Long- and short-term effects of headgear traction with and without the maxillary second molars

• Headgear treatment was evaluated at different force levels.
• Distalization in the absence or presence of the maxillary second molars was assessed.
• Distalization was measured with tightness of dental contact point and space gauges at 3 time points.
• Headgear therapy is more effective before the eruption of the second molars.
• The initial effective headgear force level is 3 to 6 N and should not exceed 9 N.

IntroductionA quantitative assessment of maxillary first molar distalization with and without the maxillary second molar (M2) was carried out.MethodsFifty-six cervical headgear patients undergoing fixed appliance orthodontic treatment were divided into 2 groups: before (G − M2) and after (G + M2) eruption of the maxillary second molars (ages, 11.87 ± 1.20, and 13.05 ± 1.55 years, respectively). The tightness of the dental contact point (TDCP) and the space between the second premolar and the maxillary first molar were measured at 6 levels of headgear force (0-15 N) at 3 intervals 6 months apart (T0, T1, T2).ResultsRelationships were found between space and TDCP, time, and presence or absence of the maxillary second molar at T1 and T2 (P <0.001). The TDCP decreased and space increased with increase in initial headgear force. An increase in initial force beyond 6 to 9 N did not significantly increase the initial maxillary first molar distalization. The G − M2 TDCP and space measurements were similar to those of G + M2 at T2 with the eruption of the maxillary second molar. From T0 to T1, maxillary first molar distalization was greater in G − M2. In comparison with our previous headgear-alone study, initial distalization with a fully bonded appliance was reduced by 4-fold.ConclusionsHeadgear therapy is more effective before the eruption of the maxillary second molar. Once it erupts, the distalization pace of the maxillary first molar is reduced, but it can nevertheless be pursued at a slower pace when the maxillary second molar is present.