title: Effect of whitening dentifrices on the surface roughness of commercial composites.
abstract: OBJECTIVE
  Our study aimed to test the null hypothesis that whitening and non-whitening dentifrices affect similarly the surface roughness of commercial microhybrid composites, independent of the brushing time.
  
  
  METHODS
  One hundred and ninety-two disc-shaped specimens of Filtek Z250 (3 M/ESPE, St. Paul, MN, USA) and Rok (SDI, Australia) were built up and randomly assigned to 24 groups, based on the dentifrices used (two whitening dentifrices: Colgate Max White-Colgate-Palmolive, São Bernardo do Campo, São Paulo, Brazil and Close Up Extra Whitening-Unilever, Brasil Higiene Pessoal e Limpeza Ltda, Ipojuca, Pernambuco, Brazil; and one non-whitening dentifrice: Colgate Total 12 Clean Mint-Colgate-Palmolive), and on the simulated brushing times (24 hours, 6, 12 and 24 months). The specimens were submitted to the toothbrushing regimens after which the surface roughness (Ra) was measured. Data was submitted to analysis of variance and Tukey test (α=0.05).
  
  
  RESULTS
  The composite's surface roughness was significantly affected by the composites (p=0.0007), the dentifrices (p=0.0001), and the simulated brushing time (p=0.0001). Higher roughness was observed when the whitening dentifrices were used and when the brushing time increased. Filtek Z250 was more affected than Rok, especially after 24 months of simulated brushing.
  
  
  CONCLUSIONS
  Whitening dentifrices produced higher surface roughness in the composites tested. The degree of surface compromising increased with brushing time and depends on the composite's microstructure and composition.
authors: School of Dentistry, Department of Restorative Dentistry, Pontifical Catholic University of Rio Grande do Sul, Porto Alegre, RS, Brazil.
authors: Guilherme Machado
authors: GM
authors: Barbieri
authors: Eduardo Gonçalves
authors: EG
authors: Mota
authors: Sinval Adalberto
authors: SA
authors: Rodrigues-Junior
authors: Luiz Henrique
authors: LH
authors: Burnett
mesh_terms: D000704:Analysis of Variance; D003188:Composite Resins / Q000737:chemistry; D003802:Dentifrices / Q000737:chemistry*; D011897:Random Allocation; D013499:Surface Properties; D058205:Tooth Bleaching Agents / Q000737:chemistry*; D014099:Toothbrushing
chemical_list: D003188:Composite Resins; D003802:Dentifrices; D058205:Tooth Bleaching Agents