Comparsion of the effects of transpalatal arch and mini-screw on anterior teeth retraction for patients with bimaxillary protrusion

Objective:To compare the effects of transpalatal arch(TPA) and mini-screw(MS) applicated in anterior teeth retraction for patients with bimaxillary protrusion.Methods:Forty-two patients with bimaxillary protrusion treated with pulling four first pairs of fangs were divided into MS group(24 cases),which were used by mini-screw and T group(18 cases),which were used by transpalatal arch for strengthening anchorage.The changes of skeletal,dental and soft tissue of all cases were measured by X-ray.Results:The angle differences of ANB of two groups had statistical significance(P0.01),SN-MP of MS group decreased,but increased in T group(P0.05).The adduction quantities of front upper teeth of MS group were obviouser than that of group T.Upper molars and incisor teeth of MS group were kept down,while its were extended in T group(P0.05).The linear measurement(UL-E) of MS group were significantly higher than that of T group(P0.01).Conclusions:Mini-screw implants could provide absolute anchorage in vertical and sagittal directions,and can obtain good effects on skeletal,dental and soft tissue.