GCF Volume Changes in Aligners and Fixed Appliances

Inclusion Criteria: * Systemically healthy individuals with no history of systemic disease * No regular pharmacological medication use within the last 6 months * Individuals with completed mixed dentition and full permanent dentition (excluding third molars) * No missing or impacted teeth other than third molars * Indication for non-extraction orthodontic treatment * Mild malocclusion with 2-4 mm crowding (Celikoglu, 2010) * Skeletal Class I relationship (0° ≤ ANB ≤ 4°) * Periodontally healthy individuals (gingival index \<1, plaque index \<1, probing depth ≤3 mm, \<10% bleeding on probing, and no radiographic bone loss) * No caries, fractures, wear, or restorations in the teeth selected for gingival crevicular fluid sampling * Absence of parafunctional habits that could cause traumatic oral lesions Exclusion Criteria: * Presence of periodontal disease or radiographic bone loss * Poor oral hygiene * Skeletal anomalies or need for orthognathic treatment * Temporomandibular joint disorders * Known allergy to any medication or material * Tobacco or alcohol use * Personal or family history of cancer or history of chemotherapy/radiotherapy * Participation in another clinical trial during the study period * Presence of mixed dentition or missing teeth other than third molars