title: Lactate dehydrogenase activity in gingival crevicular fluid as a marker in orthodontic tooth movement.
abstract: OBJECTIVE
  This study aims at analyzing the changes in gingival crevicular fluid (GCF) lactate dehydrogenase (LDH) activity during orthodontic movement.
  
  
  METHODS
  Twenty patients all requiring first premolar extractions were selected and treated with conventional straight wire mechanotherapy. Canine retraction was done using 125 g Nitinol closed coil springs. The maxillary canine on one side served as the experimental site while the contralateral canine served as the control. GCF was collected from the canines before initiation of retraction, then 1 hour after initiating canine retraction, followed by 1 day, 7 days, 14 days and 21 days. GCF LDH levels were estimated and compared with the control site.
  
  
  RESULTS
  The results revealed significantly higher LDH levels on the 7(th), 14(th) and 21(st) day at the sites where orthodontic force had been applied. The levels also showed a significant increase from 0 hour to the 21st day. Peak levels were seen on 14(th) and 21(st) day following initiation of retraction.
  
  
  CONCLUSIONS
  The study showed that LDH could be successfully estimated in the GCF and its increased levels could indicate active tooth movement, which could aid the clinician in monitoring active orthodontic tooth movement.
authors.affiliation: Department of Pediatric Dentistry and Orthodontics, College of Dentistry, King Saud University, Post Box: 60169, Riyadh11545, Kingdom of Saudi Arabia.
authors.forename: Sarah A
authors.initials: SA
authors.lastname: Alfaqeeh
authors.forename: Sukumaran
authors.initials: S
authors.lastname: Anil