Nickel Ions Release from Orthodontic Retention Wires after Dental Bleaching

Abstract

In order to preclude relapse after the orthodontic treatment have been completed, majority of orthodontists depend on the permanent retention with bonded lingual retainer wires. It is essential to study the home dental bleaching effect on ions release from permanent retention wires with the increasing demand for bleaching to have gorgeous smile. Our vitro study intended to demonstrate the home dental bleaching gel (carbamide peroxide) effect on Nickel release from orthodontic fixed retainer wires, and how does the type of retainer wire, the carbamide peroxide concentration and the exposure duration effect of carbamide peroxide on the release of nickel ions. The sample was composed of 60 lingual retainer wires of two types (3 braided strands/orthotechnology, and 6 coaxial strands/orthotechnology) and two types of at-home bleaching gel (35% carbamide peroxide/opalescence PF/Ultradent, and 16% carbamide peroxide/polanight SDI). By using a brush, a thin coating of bleaching gel about 1-mm thickness was added onto one surface of the wire and kept for (30 minutes for 35% carbamide peroxide bleached wires and 90 minutes for 16% carbamide peroxide bleached wires-following the instructions of the manufacturer), for each kind of bleaching, after that the wires were bathed and kept at room temperature in 10 ml of artificial saliva in a wrapped container, for 7 days this process was repeated day-to-day. Via flameless atomic absorption spectrophotometer in ppm, nickel ions release was measured. Non significant differences were result between two types of wires and between 30% carbamide peroxide and control group, 16% carbamide peroxide showed significantly less Nickel release compared with control group and 35% carbamide peroxide group. Nickel release was not affected by the wire kind, but if may be affected by the carbamide peroxide concentration and the exposure time. The 16% carbamide peroxide documented the smallest values, that means the nickel release from retention wires was decreased as the exposure time increased to low carbamide peroxideconcentration.