Mini-implant-supported Twin-Block in Treating Patients With Class II Division 1 Malocclusion

Correcting the skeletal class II using functional appliances, whether removable or fixed, always leads to skeletal and alveolar effects. However, some of these effects are unfavorable, the most significant being the loss of support in the lower dental arch. This loss of support leads to an uncontrolled labial inclination of the lower incisors and mesial movement of the lower; these dentoalveolar effects impact the degree of skeletal correction that can be achieved. Therefore, this study aimed to evaluate the skeletal and dentoalveolar effects following the use of a mini-implant-supported Twin-Block appliance compared to the conventional Twin-Block.

Many attempts have been made to modify the Twin-Block appliance to decrease the dentoalveolar effects, such as omitting the upper labial bow, including torquing spurs on the upper incisors, and adding acrylic capping on the lower incisors. However, these modifications have not been successful in eliminating the dentoalveolar effects. This is because the Twin-Block and other functional appliances are supported by teeth rather than bone. As a result, the components of the appliance exert force on the teeth while the mandible attempts to return to its natural resting position. No previous clinical trial described the use of the Twin-Block appliance supported by orthodontic mini-implants and the potential benefits of using mini-implants with Twin-Block in functional treatment.