Analysis of Interleukin-1 Receptor Antagonist Levels and Orthodontic Root Resorption During Retraction with Nickel Titanium Closed Coil Springs and Active Tiebacks: A Prospective Cohort Study

TITLE

Analysis of Interleukin-1 Receptor Antagonist Levels and Orthodontic Root Resorption During Retraction with Nickel Titanium Closed Coil Springs and Active Tiebacks: A Prospective Cohort Study

INTRODUCTION, RATIONALE, RELEVANCE

Orthodontic tooth movement is a highly orchestrated biological process driven by mechanical forces, leading to bone remodeling through the activation of inflammatory and immunological pathways in the periodontal ligament (PDL) and alveolar bone. Apical root resorption is a common occurrence during orthodontic tooth movement, varying in severity and often considered an unavoidable aspect of treatment. If left unchecked, severe root resorption can compromise the long-term prognosis of the affected teeth. Moreover, previous studies by Lupi JE et al have noted that incisors are more affected than posterior teeth.

Orthodontic mechanics influences the extent of root resorption. The second stage of comprehensive fixed orthodontic treatment, space closure, is a complex process focused on achieving normal occlusion by correcting molar and buccal segment relationships, closing extraction spaces, and addressing overjet issues.Active tie-back mechanics are employed for space closure and controlled tooth movement in orthodontic treatment after premolar extraction. Similarly, NiTi (nickel-titanium) wires are widely used in orthodontics due to their superior flexibility and consistent force delivery, which promote efficient tooth movement.NiTi closed coil springs demonstrated a faster rate of space closure and anchorage loss compared to active tiebacks.

Traditionally, orthodontic root resorption (ORR) is assessed using panoramic or periapical radiographs. However, these two-dimensional imaging techniques are limited in detecting early stages of resorption, as significant root length reduction is necessary for changes to appear on the radiographs. This highlights the need for more sensitive and advanced diagnostic methods to identify ORR at an earlier stage. The search for a safe and effective method to diagnose and monitor ORR has gained significant attention, leading to numerous studies exploring gingival crevicular fluid (GCF) as a source of biomarkers.

According to Rody et al, Interleukin-1 receptor antagonist (IL-1RA) is an anti-inflammatory cytokine that regulates inflammatory processes and prevents bone resorption by counteracting the effects of interleukin-1 (IL-1). The decreased levels of IL-1RA in resorbing teeth suggest its potential as a valuable biomarker for detecting root resorption. This study underscores the critical role of IL-1RA in periodontal tissue remodelling, offering significant insights into its involvement in resorption-related activities and its implications for orthodontic treatment strategies. This raises the possibility that IL-1RA levels in gingival crevicular fluid (GCF) could serve as a biomarker for predicting and monitoring ORR severity during treatment.

There was another experimental animal study, specifically involving mice models which investigated the effect of the interleukin-1 receptor antagonist (IL-1RA) on orthodontic tooth movement (OTM). However a prospective cohort study that involves human beings have not yet been done to the best of my knowledge. NiTi coil springs and active tie-backs are utilized as they are two distinct retraction modalities, allowing for a comparative evaluation of the root resorption rate associated with each method.

 The rationale for this study lies in its potential to elucidate the biological mechanisms linking IL-1RA with ORR and to identify new avenues for early detection and intervention. By analyzing changes in IL-1RA levels in GCF and correlating them with radiographic measures of ORR in patients undergoing space closure with NiTi closed coil springs and active tiebacks, this study seeks to provide a comprehensive understanding of how cytokine dynamics influence resorptive processes during orthodontic treatment. This diagnostic method holds great promise as it can eliminate the need for unnecessary exposure to radiation and shows potential for integration into routine dental care. In the long term, it could have a profound impact on the broader healthcare system.

 NOVELTY

This study represents a novel approach to understanding the biological underpinnings of orthodontic root resorption (ORR) by focusing on the anti-inflammatory cytokine interleukin-1 receptor antagonist (IL-1RA). Unlike previous studies that primarily emphasize pro-inflammatory mediators such as interleukin-1 (IL-1) or clinical variables, this study highlights the protective role of IL-1RA and its potential as a biomarker for predicting ORR. Additionally, the prospective cohort study design allows for the longitudinal analysis of cytokine dynamics and their correlation with ORR severity. The study also compares IL-1RA levels and their association with ORR severity between two commonly used orthodontic mechanics, NiTi closed coil springs and active tiebacks, providing insights into their respective biological and mechanical impacts on tooth movement. Furthermore, the exploration of IL-1RA levels in gingival crevicular fluid (GCF) as non-invasive biomarkers introduces a promising avenue for early detection of orthodontic root resorption in patients reporting to the Department of Orthodontics and Dentofacial Orthopaedics, MES Dental College Perinthalmanna.

RESEARCH QUESTION

How do changes in interleukin-1 receptor antagonist (IL-1RA) levels in gingival crevicular fluid (GCF) compare with the severity of orthodontic root resorption (ORR) in patients with Angle’s Class I bimaxillary protrusion undergoing space closure with NiTi closed coil springs and active tiebacks, at 3 time points, in the Department of Orthodontics and Dentofacial Orthopaedics, MES Dental College, between 04/09/2025 and 31/2/2027?

 AIM

To compare the changes in interleukin-1 receptor antagonist (IL-1RA) levels in gingival crevicular fluid (GCF) with the severity of orthodontic root resorption (ORR) using RVG at 3 time points in patients with Angle’s class I bimaxillary protrusion undergoing space closure with NiTi closed coil springs and active tiebacks, who report to the Department of Orthodontics and Dentofacial Orthopaedics, MES Dental College.

INCLSION CRITERIA

Patients with complete dentition and Angle’s Class I Bimaxillary protrusion

Patients in the age group of 18 to 25 years

Patients should have no radiographic sign of root resorption

Patients should have healthy gingival and periodontal status

EXCLUSION CRITERIA

Missing molars or any anterior teeth

Previous history of ortho treatment

Erupted or unerupted supernumeraries in the maxillary anterior segment

Impacted canines, Endodontically treated teeth

Upper anterior crowding greater than or equal to 4mm

Periodontitis