Relationship Between Expansion Magnitude and Relapse in Multi-Segment Le Fort I Osteotomy: A Retrospective Cohort...

Area of Science:

• Orthognathic Surgery
• Craniofacial Reconstruction
• Dental and Maxillofacial Surgery

Background:

• Maxillary transverse deficiency often requires multisegment Le Fort I osteotomies for correction.
• The relationship between expansion magnitude and relapse after these procedures is not well-established, particularly for expansions exceeding 4 mm.

Purpose of the Study:

• To quantify the association between the magnitude of surgical maxillary expansion and relapse rates in patients undergoing multisegment Le Fort I osteotomies.

Main Methods:

• A retrospective cohort study comparing patients with maxillary molar expansion <4 mm versus ≥4 mm.
• Utilized cone-beam computed tomography (CBCT) for pre-operative and post-operative measurements of intermolar, intercanine, piriform aperture, and greater palatine foramen widths.
• Relapse was assessed at 2 weeks, 8 weeks, and at least 6 months postoperatively; time-to-event analyses were performed.

Main Results:

• The ≥4 mm expansion group showed a significantly higher rate (23%) of relapse compared to the <4 mm group (55%) relative to initial expansion, with relapse occurring earlier.
• Kaplan-Meier analysis indicated significantly shorter relapse-free survival for the ≥4 mm expansion group.
• While molar relapse was correlated with expansion magnitude, this may be influenced by postoperative orthodontic treatment; skeletal relapse (piriform aperture, greater palatine foramen) was not significantly different between groups.

Conclusions:

• Surgical maxillary expansion exceeding 4 mm is associated with a higher incidence of clinically significant relapse.
• Postoperative orthodontic management may impact observed molar relapse, necessitating careful consideration.
• No significant difference in skeletal relapse was found between the <4 mm and ≥4 mm expansion groups for secondary outcome measures.