Microdureza de uma resina composta micro-híbrida submetida a diferentes tempos de exposição e aparelhos fotopolimerizadores (AU) / Microhardness of a microhybrid composite resin submitted to different exposition times and lightcuring devices

Introdução - A proposta deste trabalho foi avaliar o desempenho de três aparelhos fotopolimerizadores utilizados com tempos de exposição diferentes sobre a microdureza de um compósito, em diferentes profundidades (1/2/3mm). Material e Método - Foram utilizados os aparelhos Curing Light com 10/40 segundos, o Kreativ com 6/10/40 segundos e o Apollo 95E com 6/10 segundos. Cinco amostras foram confeccionados para cada aparelho, utilizando uma matriz metálica contendo 4 mm de diâmetro e 5 mm de altura. As amostras foram mantidas por 24h a 37 0 C até serem submetidos ao teste de microdureza Vickers. Foram realizadas seis impressões a cada milímetro. Resultados - A partir da análise estatística, usando o teste Kruskal-Wallis (p<0,0001), observou-se que, independente do tempo e aparelho, no 1 0 mm sempre se obteve melhor microdureza. Conclusões - Com 10 segundos, independente da profundidade, o Kreativ e o Apollo foram melhores que o Curing Light. Utilizando-se o teste Mann-Whitney com 6 segundos, os aparelhos Kreativ e Apollo tiveram no 1ºmm o mesmo grau de polimerização, sendo o Apollo significativamente melhor no 2ºmm e 3ºmm (p<0,0001). O mesmo foi observado para o Curing Light e o Kreativ, em relação ao tempo de 40 segundos, tendo o primeiro obtido melhores valores de microdureza no 2ºmm e 3ºmm (p<0,0001). O Curing Light, quando utilizado com 40 segundos, mostrou-se melhor do que os demais aparelhos testados

Introduction - The aim of this study was to evaluate the performance of 3 lightcuring devices used with different exposition times on the microhardness of a composite, Charisma-A3, in different depths (1/2/3mm). Material and Method - The used devices were the Curing Light with exposition time of 10/40 seconds, the Kreativ with exposition time of 6/10/40 seconds and the Apollo 9Ë with exposition time of 6/10 seconds. The light intensity of the devices was determined using a radiometer. Five specimens were confectioned for each device, using a metallic matrix contends 4 mm of diameter and 5 mm of height. After lightcuring, the specimens were kept for 24 hours at 37º C in specific incubator till they were submitted to the Vickers microhardness test. In order to do that, six impressions to each millimeter in a standardized depth of 3 mm were made. Results - From statistic analysis using the Kruskal-Wallis test (p<0,0001), it was observed that independent of time and device in 1ºmm always microhardness was gotten better. Conclusions - In relation to 10 seconds of polymerization, independent of the depth, the Kreativ and the Apollo were better than the Curing Light. Using the Mann-Whitney test, it was observed that with 6 seconds the devices Kreativ and Apollo had the same polymerization degree in 1ºmm, being Apollo significantly better in 2º mm and 3º mm (p<0,0001). The same was observed for the devices Curing Light and Kreativ in relation to the time of 40 seconds, with the first one getting better values of microhardness in 2ºmm and 3ºmm (p<0,0001). Curing Light device when used with exposition time of 40 seconds revealed to be the best

Storage effect on the shear bond strength of adhesive systems

The purpose of this study was to evaluate the effects of storage (1 day, 3 months and 6 months) on the shear bond strength of five adhesive systems on bovine dentin substrate. One hundred and fifty bovine incisors were flattened until areas of a minimum of 5 mm in diameter were exposed. A round area of 4 mm in diameter was marked on the dentin to be treated with the following adhesive systems: Clearfil Liner Bond 2V (CLB2V), Scotchbond Multi Purpose Plus (SBMP), Optibond Solo (SOLO), Prime & Bond NT (PBNT) and Etch & Prime 3.0 (E&P). To perform the test, a composite restoration (Z100) was made in a cylindrical shape on the treated surface. After the storage period in distilled water at 37ºC, the samples were tested on an Instron testing machine. Results were submitted to ANOVA and Tukey's test at 5 percent significance level. SBMP, PBNT and E&P were statistically similar at all storage times (p>0.05). CLB2V demonstrated the highest mean shear bond strength at 3 months which was not significantly different at 6 months (p>0.05). In addition, CLB2V had the highest means at all times tested. SOLO had the lowest mean shear bond strength at 6 months, which was statistically lower than means at 3 months and 1 day (p<0.05)