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

Introduction: A quantitative assessment of maxillary first molar distalization with and without the maxillary secondmolar (M2) was carried out.

Methods: Fifty-six cervical headgear patients undergoing fixed appliance orthodontictreatment were divided into 2 groups: before (G - M2) and after (G1M2) eruption of the maxillary secondmolars (ages, 11.87 ±1.20, and 13.05 6 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 levelsof headgear force (0-15 N) at 3 intervals 6 months apart (T0, T1, T2).

Conclusions: Headgear therapy is more effective before the eruption of the maxillary second molar. Once iterupts, the distalization pace of the maxillary first molar is reduced, but it can nevertheless be pursued at a slowerpace when the maxillary second molar is present.

Results: Relationships were found betweenspace 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 ininitial force beyond 6 to 9 N did not significantly increase the initial maxillary first molar distalization. TheG - M2 TDCP and space measurements were similar to those of G 1 M2 at T2 with the eruption of the maxillarysecond molar. From T0 to T1, maxillary first molar distalization was greater in G - M2. In comparison with ourprevious headgear-alone study, initial distalization with a fully bonded appliance was reduced by 4-fold.