Evaluation of Physical Changes in Single-Layer and Multi-Layer Clear Aligners

NCT07449598 | Active Not Recruiting

• 1 other identifier: MS.25.11.85
• Study Type: interventional
• Target: 20
• Locations: 1 country
• Sites: 1

Brief Summary

aim of the study: to evaluate and compare the surface roughness (Ra, Rq, Rz), Vickers microhardness (VHN), and thickness of single-layer and multi-layer clear aligner sheets. material and methods: the study will be conducted on clear aligners fabricated from two commercial thermoplastic materials: single-layer (0.76 mm, ) and multi-layer (0.76 mm, ). Each material will be evaluated at three stages: before thermoforming, after thermoforming on 3D-printed casts, and after 2 weeks of intraoral wear. Specimen Preparation For each group, specimens will be prepared at three stages: before thermoforming (T0), after thermoforming (T1), and after intraoral wear (T2). At T0, square-shaped specimens (approximately 5 × 5 mm) will be cut directly from the unused raw sheets. At T1 and T2, specimens of the same dimensions will be obtained from the mid-labial surface of the central incisor region of the thermoformed aligners, both immediately after thermoforming and after two weeks of intraoral wear. The full thickness of the material will be preserved in all specimens to ensure consistency across groups. Outcomes: Primary Outcome: Surface Roughness (Ra): Measured at three stages: T0: Raw, unused sheet specimens (baseline) T1: After thermoforming on dental casts T2: After 2 weeks of intraoral use Secondary Outcomes: Hardness: Measured at T0, T1, and T2. Tested using Vickers hardness method (ISO 6507 compliant).

Conditions

Surface Roughness and Thickness Clear Aligner Sheat

Outcome Measures

Primary Outcomes (1)

• surface roughness of clear aligner

  evaluate and compare the surface roughness of single-layer and multi-layer clear aligner sheets at three stages: before thermoforming, after thermoforming, and following intraoral wear. Quantitative evaluation of the arithmetic mean surface roughness (Ra) using profilometer

  2 weeks

Secondary Outcomes (2)

• microhardness of clear aligner

  2 weeks

• thickness change of clear aligner

  2 weeks

Study Arms (2)

Multi-layer clear aligners

EXPERIMENTAL

clear aligners fabricated from thermoplastic materials: multi-layer (0.76 mm). the material will be evaluated at three stages: before thermoforming (raw sheet), after thermoforming on 3D-printed casts, and after 2 weeks of intraoral wear. At each stage, specimens will be retrieved and tested for changes in mechanical properties, specifically surface roughness and hardness. Baseline control: Unused aligner sheets of both types to serve as reference for measurements.

Device: clear aligner

Single-layer clear aligners

EXPERIMENTAL

clear aligners fabricated from thermoplastic materials: single-layer (0.76 mm) . the material will be evaluated at three stages: before thermoforming (raw sheet), after thermoforming on 3D-printed casts, and after 2 weeks of intraoral wear. At each stage, specimens will be retrieved and tested for changes in mechanical properties, specifically surface roughness and hardness. Baseline control: Unused aligner sheets of both types to serve as reference for measurements.

Device: clear aligner

Interventions

clear aligner DEVICE

Appliance Fabrication and Treatment Protocol * Digital impressions will be taken for all patients. * Treatment setup will be performed with standardized staging: maximum 0.25-0.3 mm linear movement or 2-3° rotation per stage. * Aligners will be fabricated by thermoforming using single and multilayer sheets (0.76 mm), cut and finished identically.

Multi-layer clear aligners; Single-layer clear aligners

Eligibility Criteria

• Age: 16 Years - 24 Years
• Sex: all
• Healthy Volunteers: No
• Age Groups: Child (0-17), Adult (18-64)

You may qualify if:

• Class I malocclusion with mild-moderate crowding (≤5 mm per arch).
• Full permanent dentition (excluding third molars).
• No restorations, caries, or attachments planned on the labial surface of upper/lower central incisors.

You may not qualify if:

• Systemic disease affecting saliva.
• Parafunctional habits (bruxism, nail-biting).
• Smoking.
• Pregnancy.
• Previous orthodontic treatment within 1 year.

Sponsors & Collaborators

• Mansoura University: lead

Study Sites (1)

Mansoura university

Al Mansurah, Egypt

Location

MeSH Terms

Interventions

Orthodontic Appliances, Removable

Intervention Hierarchy (Ancestors)

Orthodontic Appliances; Orthodontics; Dentistry

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: NONE
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: February 15, 2026
• First Posted: March 4, 2026
• Study Start: January 1, 2026
• Primary Completion (Estimated): January 1, 2027
• Study Completion (Estimated): February 1, 2027
• Last Updated: March 4, 2026

Record last verified: 2025-12

Locations

EG (1)