Instability of the mandibular dental arch? Look again!

Abstract

Changes in mandibular dental arch parameters have been thoroughly investigated as a function of time after removal of orthodontic appliances and instability tenets have emerged. To date, only permanent fixed retention as a posttreatment strategy has been demonstrated effective against changes in mandibular anterior alignment. No active orthodontic therapy has been shown to improve mandibular arch outcome stability except augmented corticotomy significantly reduced 5- and 10-year rate of change in mandibular irregularity index. The purposes of this study were as follows: (1) to evaluate efficacy of augmented corticotomy in stabilizing posttreatment mandibular arch widths and length and (2) to review mandibular dental arch instability data from the scholarly literature. Results demonstrated augmented corticotomy effective in the 5-year short term for stabilizing intercanine width and arch length but not 10-year long term. Data extracted from 76 separate publications representing 4250 subjects reaffirmed the consensus view that irregularity index will increase and there will be decreases in arch width and length as a function of time. It was concluded that alveolar decortication + augmentation bone grafting (PAOO) is the only active orthodontic treatment strategy that will stabilize mandibular irregularity index for at least a decade, and permanent fixed canine-to-canine retention is the only posttreatment orthodontic strategy that will preclude recrowding and intercanine width decrease in the mandibular anterior segment.