Investigation of the effects of whitening toothpastes on enamel and cementum surfaces

Introduction
Toothpastes with whitening properties have emerged as an option to enable and improve the whitening of tooth structure. In recent years, toothpastes have become more specialized and can be classified as therapeutic or cosmetic. One of the most important features regarding the cosmetic function of toothpastes is the capacity to prevent or remove stains on the tooth surface, thereby whitening the teeth.

Objectives
The purpose of this in vitro study was to investigate the effects of different whitening toothpastes on both human enamel and cementum surfaces.

Material and methods
In total, 140 of human extracted incisor teeth were split from cemento-enamel junction and embedded in gypsum blocks. Ra values were measured with a three-dimensional profilometer. Images were obtained from the samples with a scanning electron microscope. One of the seven groups created was the control group, in which the teeth were brushed with water only, and in six groups (groups 2-7), they were brushed with different whitening toothpastes. Each sample was brushed for 5 seconds for 30 days with an automatic toothbrushing machine.

Results
Regarding the surface roughness in cementum, no differences were detected in the control group. While all toothpastes caused a decrease in roughness, this difference was significant (p < 0.05) in group 3 and group 4. For enamel roughness, no differences were detected in the control group. The roughness decreased significantly (p < 0.05) in group 3 and group 4. In other whitening toothpaste groups, surface roughness increased but the difference was not significant (p > 0.05).

Conclusions
The results of this in vitro study showed that all whitening toothpastes in this study reduced the roughness on the cementum surface. Most whitening toothpastes increased the enamel roughness, while two whitening toothpastes (Splat Special Blackwood and Colgate Optic White) reduced the enamel roughness.