Effects of aging and irradiation time on the properties of a highly translucent resin-based composite

Abstract

This study investigated the effects of aging and irradiation time on the macro-and micro-mechanical properties of a highly translucent nanohybrid composite (IPS Empress Direct, Trans Opal shade, Ivoclar Vivadent). Flexural strength, flexural modulus, indentation modulus, Vickers hardness, and creep were measured after being irradiated with different durations (5, 10, 20, and 40 s) and aged under different conditions (24 h at 37°C in water; 5,000 times of thermocycling between 5°C and 55°C followed by 4-week storage in artificial saliva or alcohol). Rate of cure was also measured for these four irradiation times at composite specimen surface and at 2 mm depth. Effects of aging and irradiation time were statistically analyzed using one-way ANOVA with Tukey's HSD post hoc test (α=0.05), partial eta-squared statistic, and Weibull analysis. Alcohol aging significantly reduced the mechanical properties. Aging in saliva produced a positive effect on micro-mechanical properties. Irradiation time should be at least 20 s to yield favorable mechanical properties.

Mechanical properties of contemporary orthodontic adhesives used for lingual fixed retention

“…TBXT showed identical HV values as those provided by Iijima et al [12] and close to those provided by Uysal et al [20]. Similarly IPS-ED demonstrated similar values to the ones given by Bauer & Illie [1]. The differences in HV values might be appended to the different loading conditions (2.94 N compared to 9.8 N) and the possible implication of indentation size effect (ISE), a complication where the hardness testing tends to over-or underestimate Vickers values [17] below a threshold, which is dependent of the material type.…”

“…The differences in HV values might be appended to the different loading conditions (2.94 N compared to 9.8 N) and the possible implication of indentation size effect (ISE), a complication where the hardness testing tends to over-or underestimate Vickers values [17] below a threshold, which is dependent of the material type. Indentation modulus of ZNano was found to be close to the value given by the manufacturer (9 GPa) [11], and IPS-ED to 7.1 given by Bauer & Illie [1]. The total work of indentation is divided into elastic and plastic parts, but as the absolute values are load-dependent the elastic index is defined as the elastic to total work ratio, which is independent of the load applied [15].…”

“…Therefore, material hardness [19], wear resistance and water absorption [20,24] are among the critical mechanical properties for the longevity of fixed retainers under intra-oral conditions. In addition, fixed retainer adhesives are more vulnerable to aging mechanisms as they remain in the oral cavity for longer periods than the bracket adhesives [1,16].…”

Comparison of Different Bleaching Treatments Effect on Micro Hardness of Four Different Aged Composites

“…In 2011, Yu reported that by increase in composites environment temperature, composite microhardness rate is decreased, because it leads to hydrolysis of composite polymeric section (1). Cathelan (30), Schmidt (28) and Bauer (27) stated in different researches that aging process decreases composite microhardness due to the softening of the polymeric matrix in the aging process. Also, organic and inorganic composite structure was affected with exposure to bleaching agents and leads to chemical changes (8).…”

“…After this time, the samples were exposed to a temperature of 5 -55°C for 30 seconds, and at each temperature (27) thermo-cycling (Vafay -Iran) of up to 5000 cycles was performed in order to simulate the thermal aging process (28). Then, the composite samples of each group were randomly divided to three subgroups with 12 samples (2):…”