Relationship between substance P and interieukin-1β in gingival crevicular fluid during orthodontic tooth movement in adults

Metabolism by peptidases plays an important role in modulating the levels of biologically-active neuropepticles, while that of substance P (SP), a component of gingival crevicular fluid (GCF), may potentiate the inflammatory process in orthodontic tooth movement. The aim of this study was two-fold: (1) to investigate GCF levels of SP and interleukin-1 beta (IL-1 beta) during human orthodontic tooth movement, and (2) to determine the correlation coefficients between SP and IL-1 beta levels in the GCF. The subjects were 3 males, with a mean age of 21.3 +/- 2.8 years old, and 6 females, with a mean age of 23.1 +/- 2.4 years, undergoing orthodontic movement of a single tooth, with the contralateral tooth used as the control. GCF was sampled at the control and treatment (compression) sites before and 1, 4, 8, 24, 72, 120, and 168 hours after initiation of orthodontic treatment. Prevention of plaque-induced inflammation allowed assessment of the dynamics of mechanically stimulated SP and IL-1 beta levels in the GCF, which were determined using enzyme-linked immunosorbent assay (ELISA) kits. GCF levels of SP and IL-1 beta for the treated teeth were significantly higher (P < 0.001) than for the corresponding control teeth from 8 to 72 hours, and peaked at 24 hours. These results show that the amounts of SP and IL-1 beta in GCF increase with orthodontic tooth movement, and indicate that such increases may be involved in inflammation in response to mechanical stress.