Comparison of three different methods of decolorization, polishing, brushing and immersion in sodium hypochlorite from composite and acrylic teeth of removable dentures

Abstract

Background and Aim: Due to the great importance of tooth color in the beauty and dissatisfaction of many patients with discoloration of removable dentures in long-term use due to exposure of teeth to a variety of colored drinks in the oral environment, many patients desire to replace their denture, which imposes a financial and time cost. Most studies have been performed to evaluate the color changes and staining rate of dental materials used in removable dentures and few studies have been performed to compare different cleansers. Therefore, in this study, the cleanser effect of sodium hypochlorite, tooth brushing and polishing in two types of acrylic and composite teeth used in removable dentures was investigated.

Materials and Methods: This in-vitro study was performed on samples of Polident acrylic and Yamahachi composite teeth. First, all samples were immersed in tea solution for 3 weeks. Then, for decolorization, they were divided into 4 groups of 14 (7 acrylic and composite dental specimens). The first group was brushed 10 times with soap and water and this cycle was repeated 4 times. In the second group, the samples were polished five times with pumice powder. Each cycle was repeated 5 times for 10 seconds. In the third group, the samples were immersed in 0.5% sodium hypochlorite solution for 3 minutes once a day for 90 days. In the control group, the samples were immersed in distilled water. Then the color of all samples was measured by spectrophotometer. Color changes before decolorization and after decolorization were calculated and analyzed by repeated measures of ANOVA followed by Sidak test.

Results: All three methods of decolorization by sodium hypochlorite, using toothbrush and polishing led to discoloration of acrylic and composite samples and all three methods were more effective than immersion in distilled water (P = 0.000). Immersion in sodium hypochlorite causes the most discoloration effect (P <0.05) and toothbrush use causes the least discoloration effect (P <0.05). The rate of discoloration in composite teeth after brushing and polishing was higher than acrylic (P <0.05).

Conclusion: All methods of decolorization by sodium hypochlorite, the use of toothbrushes and polishing are effective in reducing the color of acrylic and composite samples. Immersion of removable dentures daily for 3 minutes in sodium hypochlorite for 30 days causes discoloration of denture teeth. Also, polishing dentures is more effective in decolorizing than using a toothbrush.