Reverse Engineering Techniques to Evaluate Palatal Morphologic and Volumetric Changes After the Use of a Rapid Expander

The rapid palatal expander (RPE) is an orthopaedic appliance that widens the upper jaw by separating the midpalatal suture. This procedure also allows for the creation of more space for the eruption of the permanent teeth. The procedure for RPE is still controversial and many different methods have been described since the time of Angell, when he presented the first case of correction of maxillary transverse discrepancy in 1860. A permanent increase in maxillary transverse width is attained routinely in children and adolescents using orthodontic expansion appliances and retention, and this treatment does not normally cause any problem. In this work is presented a preliminary study, based on a reverse engineering measurement approach, to evaluate the palatal morphologic and volumetric changes after the use of a RPE appliance in four children patients (aged 7-8 years) in mixed dentition with a posterior crossbite, a skeletal Class II malocclusion and with narrow maxillary arches. The patients were treated using the Haas RPE in order to solve the maxillary contraction. For each patient three measurements were done: pretreatment (T1), after expansion therapy (T2), and six months after the removal of the expander (T3).