Investigation of bone remodeling in gingival crevicular fluid in patients treated with rapid maxillary expansion during pubertal period

Aim: This prospective clinical study aimed to evaluate the bone remodeling following 3-month and 6-month retention periods of rapid maxillary expansion (RME) in gingival crevicular fluid (GCF). Material and Methods: A total of 23 participants in the pubertal period, including 15 girls and 8 boys, aged between 12 and 15 years, with maxillary transversal deficiency, were enrolled in the study. Immediately after the banded type RME appliance consisting of a modified hyrax screw was introduced into the mouth, the RME protocol was initiated by turning the hyrax screw twice daily (in the morning and evening) with ¼ rotation. GCF samples were taken from the right maxillary first molars at four different time points (T0: before the appliance was deployed, T1: following the active phase, T2: at the end of the 3-month retention period, T3: at the end of the 6-month retention period) using paper strips and then, the probing depth, gingival index, plaque index and bleeding percentage at probing were recorded. The BALP, OPG, RANKL, and TNF-α levels were measured in the obtained GCF samples using ELISA kits. Results: Our study revealed that BALP and OPG levels in the GCF remained unchanged over time in the regions of tension and pressure, and there were no statistically significant differences among the regions at each time point (p>0.05). The level of RANKL was statistically significantly increased in the buccal region, which is the region of pressure at time T1 (p=0.042). The TNF-α level of the palatinal region was statistically significantly higher than that of the buccal region at T0, T2, and T3 time points (p=0.005, p=0.042, and p=0.006, respectively). Conclusion: Our study showed no correlation between 3-month and 6-month retention periods and the biomarkers indicating bone metabolic activities of RME. Further studies with different retention periods and larger sample sizes may be suggested. Keywords: Expansion, Remodeling, Retention.