Effects of continuous and interrupted orthodontic force patterns on chondroitin sulfate (WF6 epitope) levels during orthodontic canine movement

Abstract

The main purpose of this study was to compare chondroitin sulfate (CS; WF6 epitope) levels in gingival crevicular fluid (GCF) during orthodontic mandibular canine movement by continuous and by interrupted orthodontic force patterns. Fifteen orthodontic patients (ten females and five males, aged 17.00 + 3.18 years) who required first premolar extraction and distal canine movement participated in this study. The left mandibular canine was moved by using a Nickel-Titanium closed coil springs (Sentalloy®), generating 120 gm for an initial continuous force, and the right mandibular canine was moved by using elastomeric chains (Dynaflex®), generating 120 gm initial interrupted force. The GCF was collected by Periopaper® strips from the distal sulcus of the experimental canines at the end of every week during the 8-week unloaded period for control data, before mandibular canine retraction (the beginning of the 1stweek of the loaded period) for baseline data and at the end of every week during the 8-week loaded period for experimental data. CS levels were measured by competitive ELISA of WF6 monoclonal antibody. In addition, the rate of mandibular canine movement (mm/month) and patients’ pain and discomfort, evaluated by a VAS score at the end of the 1st and the 5th weeks during the loaded period, were examined in this study. CS (WF6 epitope) levels for the left mandibular canines, moved by a continuous force, ranged from 0.001 to 7.44 (median 0.37) at the beginning of the 1st week during the loaded period, and from 0.001 to 417.68 (median 0.66) ng/µg of total protein content during the loaded period. CS (WF6 epitope) levels for the right mandibular canines, moved by an interrupted force, ranged from 0.001 to 4.29 ng/µg (median 0.21) at the beginning of the 1st week during the loaded period, and from 0.001 to 190.53 ng/µg (median 0.57) ng/µg of total protein content during the loaded period. The results showed that the medians of CS (WF6 epitope) levels resulting from continuous force and those from interrupted force at each week during the loaded period were not significantly different (P > 0.05). In addition, the mean rate of mandibular canine movement by a continuous force pattern was 0.86 + 0.37 mm/month and that by an interrupted force pattern was 0.70 + 0.55 mm/month. Both were insignificantly different (P = 0.369). Mean VAS scores of patients’ pain and discomfort during mandibular canine movement at the end of the 1stweek and at the end of the 5th week during the loaded period demonstrated insignificant xdifference between continuous and interrupted force patterns (P = 0.707 and 0.512, respectively). In conclusion, it can be implied that continuous and interrupted orthodontic force patterns at 120 gm initial force magnitude have similar biochemically assessed amounts of alveolar bone remodeling, rates of mandibular canine movement and severity of patients’ pain and discomfort.