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

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.

Inclusion criteria

Adult patients aged 18 to 30 years with fully erupted permanent dentition. Anterior open bite equal to or greater than 2 mm. Angle Class I malocclusion. Good oral hygiene and healthy periodontal status.

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Exclusion criteria

• Previous orthodontic treatment. Presence of craniofacial anomalies or cleft lip/palate. Active periodontal disease or severe bone loss. History of temporomandibular joint disorders (TMD). Systemic conditions or medications affecting bone metabolism and tooth movement.