Clinical Performance of Direct-Printed Versus Thermoformed Aligners

Clinical Performance of In-Office Directly Printed Versus Thermoformed Aligners: A Randomized Clinical Trial

The goal of this study is to evaluate and compare the clinical effectiveness of in-office directly 3D-printed clear aligners versus conventional multilayered thermoformed aligners.

The main question it aims to answer is:

Does the use of in-office direct-printed shape-memory aligners result in superior clinical effectiveness, compared to established multilayer thermoformed aligner systems?

Researchers will compare a Direct-Printed Aligner (DPA) group using Senertek Clear-A V2 resin to a Thermoformed Aligner (TFA) group using Zendura FLX multilayer sheets to see if the additive manufacturing process improves clinical outcomes and patient satisfaction.

Participants will:

• Undergo initial records including intraoral digital scans, photos, and a panoramic radiograph for treatment planning.
• Wear their assigned clear aligners (either direct-printed or thermoformed) for at least 22 hours per day, changing them every 7 days.
• Attend follow-up appointments every 5 weeks.

This is a prospective, parallel-arm randomized controlled multi-center clinical trial, to assess and compare the clinical effectiveness of in-office 3D-printed clear aligners with multilayered thermoformed aligners.

The subject population for this study will be male and female subjects aged 16-30 years who have fully erupted permanent dentition and mild dental crowding or spacing.

Methodology:

Patients requiring orthodontic treatment are randomly allocated into two groups.

Experimental Group (DPA): Aligners are fabricated using additive manufacturing (direct 3D printing) with Senertek Clear-A V2 shape-memory resin. This process eliminates the intermediate physical model, potentially reducing cumulative manufacturing errors.

Control Group (TFA): Aligners are fabricated by thermoforming multilayered thermoplastic sheets (Zendura FLX) over 3D-printed resin molds.

Assessment:

Digital models (STL files) will be obtained at the start (T0) and at the end of the treatment (T1). These will be compared to the digital treatment plan (Tp) using 3D superimposition and trigonometric analysis. Stable anatomical structures, such as the palatal rugae, will serve as reference points for superimposition. The primary outcome is the "Tracking Accuracy Percentage," which measures how closely the actual clinical tooth movement matches the digitally predicted movement. Secondary outcomes include clinical efficiency, patient-reported pain levels, and Manufacturing complexity, including total fabrication time.

Inclusion Criteria:

1. Adult patient with an age range of 15-30 with fully erupted all permanent dentitions excluding third molars, and a willingness to participate in the trial.
2. Angle Class I non-extraction cases, presented with mild crowding or spacing (<5 mm) and dental rotation <30° .
3. Good oral hygiene; no active caries/periodontal disease, no history of trauma or root resorption.

Exclusion Criteria:

1. Pregnancy, smoking, and systemic conditions affecting bone remodeling.
2. Subject with poor oral hygiene, using simplified oral hygiene index (OHI-S ≥ 3.1 ) (Greene & Vermillion, 1963).
3. Patient with malposed lower second molars (need orthodontic alignment).
4. Allergy to materials used (resins, plastics, solvents).
5. History of trauma, root resorption, and dilacerated roots.
6. Previous extraction or history of previous orthodontic treatment.