Effectiveness of a miniscrew-assisted technique for protracting mandibular second molars: A prospective quasi-experimental study

Objective: This study assessed the effectiveness of a miniscrew-assisted rectangular loop technique for protracting mandibular second molars without using full-arch appliances.Methods: This prospective pilot quasi-experimental study included ۱۰ orthodontic patients (۱۲ sites), aged ۱۵–۲۵ years, who had their mandibular first molars extracted at least three years earlier, and presented an interdental space of ۴–۷ mm between the second premolar and second molar. Two miniscrews were placed mesially and distally to the second premolar. Molar uprighting and protraction were performed using rectangular and T-loop mechanics. CBCT scans and study casts were obtained at baseline and after six months to measure primary and secondary outcomes. Primary outcome variables included crown- and root-level distances between the mandibular second premolar and second molar. Secondary outcomes included measurements of alveolar bone parameters (height, thickness, and density), second molar angulation, marginal ridge distance, and second molar first-order angulation. Data were analyzed using paired t-tests with a significance level of α = ۰.۰۵.Results: Significant reductions were observed in crown-level (۳.۳ ± ۱.۴۵ mm, P=۰.۰۰۳) and root-level distances (۴.۳۹ ± ۱.۶۴ mm, P<۰.۰۰۱) between the second premolar and second molar. Second molar angulation relative to the mandibular plane increased significantly (۵.۵۶ ± ۶.۲۳°, P=۰.۰۱). Alveolar bone parameters showed no significant changes (P>۰.۰۵). Marginal ridge distance decreased significantly (۳.۰۶ ± ۱.۵۳ mm, P< ۰.۰۰۱), whereas second molar first-order angulation remained unchanged (P=۰.۸۲۸).Conclusions: The miniscrew-assisted rectangular loop technique allows effective protraction of mandibular second molars and improves molar angulation, while minimally affecting the alveolar bone.

کلیدواژه ها:

Orthodontic anchorage ، Orthodontic tooth movement ، Orthodontics ، Tooth movement techniques ، x-ray computed tomography ، Temporary anchorage devices