title: Wear and surface roughness of silorane composites after pH cycling and toothbrushing abrasion.
abstract: OBJECTIVE
  To evaluate the effects of toothbrushing abrasion associated with pH cycling on the surface roughness and wear of methacrylate- and silorane-based resin composites.
  
  
  METHODS
  Microhybrid methacrylate-based (Filtek Z250), nanofilled methacrylate-based (Filtek Supreme Ultra) and microhybrid silorane-based (Filtek LS) composites were selected for this investigation. For each composite, two groups (n = 10) of rectangular specimens were made. The initial roughness (Ra) of all of the groups was evaluated based on the average of three random tracings with a profilometer, and each specimen had half of its surface protected with two layers of nail varnish to serve as controls. Half of the specimens of each resin were submitted to pH cycling, while the other half were stored in deionized water for 14 days. Subsequently, 100,000 strokes of simulated toothbrushing were performed. Final roughness and wear were measured with the same profilometer, and the values were submitted to ANOVA, Student's t-test and Tukey's test (P < 0.05).
  
  
  RESULTS
  The data revealed an increase in surface roughness for Filtek Z250 and Filtek Supreme Ultra after toothbrushing, while Filtek LS showed the opposite behavior. Methacrylate-based composites presented lower wear values [Z250 (4.19 ± 1.73 μm); Supreme Ultra (4.16 ± 0.95 μm)], while the silorane-based composite presented increased surface roughness (11.51 ± 5.69 μm), particularly when submitted to pH cycling (15.31 ± 5.41 μm). Despite the good properties of silorane-based composites, particularly its smooth surface roughness even after pH cycling and toothbrushing abrasion, this composite still presented increased wear, which is an important issue for the development of new resin compositions.
authors.forename: Sérgio Kiyoshi
authors.initials: SK
authors.lastname: Ishikiriama
authors.forename: Gabriela Ulian
authors.initials: GU
authors.lastname: De Oliveira
authors.forename: Rafael Massunari
authors.initials: RM
authors.lastname: Maenosono
authors.forename: Linda
authors.initials: L
authors.lastname: Wang
authors.forename: Marco Antonio Húngaro
authors.initials: MA
authors.lastname: Duarte
authors.forename: Rafael Francisco Lia
authors.initials: RF
authors.lastname: Mondelli
mesh_terms: D006863:Hydrogen-Ion Concentration; D062047:Silorane Resins; D013499:Surface Properties; D014099:Toothbrushing
chemical_list: D062047:Silorane Resins