Salivary Nickel and Chromium Levels in Orthodontic Patients with and Without Fixed Metallic Appliances

Background/Objectives: Dental malocclusions are often treated with appliances made of metal alloys. These alloys biodegrade in oral cavity and release toxic metals such as nickel and chromium. This study aimed to assess nickel and chromium content in the saliva of patients with and without fixed metallic orthodontic appliances. Methods: This was a descriptive cross-sectional study aiming to assess nickel and chromium content in saliva. A survey was conducted to record socio-demographic characteristics and clinical signs due to the wearing of fixed metallic orthodontic appliances. A 10 mL saliva sample was used to measure salivary pH and assess nickel and chromium concentrations using atomic emission spectrophotometry. A Student’s t-test compared saliva metal levels in non-wearers and wearers of metal orthodontic appliances. A Chi-square test was used to assess the influence of pH on metal release in patients. Results: A total of 92 participants, divided in two groups; 46 without appliance and 46 wearing appliance were received during the study period. Their mean age was 17.05 ± 6.46 years. Patients’ mean saliva pH was 6.97 ± 0.44. The mean nickel concentration was 4.39 ± 4.01 µg/L in the saliva of non-appliance wearers and 20.41 ± 18.56 µg/L in the saliva of appliance wearers, respectively. The chromium mean concentration was 1.3 ± 1.33 µg/L for non-appliance wearers and 9.38 ± 19.49 µg/L and for appliance wearers. Metal release is influenced by the pH of foods. Conclusions: Metal orthodontic appliances increase the release of nickel and chromium in saliva. It is necessary to monitor the risk of intolerance and optimize treatment duration.