Color stability of reline resin after microwave disinfection: clinical evaluation

Objective: The purpose of this study was to evaluate the effect of microwave disinfection on the color stability of hard chairside reline resin after 180 days service period. Methods: Forty adult patients, who required denture reline treatment, participated in this study. Tokuyama Rebase II was used to reline complete maxillary dentures. Adaptation of each denture was examined and the surface to be relined was reduced by means of a rotary cutting instrument. The relining material was spatulated, poured into the relining area, inserted and adjusted after setting. The edentulous subjects were randomly divided into 2 groups (n=20) and dentures were cleansed according to two methods: CG (control group)- brushing with coconut soap and soft toothbrush; DG (disinfection group)- brushing according to previous methods and microwave disinfection for 3min at 650W. Color parameters in L*a*b* were recorded with a spectrophotometer. Each relined denture was subjected to base line evaluation and after 7, 15, 30, 90 and 180 days. Based on the L*a*b* values the color difference (ΔE) was calculated. Data were analyzed using Mann-Whitney and Kruskal-Wallis tests (P=0.05). Results: The reline material showed color changes (ΔE) from 0.64 to 3.21. The results demonstrated that the color change values of disinfection group were significantly lower than those of control group after each one of the time periods tested (P<0.05). When comparing the results of the control group, it can be seen that the color change values were not significantly different after all use periods of the complete denture (P>0.05). The results also revealed that no significant differences were found among the periods of use of relined denture for disinfection group (P>0.05). Conclusion: The color of Tokuyama Rebase II was not affected after 180 days observation period. The microwave disinfection produced higher color stability for the tested material.

Grants: FAPESP-05/02194-0 and 05/04693-4