Effect of surface treatments of laboratory-fabricated composites on the microtensile bond strength to a luting resin cement Efeito dos tratamentos de superfície de resinas compostas de laboratório na resistência a microtração de um agente de fixação resinoso

The purpose of this study was to evaluate the influence of different surface treatments on composite resin on the microtensile bond strength to a luting resin cement. Two laboratory composites for indirect restorations, Solidex and Targis, and a conventional composite, Filtek Z250, were tested. Forty-eight composite resin blocks (5.0 x 5.0 x 5.0mm) were incrementally manufactured, which were randomly divided into six groups, according to the surface treatments: 1- control, 600-grit SiC paper (C); 2- silane priming (SI); 3- sandblasting with 50 mm Al2O3 for 10s (SA); 4- etching with 10% hydrofluoric acid for 60 s (HF); 5- HF + SI; 6 - SA + SI. Composite blocks submitted to similar surface treatments were bonded together with the resin adhesive Single Bond and Rely X luting composite. A 500-g load was applied for 5 minutes and the samples were light-cured for 40s. The bonded blocks were serially sectioned into 3 slabs with 0.9mm of thickness perpendicularly to the bonded interface (n = 12). Slabs were trimmed to a dumbbell shape and tested in tension at 0.5mm/min. For all composites tested, the application of a silane primer after sandblasting provided the highest bond strength means.<br>O objetivo deste estudo foi avaliar a influência de diferentes tratamentos de superfície na resistência de união de resinas compostas a um agente de fixação resinoso. Dois compósitos de laboratório, Solidex e Targis, e um compósito convencional, Filtek Z250, foram testados. Quarenta e oito blocos de resina composta (5.0 x 5.0 x 5.0mm) foram confeccionados através da técnica incremental, para cada compósito testado, e foram aleatoriamente divididos em 6 grupos. Os blocos foram submetidos a seis tratamentos de superfície: 1 - Controle, Lixa 600-SiC (C); 2 - Silanização (SI); 3 - Jateamento com Al2O3 50µm por 10 segundos (SA); 4 - Condicionamento com ácido fluorídrico por 60 segundos (HF); 5 - HF + SI; 6 - SA + SI. Blocos submetidos ao mesmo tratamento foram unidos com o agente de fixação resinoso Rely X. Uma carga de 500g foi aplicada por 5 minutos e as amostras foram fotoativadas por 40 segundos. Os blocos unidos foram seccionados em fatias de 0.9mm de espessura perpendicularmente à interface de união (n = 12). Foram realizadas constrições limitando a interface de união a 1mm e as amostras foram levadas para o ensaio de tração. As maiores médias de união foram obtidas para as amostras submetidas à aplicação do silano após o jateamento com Al2O3

Comparison of microleakage of photo-cured composites using three different light sources: halogen lamp, LED and argon laser: an in vitro study

In this study, we compared the microleakage of composite fillings cured with halogen bulb, LED and argon ion laser (488 nm). Twenty-four extracted human molars were divided randomly in three groups. Six cavities were prepared on the coronal part of each tooth. Standard cavities (1.7 x 2 mm) were prepared. Cavities were acid etched, sealed with Scotch Bond 1 and filled by a hybrid composite. Cavities were exposed to one light source, thermocycled and immersed in a 2% methylene blue dye solution. Dye penetration in the leakage of cavities was recorded using a digital optical microscope. Mean values of percentage of dye penetrations in microleakages of cavities were 49.303 +/- 5.178% for cavities cured with LED, 44.486 +/- 6.075% with halogen bulb and 36.647 +/- 5.936% for those cured by argon laser. Statistically significant difference exists between cavities cured by halogen vs LED (P < 0.01), halogen vs laser (P < 0.001) and LED vs laser (P < 0.001). The lowest microleakage was observed in the cavities and composites cured with argon ion laser