Abstract: Objective To introduce a new method for distal movement of unilateral mandibular first permanent molar and evaluation of its clinical efficacy. Methods Fifteen cases in mixed dentition were selected, where mandibular anterior teeth were crowded, and the first permanent molar moved mesially. A new type of molar distalization appliance was used to move the unilateral first permanent molar that moved mesially to distal, and the analysis of gypsum model measurement and cephalometry before and after the orthodontic treatment and the data was processed by statistical software. Results After 3-7 months of treatment, the ipsilateral first permanent molar moved to distal (4.85±2.07) mm; the crowding degree of mandibular anterior teeth decreased by (1.25±1.32) mm. The anterior and inferior intersection angle formed by the long axis of the ipsilateral mandibular first permanent molar on the panoramic film and the reference plane decreased by (10. 40°±4.70°); the lower incisor axis was labial inclination by (2.51°±3.33°), and the overjet decreased by (0.92±1.79) mm. The difference was statistically significant (P<0.05). Conclusion The new method for distal movement of unilateral mandibular first permanent molar can move the mandibular first permanent molar faster, but it should be noted that when pushing the first permanent molar to distal in, it can also cause distal tilting movement and labial inclination of the mandibular incisor.

Key words: mixed dentition, mandibular first permanent molar, distal movement, molar appliance, cephalometry