Innovative recent materials are trying to achieve the most of orthodontic movements using the least number of aligner, also trying to reduce the manufacturing steps combined by enhancing the accuracy of each aligner.

The aim of many recent interdisciplinary research studies is to introduce novel materials that can play an active role in the appliances. These materials are called smart materials or stimuli-responsive materials which have the ability to react suitably with external stimuli, such as thermal, electrical, or magnetic input, producing a predictable repeatable output. Shape memory materials are subcategory of smart materials which have the ability of changing their macroscopic shape upon a proper stimulus. Unlike shape changing materials, shape memory materials have the capacity to maintain a stable temporary shape until they are appropriately activated to recover their original shape.

Additive manufacturing, also known as 3D printing, dates back to the 1980s and is now reaching a level of maturity where it is now increasingly being used in the fields of both dental and medical modeling. There are multiple applications in oral surgery, prosthodontics, restorative dentistry, orthodontics, implantology and instrument manufacturing. Three-dimensional printing enables the manufacturing of pieces' layer-by-layer instead of common manufacturing methods that rely on machining, molding, and subtractive methods.

-Primary outcomes: Evaluation of the efficiency of both linear and angular tooth movement using directly printed shape memory orthodontic aligners Vs thermoformed shape memory orthodontic aligners (predicted Vs actual tooth movement).

-Secondary outcome: Evaluation of patient's compliance, comfort and color stability via written questionnaire.

Inclusion Criteria:

• Crowding in lower anterior teeth ranging from 4 to 6 mm.
• Participants whose treatment plan need lower anterior teeth alignment.
• Presence of permanent teeth except for lower premolar extraction performed for orthodontic purposes.
• Participants who need orthodontic treatment after relapse in lower anterior teeth take place one-year post retention.

Exclusion Criteria:

• Active systemic diseases that affect tooth movement (e.g. osteoporosis, bisphosphonate therapy, etc...).
• Patients with biting habits (clinching, bruxism, etc…)
• Patients with bad oral hygiene or high caries index or periodontal inflammation or gingival recession.
• Presence of active labial caries or class V restorations or enamel hypoplasia in lower anterior teeth.

still thinking about it