Abstract
PURPOSE: To examine and compare the levels of several metal ions released in the saliva of patients with orthodontic appliances, at different time points before and after insertion of a miniscrew. METHODS: Saliva of patients (n=20) was collected at four time points: before miniscrew placement (T1), 10 minutes (T2), 7 days (T3) and 30 days after miniscrew placement (T4). The salivary samples were analyzed by inductively coupled plasma mass spectrometry (ICP-MS) and inductively coupled plasma optical emission spectrometry (ICP-OES). The release of nine different metal ions was observed: titanium (Ti), zinc (Zn), chromium (Cr), nickel (Ni), iron (Fe), copper (Cu), aluminum (Al), Vanadium (V) and cobalt (Co). Data were analyzed by descriptive statistics. Salivary metal concentrations from different time points of miniscrew treatment were compared using Wilcoxon paired tests (a=5%). RESULTS: At time point T4, there was a quantitative increase in the salivary concentration of Cu, Ti, V, Zn, as well as a quantitative decrease in the salivary concentration of Al, Co, Cr, Fe, Ni, when compared with T1. CONCLUSION: It can be concluded that the placement of fixed orthodontic appliances associated with miniscrews does not lead to an increase of salivary metal ion concentrations.
Highlights
Ti -6A- 4V is the most frequently used titanium alloy for medical implants and orthodontic miniscrews because of its excellent properties [1,2]
The aim of the present study was to examine and compare the levels of several metal ions released in the saliva of patients with orthodontic appliances and with miniscrews as orthodontic anchorage
At 7 days after miniscrew insertion, there was a quantitative increase of Al, Co, Cr, Cu, Ni, Ti and V
Summary
Ti -6A- 4V is the most frequently used titanium alloy for medical implants and orthodontic miniscrews because of its excellent properties [1,2]. Several studies suggested the cytotoxicity and dissolution of this alloy [2,3,4] and its corrosion products [5,6,7,8]. In the alloy Ti-6Al-4V, superficial oxide is composed of TiO2, with small amounts of Al2O3, hydroxylic groups and water [10]. Its superficial oxide layer is less stable than that of commercially pureTi because the Al and V, which are added to stabilize the α and β phases, respectively, desestabilize the alloy, making it more vulnerable to corrosion [11]. As V is not present in the superficial oxide layer of Ti-6Al-4V [10], Ti and Al are the metal ions most likely to be released from the Ti-6Al-4V surface[12]
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