Clinical Comparison of Clear Aligners and Fixed Appliances in Dental Anterior Open Bite

Overview

Dental anterior open bite is a challenging orthodontic condition with a high risk of relapse in adults. This randomized controlled clinical trial aims to compare the effectiveness and post-treatment stability of in-house clear aligners versus fixed orthodontic appliances in treating adult patients aged 18-30 years with dental anterior open bite (0 to -4 mm). A total of 46 eligible participants will be randomly allocated into two equal groups (23 treated with clear aligners and 23 with fixed appliances). Treatment outcomes, vertical dentoalveolar changes, and skeletal changes will be evaluated using digital intraoral scans, virtual model superimposition, and lateral cephalometric analysis. Following active treatment, an 8-month retention phase (bonded lingual retainer combined with a vacuum-formed retainer) and an 8-month post-retention follow-up phase will be implemented to comprehensively evaluate treatment stability and relapse tendency over a total observation period of 16 months.

Anterior open bite (AOB) in adults presents significant treatment challenges due to the absence of remaining growth and a high relapse tendency. While fixed orthodontic appliances remain the standard approach for vertical control, clear aligner therapy has gained popularity despite limited randomized controlled evidence regarding its long-term predictability and stability. This study is designed as a single-center, parallel-group, randomized controlled clinical trial conducted at the Faculty of Dentistry, Sana'a University. Enrolled participants meet strict inclusion criteria: adult age (18-30 years), dental anterior open bite (0 to -4 mm), Class I malocclusion with normal molar relationships, non-extraction treatment requirements (crowding/spacing \\le 4\\text{ mm}), and good oral hygiene. Participants in the Clear Aligner group receive fully digital in-house aligners fabricated using Zahndent intraoral scans, 3D Maestro setup software, Elegoo Saturn 4 Ultra 16K printing, and PETG thermoforming sheets (0.75-0.8 mm). Aligner mechanics include optimized attachments and medium power intermaxillary elastics (3-4.5 oz) worn 20-22 hours per day. Participants in the Fixed Appliance group are treated using 0.022-inch MBT prescription brackets with a two-segment arch mechanics approach (canine-to-canine anterior segment and premolar/molar posterior segment) combined with progressive wire sequencing and vertical elastics. Primary and secondary outcomes-including overbite increase, cephalometric vertical changes, treatment efficiency, patient compliance, and satisfaction-will be recorded at baseline, post-treatment, after 8 months of retention, and after 8 months of post-retention follow-up.