Early treatment of unilateral posterior crossbite in children with bilaterally contracted maxillae

Thirty-two children aged 3–6 years with high and narrow palatal vaults and functional posterior crossbites of the primary dentition were treated by transverse expansion with a lingual arch incorporating a Coffin loop. Average treatment time was 3.5 months. The children were followed until the first permanent molars were in occlusion. All crossbites were corrected; functional deviations were eliminated and no relapse was observed. The width of the maxilla increased on average by 2 mm in the molar region and 3 mm in the canine region. Follow-up showed normal transverse relations between the first permanent molars in 27 cases (84%). The earlier the treatment was instituted, the higher the frequency of normal transverse first molar relation.