Piriform Rim Asymmetry in Unilateral Cleft Lip and Palate Patients Before Orthognathic Surgery

Abstract

Complete unilateral cleft lip and palate (UCLP) creates a continuity defect on the nasal floor, which contributes to nasal asymmetry. Traditionally, piriform rim symmetry has been evaluated by comparing cleft and noncleft sides. No study has compared the magnitude of perinasal asymmetry in UCLP patients with a control group of patients without clefts. To address the following question: In UCLP patients, whose alveolar clefts are reconstructed with alveolar bone grafts (ABGs), is the magnitude of remaining piriform rim asymmetry similar to that of patients without UCLP? This is a retrospective cohort study that used the CBCT of UCLP and non-UCLP patients to evaluate the piriform rim symmetry. The sample was derived from patients who presented for orthognathic surgery between January 2015 and December 2022. To be included, patients had to have a maxillary deficiency. The cleft group had ABG performed with symphyseal bone harvest and BMP application. Patients were excluded from the control group if they had clinical asymmetry and nasal septum deviation. Patients from the UCLP group were excluded if they failed the first attempt of ABG or had a syndrome. Preorthognathic CBCT was used to measure the distance from the inferior and lateral aspects of the piriform rim to reference lines. UCLP status grouped as present or absent (control). The magnitude of piriform rim asymmetry defined as the millimetric distance from the inferior and lateral aspects of the piriform rim to reference lines. The covariates were age, sex, tissue thickness at the level of the alar base, and turbinate size. Welch's two-sample t-test was utilized to compare means. A level of significance of 5% (P<.05) was used for all analyses. To analyze the reliability of the measurements intraexaminer and interexaminer errors were tested using the Weir method. A total of 60 patients were included, 30 in each group. The mean age of UCLP patients was 16.76 (range 13 to 25), and the control group was 17 (range 13 to 25), P=.71. The UCLP group had 12 girls, and the control had 18 girls (P=.12). In the UCLP group, the mean discrepancy between affected and unaffected sides at the inferior aspect of the piriform rim was 3.9mm (range 0.9 to 7mm, P<.01), and in the control group the discrepancy between right and left sides was 0.1mm (0-2.1mm, P=.87). The mean discrepancy between affected and unaffected sides at the lateral aspect of the piriform rim was 3.6mm (range 0.7 to 7.6mm, P<.01) in the UCLP group, and in the control group the discrepancy between right and left sides was 0.1mm (range 0.1 to 5.8mm, P=.78) in the control group. The mean alar base soft tissue thickness discrepancy was 3.1mm (range 0.9 to 7.9mm, P<.01) in the UCLP group and 0mm (range -1.8 to 1.9mm, P=.97) in the control group. The mean difference in the turbinate area in the UCLP group was 314mm2 (range 797 to 2,898) and in the control group 35mm2 (range 702 to 2,302) (P=.19). ABG with symphyseal bone and BMP was not able to provide the same level of piriform symmetry observed in patients without a cleft. Alar base tissue was thicker on the cleft side, and the turbinate size demonstrated greater variability in the UCLP patients.