Longitudinal study and cost-benefit analysis of the effect of early treatment of posterior cross-bites in the primary dentition.

The aim of this study was to follow longitudinally a cohort of preschool children regarding the prevalence of lateral cross-bites and the effect of treatments carried out. Two-hundred-and-twenty-four children were examined when they were 3-5 years old and re-examined at 13-15 years of age. Orthodontic treatment of lateral cross-bites was registered from annual dental records from the Public Dental Service. In the primary dentition, 23.3 per cent of the children showed lateral cross-bites, of whom 5.7 per cent showed a lateral edge-to-edge relation. Selective grinding was carried out in the Public Dental Service in 62 per cent of the cross-bite children. Correction was registered in 64 per cent of these cases. Nine (45 per cent) of the 20 children with untreated lateral deviation showed spontaneous correction. Of the 171 children without cross-bites in the primary dentition, 14 (8 per cent) developed cross-bites in the permanent dentition. Although the benefits of early treatment for the developing dentition are obvious for functional reasons, the effectiveness of grinding, the type of treatment and the timing can be discussed from a cost-benefit point of view.