INTRODUCTION: Because most patients with skeletal Class II malocclusions also have mandibular deficiencies, treatment plans should include improvement in chin projection. On that basis, the purposes of this study were to (1) determine how Class II treatment affects anteroposterior (AP) chin position in growing subjects and (2) ascertain the most important determinants of AP chin position. METHODS: Pretreatment and posttreatment lateral cephalograms of 67 treated patients (25 extraction headgear and Class II elastics, 23 nonextraction headgear, and 19 Herbst) were collected, traced, and digitized. The average pretreatment age was 12.2 years (range, 9-14 years), and the average treatment duration was 30.2 months (range, 17-65 months). Cephalometric changes were compared with 29 matched untreated Class II controls. Mandibular superimpositions were used to evaluate condylar growth and true mandibular rotation. RESULTS: All 3 treatment methods produced normal dental relationships and restricted or inhibited AP maxillary growth, with no significant improvement of AP chin position. Differences between changes in vertical position of the maxilla, maxillary and mandibular molars, and condylar growth could not reliably predict changes in chin position. Analyses demonstrated that true mandibular rotation was the primary determinant of AP chin position. Stepwise multiple regression showed that, combined with true mandibular rotation, condylar growth and movements of the glenoid fossa accounted for 81% of the variation in AP changes of pogonion. CONCLUSIONS: Contemporary treatments do not adequately address mandibular deficiencies. Future treatments must incorporate true mandibular rotation into Class II skeletal correction.
INTRODUCTION: Because most patients with skeletal Class II malocclusions also have mandibular deficiencies, treatment plans should include improvement in chin projection. On that basis, the purposes of this study were to (1) determine how Class II treatment affects anteroposterior (AP) chin position in growing subjects and (2) ascertain the most important determinants of AP chin position. METHODS: Pretreatment and posttreatment lateral cephalograms of 67 treated patients (25 extraction headgear and Class II elastics, 23 nonextraction headgear, and 19 Herbst) were collected, traced, and digitized. The average pretreatment age was 12.2 years (range, 9-14 years), and the average treatment duration was 30.2 months (range, 17-65 months). Cephalometric changes were compared with 29 matched untreated Class II controls. Mandibular superimpositions were used to evaluate condylar growth and true mandibular rotation. RESULTS: All 3 treatment methods produced normal dental relationships and restricted or inhibited AP maxillary growth, with no significant improvement of AP chin position. Differences between changes in vertical position of the maxilla, maxillary and mandibular molars, and condylar growth could not reliably predict changes in chin position. Analyses demonstrated that true mandibular rotation was the primary determinant of AP chin position. Stepwise multiple regression showed that, combined with true mandibular rotation, condylar growth and movements of the glenoid fossa accounted for 81% of the variation in AP changes of pogonion. CONCLUSIONS: Contemporary treatments do not adequately address mandibular deficiencies. Future treatments must incorporate true mandibular rotation into Class II skeletal correction.
Authors: Alexa Helena Kohler Moresca; Nathaly Dias de Moraes; Francielle Topolski; Carlos Flores-Mir; Alexandre Moro; Ricardo Cesar Moresca; Gisele Maria Correr Journal: Angle Orthod Date: 2020-07-01 Impact factor: 2.079
Authors: E Erin Bilbo; Steven D Marshall; Karin A Southard; Verrasathpurush Allareddy; Nathan Holton; Allyn M Thames; Marlene S Otsby; Thomas E Southard Journal: Angle Orthod Date: 2018-04-18 Impact factor: 2.079
Authors: Johan Willem Booij; Marco Serafin; Rosamaria Fastuca; Anne Marie Kuijpers-Jagtman; Alberto Caprioglio Journal: J Clin Med Date: 2022-06-02 Impact factor: 4.964