The influence of premature extraction of primary teeth. The influence of the site of extraction was analyzed by studying the frequency of malocclusion in the group of children with extraction in the mandible or maxilla only. It was found that early loss of primary teeth would result in an increased frequency of sagittal, vertical as well as transversal malocclusion. As a consequence the need for treatment would increase significantly by early extraction of primary teeth. Whereas extraction in the maxilla would tend to result in need for extraction of permanent teeth; extraction in the mandible would often lead to need for orthodontic treatment of longer duration. On the basis of these findings it could be concluded that maintaining a high standard of dental service for preschool children must be considered good economy, since the need for premature extractions is reduced.