title: Labial root torque: effect on the maxilla and incisor root apex.
abstract: This study was designed to determine the effectiveness of labial root torque on anterior nasomaxillary development. Quantification was made of the angular and linear changes in Downs' point A (representing midsagittal basal bone) and incisor point A (representing the dentoalveolar bone) and any concomitant incisor root resorption. The study was divided into two parts: part 1--to determine the anatomic configuration of the premaxillary region by use of laminagraphy on skulls, and part 2--to use the morphologic landmarks found in part 1 to assess the development of the nasomaxillary complex in maxillary retrusive patients. The clinical study involved 17 maxillary retrusive patients, aged 8.0 to 15.7 years, who had been treated for a period between 0.31 and 3.70 years with edgewise advancing mechanics. Clinical results indicate that during the first phase of orthodontic treatment with labial root torque, encompassing a 0.63-year mean treatment period, a greater rate of advancement of Downs' point A was produced when compared with normal growth. The skeletal convexity increased, whereas normal growth straightened the profile. Incisor point A advanced at a greater rate than Downs' point A, suggesting that treatment caused a larger dentoalveolar effect than the effect on midsagittal basal bone. When treatment was extended to 1.57 years, similar changes were found but at a reduced rate. Overall apical root resorption was 12.7%/year. Sex and age were not found to have any correlation to the amount of apical root loss.
authors.affiliation: Department of Orthodontics, Eastman Dental Center, Rochester, N.Y.
authors.forename: B
authors.initials: B
authors.lastname: Goldin
mesh_terms: D002508:Cephalometry; D002648:Child; D005147:Facial Bones / Q000254:growth & development; D006801:Humans; D007180:Incisor; D008297:Male; D008437:Maxilla / Q000254:growth & development*; D009295:Nasal Bone / Q000254:growth & development*; D012391:Root Resorption / Q000209:etiology*; D014087:Tooth Movement Techniques / Q000379:methods; D014092:Tooth Root / Q000503:physiopathology*