Early headgear effect on the eruption pattern of maxillary second molars

Area of Science:

• Orthodontics
• Craniofacial Development
• Dental Arch Mechanics

Background:

• Early Class II malocclusion treatment often involves multi-phase approaches.
• Headgear is a common appliance used to modify maxillary growth and tooth movement.

Purpose of the Study:

• To evaluate the effect of combination headgear (HG) on the eruption pattern of maxillary second permanent molars (U7).
• To test the hypothesis that HG has no effect on U7 eruption during phase I orthodontic treatment.

Main Methods:

• Retrospective analysis of records from a randomized clinical trial on early Class II treatment.
• Comparison of cephalometric and panoramic data between an HG group (n=47) and a control group (n=52).
• Measurement of vertical and horizontal movements of maxillary first (U6) and second (U7) molars over 15 months.

Main Results:

• Significant differences in distal and vertical displacement of U6 and U7 were observed between HG and control groups (P < .001).
• No U7 were diagnosed as malposed or impacted at the end of phase I.
• All U7 erupted by the end of phase II, except for one case with a cystic lesion.

Conclusions:

• The hypothesis is rejected; combination headgear influences U7 eruption.
• Forces from combination headgear cause distalization of U6 and a temporary delay in U7 eruption.
• Maxillary second molars generally erupt successfully, irrespective of headgear use, unless pathological conditions are present.