The importance of masticatory function during development, the aim of early therapies. Hypoplasia of the upper maxilla is a widespread condition which orthodontists often need to face during early treatment. Mechanical maxillary expansion (both rapid and slow) produce undiagnosed effects on the palatal suture and unwanted side- effects on the periodontium and alveolar process, as well as anchorage-teeth displacement, root resorption, bone fenestration. It is clear that early therapies need a non-mechanical and non-traumatic approach in the respect of the physiology and biology of one of the most important systems for the future health of the developing patient.