Sucking habits and their relation to posterior cross-bite in 4-year-old children.

Sucking habits and their relationship to posterior cross-bite were studied in 4-year-old children (n = 588) living in the municipality of Huddinge on the outskirts of Stockholm. Previous or persisting sucking habits were registered for 88% of the children with dummy sucking as the dominating type (78%). At the age of 4 years 48% of all children still exhibited some form of sucking habit. The incidence of normal buccolingual occlusion steadily decreased in cases where sucking habits persisted. The increase in unilateral cross-bite occurrence was most pronounced in cases where the children continued sucking after 2 years of age. The variable "intensity of sucking habit" was significantly correlated to the occurrence of unilateral cross-bite (P less than 0.05). From a dental point of view these results indicate that sucking habits in children should be brought under control by 2 years of age.