• Disinfection;
  • colour stability;
  • acrylic resins

Effect of thermal cycling and disinfection on colour stability of denture base acrylic resin

Objectives:  The purpose of this study was to investigate the effect of thermal cycling and disinfection on the colour change of denture base acrylic resin.

Materials and Methods:  Four different brands of acrylic resins were evaluated (Onda Cryl, QC 20, Classico and Lucitone). All brands were divided into four groups (n = 7) determined according to the disinfection procedure (microwave, Efferdent, 4% chlorhexidine or 1% hypochlorite). The treatments were conducted three times a week for 60 days. All specimens were thermal cycled between 5 and 55°C with 30-s dwell times for 1000 cycles before and after disinfection. The specimens’ colour was measured with a spectrophotometer using the CIE L*a*b* system. The evaluations were conducted at baseline (B), after first thermal cycling (T1), after disinfection (D) and after second thermal cycling (T2). Colour differences (ΔE) were calculated between T1 and B (T1B), D and B (DB), and T2 and B (T2B) time-points.

Results:  The samples submitted to disinfection by microwave and Efferdent exhibited the highest values of colour change. There were significant differences on colour change between the time-points, except for the Lucitone acrylic resin.

Conclusions:  The thermal cycling and disinfection procedures significantly affected the colour stability of the samples. However, all values obtained for the acrylic resins are within acceptable clinical parameters.