A distinctive clinical manifestation of a successful Rapid Maxillary Expansion is:

Rapid maxillary expansion (RME) results in rapid correction of the cross-bite occurring in 2–6 weeks. A midline diastema may appear which is suggestive of the mid-palatal split. This diastema would close spontaneously due to the recoil of the stretched trans-septal group of gingival fibres. Reference: Orthodontics: Diagnosis and Management of Malocclusion and Dentofacial Deformities 3rd O P Kharbanda, pdf no 2403