OBJECTIVES: To compare short-term changes in the levels of interleukin-8 (IL-8) and interleukin-6 (IL-6) in the gingival crevicular fluid (GCF) of individuals undergoing orthodontic treatment with clear aligners. MATERIALS AND METHODS: This study included 15 individuals. Each patient used clear aligners designed not to cause tooth movement in the GCF sampled teeth, to be changed every 10 days. GCF samples were collected from teeth 16 (upper right first molar) and 31 (lower left central incisor) at baseline and after the procedure at the first hour, third, seventh, 14th, and 21st days. In addition, clinical periodontal parameters for the full mouth and the teeth from which GCF was collected were recorded initially and on the 21st day. RESULTS: A statistically significant difference was observed between the levels of IL-8 before the procedure, on the third and seventh days, and on the 21st day (P <
.01). The increase in IL-6 levels on the 14th and 21st days was significantly different compared to the levels before the procedure (P <
.01). A positive correlation was detected between IL-8 and IL-6 levels at the first hour, a negative correlation on the third day, and a lower level of positive correlation on the seventh, 14th, and 21st days. CONCLUSIONS: Within 21 days, the levels of IL-8 and IL-6 significantly increased in individuals undergoing orthodontic treatment with clear aligners. Within the limits of this study, the clear aligner material may affect the levels of IL-8 and IL-6 in the GCF.