This study aims to compare two different methods for maxillary expansion in adult patients with transverse maxillary deficiency. Participants will receive either miniscrew-assisted rapid palatal expansion (MARPE-MICRO-4). We want to compare the surgically assisted rapid palatal expansion (SARPE) and the non surgical/conservative method. Clinical (3D scans of the upper jaws) measurements will be used to evaluate skeletal expansion and stability over time. Approximately 40 adult patients will be included and followed for 12 months. The results of this study may help clinicians choose the most appropriate treatment method for adult maxillary expansion.

Inclusion Criteria:

• Presence of transverse maxillary deficiency requiring maxillary expansion
• Indication for either non-surgical (MARPE) or surgically assisted (SARPE) maxillary expansion
• Permanent dentition
• Ability to understand the study procedures and provide informed consent

Exclusion Criteria:

• Previous maxillary expansion treatment
• Craniofacial syndromes or cleft lip/palate
• Severe periodontal disease
• Active oral infection
• Systemic conditions affecting bone metabolism
• Pregnancy or breastfeeding
• Inability to comply with study procedures or follow-up visits

De-identified individual participant data will be shared upon reasonable request after publication of the primary results. Requests will be reviewed by the study investigators and data will be provided in accordance with institutional and ethical regulations.

De-identified individual participant data and the study protocol will be available after publication of the primary results and will remain available for 5 years.

Access to de-identified individual participant data and supporting documents will be provided to qualified researchers upon reasonable request. Requests will be reviewed by the study investigators and data will be shared in accordance with institutional policies and ethical approvals.