Results of 310 cases of rapid maxillary expansion selected for medical reasons.

1. Rapid Maxillary Expansion is a comparatively simple, conservative method of treating impaired nasal respiration. 2. It can be used from 4 years to 25 or 30 years of age, but the younger the patient the better the long term results. 3. The medical indications are a combination of poor nasal airway, septal deformity, recurrent ear or nasal infection, allergic rhinitis and asthma, and prior to septoplasty. 4. The dental indications are mainly unilateral or bilateral cross bite, class III (prognathoid) malocclusion, maxillary compression, and cleft palate. 5. The dental contra-indications are normal occlusion in the permanent dentition and to a lesser degree severe class II occlusion and micromandible. 6. In selected cases, it produces a change of over 80 percent from mouth to nose breathing. In this series of 310 consecutive cases 87 percent were greatly improved, 9 percent had a fair result and 4 percent a poor result. 7. It also gives considerable improvement in colds and respiratory infection, nasal allergy and many cases of asthma. The improvement in health and confidence and concentration in over 30 percent of cases is particularly pleasing. 8. The rationale of Rapid Maxillary Expansion can be explained by the maxillary moulding theory of production of septal and facial deformities.