Abstract
In individuals with cleft lip and palate (CLP) an iatrogenic effect of operations on subsequent maxillary growth is well-known. Much less is known about the association between occurrence of CLP and intrinsic growth deficiency of the maxillofacial complex. The aim of this study was to compare morphological variability in subjects with unilateral cleft lip and alveolus/palate and unaffected controls using geometric morphometric methods. The research hypothesis was that if subjects with unrepaired unilateral CLP have intrinsic growth deficiency, the pattern of their craniofacial growth variation may differ from that in unaffected individuals. Lateral cephalograms were available of three groups of the same ethnic background (Proto-Malayid): (a) non-syndromic unrepaired unilateral complete cleft lip, alveolus, and palate (UCLP), N = 66, mean age 24.5 years (b) non-syndromic unrepaired unilateral complete cleft lip and alveolus (UCLA), N = 177, mean age 23.7 years, and (c) NORM (N = 50), mean age 21.2 years without a cleft. Using geometric morphometrics shape variability in groups and shape differences between groups was analyzed. Principal component analysis (PCA) was used to examine shape variability, while differences between groups and sexes were evaluated with canonical variate analysis. Sexual dimorphism was evaluated with discriminant function analysis (DA). Results showed that in comparison to NORM subjects, shape variability in UCLA and UCLP is more pronounced in the antero-posterior than in vertical direction. Pairwise comparisons of the mean shape configurations (NORM vs. UCLA, NORM vs. UCLP, and UCLA vs. UCLP) revealed significant differences between cleft and non-cleft subjects. The first canonical variate (CV1, 68.2% of variance) demonstrated that differences were associated with maxillary shape and/or position and incisor inclination, while in females, the CV1 (69.2% of variance) showed a combination of differences of “maxillary shape and/or position and incisor inclination” and inclination of the cranial base. Shape variability demonstrated considerable differences in subjects with UCLA, UCLP, and NORM. Moreover, in subjects with a cleft, within-sample variability was more pronounced in the antero-posterior direction, while in non-cleft subjects, within-sample variability was more pronounced in the vertical direction. These findings may suggest that subjects with unilateral clefts have intrinsic growth impairment affecting subsequent facial development.
Highlights
Cleft lip with or without cleft palate shows a large phenotypic variation ranging from complete open clefts of the lip, alveolus and palate to microforms and subclinical phenotypes like submucous cleft lip or palate
Numerous animal experiments have shown that scar tissue that develops after the palatal surface has been denuded to close the cleft and the palate, is a strong inhibitor of maxillary growth and the adverse growth effect persists into adulthood (Li et al, 2015)
Variability was mainly present in the vertical direction in non-cleft subjects, while in bilateral cleft lip and palate (CLP) subjects the anteroposterior component of variation was marked. We suggested that this difference might point to intrinsic growth impairment in bilateral CLP
Summary
Cleft lip with or without cleft palate shows a large phenotypic variation ranging from complete open clefts of the lip, alveolus and palate to microforms and subclinical phenotypes like submucous cleft lip or palate. Surgical rehabilitation of patients with cleft lip and palate aims at restoration of the anatomy, function, and aesthetics of the face, but is associated with growth disturbance of the midface. Identification of factor(s) leading to maxillofacial growth disturbance in individuals with cleft lip and palate (CLP) is critical for improvement of treatment results. For obvious reasons it is difficult to collect a large sample of untreated CLP individuals. Data for unoperated bilateral clefts is even more scarce and comprise mostly case reports (Will, 2000). These inconsistent findings may be due to the error of the method, different ages of evaluation, or the use of samples with mixed cleft types
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