Described by W. Bolton in 1958, this term refers to the differences in size that often occur between the teeth of the upper and lower jaw. Above a certain degree of Bolton-Discrepancy it is no longer possible to position the teeth in a normal bite. In such cases it is generally a choice between either an approximal enamel reduction (reduction) of the teeth that have become too big or enlarging the teeth that have become too small. In Germany, Bolton-Discrepancies are normally left untreated because enamel reduction cannot be charged for. The other way to compensate for the build-up of undersized teeth requires that precise, regular gaps have to be created between the teeth during orthodontic treatment. However, this is a demanding treatment task that exceeds the capabilities of many orthodontists.