The purpose of this study was to evaluate the effects of a light continuous force and an interrupted force with weekly reactivation on interleukin-1β (IL-1β) and prostaglandin E2 (PGE 2); possible interactions between these 2 potent mediators of the bone resorption process were assessed in vivo. Ten healthy young adults (mean age 20.6 years, 2 men, 8 women) with 4 premolars extracted were assessed. In each subject, 1 maxillary canine (E1) received continuous force with a nickel-titanium coil spring. The opposite canine (E2) received an interrupted force with a screw-attached retractor; the force was reactivated weekly by 2 turns of the screw. An antagonistic canine was used as a control. Gingival crevicular fluid was collected from the distal side of each tooth, 10 times in 3 weeks, and IL-1β and PGE2 levels were measured. For E1, the IL-1β level showed a significant elevation at 24 hours and then decreased and maintained an insignificant but high mean concentration, compared with the control site. The PGE2 level showed a significant elevation at 24 hours and then decreased. For E2, a significant elevation of IL-1β level was observed at 24 hours and a greater significant elevation at 24 hours after the first reactivation, compared with the control sites. The PGE2 level increased significantly at 24 hours and remained high for 1 week. The synergistic up-regulation of PGE2 by appliance reactivation and secreted IL-1β was not evident with either type of force after 1 week. Both experimental sites showed significant tooth movement compared with the control sites at 3 weeks; however, there was no significant difference between the 2 experimental sites. A well-controlled mechanical stress with timely reactivation can effectively upregulate IL-1β secretion, but there might be limitations in increasing the mediator levels, because of the feedback mechanisms in vivo. In addition, the analysis of crevicular fluid is a useful method for assessing cellular response to orthodontic force in vivo.
|Number of pages||10|
|Journal||American Journal of Orthodontics and Dentofacial Orthopedics|
|Publication status||Published - 2004 Feb|
Bibliographical noteFunding Information:
This work was supported in part by Yonsei University Research (the Yonsei University College of Dentistry and the Oral Science Research Center) Fund of 2001 and the Brain Korea 21 Project for Medical Sciences, Yonsei University.
All Science Journal Classification (ASJC) codes