Effect of a Home Bleaching Agent on the Ion Elution of Different Esthetic Materials

To investigate the effect of a 16% carbamide peroxide home bleaching agent on the ion elution of different esthetic restorative materials and to determine if the released ions exceed the minimal risk levels.

Ceramic materials comprising a low-fusing porcelain (Vita VM7), lithium disilicate glass-ceramics (IPS e.max Press and IPS e.max CAD), zirconium substructure materials (IPS e.max ZirCAD and Vita In-Ceram YZ for InLab), and ceromers (Estenia and Tescera ATL) were chosen. Thirty disk-shaped specimens (2 mm thickness and 10 mm diameter) were fabricated from each material and then were divided into 3 experimental groups to receive one of the following solutions: acetic acid (positive control), a bleaching agent and distilled water (negative control) (n = 10/group). For the bleaching agent, the specimens were subjected to a 16% carbamide peroxide solution (VOCO Perfect Bleach) for 2 hours per day for 14 days. A 4% acetic acid solution was applied at 80°C for 16 hours according to the ISO 6872:2015 protocol and specimens of negative control group were immersed in distilled water for 16 hours. Ion elution measurements were conducted with inductively coupled plasma atomic emission spectroscopy (ICP-AES) after immersion in the solutions, and the weight loss of the materials was measured with a precision scale. Changes in the surface topography were investigated by a scanning electron microscopy (SEM).The results were evaluated using multivariate analysis of variance (MANOVA).

Among the specimens tested, the most ion elution was observed in the Tescera ATL group, and the least ion elution was observed in the e.max ZirCAD group in all solutions. Ion elution was found to be greater in the bleaching agent than in the acetic acid and distilled water groups. Sodium was the most released ion, and zinc and lithium were the least released among the elements tested.

It should be noted that the bleaching-related ion release may exceed toxic doses even if restorative materials meet ISO 6872 standards, and the materials should be protected before home bleaching to prevent ion elution.