title: Effect of toothbrushing abrasion on weight and surface roughness of pH-cycled resin cements and indirect restorative materials.
abstract: OBJECTIVE
  To evaluate wear resistance, by weight loss and roughness changes, of resin cements and indirect restorative materials to toothbrushing and toothbrushing associated with pH-challenge simulation.
  
  
  METHODS
  The following materials were studied: Enforce resin cement (Dentsply), Rely X resin cement (3M ESPE), Variolink II resin cement (Ivoclar/Vivadent), Artglass indirect resin composite (Heraeus Kulzer), and Duceram Plus porcelain (Degussa). Twenty cylindrical specimens were prepared for each material for a total of 10 groups (n = 10). After finishing and polishing, the specimens were subjected to toothbrushing. One group of each material was pH cycled before abrasion. For toothbrushing, a machine containing soft-bristle tips, dentifrice, and water was used. One hundred thousand brushing cycles were performed. Weight loss was determined as the percentage difference between initial (before brushing) and final (after brushing) measurements. Roughness changes were evaluated by the difference between initial and final measurements. Data were analyzed with the paired t test, 2-way ANOVA, and Tukey test (alpha = 0.05).
  
  
  RESULTS
  Paired t test showed significant differences in weight loss and roughness after toothbrushing (P <.01). Statistically significant differences were found among materials for both weight loss, which ranged from 0.34% (Duceram Plus) to 1.85% (Enforce/pH), and roughness changes, which ranged from -0.03 microm (Duceram Plus) to 0.29 microm (Rely X/pH).
  
  
  CONCLUSIONS
  Among cements, Variolink II exhibited the least weight loss and roughness increase. Of all materials, Duceram Plus porcelain presented the lowest weight loss and became smoother after abrasion. pH cycling had no influence on material weight or roughness changes after abrasion.
authors.affiliation: Department of Resotrative Dentistry, Endodontics and Dental Materials, Bauru Dental School, University of São Paulo, São Paulo, Brazil. prakki@yahoo.com
authors.forename: Anuradha
authors.initials: A
authors.lastname: Prakki
authors.forename: Renato
authors.initials: R
authors.lastname: Cilli
authors.forename: Paulo Amarante
authors.initials: PA
authors.lastname: de Araújo
authors.forename: Maria Fidela de Lima
authors.initials: MF
authors.lastname: Navarro
authors.forename: José
authors.initials: J
authors.lastname: Mondelli
authors.forename: Rafael Francisco Lia
authors.initials: RF
authors.lastname: Mondelli
mesh_terms: D000704:Analysis of Variance; D003188:Composite Resins; D003776:Dental Porcelain; D019554:Dental Restoration Wear; D003799:Dental Stress Analysis; D006863:Hydrogen-Ion Concentration; D007284:Inlays; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D019279:Resin Cements; D018709:Statistics, Nonparametric; D013499:Surface Properties; D014099:Toothbrushing
chemical_list: D003188:Composite Resins; D019279:Resin Cements; D003776:Dental Porcelain