Flexural strength of a composite resin light cured with different exposure modes and immersed in ethanol or distilled water media

Abstract

Aim:The aim of this in vitro study was to evaluate the flexural strength of a composite resin polymerized with three different modes of light exposure.Materials and Methods:The three different modes of light exposure were conventional, 600 mW/cm2/40s; soft start, 300 mW/cm2/10s + 600 mW/cm2/30s; pulse delay, 600 mW/cm2/1s + 60 s of waiting time + 600 mW/cm2/39s). Twenty samples were prepared for each polymerization method. Flexural strength (FS) tests were carried out with a 2 kN load at a speed of 0.5 mm/ min. All tested groups were submitted to analysis of variance (one-way-ANOVA) and Tukey's test (P < 0.05).Results:When stored in water, conventional and pulse delay groups presented higher FS values which were statistically different from the soft start group. When stored in 100% ethanol, conventional and soft start groups presented higher FS values which were statistically different from the pulse delay group.Conclusion:Different polymerization modes and immersion media can affect the physical properties (flexural strength) of composite resin.

Effect of radiant exposure and UV accelerated aging on physico-chemical and mechanical properties of composite resins

“…These results corroborate with other studies that have also demonstrated a direct relation between radiant exposure and flexural properties of composite resins. 31 , 32 …”

Impact of dietary solvents on flexural properties of bulk-fill composites

“…While flexural strength signifies the highest stress experienced by the composites before they fail, flexural modulus represents their stiffness. Flexural testing results in complex tensions stemming from the integration of compression, shear and tensile stresses (dos Santos et al, 2012). Different clinical situations necessitates the use of composites with dissimilar flexural strength and modulus (Anusavice, 2003, Rodrigues et al, 2007, Yap et al, 2002).…”

“…ISO 4049 flexural test specimens are typically 25 mm long (International Organization for Standardization, 2000). These elongated composite specimens are technically challenging to fabricate and require the use of several overlapping light irradiation owing to the relatively smaller light exit windows of most curing tips (dos Santos et al, 2012). As the mesio-distal widths of molars are usually around 11 mm, the ISO recommended length is also not really clinically appropriate.…”

Influence of different crosshead speeds on diametral tensile strength of a methacrylate based resin composite: An in-vitro study

“…[ 16 ] Diametral tensile testing is a common method for measuring the tensile strength of brittle materials because it avoids some of the difficulties inherent in direct and flexural tensile testing. [ 20 ]…”