Relationship between analysis of laser speckle image and Knoop hardness on softening enamel.

Background: In this study is presented the correlation between laser speckle images and enamel hardness loss.

Methods: In order to shift the enamel hardness, a dental demineralization model was applied to 32 samples of vestibular bovine teeth. After they were cleaned, cut and polished, the samples were divided into 4 groups and immersed in 30ml of a cola-based soft drink for 10, 20, 30 and 40min twice a day for 7 consecutive days with half the surface protected by two layers of nail polish.