Abstract
BACKGROUND: Orthodontically induced root resorption (OIRR) is a common iatrogenic consequence of orthodontic treatment, often going undetected until significant damage occurs. Noninvasive biomarkers could allow early detection and monitoring of OIRR. Salivary exosomal microRNAs (miRNAs) have emerged as potential indicators of inflammatory and resorptive processes in oral tissues. OBJECTIVE: To evaluate the expression of specific salivary exosomal miRNAs as potential biomarkers for early detection of OIRR in patients undergoing fixed orthodontic treatment. METHODS: A total of 60 patients (aged between 12 and 18 years), scheduled for fixed appliance therapy, were enrolled in a prospective cohort study. Saliva samples were collected at baseline, three months, and six months. Exosomes were isolated using ultracentrifugation, and miRNA profiling was performed using qRT-PCR. Cone-beam computed tomography (CBCT) was used to assess root resorption. The expression of miR-29a, miR-146a, and miR-155 was correlated with radiographic findings. RESULTS: Significant upregulation of salivary exosomal miR-146a and miR-155 was observed at three months (2.4 ± 0.7-fold and 3.1 ± 0.6-fold, respectively) and six months (3.7 ± 0.9-fold and 4.2 ± 1.1-fold, respectively; P < 0.001). Patients showing moderate-to-severe root resorption on CBCT had higher levels of these miRNAs. miR-29a showed no significant variation (P = 0.218). A strong correlation was observed between miR-155 levels and resorption scores (r = 0.79; P < 0.001). CONCLUSION: Salivary exosomal miR-146a and miR-155 levels increase significantly during OIRR and may serve as early noninvasive biomarkers. This opens new avenues for chairside screening and preventive orthodontic strategies.