title: Surface and bulk properties of dental resin- composites after solvent storage.
abstract: To investigate the surface micro-hardness and the diametral tensile strength (DTS) of bulk-fill and conventional resin-composites after storage in food simulating solvents.
  
  
  
  Eight materials were investigated. For the micro-hardness measurement, Teflon mould with an internal dimensions of 10mm and 2mm (n=15). For the DTS measurement, Split stainless steel moulds were used to make disk-shaped specimens of 6mm diameter and 2mm thickness (n=15). Materials were subdivided in to three groups (water, 75% ethanol/water and MEK). Micro-hardness measurements were made under a load of 300gm with a dwell time of 15s at 7, 30, and 90ds after storage. DTS was measured after 30ds at a cross head speed of 0.5mm/min.
  
  
  
  The storage time and type of solvent had a significant influence on the micro-hardness. MEK showed more drastic reduction in the material micro-hardness with an exception of G-aenial universal flo (GA-F) which showed similar results in water/ethanol and MEK. DTS values of materials stored in water ranged from 48.7MPa for the GA-F and 30.6MPa for Ever X posterior (EXP). Generally, the results are observed to decrease with increasing solvent power, except for GA-F.
  
  
  
  Bulk-fill materials showed no superior results compared with the other materials. For the bulk-fill materials that are designed to be used as a base, their penetration by the solvents may be shielded and thus the changes observed in this study may not be of clinical importance.
authors.affiliation: Biomaterials Science Research Group, School of Dentistry, University of Manchester, United Kingdom; College of Dentistry, King Saud University, Riyadh, Saudi Arabia.
authors.forename: Hanan Al
authors.initials: HA
authors.lastname: Sunbul
authors.affiliation: Biomaterials Science Research Group, School of Dentistry, University of Manchester, United Kingdom. Electronic address: nick.silikas@manchester.ac.uk.
authors.forename: Nick
authors.initials: N
authors.lastname: Silikas
authors.affiliation: Biomaterials Science Research Group, School of Dentistry, University of Manchester, United Kingdom; Photon Science Institute, University of Manchester, United Kingdom.
authors.forename: David C
authors.initials: DC
authors.lastname: Watts
mesh_terms: D003188:Composite Resins; D006244:Hardness; D006801:Humans; D008422:Materials Testing; D012997:Solvents; D013499:Surface Properties; D013718:Tensile Strength; D014867:Water
chemical_list: D003188:Composite Resins; D012997:Solvents; D014867:Water
keywords: Bulk-fill; Diametral tensile strength; Micro-hardness; Resin-composite; Solvents