Effect of Orthodontic Forces on Gingival Crevicular Fluid Alkaline Phosphatase

Background: The effect of continuous and interrupted forces on alveolar bone remodeling after orthodontic tooth movement has not been evaluated. Alkaline phosphatase activity in the gingival crevicular fluid (GCF) could be use as an indicator of alveolar bone remodeling. Objective: To evaluate the effect of continuous and interrupted forces on alkaline phosphatase activity in the GCF of the tension site. Methods: Pre and post-treatment block randomized control group design was conducted on 7 orthodontic patients who need distally retraction of their maxillary canines prior to first premolar extraction. Based on split mouth design two modes of force were randomly distributed to each canine of each patient. The maxillary canines allocated to the continuous force group were retracted using NiTi closed spring while those allocated to the interrupted force group were retracted using module chain. GCF was collected before treatment and 1 hour, 24 hours, 168 hours, and 504 hours after treatment using 2 x 8 mm² Whatmann filter paper. The activity of alkaline phosphatase was measured by spectrophotometric method. Results: Using ANOVA two ways showed that there was no significant difference (F = 3.04; p = 0.086) between the two groups, but there was significantly different (F = 5.74; p = 0.001) in times of measurement, Twenty-four hours after treatment, the alkaline phosphatase activity was decreased and slowly increased until 504 hours. Conclusion: Based on this study it was concluded that there was no difference between the continuous and interrupted orthodontic forces on alkaline phosphatase activity.