Hard- and soft-tissue changes following the treatment of growing patients with skeletal class III malocclusion using the lower-clear-plate based intermaxillary traction versus the removable mandibular retractor: a two-arm randomized controlled trial.

BACKGROUND

Increased interest in intraoral devices like Bionator III, reverse twin block, and removable mandibular retractor (RMR), which modify tissues beneficially. The emerging Orthodontic Removable Traction Appliance (ORTA™) or the lower-clear-plate-based intermaxillary traction (LCP-IMT) has shown promising results, especially in stimulating maxillary growth and inhibiting mandibular growth in Class III malocclusion.

OBJECTIVES

To evaluate the effectiveness of the LCP-IMT against the RMR during the early correction of Class III deformities in growing patients regarding skeletal, dental, and soft tissue variables.

METHODS

A two-arm randomized controlled clinical trial was conducted from July 8, 2023, to June 15, 2024, at the Department of Orthodontics, University of Damascus. It enrolled patients aged 9 to 13 with mild to moderate skeletal Class III malocclusion (ANB + 1 to -3 degrees), an anterior crossbite involving two or more teeth, or an edge-to-edge relationship. Participants had normal or horizontal growth patterns (MM ≤ 35; SN.ManP ≤ 40) and lower incisor inclination (IMPA 85–100 degrees). Patients were randomly assigned to receive orthodontic treatment with either the LCP-IMT or the RMR appliance. Standardized lateral cephalometric images were collected before treatment (T1) and after active treatment (T2), using specialized orthodontic software (Viewbox). Soft- and hard-tissue changes in both groups were evaluated. Blinding was limited to data analysis due to feasibility constraints.

RESULTS

The sample consisted of 30 patients (12 males and 18 females) (n = 15 for each group). All 30 patients were included in the analysis. Skeletal cephalometric analysis revealed no statistically significant differences between the LCP-IMT and RMR groups across all variables (P > 0.05), despite slightly greater SNA and ANB changes in the LCP-IMT group. Dentally, both groups showed favorable outcomes; however, the RMR group exhibited significantly greater lower incisor lingual inclination (L1.ManP: − 7.66° vs. − 5.05°, P = 0.016). Differences between the two groups in overjet, overbite, and soft tissue parameters—including upper lip protrusion and nasolabial angle did not reach statistical significance.

CONCLUSIONS

Both appliances produced comparable short-term dental and soft-tissue improvements; a between-group difference in lower-incisor inclination favored LCP-IMT. These preliminary results require confirmation in larger and longer-term trials. TRIAL REGISTRATION: This study was retrospectively retrospectively registered in the Clinical Trials database (ID: NCT06596239) on the 11/09/2024. URL: https://clinicaltrials.gov/study/NCT06596239 .