Effectiveness of Clear Aligner Systems in Mixed Dentition Maxillary Transverse Deficiency

In patients treated with the Invisalign Palatal Expander (IPE) (Align Technology, Santa Clara, CA), three-dimensional digital models were obtained using an intraoral scanner (iTero Lumina™, Align Technology). Individualized maxillary expansion amounts were prescribed based on clinical objectives. Unlike conventional aligner therapy, the IPE system does not involve full digital treatment simulation; expansion was defined by the planned transverse increase. Following approval, customized IPE appliance sets were manufactured and delivered. Patients were instructed to wear the appliance full-time, including during meals, removing it only for oral hygiene procedures. The activation protocol consisted of appliance changes every 2 days, providing 0.25 mm transverse expansion per stage. After completion of expansion, retention was achieved using Invisalign Palatal Holder appliances fabricated from new digital scans.

In-house clear aligners were fabricated using a fully digital workflow. Digital impressions were obtained with an intraoral scanner (3Shape TRIOS), and maxillary models were processed in CAD software for segmentation and attachment planning. Buccal retention attachments were placed on primary canines, primary molars, and permanent first molars. Maxillary models were digitally expanded in 0.2 mm increments per stage, generating sequential STL files. Models were 3D-printed and thermoformed to fabricate aligners, which were then trimmed, polished, and labeled. Patients received five aligners at each visit and were instructed to change them every 2 days. Follow-up visits were scheduled at 10-day intervals. At each visit, treatment progress was assessed, and the next series of aligners was provided.

In-house clear aligners were fabricated using a fully digital workflow. Digital impressions were obtained with an intraoral scanner (3Shape TRIOS), and maxillary models were processed in CAD software for segmentation and attachment planning. Buccal retention attachments were placed on primary canines, primary molars, and permanent first molars to enhance retention and support transverse expansion. Models were digitally expanded in 0.2 mm increments per stage and converted into sequential STL files. These models were 3D-printed (Asiga MAX UV) and thermoformed (MINISTAR S) to produce aligners. The appliances were trimmed, polished, and labeled with sequence numbers. Patients received five aligners per visit and were instructed to change them every 5 days. Follow-up visits were scheduled at 25-day intervals, during which treatment progress was evaluated and new aligners were delivered.

In patients treated with Invisalign First (Align Technology, Santa Clara, CA), three-dimensional digital models were obtained using an intraoral scanner (3Shape TRIOS). Intraoral, extraoral photographs and radiographs were collected and uploaded to the ClinCheck digital treatment planning platform. Individualized treatment objectives were defined, and expansion was planned without concurrent tooth movement to isolate maxillary transverse effects. After achieving the desired expansion, comprehensive orthodontic treatment was continued. Virtual treatment plans were reviewed and revised when necessary before approval. Attachments were placed on posterior teeth to enhance retention and support expansion. Enamel surfaces were etched, bonded, and light-cured using standard orthodontic protocols. Patients were instructed to wear aligners 20-22 hours daily,and aligners were replaced every 5 days.