Temperature and curing time affect composite sorption and solubility

Abstract

Objective:This study evaluated the effect of temperature and curing time on composite sorption and solubility. Material and Methods:Seventy five specimens (8x2 mm) were prepared using a commercial composite resin (ICE, SDI). Three temperatures (10º C, 25º C and 60º C) and five curing times (5 s, 10 s, 20 s, 40 s and 60 s) were evaluated. The specimens were weighed on an analytical balance three times: A: before storage (M1); B: 7 days after storage (M2); C: 7 days after storage plus 1 day of drying (M3). The storage solution consisted of 75% alcohol/25% water. Sorption and solubility were calculated using these three weights and specimen dimensions. The data were analyzed using the Kruskal-Wallis and Mann-Whitney U Tests (α=5%). Results:The results showed that time, temperature and their interaction influenced the sorption and solubility of the composite (p<0.05). At 60º C, the composite sorption showed an inverse relationship with the curing time (p<0.05). The composite cured for 5 s showed higher sorption for the 40 s or 60 s curing times when compared with all temperatures (p<0.05). Curing times of 20 s and 40 s showed similar sorption data for all temperatures (p>0.05). The 60º C composite temperature led to lower values of sorption for all curing times when compared with the 10º C temperature (p<0.05). The same results were found when comparing 10º C and 25º C (p<0.05), except that the 20 s and 40 s curing times behaved similarly (p>0.05). Solubility was similar at 40 s and 60 s for all temperatures (p>0.05), but was higher at 10º C than at 60º C for all curing times (p<0.05). When the composite was cured at 25º C, similar solubility values were found when comparing the 5 s and 10 s or 20 s and 40 s curing times (p>0.05). Conclusion:In conclusion, higher temperatures or longer curing times led to lower sorption and solubility values for the composite tested; however, this trend was only significant in specific combinations of temperature and curing times.

Pre-heating mitigates composite degradation

“…Pre-heated specimens (cured at 60°C) were fabricated using a non-commercial heater 3 . The metallic matrix was positioned on the heater, the composite was inserted in the matrix in a single increment using a Centrix syringe, and then covered with a polyester strip and a glass coverslip.…”

“…Pre-heating, for instance, has been shown to result in higher degrees of conversion when the composite is cured at high temperatures, probably due to the enhanced molecular mobility and greater number of collisions of reactive species achieved during high-temperature polymerization 2 , 5 , 6 , 8 , 23 . It is likely that this higher degree of conversion causes the free volume within the polymer network to reduce, which may be responsible for the lower sorption and solubility found in pre-heated composites compared to materials cured at room temperature 3 . Thus, hypothetically, the higher degree of conversion produced by pre-heating could cause these composites to degrade less.…”

The effect of polymerization conditions on the amounts of unreacted monomer and bisphenol A in dental composite resins

“…The safe use of composite resins with aesthetically pleasing results is dependent on several factors such as light wavelength 17) , exposure time 18) , distance from light guide exit 19) , light source 13) , and light intensity 20) . These factors influence the degree of polymerization, hardness of the composite solid, and the amount of released cytotoxic monomers 21) .…”

Efeito da variação dos parâmetros de potência e energia por pulso na resistência de união à dentina de sistema adesivo irradiado com laser de diodo

“…De acordo com os resultados expostos sugere-se que o uso de uma Potência mais baixa (0,5 W) com uma Energia por pulso maior (0,08 J e 0,1 J) possa melhorar a resistência de união à dentina, provavelmente porque uma Ep mais elevada gera um aquecimento maior da superfície dentinária, que pode favorecer a evaporação do solvente e da água residual. Outros estudos que avaliaram a influência da temperatura na evaporação do solvente demonstraram aumento na resistência de união (MALACARNE et al,2009;HOSAKA et al, 2010;BAIL et al, 2012;CASTRO et al, 2013;VALE et al, 2014). et al (1999), Matos et al (2000), Araújo et al (2007), Malta et al (2008), Ribeiro et al (2013) e Silva et al (2016) observaram que Potências de 0,6 W e 1 W e Energias por pulso de 0,04 J; 0,06 J e 0,1 J não alteram a resistência de união dos sistemas adesivos, o presente trabalho, assim como o de De Carvalho et al (2008), sugerem que Potências menores e Energias por pulso maiores são capazes de favorecer o processo de adesão.…”