title: Changes in hardness and surface topography of tissue conditioners submitted to chemical disinfection.
abstract: OBJECTIVE
  The aim of this study was to evaluate the longitudinal effect of chemical disinfection on Shore A hardness, surface roughness (Ra) and morphology of two tissue conditioners (Dura Conditioner [DC] and Softone [SO]).
  
  
  METHODS
  Twenty-four specimens (2 mm-thick) were made of each material and randomly divided into three groups (N.=8): control (no disinfection), 10 000 ppm chloride solution (sodium hypochlorite) and Corega Tabs solution (peroxide solution). Soaking was performed daily for 15 min, and Shore A hardness and Ra were measured at baseline and 3, 7, 10, and 14 days. Data were analyzed by repeated measures ANOVA and Bonferroni's test (alfa= 0.05).
  
  
  RESULTS
  Chemical disinfection for 14 days with sodium hypochlorite and Corega Tabs affected differently the tested materials. Hardness varied from 8 to 20 for DC and from 8 to 23 for SO with significant interaction (P<0.05) between material and disinfection treatment up to day 7. Ra values (in microm) varied from 1.51 to 4.35 for DC and from 2.08 to 4.15 for SO; there was a significant difference between disinfection treatments (P=0.043) but not between materials (P=0.119). Sodium hypochlorite groups displayed smaller Ra values than the control groups, but did not differ from Corega Tabs groups. Scanning electron microscopy showed different pattern of degradation for each material.
  
  
  CONCLUSIONS
  The results suggest that the effect of chemical disinfection on degradation of tissue conditioners is material-specific, but hardness is less affected than surface topography. The overall results support the use of the tested materials for up to three days, independently from the disinfection treatment.
authors.affiliation: Pontificial Catholic University of Rio Grande do Sul, Porto Alegre, RS, Brazil.
authors.forename: A
authors.initials: A
authors.lastname: Cunegatti Zottis
authors.forename: D
authors.initials: D
authors.lastname: Caldas Cosme
authors.forename: R
authors.initials: R
authors.lastname: Brasiliense Elsemann
authors.forename: H
authors.initials: H
authors.lastname: Mitsuo Silva Oshima
authors.forename: R S
authors.initials: RS
authors.lastname: Arai Shinkai
mesh_terms: D003820:Denture Cleansers / Q000494:pharmacology*; D003822:Denture Liners; D004202:Disinfectants / Q000494:pharmacology*; D004203:Disinfection; D006244:Hardness / Q000187:drug effects*; D006245:Hardness Tests; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D011109:Polymethacrylic Acids / Q000494:pharmacology*; D019904:Polymethyl Methacrylate / Q000494:pharmacology*; D011897:Random Allocation; D012973:Sodium Hypochlorite / Q000494:pharmacology*; D013499:Surface Properties / Q000187:drug effects*; D013997:Time Factors; D055682:Viscoelastic Substances
chemical_list: D003820:Denture Cleansers; D004202:Disinfectants; D011109:Polymethacrylic Acids; D055682:Viscoelastic Substances; C540407:corega tabs; C540405:dura conditioner; C540406:softone; D019904:Polymethyl Methacrylate; D012973:Sodium Hypochlorite