Optimizing Frictionless Space Closure in Bimaxillary Dentoalveolar Protrusion with Opus Loop Mechanics : A Case Report

Authors: Poonam Bharat Ghodke, Atul Singh, Ankit Chaudhari, Joggeswar Kundu, Rashmi Singh

Keywords: Opus loop, Orthodontic premolar extraction, Bimaxillary protrusion, Frictionless mechanics, Orthodontic space closure, Orthodontic Biomechanics

Abstract: Bimaxillary dentoalveolar protrusion is a common malocclusion marked by forward positioning and pronounced proclination of both upper and lower anterior teeth. It often results in lip incompetence, a convex facial profile, and compromised soft tissue balance. Management typically involves premolar extractions to enable significant anterior tooth retraction. This case report presents the successful orthodontic treatment of a 14-year-old male with Class I bimaxillary dentoalveolar protrusion, using frictionless biomechanics. Following the extraction of all four first premolars, space closure was achieved with titanium molybdenum alloy (TMA) Opus loops. Designed for a high moment-to-force ratio, these loops enabled controlled bodily movement and effective en-masse retraction, preserving Class I molar and canine relationships and improving facial esthetics. The patient initially showed proclined incisors (U1 to NA: 28°, L1 to NB: 36°), lip strain, and a convex profile. Treatment aimed to correct incisor proclination, midline deviation, and crowding, while maintaining occlusal relationships and enhancing facial appearance. Leveling and alignment were done with sequential NiTi and stainless steel archwires in an MBT 0.022” × 0.028” prescription. Anchorage was reinforced using a Nance palatal arch and lingual holding arch. Opus loops, fabricated from 0.017” × 0.025” TMA, were activated initially by 5.5 mm, generating 200 g of force per side, followed by 1 mm reactivations every 5–6 weeks. The high moment-to-force ratio (8:1–9:1) allowed for efficient en-masse retraction with minimal tipping. Treatment concluded in 14 months. Post-treatment cephalometrics showed improved incisor angulations (U1-NA: 20°, L1-NB: 25°) and reduced protrusion (U1-NA: 10 mm to 5 mm; L1-NB: 11 mm to 5 mm). Soft tissue enhancements included a nasolabial angle increase (90° to 110°) and reductions in upper and lower lip protrusion by 2 mm and 4 mm, respectively, relative to Rickett’s E-line. The case highlights the clinical effectiveness of Opus loops as a precise and efficient tool in contemporary orthodontic biomechanics.