Allergic response to nickel in the oral mucosa from nickel containing orthodontic appliances is more infrequent than from nickel contact on the epidermis, it can occur, particularly in females. If nickel-related intraoral clinical signs and symptoms appear, the orthodontist should be prepared to undertake or continue treatment without the use of Ni-Ti wires and even without stainless steel. The frequency of orthodontic treatment and the common use of nickel containing orthodontic materials raises the interesting question of whether orthodontic treatment may act to increase or decrease the...