças signifi cativas entre as amostras estudadas

TESTES DE ACEITAÇÃO EM AMOSTRAS DE CACHAÇA: AVALIAÇÃO DE MÉTODOS ESTATÍSTICOS E DE NÚMERO MÍNIMO DE JULGADORES

A partir de dados obtidos em testes de aceitação em relação ao atributo “Impressão Global” de quatro cachaças avaliadas por 120 julgadores, foram realizadas comparações entre procedimentos estatísticos, paramétricos e não-paramétricos. A partir dos dados obtidos conforme descrito acima, foram criadas 5400 amostras sistemáticas com diferentes números de julgadores e sobre as quais, aplicados os diferentes procedimentos estatísticos. Os resultados obtidos mostraram que, a ANOVA de dois fatores e o teste de Friedman são equivalentes para determinar diferenças signifi cativas entre as amostras de cachaça e em relação ao número de julgadores os resultados apontaram 45 como número o mínimo necessário para detectar diferenças signifi cativas entre as amostras estudadas

<b>EFFECTS OF HEAT TREATMENT AND CALCIUM ON POSTHARVEST STORAGE OF ATEMOYA FRUITS*</b>

<p align="justify">The aim of the present study was to investigate the effect of postharvest warm dipping with calcium chloride (CaCl2) on atemoya fruit (Annona cherimola Mill x Annona squamosa L.) storage. Fruits were immersed in 6% CaCl2 solution at 20 and 40°C for 20 min followed by storage at room temperature. The effectiveness of the treatment was assessed in terms of its impact on peel and fl esh appearance, weight loss, total soluble solids (TSS), total titratable acidity (TTA), pH, ascorbic acid content, total phenolics, and enzyme activities of polyphenoloxidase (PPO) and peroxidase (POD). Treatment at 40°C preserved eatable conditions up to 6 days, although calcium affected the appearance of the peel as soon as 4 days. Flesh browning was detected only on the 8th day in untreated fruits, after an increase in PPO and POD activities and total phenolics, and a decrease in ascorbic acid content. The weight loss was continuous throughout the storage period, with no signifi cant difference between treatments. TTA and TSS contents increased and pH decreased during the experiment. Results suggest that CaCl2 dipping had a positive effect on fl esh browning, which was reduced, while heat treatment showed a synergic effect, which could be related broadly with a fall in PPO activity. The variations in ascorbic acid content during storage suggest that the warm dipping combined with CaCl2, contributed to the antioxidant capacity of the fruit.</p&gt

Human teeth versus bovine teeth: cutting effectiveness of diamond burs

Aim : In this study, a mass-loss method was used to verify whether bovine enamel has the same wear pattern as human enamel in cutting efficiency tests of diamond burs. Methods: Seventy-two teeth were used: 36 human molars (HT) and 36 bovine mandibular central incisors (BT). The enamel of the teeth was cut using diamond bur #1092 attached to a high-speed handpiece under controlled pressure (50-80 g). Each bur (n=12) cut for a total of 72 min, divided into 6 periods of 12 min each (12-min, 24-min, 36-min, 48-min, 60-min, and 72-min). The amount of enamel removed was determined by the difference between pre- and post-cut tooth masses. Results: The mean amounts (g) of enamel removed were: HT- 12-min=0.11; 24-min=0.12; 36-min=0.11; 48-min=0.11; 60-min=0.10; 72-min=0.12; BT- 12-min=0.12; 24-min=0.15; 36-min=0.15; 48-min=0.13; 60-min=0.16; 72-min=0.14. Data were analyzed using ANOVA followed by Tukey′s test, and the results showed statistically significant differences between human and bovine teeth (p<0.001) and among the cutting periods (p<0.001). Conclusions : It was concluded that the cutting efficiency of the burs was different between the tested substrates, and that bovine enamel underwent greater mass loss than did human enamel

Human teeth versus bovine teeth: cutting effectiviness of diamond burs

Aim: In this study, a mass-loss method was used to verify whether bovine enamel has the same wear pattern as human enamel in cutting efficiency tests of diamond burs. Methods: Seventy-two teeth were used: 36 human molars (HT) and 36 bovine mandibular central incisors (BT). The enamel of the teeth was cut using diamond bur #1092 attached to a high-speed handpiece under controlled pressure (50-80 g). Each bur (n=12) cut for a total of 72 min, divided into 6 periods of 12 min each (12-min, 24-min, 36-min, 48-min, 60-min, and 72-min). The amount of enamel removed was determined by the difference between pre- and post-cut tooth masses. Results: The mean amounts (g) of enamel removed were: HT- 12-min=0.11; 24-min=0.12; 36-min=0.11; 48-min=0.11; 60-min=0.10; 72-min=0.12; BT- 12-min=0.12; 24-min=0.15; 36-min=0.15; 48- min=0.13; 60-min=0.16; 72-min=0.14. Data were analyzed using ANOVA followed by Tukey’s test, and the results showed statistically significant differences between human and bovine teeth (p<0.001) and among the cutting periods (p<0.001).Conclusions: It was concluded that the cutting efficiency of the burs was different between the tested substrates, and that bovine enamel underwent greater mass loss than did human enamel.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP