by uni or bilateral posterior cross-biting, parafunctional buccal habits, alterations in swallowing, respiratory dysfunctions or hereditary or congenital problems then we can detect alterations in those relations. It has been estimated that maxillary transverse deficiency affects 15% of adolescents and as much as 30% of the adult population [2].Clinical and radiographic examinations and the study of models help in the diagnosis of maxillary transverse deficiency [3]. Clinical indicators for the presence of transverse deficiency are: paranasal sinus hypoplasia, shortening of the nasal base, deepening of the nasogenial groove and zygomatic hypoplasia. Cross-biting, dental crowding, mal-positioning of the teeth in the palatine region, narrowing of the superior arch and high narrow palatine can also be part of this condition leading to negative space in the buccal passage and alterations in the soft tissues. In radiographic terms, superimposing frontal cephalometric radiographs taken over a period of time allows for comparisons of linear measurements [4,5].Transverse maxillary Atresia is associated to functional and aesthetic harm involving unilateral or bilateral cross-biting, vestibular or palatine inclination of the posterior teeth, ogival palate, narrow maxillary arch, evidence of negative space in the buccal corridor and alterations to the soft tissues among which we can mention narrow alar base, and flattening of the paranasal region [4,5]. The causes of those discrepancies include, hereditary causes, traumatic damage, whether iatro- AbstractTo obtain a functional and stable occlusion, it is important to have an adequate transverse maxillary dimension. It is estimated that 8 to 18% of patients seeking an orthodontic assessment present alterations to that dimension associated to multiple etiological factors. Orthopaedic palatal expansion is a successful treatment before palatal suture closure, which occurs around 14 to 15 years of age in males and 15 to 16 in females. However, once bone maturity has occurred, such procedures have poor results. The preferable indication is surgically assisted rapid maxillary expansion which is also recommended in cases of severe maxillary atresia accompanied by tilting, or when there is real unilateral, maxillary deficiency or horizontal bone loss, etc. We discuss this technique, when it is indicated, its efficacy, stability, possible complications according to the indication, and factors that contribute to its success.