Introduction:

The effect of oxygen on the surface of resins at the moment of photopolymerization creates a layer which is susceptible to pigments. The use of glycerin may block this effect.

Objective:

Determine whether there is a difference in the color stability of nanohybrid composite resin subjected to a coloring agent when glycerin is either applied or not applied.

Methods:

Sixty resin disks were distributed into Group 1 (without glycerin) and Group 2 (with glycerin). Photopolymerization was performed for 20 s with a Bluephase®N LED lamp. The first color measurement was taken with an Easyshase®V spectrophotometer, recording the values obtained for L* (luminosity), a* (red-green axis) and b* (blue-yellow axis). The second color measurement was taken after immersion of the samples for one month in Coca-Cola®, maintaining them in an incubator at 37ºC. Statistical data analysis was performed with Student's t test to determine the color stability changes occurring in the two groups and compare them.

Results:

Color stability changes were observed in all the resin samples. Mean distance between initial and final color was ΔE = 6.91 in Group 1 and ΔE = 3.74 in Group 2. A statistically significant difference was found between the two groups analyzed (p < 0.001).

Conclusions:

Glycerin is an effective substance to block the effect of oxygen on the resin surface, preventing the formation of an oxygen-inhibited layer and raising the color stability of the nanohybrid composite resin.

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