Hypersensitivity to conventional and to nickel-free orthodontic brackets

Abstract

The aim of this study was to evaluate the allergenic potential of orthodontic brackets, comparing the cutaneous sensitivity provoked by metals present in conventional metallic brackets to that provoked by brackets with a low concentration of nickel, known as "nickel-free". A sample was selected from 400 patients undergoing treatment in the orthodontic clinic of the Pontifical Catholic University of Minas Gerais (Belo Horizonte, MG, Brazil), in the period from the beginning of 2002 to the end of 2003. A cutaneous sensitivity patch test containing 5% nickel sulphate was used in 58 patients (30 males and 28 females), aged between 11 and 30, which were using fixed appliances with Morelli brackets in both arches. In a second phase, 30 days later, a comparative test of cutaneous sensitivity was applied to the whole sample with two types of test specimens, in the form of a disc. Two alloys were tested: discs composed of the alloy used in the construction of conventional brackets and discs composed of a nickel-free alloy. The internal part of the forearm was chosen for testing, and 20 test specimens of each experiment (corresponding to the twenty brackets of a complete fixed appliance) were applied. Of the 58 patients evaluated, 16 patients were sensitive to the patch test with 5% nickel sulphate. Out of these 16 patients, 12 developed an allergic reaction to experiment 1 (test specimen with nickel), while in experiment 2, only 5 patients showed sensitivity to that sample. The McNemar test revealed that the nickel-free test specimens provoked less allergic reaction when compared with the conventional alloy (p=0.016).

Longitudinal assessment of periodontal status in patients with nickel allergy treated with conventional and nickel-free braces

“…30,31 Nickel-free stainless steel braces produced by Morelli (Monobloc) do not have a significant amount of nickel in their composition and may be a viable alternative for allergic patients, in agreement with previous studies. 4,9 However, this composition decreases their mechanical properties, because nickel considerably enhances resistance to oxidation and corrosion. 32 Thus, the presented results are relative specifically to the Morelli brackets.…”

“…Such appliances are denominated nickel-free and are advertised as releasing low quantities of nickel ions, which may diminish the allergic response in sensitive patients. [7][8][9][10] A critical evaluation of the literature reveals little consistent evidence regarding the actual effectiveness of nickel-free appliances in orthodontic patients allergic to nickel. In a recent systematic review, Pazzini et al 4 found only four studies suggesting that nickel-free braces may favor orthodontic treatment in allergic patients, and the authors stress the need for clinical trials that can provide more consistent evidence with regard to this issue.…”

Allergic reactions and nickel-free braces: a systematic review

“…8,16 Nickel is capable of influencing the periodontal condition of allergic orthodontic patients. 2 In a study by Pazzini et al, 2 the patient's history of allergic reactions to nickel (reported in the patient history) and the patch test were conclusive for a diagnosis of nickel allergy.…”

“…The quality of the investigation and methodological consistency were high in one study, 14 medium in one study 15 and low in two studies 8,12 ( Table 2). There were significant differences in the number of leukocytes between the nickel-implanted animals and the nickel-free and control groups after 14 days of implantation (P < .05).…”

“…7 Other options include ceramic or plastic braces, as well as those with a low nickel concentration known as nickel-free braces. 1,8 However, there are reports in the literature that allergic reactions to nickel are frequently associated with reactions to other metals such as chrome and cobalt. [9][10][11] It is therefore difficult to assess the individual contribution of each component when considering the allergic reaction of patients.…”