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

Abstract

Purpose: 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. Materials and Methods: 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). Results: 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. Conclusions: 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.

Effect of firing cycle and aging on long-term chemical degradation of monolithic CAD-CAM ceramics

“…The chemical degradation of dental ceramics in acidic media has been previously investigated. 7,8,[11][12][13][14]19 Milleding et al 12 reported that immersion in 4% acetic acid solution at 80 C for 18 hours increased the surface roughness of leucite ceramic, a finding that was corroborated by another study, in which organic acids were reported to negatively affect lithium disilicate and zirconia-reinforced lithium silicate ceramics. 8 In another study on the chemical degradation of dental ceramics, including a leucite glass-ceramic and an yttria-stabilized zirconia, oxide ceramics eluted significantly fewer ions than glass-ceramics, which was observed on a larger scale in the acidic medium.…”

“…The minimal risk levels of these toxic ions have been specified in a previous study on the ion elution of different esthetic materials when subjected to a home bleaching agent. 7 Lower elution values for Al, Ca, K, Li, Na, P, and Zn ions than the minimal risk levels were reported, whereas Cu levels were above the threshold for certain materials, including zirconia. 7 In the present study, As, B, Be, Cd, Cr, Co, and Zn levels exceeded the stated thresholds for each material-firing pair, regardless of aging.…”

“…7 Lower elution values for Al, Ca, K, Li, Na, P, and Zn ions than the minimal risk levels were reported, whereas Cu levels were above the threshold for certain materials, including zirconia. 7 In the present study, As, B, Be, Cd, Cr, Co, and Zn levels exceeded the stated thresholds for each material-firing pair, regardless of aging. In addition, Cu levels were higher than the stated thresholds in EX-1F, EX-2F, and E after thermocycling.…”

“…1,[4][5][6] Dental ceramics are mainly referred to as insoluble or minimally soluble. 7,8 However, previous studies have shown the solubility of dental ceramics at oral pH. [9][10][11][12][13][14] Considering that chemical degradation depends on chemical and mechanical environmental factors 11,13,15 and the chemical diversity among current dental ceramics, specifying that these materials are inert would be misleading.…”

“…9 Moreover, the chemical degradation of a ceramic surface increases roughness that results in plaque accumulation, antagonist wear, and poor esthetics. 12,14,17 Previous studies on the chemical degradation of dental ceramics have focused on the effect of pH values 7,13,14,18,19 or immersion cycles. 20,21 Mechanical and optical properties of CAD-CAM ceramics after repeated firings have also been investigated.…”