| Abstrakt: |
Surface defects such as scratching, acidic erosion, and natural dimpling of the tooth enamel can significantly affect its cosmetic appearance. There are many analytical techniques that can be used to view the surface of enamel and to assess the effect of surface treatments. Light microscopy, scanning electron microscopy (SEM), profilometry, and atomic force microscopy (AFM) can usefully be applied to viewing mineral surfaces and obtaining information about surface morphology and smoothness. Energy-dispersive x-ray fluorescence and other surface-ionizing techniques can give information about surface chemistry. Microhardness instrumentation can be used to determine surface hardness, while gloss meters and reflectometry can provide measurements of gloss and whiteness. In this study, four sets of in vitro experiments were performed, which illustrate the value of three of these techniques. Specially formulated calcium-containing toothpastes, designed to fill in surface defects in tooth enamel, were evaluated in four experiments for their ability to effect cosmetic improvements in etched tooth enamel: (1) two calcium-containing, sodium-bicarbonate-based toothpaste formulations were shown by SEM to smooth tooth enamel without introducing new scratches. In contrast, a commercial whitening toothpaste removed similar scratches but also created new ones; (2) calcium-containing dentifrices were shown by SEM and hardness measurements to put mineral onto the surface of enamel and to harden it. The effects of uneven dispensing of the two-phase, bicarbonate-based, calcium-containing formulation were shown to be small; (3) a number of different calcium-containing toothpastes were shown by SEM to deliver mineral onto the etched enamel surfaces, whereas a conventional fluoride toothpaste did not; and (4) AFM was used to follow the smoothing of an etched enamel surface after serial treatments with a calcium-containing, bicarbonate-based toothpaste. After 15 in vitro cycles, surface roughness was reduced by more than 50% and peak height was reduced by about two thirds. The results illustrate the effectiveness of the three analytical techniques and show that the calcium-containing toothpastes can deposit mineral into enamel surface deformities under a wide variety of conditions and from a wide variety of formulas. |
