Colour stability of heat and cold cure acrylic resins

Effect of Novel Cycloaliphatic Comonomer Incorporation on the Color Stability of Thermo-polymerized Denture Base Resin

BACKGROUND

Denture during its in vivo service encounters myriad food pigments and numerous physico-mechanical dynamic changes. Denture discoloration is one of the unresolved problems that should be unraveled to satisfy the esthetic demands of the patients.

AIM

This study aims to evaluate the color stability of a novel denture base copolymer with 10% and 20% (vol/vol) concentration of cycloaliphatic comonomer.

MATERIALS AND METHODS

Control group (G0) comprises specimens made without cycloaliphatic comonomer. The specimens of trial groups G10 and G20 were fabricated with 10% and 20% cycloaliphatic comonomer, respectively. For each group, thirty specimens (n = 30) were made. The specimens (n = 10) were immersed in three food colorant solutions (erythrosine, tartrazine, sunset yellow) for 56 days after artificial thermal aging. Ultraviolet-visible spectrophotometer was employed to measure the tristimulus values and calculate the color change (ΔE) of the specimens prior to and following rapid thermal aging or immersion of the specimens in the food colorants.

RESULTS

G0 showed the highest ΔE and G20 exhibited the least with each colorant. G10 had an intermediate imperceptible ΔE with each colorant. Also, significant differences (P = .000) existed between the food colorants within each group. The highest ΔE value was observed with sunset yellow and the lowest ΔE with tartrazine with each group.

CONCLUSION

The addition of cycloaliphatic comonomer in denture base acrylic resins improved the color stability. The new copolymer with 20 Vol.% comonomer exhibited the highest color stability with all the food colorants.

Comparison of Colour Stability Between Various Denture Base Resins on Staining and Denture Cleansing Using Commercially Available Denture Cleansers

Statement of problem

Discoloration of denture base materials on routine usage has been one of the common esthetic problems encountered by patients.

Aim

To determine the color stability of three different denture base materials upon staining with beverages and denture cleansing using commercially available denture cleansers.

Materials and method

Three denture base materials were used for the study, processed according to the manufacturer’s recommendation, and cut into 40 study samples measuring approximately 1 cm x 1 cm with 1 mm thickness. The samples were divided into two groups, Group A and Group B, and spectrophotometric analysis of all samples was done to evaluate the base value of the color for comparative analysis. Group A was immersed in coffee and Group B was immersed in cola and color change was noted after 12 hours and then after 24 hours. The samples were then cleansed using a denture cleanser and analyzed again. All values were tabulated and statistically analyzed.

Result

On descriptive statistical analysis, polymethylmethacrylate (PMMA) had higher ∆E values at 12 hrs after immersion in coffee and cola; after 24 hrs, high impact PMMA had higher ∆E values in coffee and PMMA in cola. Two-way analysis of variance (ANOVA) analysis showed no statistically significant difference for the samples immersed in coffee, whereas samples immersed in cola at the end of 24 hrs showed a significant statistical difference.

Conclusion

Thermoplastic resin was the least staining denture base material when compared to conventional PMMA and high-impact PMMA when immersed in coffee and cola. There was no significant difference in the cleanability of all three-denture base materials.

Shade Guide for the Fabrication of Acrylic Denture Based on Mucosal Colour

This article highlights the use of a simple and convenient shade guide system which not only helps in choosing the shade tab that matches with the colour of the mucosa, but, also helps in the fabrication of the precise shade of acrylic resin for making the denture. The shade guide is fabricated by mixing specified quantities of various colours of acrylic polymer in order to obtain various shade tabs. The method for fabrication of the shade guide and the clinical procedure has been discussed.