Treatment effects of quad-helix on the eruption pattern of maxillary second molars

Objective: To evaluate the effects of quad-helix treatment on the eruption pattern of maxillary second molars in patients with maxillary incisor crowding. Materials and Methods: The lateral cephalograms of 40 consecutively treated patients in the early mixed-dentition group (treatment group) were examined in comparison with those of the same number of untreated patients with a similar form of malocclusion (control group). The cephalograms of the treated patients were taken at the start (T0) and at the end (T1) of treatment, and those of the untreated patients were also taken at about the same time as T0 and T1. The mean ages at T0 and T1 in the two groups were about the same. Results: Distal tipping and movement and impeded extrusion of the maxillary first molars were notable in the treatment group compared with the control group. The actual treatment changes with the use of the quad-helix found expression in distal tipping and impeded vertical eruption of maxillary second molars. The more the maxillary first molars were tipped distally and the less the maxillary first molars extruded, the more the vertical eruption of the maxillary second molars was impeded. Conclusion: Quad-helix treatment gives rise to spontaneous distal tipping and impeded vertical eruption of the maxillary second molars. (Angle Orthod. 2012;82:676-681.)