In vitro aging behavior of dental composites considering the influence of filler content, storage media and incubation time

Abstract

ObjectiveOver time dental composites age due to mechanical impacts such as chewing and chemical impacts such as saliva enzymes and food ingredients. For this research, the focus was placed on chemical degradation. The objective of this study was to simulate hydrolysis by using different food simulating liquids and to assess their impact on the mechanical parameter Vickers microhardness (MHV) and the physicochemical parameter contact angle (CA).MethodsSpecimen of three composites (d = 6 mm, h = 2 mm; n = 435) classified with respect to their filler content (wt%), namely low-filled, medium-filled and highly-filled, were stored for 0, 14, 30, 90 and 180 days in artificial saliva (pH 7), citric acid (pH 3; pH 5), lactic acid (pH 3; pH 5) and ethanol (40%vol; 60%vol) and assessed regarding to MHV and CA. Statistics: Kruskal-Wallis test, stepwise linear regression, bivariate Spearman Rank Correlation (p < 0.05).ResultsWhile stored in artificial saliva, acid and ethanol the CA decreased especially for the low- and medium-filled composites. It was shown that rising the filler content caused less surface changes in the CA. Storage in ethanol led to a significant decrease of MHV of all composites. Regression analysis showed that the effect of in vitro aging on MHV was mainly influenced by the composite material and therefore by filler content (R2 = 0.67; p < 0.05). In contrast, the CA is more influenced by incubation time and filler content (R2 = 0.2; p < 0.05) leading to a higher risk of plaque accumulation over time. Significance: In vitro aging showed significant changes on the mechanical and physicochemical properties of dental composites which may shorten their long-term functionality. In conclusion, it can be stated, that the type of composite material, especially rising filler content seems to improve the materials’ resistance against the processes of chemical degradation.

Ageing of Dental Composites Based on Methacrylate Resins—A Critical Review of the Causes and Method of Assessment

“…At the same time, the pH inside the pores is influenced by the acid-base functionality of the degradation products, thus accelerating the hydrolysis process [75]. Degradation of the interface results in fillers debonding, leaching of ingredients, micro cracks, increase in surface roughness, reduction of fatigue resistance, and final mechanical properties [76][77][78]. Therefore, the filler-matrix interface seems to be the weakest part of the composite material.…”

Marginal Accuracy and Fracture Resistance of Posterior Crowns Fabricated from CAD/CAM PEEK Cores Veneered with HIPC or Nanohybrid Conventional Composite

“…For the last few years, the in vitro experiments have declared that artificial ageing process had a dramatic effect on both mechanical and physical properties of composites. 6,7 This made the composite developers take more attention to the oral environment effect on the durability of composite materials.…”

Mechanical Degradation of Different Classes of Composite Resins Aged in Water, Air, and Oil

“…The storage mediums used in the experiment, besides the control group stored in air, represented the conditions commonly found in the oral cavity, such as saliva, beverages, medicines, and fatty foods. [13] They have shown to be able to adversely affect the mechanical properties of investigated products.…”

“…In order to promote common challenges in the oral environment, different immersion was used, especially in the possibility of promoting an antagonistic action between an aqueous medium (water) and a lipoic environment, as suggested in previous studies. [13]…”