Effect of bleaching regimes on themetal-ion surfacelevel and micro-structural topography of twodental amalgams

الملخص EN

Objective : dental treatment is an integrated procedure ; one procedure should not jeopardize the other.

With the increased demand for vital bleaching to improve tooth whitening and perceived esthetic appearance, concerns have grown about their effect on esthetic restorative materials.

However, little attention has been directed to their effect on metallic restorations, including amalgam.

This in vitro study investigated the effect of two concentrations of car amide peroxide and ozone bleaching gel on the metal-ion surface level and topography of two aged dental amalgams.

Methods : Thirty discs (12.5 x 2.5 mm) were prepared from Trend alloy (lathe cut, Non-gamma 2, ternary, zinc free high copper amalgam) and Word Cap (spherical, Gamma 2-free, zinc-free, high copper amalgam).

The amalgam specimens were left unfinished.

The morphology and metal-ion surface levels were tested using Environmental Scanning Electron Microscope (ESEM) equipped with Electron Dispersive Analytical X-ray (EDAX).

The samples were then aged for 3 months in sterile normal saline and tested again after aging.

The samples of each amalgam type were then divided into 3 groups (n = 5), and treated with 16 % car amide peroxide, 30 % car amide peroxide or ozone.

After the specified bleaching regime, the samples were re-tested again.

The metal-ion surface levels data were statistically analyzed using Paired t-test, One-way Analysis of Variance (ANOVA) and Tukey’s post-hoc test.

Results : statistical analysis showed that, after 3 months saline aging of the two amalgams, there was a statistically significant decrease in mean Cu, Sn, Ag and Hg levels, except for Ag in World Cap amalgam (p ≤ 0.05).

After all the bleaching regimes, there was a statistically significant increase (p ≤ 0.05) in Ag and Hg surface level of ‘Trendalloy’ amalgam, but not for ‘World Cap’ amalgam.

However, bleaching with 30 % car amide Peroxide significantly decreased the copper and tin surface levels of ‘World Cap’ amalgam.

Conclusion : the metal-ion surface level, especially Hg, and the microstructure of dental amalgams could be changed by bleaching regimes, especially 30 % car amide Peroxide.