The mini-tube appliance (MTA) is comfortable and advantageous in terms of aesthetics and oral hygiene compared to conventional brackets. By using 0.012 inch Thermoactive (TA) NiTi wires, the frictional resistance is low. So treatment are possible within a short period and there are fewer side effects, such as root resorption. Light-force orthodontic treatment using MTA and thin TA NiTi wire is a suitable treatment method in pediatric dentistry, considering the increasing aesthetic needs and the nature of pediatric patients. By using the MTA and thin TA NiTi wire, the cases reported here have led to positive treatment outcomes in minor orthodontic treatment for the anterior teeth crowding and retreatment following relapse after orthodontic treatment.