title: Influence of opacifiers on dimensional stability and detail reproduction of maxillofacial silicone elastomer.
abstract: BACKGROUND
  We evaluated the influence of chemical disinfection and accelerated aging on the dimensional stability and detail reproduction of a silicone elastomer containing one of two opacifiers.
  
  
  METHODS
  A total of 90 samples were fabricated from Silastic MDX 4-4210 silicone and divided into groups (n = 10) according to opacifier content (barium sulfate or titanium dioxide) and disinfectant solution (neutral soap, Efferdent, or 4% chlorhexidine). The specimens were disinfected 3 times per week during 60 days and then subjected to accelerated aging for 1008 hours. Dimensional stability and detail reproduction tests were performed after specimens' fabrication (baseline), chemical disinfection and periodically during accelerated aging (252, 504, and 1008 hours). The results were analyzed using 3-way repeated-measures ANOVA and the Tukey HSD test (α = 0.05).
  
  
  RESULTS
  All groups exhibited dimensional changes over time. The opacifier (p = .314), period (p < .0001) and their interactions (p = .0041) affected the dimensional stability of the silicone. Statistical significant dimensional differences occurred between groups with (0.071) and without opacifiers (0.053). Accelerated aging influenced the dimensional stability of the samples. All groups scored 2 in the detail reproduction tests, which represents the fully reproducing of three test grooves with accurate angles.
  
  
  CONCLUSIONS
  Incorporation of opacifiers alters the dimensional stability of silicones used in facial prosthetics, but seems to have no influence on detail reproduction. Accelerated aging is responsible for most of the dimensional changes in Silastic MDX4 4210, but all dimensional changes measured in this study remained within the limits of stability necessary for this application.
authors.affiliation: Department of Dental Materials and Prosthodontics, Araçatuba Dental School, UNESP, Rua José Bonifácio 1193, Araçatuba, SP, Brazil. goiato@foa.unesp.br
authors.forename: Marcelo C
authors.initials: MC
authors.lastname: Goiato
authors.forename: Marcela F
authors.initials: MF
authors.lastname: Haddad
authors.forename: Mário A C
authors.initials: MA
authors.lastname: Sinhoreti
authors.forename: Daniela M
authors.initials: DM
authors.lastname: dos Santos
authors.forename: Aldiéris A
authors.initials: AA
authors.lastname: Pesqueira
authors.forename: Amália
authors.initials: A
authors.lastname: Moreno
mesh_terms: D000704:Analysis of Variance; D003116:Color; D004203:Disinfection; D020724:Elastomers / Q000737:chemistry*; D008447:Maxillofacial Prosthesis; D015203:Reproducibility of Results; D012828:Silicones / Q000737:chemistry*; D012984:Software; D013997:Time Factors
chemical_list: D020724:Elastomers; D012828:Silicones