The aim of this study was to investigate the effects of a modified spring-activated appliance (MSAA), and a combination of the modified spring-activated appliance (MSAA) + vertical chin-cup on growth and development of the maxillary and mandibular skeletal and dentoalveolar structures. Twentysix patients who had either Class I or Class II skeletal malocclusion and a skeletal and dentoalveolar anterior open-bite were selected for this study. Thirteen patients, with a mean age of 11 years 11 months were selected and composed Group 1. The modified spring activated appliance was applied to the Group 1. Group 2 included 13 patients with a mean age of 11 years 10 months and the combination of the modified-spring appliance + vertical chin-cup was applied to this group. The results of this study showed that both techniques altered the rotation of mandibular growth from forward-downward to forward-upward and produced a positive overbite relation by reducing anterior open bite. Alteration of the mandibular rotation from forward-downward to forward-upward resulted mainly from the intrusion of the upper and lower posterior dentoalveolar structures. There was no statistically significant difference between the groups.

Keywords: Skeletal openbite, modified spring-active appliance, vertical chin-cup