Cytokines in crevicular fluid and orthodontic force: a systematic review

OBJECTIVE: This paper aimed to analyze studies in the literature addressing the role of cytokines in the gingival crevicular fluid (GCF) in the orthodontic treatment. METHODS: Several databases were surveyed using both MESH terms and free terms. Additional studies were obtained by reference tracking. This review was registered in PROSPERO, and the procedures foreseen by its statement were followed. Data were obtained from the included studies addressing the orthodontic mechanics, GCF sampling/handling methods, and cytokine measurements. Clinical studies written in English were browsed. Papers were selected by one reviewer and checked by a second investigator. RESULTS: A total of 115 articles were identified, among which 25 were selected for detailed analysis. Common drawbacks consisted mainly of inadequacies in the study design (e.g. short duration and small number of study subjects). The most consistent result was a peak of cytokine levels at 1 d. Associations were observed between prostaglandin E2 (PGE2) and interleukin-1β (IL-1β) and pain, velocity of tooth movement, and treatment mechanics. Interleukin-1b and PGE2 showed different patterns of up-regulation, with IL-1β being more responsive to mechanical stress and PGE2 more responsive to synergistic regulation of IL-1β and mechanical force. The results support the use of light continuous forces for orthodontic treatment. CONCLUSION: There was a tendency of maintenance of relatively high IL-1β levels for longer periods with the use of light continuous forces, which might decrease the frequency of activation. These outcomes provide evidence at the cellular level for the utilization of light continuous forces.