[Clinical effects of modified Nance arch appliance in the treatment of ectopic eruption of maxillary first permanent molar].

OBJECTIVE: To evaluate the effect of modified Nance arch appliance in the treatment of ectopic eruption of maxillary first permanent molar. METHODS: Thirty children with unilateral ectopic eruption of maxillary first permanent molar were treated with modified Nance arch appliance. The mesial angle of the maxillary first permanent molars and the magnitude of the primary second molar distal root lesion before and after treatment were measured on the panoramic radiographs and analyzed statistically. RESULTS: All 30 children completed the treatment. The mesial angle of the ectopic side significantly changed from (75.2 +/- 7.6) degrees before the treatment to (92.9 +/- 5.2) degrees after the treatment (t = -11.082, P < 0.05). The root lesion of the ectopic side significantly enlarged after the treatment, but there was no significant change on the normal side. CONCLUSIONS: The treatment of ectopic eruption of the maxillary first permanent molar using modified Nance arch appliance was successful. The attention should be paid to the magnitude of the primary second molar distal root lesion before and after treatment and it is suggested to start the treatment when mild root resorption appears.