Dummy-sucking behaviour in 3-year old Norwegian and Swedish children.

Forty 3-year-old dummy-sucking children (22 Swedes and 18 Norwegians) together with one of their parents, were shown a specially prepared videotape for 15 minutes The child had free access to its dummy while watching the video. The dummy-sucking time and sucking reactions to the different film sequences were registered. The presence or absence of a posterior crossbite was recorded as well as the upper and lower intercanine arch widths. Dummy-suckers in these populations have earlier been reported to have different prevalences of posterior crossbite. The prevalence of posterior crossbite was especially high for Swedish girls. The results showed that Norwegian boys used their dummies significantly less, and the Swedish girls had significantly narrower upper dental arches than the other children. Dummy-sucking reactions to frightening, cheerful or boring parts of the video were not significantly different among the children. All the children showed compassion for the film characters, and all the children used the dummy when going to sleep. The study lends support to the hypothesis that dummy-sucking influences arch widths and increases the likelihood for development of a posterior crossbite.