Dentoskeletal and soft-tissue changes in growing class II malocclusion patients during nonextraction orthodontic treatment.
An investigation was conducted to determine the outcome of nonextraction edgewise orthodontic treatment of thirty-five caucasian patients with Class II molar relationships (13 division 1 and 22 division 2 cases). Twenty-three females and 12 males aged between 10 and 16 years old were treated using Class II intermaxillary elastics worn with 0.016" x 0.022" stainless steel archwires and without extra-oral traction. Thirty cephalometric landmarks were identified and digitized, and used to calculate 41 parameters. Space analyses were conducted on pretreatment study models. Most of the cases had between 0-4 mm space shortage in both maxillary and mandibular dentitions. Results of this study indicated that the mean SNA angle decreased by 1.580 degrees, and that this change was largely due to posterior movement of point A. The mean pre-treatment ANB value was 4.490 degrees which decreased to a mean posttreatment value of 2.810 degrees (p<0.05). No significant changes in the growth direction of the jaws were found, showing that the use of Class II intermaxillary elastics in this sample had no detrimental effect on this parameter (p<0.05). The SNB angle increased by a mean of 0.110 degrees, which can be attributed to anterior mandibular growth. The dentoalveolar changes included a mean overjet reduction of 3.816mm (mean posttreatment overjet was 2.2mm) and proclination of the lower incisors relative to the APo line and the mandibular plane, probably caused by the use of Class II intermaxillary elastics. The lower lip advanced relatively more than the upper lip, and this contributed to an improvement of the lip relationship. The amount of nose growth observed during the study was normal for this age group, and compared favourably with other data in the literature.