Deciduous dentition-anchored rapid maxillary expansion in crossbite and non-crossbite mixed dentition patients: reaction of the permanent first molar

This preliminary report describes our evaluation of the behavior of permanent maxillary first molars subsequent to rapid maxillary expansion (RME) in the mixed dentition in crossbite and non-crossbite cases; maxillary deciduous canines and second molars were used as anchorage. The RME appliance was cemented on the maxillary deciduous second molars and canines in 19 (13 females, six males) patients with unilateral or bilateral permanent molar crossbites (Group A) and in 13 (10 females, three males) patients who had no crossbites (Group B). After a mean appliance activation period of 15 days for 4-8 mm expansion, the appliance was stabilized and kept in place as retention for 5-10 months. Neither active nor passive retention was applied on first permanent molars. Impressions of dental arches were made before insertion of the appliance (T1), at stabilization (T2), and at debanding (T3). Dental measurements were registered at T1, T2, and T3. In Group A, the mean maxillary permanent intermo...