Comparison of two types of intra-oral fixation devices in maxillary protraction

Abstract

Objective To investigate the difference of the treatment effect of the maxillary protraction therapy with rapid palatal expansion appliance or with wrapped bite-plate removable appliance as intra-oral fixation devices. Methods Twenty-three skeletal ClassⅢ maxillary retrusion patients were selected and treated with maxillary protraction, the intra-oral devices were rapid palatal expansion appliance in 13 patients and wrapped bite-plate removable appliance in 10 patients. Paired t-test was used to compare the lateral cephalometric radiographs before and after treatment; the difference before and after treatment of two groups was compared with t-test of independent samples in group. Results SNA, Co-Po, Y-axis, MP/FH, MP/SN, PP/MP, U1/SN, ANA-Me, N-Me, S-Go increased, ANB decreased significantly in both groups. In rapid palatal expansion group, S-N, Ptm-A increased significantly, the lower incisors tipped lingual significantly. In wrapped bite-plate group, S-Ba, N-Me increased, facial angle decreased significantly (P 0.05) . Conclusion Maxillary protraction combined with rapid palatal expansion or with wrapped bite-plate removable appliance was effective in the treatment of Class Ⅲ patients with maxillary deficiency, the treatment effects had no significant difference in two groups. Key words: Rapid palatal expansion; Maxillary protraction; Maxillary retrusion