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

Abstract

Currently, there is no consensus in terms of defining the minimum radiant exposure values necessary for achieving adequate properties of composite resin. In addition, the long-term influence that radiant exposure has on the properties of composite resins is still questionable. Objective: The objective of this study was to evaluate the effect of radiant exposure and UV accelerated aging on the physico-chemical and mechanical properties of micro-hybrid and nanofilled composite resins. Material and Methods: A nanofilled (Filtek Supreme; 3M ESPE) and a micro-hybrid composite resin (Filtek Z250; 3M ESPE) were investigated under different radiant exposures (3.75, 9, and 24 J/cm2) and UV accelerated aging protocols (0, 500, 1000, and 1500 aging hours). The degree of conversion (DC), flexural strength (FS), modulus (M), water sorption (WS), and solubility (WL) were evaluated. The results obtained were analyzed using two-way ANOVA and Tukey's test. Comparisons were performed using a significance level of α=0.05. Results: The DC, FS, and M were found to be significantly influenced by both radiant exposure and accelerated aging time. The DC and EM increased with radiant exposure in the no-aging group (0-hour aging) for both micro-hybrid and nanofilled composites, whereas no correlation was found after accelerated aging protocols. WS and WL of micro-hybrid and nanofilled composite resins were scarcely affected by radiant exposure (p>0.05), whereas they were significantly reduced by accelerated aging (p<0.001). Conclusions: Although increasing radiant exposure affected the degree of conversion and mechanical properties of micro-hybrid and nanofilled composites, no influence on the hydrolytic degradation of the material was observed. In contrast, UV accelerated aging affected both the physico-chemical and mechanical properties of the composites.

Effects of Color Modifier on Degree of Monomer Conversion, Biaxial Flexural Strength, Surface Microhardness, and Water Sorption/Solubility of Resin Composites

“…Future work should, therefore, investigate the monomer elution using HPLC. The results of the current study also suggest that the DC of composites mixed with the color modifier was increased by ~10% after extending the light-curing time from 20 to 40 s. This could be due to the increase in the radiant exposure, which could promote the production of free radicals [39] to enhance the DC of the materials [40,41]. Another method to enhance the polymerization could be the use of a high-irradiance light-curing unit [42].…”

Bisphenol A released and ultrastructural changes in dental composite resins

“…Previous studies suggested that the liberation of monomers induces damage to the DCR surface by physical and chemical causes (24,25) . The micromorphology of the DCR surface after being immersed in artificial saliva, ethanol or acid solution revealed damage with degradation of the organic matrix evidenced by erosion like pores and cracks to a big lagoon with filler particles protruding from the surface (25)(26)(27)(28) .…”

Avaliação in vitro da estabilidade de cor, da rugosidade superficial e da microdureza de materiais restauradores estéticos, após imersão em bebidas infantis ou envelhecimento artificial acelerado

“…Estudos in vitro demandam menos tempo e custo para serem realizados, quando comparados a estudos clínicos 107 , porém há limitações inerentes. O sistema de Envelhecimento Artificial Acelerado tem sido utilizado para testes em resinas compostas desde 1978 [108][109][110][111] e reproduz os efeitos atmosféricos que ocorrem quando os materiais são expostos à luz solar e umidade. Este método tem sido utilizado para prever as mudanças físicas de vários tipos de materiais dentários, em condições bucais.…”