Palatally displaced upper lateral incisors: relapse after orthodontic treatment and its correlation with dentoskeletal morphology.
The purpose of the present study was to determine whether the relapse tendency of the palatally positioned upper lateral incisor differs in patients treated with or without premolar extraction, and if there is any correlation between the amount of upper lateral incisor relapse and pretreatment dentoskeletal morphology or post-treatment changes. Forty-six patients with bilateral palatally displaced upper laterals who also exhibit maxillary dental constriction were separated into two groups: a premolar extraction (30 cases) group and a non-extraction (16 cases) group. All subjects had undergone orthodontic treatment with quad helix and edgewise appliances, followed by a 2-year retention period. Differences in the amount of the upper lateral incisor relapse and their correlations with the dentoskeletal morphology before and after treatment were determined on the lateral and postero-anterior cephalograms and dental casts. Results revealed that the upper lateral incisor relapse in the extraction group was significantly greater (p=0.0002) than the relapse in the non-extraction group. There was a positive correlation between incisor relapse and the distance of lateral incisor movement in both groups (r=0.539; p=0.030). Relapse in the non-extraction group was correlated with the widths of the upper dental arch (r</=-0.507, p</=0.044), with the naso-maxillary variables before treatment (r=-0.514, p=0.041), and also with changes in the upper inter-premolar and inter-molar widths during retention (r=0.514, p=0.040).
Okamoto
M
M
Department of Orthodontics and Dentofacial Orthopedics, Graduate School of Dentistry, Osaka University, Japan; Department of Orthodontics, School of Dentistry, The University of Iowa, IA.
Takada
K
K
Yasuda
Y
Y
Bishara
S
S