LOWER ARCH PERIMETER PRESERVATION USING THE LINGUAL ARCH

The purpose of this investigation was to determine whether the placeme nt of a mandibular lingual arch maintained arch perimeter in the trans ition from the mixed to the permanent dentition, and if so, whether it was effective at preventing mesial migration of first permanent molar s, or whether this migration still occurred en masse, by increased low er incisor proclination. Thirty patients were randomly assigned to eit her a treatment group (N = 14, mean age = 11.5 years) or a control gro up (N = 16, mean age = 11.3 years). Study models, cephalograms, and to mograms of the patients, taken at the beginning and at the end of the study period, were examined. Statistically significant differences bet ween groups were found for positional changes of mandibular first mola rs and incisors, and changes in arch dimensions. The results indicate that the lingual arch can help reduce arch perimeter loss, but at the expense of slight mandibular incisor proclination.