Cephalometric and occlusal changes following maxillary expansion and protraction

Area of Science:

• Orthodontics and Dentofacial Orthopedics
• Craniofacial Growth and Development

Background:

• Skeletal Class III malocclusion presents challenges in craniofacial development.
• Maxillary hypoplasia is a key component of Class III malocclusion.
• Orthopedic treatment aims to correct underlying skeletal discrepancies.

Purpose of the Study:

• To evaluate cephalometric and occlusal changes after maxillary expansion and protraction in Southern Chinese patients with skeletal Class III malocclusions.
• To assess the long-term stability of this orthopedic intervention over a 2-year follow-up period.

Main Methods:

• A prospective clinical trial involving 20 Southern Chinese patients (mean age 8.4 years) with skeletal Class III malocclusions.
• Treatment included maxillary expansion and protraction facemask therapy, followed by a 2-year observation period post-appliance removal.
• Lateral cephalometric radiographs and dental cast analyses quantified skeletal and dental changes at multiple time points.

Main Results:

• Treatment resulted in significant forward maxillary movement (2.1 mm) and overcorrection of overjet (-2.0 mm to 3.5 mm).
• Maxillary intercanine and intermolar widths increased significantly (2.2 mm and 2.3 mm, respectively) during rapid palatal expansion.
• A positive overjet was maintained in 18 of 20 patients at 2-year follow-up, despite some relapse in maxillary width (30-45%).

Conclusions:

• Maxillary expansion and protraction provide a stable orthopedic correction for skeletal Class III malocclusions.
• The treatment leads to significant improvements in maxillomandibular relationships and overjet.
• Long-term stability is achievable, with most patients maintaining corrected occlusion after 2 years.