Cytokine levels in gingival crevicular fluid during orthodontic treatment with aligners compared to conventional labial fixed appliances: a 3-week clinical study

Objective: To test the hypothesis that the levels of IL-1 ss and TNF-alpha increased more and IL-1 alpha, IL-2, IL-6, IL-8 increased less, after 3weeks of treatment with conventional labial fixed appliance and with aligners.Material and methods: Forty patients who were treated either with labial brackets (n=20) or aligners (n=20). Gingival crevicular fluid (GCF) samples were collected at baseline and after 21days. Cytokine levels were evaluated by enzyme-linked immune sorbent assay (ELISA). Plaque index (PI), gingival index (GI), and bleeding on probing (POB) were also examined.Results: The levels of IL-1 alpha, IL-1 ss, IL-2, IL-6, IL-8 and TNF-alpha in the GCF were significantly increased in both groups. The levels of IL-2, IL-6, IL-8 increased more in patients treated with aligners compared to those treated by labial fixed appliances. There was a statistically significant difference in change of the mean cytokine levels of IL-1 alpha, IL-2, IL-6, IL-8 and TNF-alpha compared to labial fixed appliances and aligners.Conclusions: The levels of the six studied cytokines in GCF (IL-1 alpha, IL-1 ss, IL-2, IL-6, IL-8 and TNF-alpha) increased after 3weeks both after treatment with conventional labial fixed appliance and with aligners. IL-1 ss and TNF-alpha showed a prominent increase compared to the other cytokines in the GCF of teeth by both the labial fixed appliance and aligners. However, there were only minor differences in the changes of the cytokine levels from baseline to 3weeks between the two groups. There were no differences between the groups regarding PI, GI or POB.