External apical root resorption (EARR) is a common yet often undetected adverse effect of fixed orthodontic treatment. Despite its typically mild presentation, severe resorption can occur in certain patients, potentially compromising long-term dental health. Current diagnostic modalities, such as radiography, lack the sensitivity to detect early-stage resorption and cannot differentiate between active and inactive resorptive phases. As EARR is multifactorial and influenced by genetic, biological, and mechanical factors, there is a critical demand for accurate, non-invasive diagnostic markers to enable early detection and real-time monitoring of resorptive activity. Emerging evidence highlights the potential of biomarkers such as dentin sialoprotein (DSP) and interleukin-1 receptor antagonist (IL-1RA) in gingival crevicular fluid (GCF) as indicators of resorption severity. However, the variations in these biomarkers throughout fixed orthodontic treatment and their relationship to the severity of root resorption are not yet well understood.

This gap in knowledge underscores the necessity for research to establish the diagnostic utility of DSP and IL-1RA as biomarkers for predicting and assessing root resorption during orthodontic therapy.

Timely identification of teeth prone to severe resorption is essential. Although radiography is the most widely utilized diagnostic method, it has significant limitations, including its inability to identify early resorption stages or differentiate between active and inactive phases. Additionally, radiographic evidence of resorption becomes apparent only after substantial tissue loss, by which time irreversible damage may have occurred. These drawbacks highlight the urgent need for more sensitive, non-invasive, and timely diagnostic approaches.

Gingival crevicular fluid (GCF) has gained attention as a potential medium for identifying biochemical markers that reflect periodontal and resorptive activity. Dentin sialoprotein (DSP), a byproduct of dentin matrix breakdown, is a promising biomarker and has been identified in the GCF of patients undergoing fixed orthodontic therapy. Similarly, interleukin-1 receptor antagonist (IL-1RA), an anti-inflammatory cytokine, plays a pivotal role in regulating inflammatory responses and preventing excessive bone and root resorption. Variation in the concentration of these biomarkers during fixed orthodontic treatment may offer valuable insights into resorptive activity and susceptibility to EARR.

This study aims to address these unmet needs by investigating the dynamic changes in DSP and IL-1RA levels at three clinical time points to assess effect of treatment duration during fixed appliance therapy in patients with Angle’s Class 1 malocclusion with bimaxillary dentoalveolar protrusion who require all first premolar extraction followed by en-masse retraction, thereby identifying reliable, non-invasive biomarkers for early diagnosis and monitoring of EARR. Establishing such biomarkers could minimize reliance on radiography and enable timely interventions and personalized treatment adjustments, reducing the chance of significant root damage and enhancing long-term treatment outcomes.