Carlos Flores-Mir DDS, DSc, FRCD(C); Analia Veitz-Keenan DDS
Orthodontic treatment is not associated with an increase in the prevalence of nickel hypersensitivity unless subjects have a history of cutaneous piercing.
Do patients undergoing orthodontic treatment have an increased prevalence of nickel hypersensitivity as compared to the general population?
The authors searched 11 electronic databases for literature published to November 2007. They conducted hand-searches and searched trial registers. The authors searched for evidence related to two types of patient populations: orthodontically treated patients and general population.They searched all types of potentially relevant studies with no restrictions on publication date or languages. Two reviewers independently evaluated the selected studies. The authors assessed heterogeneity and publication bias. They used prevalence of nickel hypersensitivity as the main outcome.
The authors identified 324 articles, but selected only eight for the review. Of those eight studies, two trials presented data on positive nickel patch tests performed both before orthodontic treatment and after the placement of orthodontic appliances, whereas six studies contained data collected after the placement or removal of the appliances. Six studies evaluated subjects treated with fixed orthodontic appliances, one study evaluated subjects treated with removable appliances, and one study evaluated subjects with both fixed and removable appliances. Patch-testing showed no statistically significant increase in the risk of nickel hypersensitivity before orthodontic treatment and after the placement of the appliances. Patients who had cutaneous piercing before orthodontic treatment had a statistically significant higher risk of nickel hypersensitivity than did patients with no cutaneous piercing. Although the prevalence of Ni hypersensitivity in patients undergoing orthodontic treatment (21.4%) was larger compared to the general population (12.3%)the difference was not statistically significant. When cutaneous piercing was considered a factor in orthodontically treated patients then a significant difference appeared (6.1% against 30.3%).
Orthodontic treatment is not associated with a risk increase of nickel hypersensitivity unless subjects have a history of cutaneous piercing. As the actual worldwide prevalence of nickel hypersensitivity is not nil practitioners need to be prepared to manage such scenario. Alternative treatment modalities need to be available so that the patients with NiTi hypersensitivity can benefit from orthodontic treatment
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Importance and Context:
Nickel is a common allergen found in many alloys (jewelry, coins, dental alloys). Nickel hypersensitivity has been reported in up to 15 percent of the population (10 to 12 percent in females and six percent in males).1 This allergic reaction (contact dermatitis) may develop at any age. Knowledge of the frequency of nickel hypersensitivity in patients reporting for orthodontic care is therefore important.
Strengths and Weaknesses of the Systematic Review:
The authors followed meta-analysis of observational studies in epidemiology (MOOSE) guidelines. They conducted an extensive search with no restrictions. They calculated odds ratio and confidence intervals. In addition, they assessed heterogeneity among the studies. They performed a meta-analysis using only the two studies that provided data for the prevalence of nickel hypersensitivity in patients before orthodontic treatment and after the placement of the orthodontic appliance. The remaining 6 studies were not considered as they only evaluated the hypersensitivity after treatment. A subgroup analysis including data from all studies was made investigate the effect of the absence/presence of cutaneous piercing and the sequence of piercing relative to orthodontic treatment.
Strengths and Weaknesses of the Evidence:
The authors made conclusions based on their analysis of prospective and retrospective studies. The studies had heterogeneous populations with no appropriate control groups, and had unclear and short follow-up times. The studies did not consider the magnitude of the patients previous nickel exposures and reactions. There is a lack of high validity longitudinal studies with appropriate control groups. These factors need to be accounted for when the meta-analysis results are considered.
Implications for Dental Practice:
Nickel is a commonly used orthodontic material. Limited evidence demonstrates there is no association between orthodontic treatment and the development of nickel hypersensitivity. However, clinicians should be aware that patients who wear piercings or who have had a previous reaction to nickel pose a higher risk of an allergic reaction. REFERENCES: 1 Marks Jr JG, Belsito DV, DeLeo VA, et al. North American Contact Dermatitis Group patch-test results, 1998 to 2000 Am J Contact Dermatol 2003;14:59-62.