Comprehensive comparison of extraction space closure during canine retraction using nickel-titanium closed-coil springs versus elastomeric power chains during orthodontic treatment – a split-mouth randomized controlled trial

Background The two widely used methods for orthodontic tooth movement with sliding mechanics are elastomeric power chains (EPC) and nickel-titanium closed-coil springs (NCCS).Objectives To compare the rate of extraction space closure during canine retraction, degree of root resorption, dental plaque accumulation and gingival health using NCCS versus EPC in subjects undergoing first premolar extractions.Trial design Single-centered, prospective, split-mouth randomized controlled trial.Methods For canine retraction, NCCS and EPCs were randomly allocated to the right and left quadrants of both maxillary and mandibular arches in 46 subjects. Canine retraction, root resorption, plaque accumulation and gingival health were recorded at four points in time. Within groups, pairwise comparison and between-group comparisons were done using Wilcoxon signed rank test. Generalized Estimating Equation (GEE) analysis was employed to identify the factors significantly influencing the rate of extraction space closure during canine retraction and the extent of root resorption.Blinding The study investigators, patients recruited, and assessors were not blinded during the trial due to the visible nature of the orthodontic appliances used.Results NCCS exhibited faster rates in total canine retraction and during the T0-T1 (p = 0.039) and T2-T3 (p = 0.003) intervals. Root resorption exhibited non-significant differences. Whereas, NCCS demonstrated higher plaque retention at T1 (p = 0.013), T2 (p = 0.016) and T3 (p = 0.033). GI differed significantly between groups, with higher values with NCCS at T1 (p = 0.046) and EPC at T2 (p = 0.039). Extraction space closure rate displayed a significant difference between the T1-T2 and T2-T3 stages with NCCS (p = 0.025). GEE showed a significant positive association of age with root resorption (β = 0.939, CI = 0.312, 1.565, p = 0.003).Conclusion NCCS demonstrated a significantly higher rate of extraction space closure and plaque accumulation compared to EPC. However, no statistically significant differences were observed between the two groups with respect to root resorption and gingival health. Furthermore, the degree of root resorption was found to increase significantly with the advancing age.Trial registration Registered at clinicaltrials.gov under the identifier NCT06567730 on 23rd August 2024.