title: Effect of accelerated ageing and surface sealing on the permanent deformation of auto-polymerising soft linings.
abstract: OBJECTIVE
  To compare the effects of different ageing methods on the permanent deformation of two permanent soft liners.
  
  
  METHODS
  The materials selected were auto-polymerising acrylic resin and silicone-based reliners. Sealer coating was also evaluated. Sixty specimens of each reliner were manufactured (12.7 mm diameter and 19 mm length). Specimens were randomly distributed into 12 groups (n = 10) and submitted to one of the accelerated ageing processes. Permanent deformation tests were conducted with a mechanical device described within the American Dental Association specification number 18 with a compressive load of 750 gf applied for 30 s. All data were submitted for statistical analysis. Mann-Whitney test compared the effect of the surface sealer on each material and the permanent deformation of the materials in the same ageing group (p = 0.05). Kruskal-Wallis and Dunn tests compared all ageing groups of each material (p = 0.05).
  
  
  RESULTS
  The silicone-based reliner presented a lower permanent deformation than the acrylic resin-based reliner, regardless of the ageing procedure. The surface sealer coating was effective only for the thermocycled silicone group and the accelerated ageing processes affected only the permanent deformation of the acrylic resin-based material.
  
  
  CONCLUSIONS
  The silicone-based reliner presented superior elastic properties and the thermocycling was more effective in ageing the materials.
authors.affiliation: Oral Sciences School, Amazonas State University, Manaus, Amazonas, Brazil.
authors.forename: Joaquim
authors.initials: J
authors.lastname: da Silva
authors.forename: Jessica
authors.initials: J
authors.lastname: Takahashi
authors.forename: Juliana
authors.initials: J
authors.lastname: Nuňez
authors.forename: Rafael
authors.initials: R
authors.lastname: Consani
authors.forename: Marcelo
authors.initials: M
authors.lastname: Mesquita
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry*; D003799:Dental Stress Analysis; D003822:Denture Liners; D006801:Humans; D008422:Materials Testing; D010895:Pit and Fissure Sealants / Q000737:chemistry*; D012828:Silicones / Q000737:chemistry*; D013696:Temperature
chemical_list: D000180:Acrylic Resins; D010895:Pit and Fissure Sealants; D012828:Silicones