Salivary oxidative stress during and after rapid maxillary expansion

Objectives: The objectives of the study were to evaluate oxidative stress biomarkers during a rapid maxillary expansion (RME). Material and Methods: Fourteen patients were treated with an acrylic RME device, and after treatment, all were followed for 3 months. Saliva samples were collected before activation (baseline), 1st, 10th days after the first activation, and after retention. Periodontal indexes were recorded at baseline and after retention. Nitric oxide (NO) and malondialdehyde (MDA) levels were evaluated. Results: NO levels were elevated on the 10th day compared to baseline (P < 0.01), revealing a decrease after retention (P < 0.01). MDA levels were increased on the 10th day and after retention periods compared to baseline (P < 0.01, respectively). Both plaque and gingival indexes increased after retention relative to baseline (P < 0.01, respectively). Conclusion: Initial stages of orthopedic force increased salivary oxidative stress biomarkers. Long-term results showed decreased levels of NO, but still high MDA levels. The initially increased NO expression decreased after retention, despite the increase in microbial load at this period which might show the effect of mechanical stimuli to be more effective than the microbial load. MDA levels remained at high levels during the post-retention period, arising a possible consideration for the impact of material properties or deficiencies of oral hygiene. Future long-term evaluations for oxidative stress status and orthodontic appliances would be useful.