title: The effect of aging on the mechanical properties of nanohybrid composites based on new monomer formulations.
abstract: OBJECTIVE
  Nanohybrid resin-based composites (RBCs) containing new types of matrix monomers such as dimer acid-based dimethacrylate or tricyclodecane-urethane are assumed to show decreased water uptake and therefore better resistance to hydrolytic degradation than RBCs using bisphenol A diglycidyl methacrylate (BisGMA) due to their hydropobic nature. Our study aimed to analyze the effect of aging on six nanohybrid RBCs, of which two are using these new types of monomers, with regard to differences in the mechanical properties of the materials.
  
  
  METHODS
  Diametral tensile strength (DTS), Vickers hardness (HV), and creep were measured. Mechanical tests were performed after storing samples for 24 h in distilled water, as well as after aging (thermocycling for 5,000 cycles at 5-55°C and storage for 4 weeks either in distilled water, artificial saliva, or ethanol).
  
  
  RESULTS
  The effect of aging on all test parameters was lower than the effect of the material. This information was provided by a general linear model, showing higher partial η(2) values for the influence factor material than for the factor aging. The influence of aging on the micromechanical properties HV and creep was proven to be more sensitive than on the macromechanical property (DTS). This was also illustrated by lower η(2) values for the variable aging for DTS. An increase of the creep of all materials was observed after storage in alcohol.
  
  
  CONCLUSIONS
  The use of new types of monomers could not be shown to be a significant advantage to the other examined materials containing BisGMA.
  
  
  CONCLUSIONS
  Nanohybrid composites can be recommended as universal filling materials, whether based on new or conventional monomers.
authors.affiliation: Department of Restorative Dentistry, Dental School of the Ludwig-Maximilians-University, Goethestr. 70, 80336, Munich, Germany.
authors.forename: Christine
authors.initials: C
authors.lastname: Schmidt
authors.forename: Nicoleta
authors.initials: N
authors.lastname: Ilie
mesh_terms: D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D002264:Carboxylic Acids / Q000737:chemistry; D002626:Chemistry, Pharmaceutical; D003188:Composite Resins / Q000737:chemistry*; D043822:Cyclodecanes / Q000737:chemistry; D003764:Dental Materials / Q000737:chemistry*; D000431:Ethanol / Q000737:chemistry; D006244:Hardness; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D008422:Materials Testing; D055595:Mechanical Phenomena; D008689:Methacrylates / Q000737:chemistry; D053761:Nanocomposites / Q000737:chemistry*; D012464:Saliva, Artificial / Q000737:chemistry; D012997:Solvents / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties; D013696:Temperature; D013718:Tensile Strength; D013997:Time Factors; D014520:Urethane / Q000737:chemistry; D014867:Water / Q000737:chemistry
chemical_list: D002264:Carboxylic Acids; D003188:Composite Resins; D043822:Cyclodecanes; D003764:Dental Materials; C509998:Grandio; D008689:Methacrylates; C551012:N'Durance composite resin; D012464:Saliva, Artificial; C510232:Simile composite resin; D012997:Solvents; C488393:Venus (composite resin); C507210:premise composite resin; D014867:Water; D014520:Urethane; D000431:Ethanol; D017438:Bisphenol A-Glycidyl Methacrylate