Effect of Thermocycling on Nickel Release from Orthodontic Arch Wires: an In Vitro Study

Abstract

The amount of daily intake of metals from orthodontic appliances over time is a matter of great concern. Nickel results in one of the most common metal-induced allergic contact dermatitis in humans; it produces more allergic reactions than all the other metals combined together. The purpose of this study was to evaluate the effects of thermocycling on the nickel release from orthodontic arch wires stored in artificial saliva with different pH values. Forty new wire pieces were selected. Each wire piece was placed in a special capillary Pyrex tube filled with artificial saliva, which was sealed and immersed in deionized water at 37 °C. The samples were divided into four groups of ten. Group I received no treatment; group II was subjected to thermocycling. The pH of storage in groups III and IV was reduced to 4.5, and group IV was subjected to thermocycling. Thermocycling was carried out between 5 and 55 °C for 500 cycles. The release of nickel ions was statistically analyzed by two-way ANOVA for the effects of two variables: pH and thermocycling. The interaction between pH and thermocycling was found to be statistically significant (F = 12.127, P = 0.001). Two-way ANOVA showed that different storage media or pH and thermocycling had a significant effect on the nickel release (F = 52.812, P < 0.001 and F = 197.035, P < 0.001, respectively). Thermocycling and pH can adversely affect the release of nickel from orthodontic wires, while thermocycling is clearly the dominant factor.

Comparison of spring characteristics of titanium-molybdenum alloy and stainless steel

“…As mentioned earlier in the introduction section, smooth surface wires are used in clinical trials. However, useful changes in form should be ( 1 - 35 ) made to provide tooth movement ( 28 ). This is the limitation the present study did not attempt to evaluate clinically.…”

“…In orthodontics, tooth movements are achieved by the forces developed in the deformed wire, which are transmitted to the teeth through fixed or removable appliances. The appliance is continuously subjected to masticatory forces, and hence the wire must be sufficiently resilient to resist permanent deformation and thermocycling and maintain its activation ( 1 , 2 ). One of the challenges of fixed orthodontic appliances is uneven arch-wire surfaces that cause friction between the wire and bracket in sliding mechanisms ( 3 ).…”

Ions release Evaluation and Changes in Mini-implant Orthodontic Surface

“…In vitro and in vivo studies reported in the literature demonstrate the importance of released metal ions' identification from alloys in the evaluation of toxic effects. 2,16,29,30,[32][33][34] In the study reported by Marigo et al, 13 the samples analyzed in the anatomical absorption spectrophotometer showed extremely low amounts of Ti, Al, and V in all groups tested. However, significantly higher concentrations of magnesium, aluminum, silicon, phosphorus, sulfur, potassium, calcium, titanium, vanadium, manganese, iron, cobalt, copper, zinc, nickel, and chromium were observed when wires, brackets, and metal bands were stored in artificial saliva.…”

Effect of mobile phone use on metal ion release from fixed orthodontic appliances

“…The harmful effects of nickel have been systematically investigated at the levels of the cells, tissues, organs, and organisms. 2,3 According to the International Agency for Research on Cancer, nickel compounds are classified as carcinogenic to humans, but it is still unclear which forms of nickel pose the greatest risk. 4,5 Nickel complexes in the form of arsenides and sulphides are carcinogenic, allergenic, and mutating substances even at nontoxic concentrations.…”