title: Effect of denture cleansers on the surface roughness and hardness of a microwave-cured acrylic resin and dental alloys.
abstract: OBJECTIVE
  This study evaluated the effect of denture cleansers on the surface hardness of a denture base resin, and on the surface roughness of the resin and Co-Cr and Ti-6Al-4V alloys.
  
  
  METHODS
  Forty-eight disc-shaped specimens were fabricated of a microwave-cured acrylic resin, each having one of the alloys attached to its surface. The specimens were randomly divided into 6 groups, each consisting of 8 samples. Specimens were exposed to one of the three cleansing treatments (polident, manipulation pharmacy cleanser, and water) as follows. Group I: Co-Cr + polident; Group II: Co-Cr + manipulation; Group III: Co-Cr + water; Group IV: Ti-6Al-4V + polident; Group V: Ti-6Al-4V + manipulation; and Group VI: Ti-6Al-4V + water. Three exposures lasting 5 minutes each were conducted daily, and repeated after storage periods of 1, 14, and 29 days in artificial saliva at 37 degrees C. Hardness and roughness measurements were undertaken immediately after specimen preparation (T0) and on the 1st (T1), 15th (T15), and 30th (T30) day following the beginning of storage. Three roughness and hardness evaluations were carried out for each sample and testing time, and mean values were calculated. Results were analyzed using ANOVA and linear regression.
  
  
  RESULTS
  The Knoop hardness test demonstrated differences (p < 0.05) between Groups I and IV at T1 and T30 (14.30 +/- 2.78; 14.06 +/- 1.76) and between Groups II and V at T15 (16.99 +/- 2.24). Significant differences (p < 0.05) in resin roughness (in microm) were observed between Groups I and IV at T15 and T30 (0.14 +/- 0.06; 0.21 +/- 0.38). With regard to Co-Cr, roughness data showed differences (p < 0.05) for all groups at T30 (Group I: 0.15 +/- 0.07; Group II: 2.43 +/- 0.66; Group III: 4.05 +/- 1.03), for Group II at T1 (0.10 +/- 0.03), and for Group I at T15 (0.15 +/- 0.02). There were significant differences (p < 0.05) in titanium roughness for Group IV at T15 (0.12 +/- 0.01) and T30 (0.11 +/- 0.04).
  
  
  CONCLUSIONS
  Manipulated cleanser containing sodium perborate increased surface roughness and hardness, probably due to its incapacity to remove the pellicle formed on the acrylic resin and dental alloys.
authors.affiliation: Department of Prosthodontics and Peridontology, School of Dentistry of Piracicaba, University of Campinas, Brazil. regarcia@fop.unicamp.br
authors.forename: Renata Cunha Matheus
authors.initials: RC
authors.lastname: Rodrigues Garcia
authors.forename: de Souza
authors.initials: de S
authors.lastname: Joane Augusto
authors.forename: Rodrigo Nunes
authors.initials: RN
authors.lastname: Rached
authors.forename: Altair Antoninha
authors.initials: AA
authors.lastname: Del Bel Cury
mesh_terms: D000180:Acrylic Resins; D000704:Analysis of Variance; D018441:Biofilms / Q000187:drug effects; D003722:Dental Alloys; D003820:Denture Cleansers / Q000494:pharmacology*; D006244:Hardness / Q000187:drug effects*; D016014:Linear Models; D013499:Surface Properties / Q000187:drug effects*
chemical_list: D000180:Acrylic Resins; D003722:Dental Alloys; D003820:Denture Cleansers