Evaluation of salivary biomarkers during en-masse retraction of protruded teeth into recent and healed extraction sites– a Randomized Clinical Trial

Objectives The study aimed to evaluate levels of salivary biomarkers during en-masse retraction of anterior maxillary teeth into recent and healed extraction sites. Materials and methods Twenty patients with protruded anterior maxillary teeth requiring en-masse retraction were randomly allocated into two groups. In the healed extraction (HE) group, first premolar extraction was performed at the beginning of treatment while in the recent extraction (RE) group, it was done just before the initiation of en-masse retraction. Saliva and study model collection was done at start of treatment, after leveling, and after 2, 8 and 12-weeks of retraction, respectively. The primary outcome was to evaluate concentrations of salivary biomarkers; receptor activator of nuclear factor kappa-B ligand (RANKL) and osteoprotegerin (OPG). Rate of en-masse retraction was secondary outcome. One-way repeated-measures ANOVA was applied for within-group changes, and an independent t-test for the intergroup comparison (P < 0.05). Results An increase in concentration of RANKL and decrease in OPG concentration was observed in both the RE and HE groups at 12 weeks; however, the intergroup comparison showed no statistically significant differences (P = 0.517). RANKL/OPG ratio was significantly higher in the RE group (P = 0.015) at 12 weeks. A significantly higher rate of en-masse retraction was found in the RE group (P < 0.001). Conclusion Variations in RANKL/OPG ratio can be considered a better predictor of orthodontic tooth movement. A significant higher rate of retraction in the RE group suggests that immediate application of retractive forces towards the RE site may hasten space closure. Clinical Relevance Findings of the present study suggest that immediate application of activation forces at the recent extraction site may hasten initial orthodontic tooth movement by preventing excessive strain on the alveolar bone, which has had time to heal during the tooth movement at healed extraction site. Additionally, the study contributes to existing literature that highlights saliva as an easily accessible alternative to crevicular fluid for sampling purposes.