Expression of secretory proteins in oral fluid after orthodontic tooth movement

Orthodontic treatment alters the expression of secretory proteins at the local level in bone and the oral cavity, but its systemic effects are not well understood. Total secretory proteins and a cyclic adenosine monophosphate (AMP)-dependent protein kinase subunit (RII) were measured in saliva and gingival crevicular fluid (GCF) after the placement of orthodontic separators to determine if mechanical force applied to teeth affects protein secretion. Whole saliva and GCF were collected before and 1 day after treatment. Electrophoresis and Western blotting were carried out to establish the banding patterns of total proteins and to measure the isotype and amount of RII that serves as an apparent stress indicator. Digitized image files were used for densitometric analyses of the relative concentrations of RII and total protein. Individual protein values showed no statistically significant changes in saliva or GCF. Western blots, however, showed a dramatic difference in RII after the placement of separators: the 50-to-55 kilodaltons (kd) band virtually disappeared and was replaced by a fragment in the 20-kd range. These results suggest that although the expression of total proteins is not altered by mechanical force applied to teeth, a systemic response via the cyclic AMP signaling pathway might have been activated.