Diastema Closure and Stability: Clear Aligners vs Fixed Appliances With Laser Frenectomy

Diastema associated with generalized interdental spacing (>= 3 mm) represents a challenging orthodontic condition with a heightened risk of post-treatment relapse. While fixed appliances provide reliable three-dimensional tooth movement control, clear aligners offer improved esthetics and patient comfort. Additionally, the role and timing of adjunctive laser frenectomy in stabilizing space closure remain controversial in generalized spacing cases.

This prospective 2x2 factorial randomized clinical trial is conducted at the Orthodontic Clinics, Faculty of Dentistry, Sana'a University, Yemen. A total of 48 eligible participants are randomly allocated into four equal groups (n=12 per group):

• Group 1: Clear Aligner Therapy with Adjunctive Laser Frenectomy
• Group 2: Clear Aligner Therapy without Frenectomy
• Group 3: Fixed Orthodontic Appliance with Adjunctive Laser Frenectomy
• Group 4: Fixed Orthodontic Appliance without Frenectomy

Treatment Protocols:

• Clear Aligner Group: Digital intraoral scans are obtained using a Zahndent scanner. Virtual treatment planning ensures sequential space closure with root control. Aligners are manufactured by Dentalign Company (Sana'a, Yemen) and worn 20-22 hours daily.
• Fixed Appliance Group: Treated using MBT prescription brackets with a 0.022-inch slot. The archwire sequence includes initial leveling with 0.012 to 0.018 NiTi wires, followed by rectangular stainless steel wires (0.016x0.022, 0.017x0.025, and 0.019x0.025 inches) for space closure and torque control.
• Auxiliary Mechanics: Cervical buttons are bonded in selected teeth across aligner and fixed groups to enhance bodily movement control.
• Adjunctive Laser Frenectomy: Performed using standardized laser technique following partial or complete space closure in designated groups.

Retention and Evaluation:

All participants follow a standardized retention protocol for 6 months post-treatment. Clinical, digital (Zahndent intraoral scanner), and radiographic (digital periapical sensor) assessments are conducted at five measurement time points:

• T0: Baseline (pre-treatment)
• T1: End of active orthodontic treatment
• T2: End of retention period (6 months)
• T3: 6 months post-retention
• T4: 8 months post-retention

The primary outcome is the amount of diastema relapse (mm). Secondary outcomes include total space closure, root parallelism, and relapse rates.

Inclusion criteria

• Adult patients aged 18 to 35 years.
• Presence of maxillary median diastema associated with generalized interdental spacing (width >= 3 mm).
• Fully erupted permanent teeth (excluding third molars).
• Good periodontal health with probing depths <= 3 mm and no bone loss.
• High motivation and commitment to follow treatment protocols and compliance.
• Written informed consent provided.

Exclusion criteria

• Previous orthodontic treatment.
• Severe skeletal malocclusion or craniofacial anomalies.
• Active periodontal disease, poor oral hygiene, or untreated caries.
• Missing or impacted permanent teeth in the maxillary arch (excluding third molars).
• Systemic diseases or long-term medication use affecting bone metabolism or tooth movement (e.g., bisphosphonates, systemic corticosteroids).
• Pregnant or lactating females.
• Heavy smokers or individuals with severe parafunctional