Relationship of Lower Lingual Arch Appliance Use and Impaction of Second Molars: A Retrospective Study.

The purpose of this study was to determine the prevalence of permanent mandibular second molar impaction in pediatric patients treated with a lower lingual holding arch (LLHA) to maintain lower arch perimeter. In this retrospective study, 259 radiographs of nine- to 17-year-old pediatric patients were examined for permanent mandibular second molar impaction. A total of 127 patients with LLHA were compared to a control group of 132 patients who had not received LLHA.