Evaluation of the Efficiency of Pendulum Appliance for Molar Distalization Related to Second Molar Eruption Stage

Objective To assess the efficiency of the pendulum appliance for molar distalization related to second molar eruption stage.Methods 25 patients with mild maxillary dental crowding and molar class Ⅱ relationship were selected.The patients were divided into 2 groups according to the different eruption stage of upper second molars.Pendulum appliance was used for maxillary molar distalization. Cephalograms were analyzed.Results ①The difference of the amount of the first molar distal movement between two groups was not significant.②The degree of the first molar distal tipping in the second molar unerupted group is more than that in the second molar erupted group,whereas the second molar distally tipped more in the second molar erupted group than that in the second molar unerupted group.③The upper first molars extruded significantly more in the second molar erupted group.④In the second molar erupted group,the upper incisors flared with the result of more increase in overjet.Conclusions ①The erupted upper second molars have no significant effect on the upper molar distalization.②It influences the distal tipping of maxillary molars whether the maxillary second molars have erupted or not.③The erupted maxillary second molars result in more anchorage loss.④For the patients whose maxillary second molars erupted,the upper first molars would extrude after molar distalization.