The Protruding Premaxilla: Is Our Current Approach the Right Answer?
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Published on: October 18, 2021
Katelyn G Bennett1, Heather M Hendricks, Todd E Thurston
1*Section of Plastic Surgery, Department of Surgery, University of Michigan Health System †Department of Orthodontics, University of Michigan Health System, Ann Arbor, MI.
Background:
In bilateral cleft patients, surgeons usually attempt to move the premaxillary segment posteriorly. These patients almost always develop maxillary hypoplasia, rendering our current algorithms questionable. The authors sought to determine if the lateral segments are in an appropriate position to serve as a target for movement of the premaxilla.
Methods:
Bilateral cleft lip and palate patients treated at the University of Michigan from 1997 to 2015 were reviewed. Patients with skull radiographs or computed tomography (CT) imaging performed at age 3 or younger were included. Noncleft patients <3 years old seen in the craniofacial clinic during 2015 with negative imaging were included as comparative norms. Sella-nasion-A (SNA), sella-nasion-piriform (SNP), and sella-nasion-posterior nasal spine (SN-PNS) angles were determined in both the cleft patients and the comparative norms. Paired t tests assuming unequal variance were used to compare angles between normal and cleft patients.
Results:
Eighty-six bilateral cleft patients were identified, and 16 had imaging. Only 7 patients had a CT or skull radiograph. Thirteen noncleft patients with negative imaging were included. The mean SNA angle was 100.8 in cleft patients and 86.1 in noncleft patients (P = 0.002). The mean SNP angle was 62.9 in cleft patients and 71.3 in noncleft patients (P = 0.02). The mean SN-PNS angle was 23.2 in cleft patients and 33.8 in noncleft patients (P = 0.005).
Conclusions:
Our results indicate that the maxilla is deficient early in life with posterior positioning of the lateral segments. Therefore, the lateral segments should not serve as a reference point when treating the premaxilla.
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