Integration of a Fluoride- and Mint-Based Spray in Nighttime Aligner Therapy: Effects on Salivary Concentration and Biofilm

Continuous use of clear aligners modifies the oral environment and may favor bacterial colonization. Integration of topical fluoride-based agents could strengthen enamel and reduce biofilm formation. This study evaluated the effects of a galenic fluoride-mint spray (225–250 ppm fluoride and 1–2% peppermint essential oil) on salivary fluoride concentration and bacterial biofilm during orthodontic treatment. Ten patients using 3D-printed nighttime aligners were enrolled. Saliva samples were analyzed with an ion-selective electrode (ISE) at baseline, immediately after inserting the sprayed aligners and after 15, 30, 45 min post application. Biofilm morphology was qualitatively assessed by scanning electron microscope (SEM) in three aligners: unused, worn 14 nights without spray, worn 14 nights with spray. Salivary fluoride increased from 0.7–0.8 mg/L at baseline to 5.96 mg/L when the spray was applied on a new aligner and 8.42 mg/L on a used aligner, then progressively decreased, returning close to baseline at 45 min with the new aligner and remaining higher with the used aligner. SEM images showed mature and heterogeneous biofilm on used aligners without the spray, while aligners with nightly spray application exhibited qualitatively reduced and less organized surface deposits. The fluoride- and mint-based spray rapidly increases salivary fluoride and reduces biofilm formation on nighttime clear aligners, improving preventive oral health during orthodontic treatment.