title: Effect of thermocycling on roughness of nanofill, microfill and microhybrid composites.
abstract: OBJECTIVE
  This study aimed to investigate the surface roughness of composite resins subjected to thermal cycles procedure.
  
  
  METHODS
  Two microfill, four microhybrid and four nanofill composites were used. The surface roughness (Ra) was initially measured in a profilometer using a cut-off 0f 0.25 mm, after 3000 and 10,000 thermal cycles. Data were subjected to ANOVA and Fischer's test (α = 0.05).
  
  
  RESULTS
  Overall, 3000 thermal cycles increased the surface roughness values for all materials and there was a trend in all groups to decrease the roughness after 10,000 thermal cycles.
  
  
  CONCLUSIONS
  The composition of material, including the type of organic matrix, could be more relevant to roughness maintenance over time than the general behavior of composites based on particles fillers. The maintenance of smooth surface in resin-based composite restorations is totally dependent of organic composition of the material.
authors.affiliation: Department of Dental Materials and Prosthodontics, Araçatuba School of Dentistry, São Paulo State University , Araçatuba, SP , Brazil.
authors.forename: Paulo Henrique
authors.initials: PH
authors.lastname: Dos Santos
authors.forename: Anderson
authors.initials: A
authors.lastname: Catelan
authors.forename: Ana Paula
authors.initials: AP
authors.lastname: Albuquerque Guedes
authors.forename: Thaís Yumi
authors.initials: TY
authors.lastname: Umeda Suzuki
authors.forename: André Gustavo
authors.initials: AG
authors.lastname: de Lima Godas
authors.forename: André Luiz
authors.initials: AL
authors.lastname: Fraga Briso
authors.forename: Ana Karina
authors.initials: AK
authors.lastname: Bedran-Russo
mesh_terms: D003188:Composite Resins / Q000737:chemistry*; D055117:Curing Lights, Dental / Q000145:classification; D003764:Dental Materials / Q000737:chemistry*; D003775:Dental Polishing / Q000295:instrumentation; D006801:Humans; D055115:Light-Curing of Dental Adhesives / Q000295:instrumentation; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry; D008855:Microscopy, Electron, Scanning; D053761:Nanocomposites / Q000737:chemistry*; D010316:Particle Size; D011109:Polymethacrylic Acids / Q000737:chemistry; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors
chemical_list: C112828:Clearfil AP-X; D003188:Composite Resins; D003764:Dental Materials; C515951:Filtek Supreme Plus; C444701:Filtek Z250; D008689:Methacrylates; D011109:Polymethacrylic Acids; C541508:clearfil majesty; C451741:point 4 composite resin; C507210:premise composite resin; C444445:renamel microfill; C039734:Durafill
keywords: composite resin; degradation.; roughness