11 February 2026

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Effect of blue covarine containing whitening toothpaste on the color of resin composites and teeth

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OBJECTIVES

Resin composites have become increasingly popular; however, one problem associated with their use is discoloration. Bleaching (whitening by chemical methods) is an accepted way to remove external and internal pigments, thereby improving appearance.

One cost-effective method to enhance tooth color is the use of whitening toothpastes.

The objective of the present study is to investigate the effects of whitening toothpastes containing blue covarine and hydrogen peroxide on the discoloration of resin composites and teeth.

MATERIALS AND METHODS

This experimental laboratory study was conducted on 72 samples of Omnichroma resin composite (One-Shade, Tokuyama, Japan [Item 3]) and extracted human anterior teeth. First, disk-shaped samples with a diameter of 8 mm and a thickness of 2 mm were prepared from the resin composite. Tooth samples that were free of caries, fractures, and restorations were selected.

The samples (teeth and resin composites) were divided into three groups: Colgate Max White Ultimate Catalyst toothpaste (Colgate, USA [Item 1]), Close Up Diamond Attraction toothpaste (Close Up, USA [Item 2]), and a control group (distilled water) (n = 12). The samples (24 teeth and 24 composites) were then immersed in a black tea (Jahan, Iran) concentrate solution for one week (7 days) to achieve coloration, while the control group was placed in distilled water.

In the Colgate Max White and Close Up Diamond Attraction groups, 0.25 g of each toothpaste was mixed with water at a ratio of 1:3 and brushed twice a day for 30 seconds with an electric toothbrush (Pro-Expert, Oral-B, USA) by an operator. The samples were brushed with circular movements and washed under running water. The color of the samples was measured by a spectrophotometer at three stages: before staining, after staining, and after brushing.

One-way analysis of variance and Tukey’s test were used for data analysis. An independent t-test was used to compare composite and tooth samples. In all cases, differences with P less than 0.05 were considered statistically significant.

RESULTS

The results showed that the tea solution significantly discolored the composite and tooth samples (ΔE >3.3), whereas the ΔE in the control group was less than 3.3. The use of whitening toothpastes led to significant discoloration of the composite and tooth samples, although the color of the samples did not return to the baseline level. Intra-group comparison of resin composite samples revealed that the ΔE after brushing with Item 1 was significantly higher than that of the Item 2 group (P <0.05); however, no critical difference was observed between the two groups in the tooth samples (P >0.05).

CONCLUSIONS

Item 1 and Item 2 were more effective in restoring the original color of composite specimens discolored by a tea solution.

CLINICAL SIGNIFICANCE

Evaluating the effects of whitening toothpastes containing blue covarine and hydrogen peroxide on resin composite and tooth discoloration may contribute to improving the color of stained resin composites and teeth (at-home by the patient). This approach offers a cost-effective method for enhancing the color of both teeth and resin composites.

Authors: Paria Faraji Dizaji, Elham Zajkani, Saeedeh Asdagh

Source: https://www.dentalcadmos.com/