The study will evaluate the impact of replacing aligners after 7 days with new aligners made of different materials on the predictability of planned dental movements. Three groups of participants will follow different aligner protocols, and the planned movements will be compared with the achieved ones. The study aims to provide relevant data for clinical practices with orthodontic aligners and assess participants' satisfaction with the treatment.

This prospective clinical trial aims to determine whether replacing an aligner after 7 days with a new aligner of a different material affects the predictability of planned dental movements. A total of 114 adult patients undergoing orthodontic treatment with aligners-requiring bilateral tooth movements (extrusion, intrusion, rotation, tipping, or mesiodistal translation)-will be recruited and randomized into three groups with distinct aligner exchange protocols.

Group 1: 10 days of exclusive FLX aligner use. Group 2: 7 days of FLX aligner use followed by 3 days of FLX35 use. Group 3: 7 days of FLX aligner use followed by 3 days of a new FLX aligner. Within each group, patients will be further categorized into subgroups based on horizontal, vertical, and rotational movements. Digital study models, radiographs, and standardized clinical photographs will be used to compare planned versus achieved tooth movements. The primary outcome is the predictability of movement, defined as the difference and percentage of planned versus actual movement. Secondary outcomes include participant satisfaction measured via the OHIP-14 questionnaire. Data will be analyzed using descriptive statistics and paired tests appropriate for the split-mouth design. The study is conducted in accordance with the Declaration of Helsinki, and all treatment costs will be covered by the sponsor, NeoDent (JJGC Industria e Comercio de Materiais Dentarios S.A.).

Inclusion Criteria:

• Adults aged 18 years or older, with full permanent dentition.
• Interested in orthodontic treatment with aligners.
• Planned movements include extrusion, intrusion, rotation, tipping, or mesiodistal translation.
• Signed informed consent.

Exclusion Criteria:

• Contraindications to aligner use, including allergies to polyurethane or PETG.
• Poor oral hygiene or active periodontal disease.
• Malocclusions involving multiple missing teeth or short clinical crowns.