Effect of polymerization methods and thermal cycling on color stability of acrylic resin denture teeth.
BACKGROUND
Acrylic resin denture teeth are widely used due to the chemical bond to the acrylic resin of the denture base. However, discoloration of acrylic resin denture teeth can be a problem.


OBJECTIVE
The purpose of this study was to investigate the effect of polymerization methods and thermal cycling on the color change of acrylic resin denture teeth.


METHODS
Ten different brands of acrylic resin denture teeth were evaluated: Art Plus (AP), Biolux (BX), Biotone IPN (BI), Magister (MG), Mondial 6 (MD), Premium 6 (PR), SR Vivodent PE (SR), Trilux (TR), Trubyte Biotone (TB), and Vipi Dent Plus (VP). Each brand was divided into 2 groups (n=12); each group was subjected to 1 of 2 polymerization methods (microwave, 500 W for 3 minutes, or water bath, 74 degrees C for 9 hours). After polymerization, all of the specimens were thermal cycled between 5 degrees C and 55 degrees C with 30-second dwell times for 5000 cycles. The specimen colors were measured with a spectrophotometer, using the CIE L*a*b* system, at baseline (B), after polymerization (P), and after thermal cycling (T). Color differences (DeltaE) were calculated for periods between P and B (PB), T and B (TB), and T and P (TP). A DeltaE of < or =3.3 was considered clinically acceptable. The data were evaluated by 3-way repeated-measures ANOVA and the Tukey HSD test (alpha=.05).


RESULTS
The highest DeltaE values were obtained for BI and SR teeth; these were significantly higher than the values obtained for the other brands (P<.05). There was no significant difference between the 2 polymerization methods. There was no significant difference between TB and PB for either polymerization method.


CONCLUSIONS
The DeltaE values are within acceptable clinical limits for all brands, for both polymerization methods and different measurement periods.
Assunção
Wirley Gonçalves
WG
Associate Professor, Department of Dental Materials and Prosthodontics, Araçatuba Dental School, São Paulo State University (UNESP), São Paulo, Brazil. wirley@foa.unesp.br
Barão
Valentim Adelino Ricardo
VA
Pita
Murillo Sucena
MS
Goiato
Marcelo Coelho
MC
D000180:Acrylic Resins; D003116:Color; D003124:Colorimetry; D003799:Dental Stress Analysis; D006244:Hardness; D006358:Hot Temperature; D008422:Materials Testing; D008872:Microwaves; D044367:Phase Transition; D017797:Prosthesis Coloring; D014093:Tooth, Artificial; D014867:Water
D000180:Acrylic Resins; D014867:Water