More extensive analysis is needed when assessing facial structure in SIDS.
Explore the source record for details and available documents.
Face↗
Biomedical subjects
G D Singh
Publications and source records attributed to G D Singh.
Morphologic determinants in the etiology of class III malocclusions: a review.
Morphospatial disharmony of the craniomaxillary and mandibular complexes may yield apparent mandibular prognathism, but Class III malocclusions can exist with any number of aberrations of the craniofacial complex. Deficient orthocephalization of the cranial base allied with a smaller anterior cranial base component has been implicated in the etiology of Class III malocclusions. Whereas the more acute cranial base angle may affect the articulation of the condyles resulting in their forward displacement, the reduction in anterior cranial size may affect the position of the maxilla. As well, intrinsic skeletal elements of the maxillary complex may be responsible for maxillary hypoplasia that may exacerbate the anterior crossbite seen in the Class III condition. Conversely, with an orthognathic maxilla, condylar hyperplasia and anterior positioning of the condyles at the temporo-mandibular joint may produce an anterior crossbite. Aside from the skeletal components, soft tissue matrices, particularly labial pressure from the circumoral musculature, may influence the final outcome of craniofacial growth of a child skeletally predisposed to Class III conditions. Indeed, as some Asian ethnic groups demonstrate an increased prevalence of Class III malocclusions, it is likely that the skeletal components and soft tissues matrices are genetically determined. Presumably, the co-morphologies of the craniomaxillary and mandibular complexes are likely dependent upon candidate genes that undergo gene-environmental interactions to yield Class III malocclusions. The identification of such genes is a desirable step in unraveling the complexity of Class III malocclusions. With this knowledge, the clinician may elect an early course of dentofacial orthopedic and orthodontic treatments aimed at preventing the development of Class III malocclusions.
Humans↗
Finite-element morphometry of soft tissues in prepubertal Korean and European-Americans with Class III malocclusions.
The purpose was to test the hypothesis that soft-tissue morphology differs consistently in people of diverse ethnic origin exhibiting Class III malocclusions. Lateral cephalographs of 70 Korean and 71 European-American children aged between 5 and 11 years were traced and 12 homologous, soft-tissue landmarks digitized. The total sample was subdivided into seven age- and sex-matched groups, and Procrustes superimposition was used to generate average geometries scaled to an equivalent size. Statistical differences were tested by ANOVA. Graphical analysis using a colour-coded finite-element (FEM) program was used to localize differences in morphology. Procrustes' results indicated that the overall mean Korean and European-American soft-tissue configurations differed statistically (p<0.001), and this difference was also true in all seven age groups tested (p<0.001). On comparing mean Korean and European-American Class III soft-tissue configurations for local size change, FEM analysis revealed that whereas the Korean mental regions generally were smaller (approx. 43% on average), local increases in size were apparent for the lower lip (approx. 29% on average). For shape change, the mean Korean and European-American soft-tissue configurations were fairly isotropic except in the region of the columella, lower lip and the anterior part of the mental region. Features of the soft-tissue integument in individuals of diverse ethnic origins appear to be associated with the underlying skeletal Class III morphology.
Americas↗
Finite-element morphometry of soft tissue morphology in subjects with untreated Class III malocclusions.
Soft tissue dynamics may contribute to maxillomandibular allometry (size-related changes in shape) associated with the development of Class III malocclusions. Lateral cephalographs of 124 prepubertal European American children were traced and 12 soft tissue landmarks were digitized. Resultant geometries were normalized, and Procrustes analysis established the statistical difference (p<0.001) between mean Class III and Class I configurations. Comparing the Class III configurations with normals for size-change, color-coded finite element analysis revealed a superoinferior gradient of positive allometry of the Class III facial nodal mesh. A conspicuous area of negative allometry (approximately 40%) was localized near soft subspinale, with a approximately 70% increase in size in the mental region. For shape-change, the Class III facial mesh was isotropic, except in the anisotropic circumoral regions. Conventional cephalometry revealed that about 50% of linear and 75% of angular parameters differed statistically (p<0.001). Soft tissue dynamics during early postnatal development may contribute to the development of Class III malocclusions.
Case-Control Studies↗
Allometry of the cranial base in prepubertal Korean subjects with class III malocclusions: finite element morphometry.
Sphenoethmoidal allometry could be associated with ethnic heterogeneity of the midfacial profile. Thirteen cranial base landmarks were digitized from cephalographs of 69 Korean and 73 European American prepubertal children exhibiting Class III malocclusion. Average geometries were normalized, and a color-coded finite element (FEM) program was used to localize differences in morphology. ANOVA indicated that mean Korean and European American cranial base configurations differed statistically (p < 0.01); this was also true for seven age groups tested (p < 0.001). For size-change, FEM analysis revealed that in the anterior cranial base, Korean sphenoethmoidal and sella turcica regions were smaller (=12%). Local increases in size were apparent for the posterior region of the Korean cranial base (=35%). For shape-change, Korean and European American cranial base configurations were isotropic with minor anisotropy in the sphenoethmoidal and spheno-occipital regions. A sphenoethmoidal mechanism of midfacial retrognathism appears to be implicated in the development of a skeletal Class III morphology.
Analysis of Variance↗
Morphometry of the mandible in prepubertal craniofacial microsomia patients following an inverted L osteotomy.
The aim of this study was to undertake finite element modeling of craniofacial microsomia (CFM) patients who exhibited a unilateral mandibular deformity that was surgically corrected by an inverted L osteotomy and autogenous bone graft. Preoperative, 1-year, and 3-year postoperative anteroposterior cephalographs of 14 consecutive children (mean age, about 9 years) with CFM were employed. All cephalographs were scanned, and 8 homologous mandibular landmarks were digitized in triplicate (digitization error < 1%; P > 0.05). Average mandibular geometries, scaled to an equivalent size, were generated using Procrustes superimposition and subjected to analysis of variance. Results showed that while the mean pre- and early postoperative mandibular configurations marginally failed to differ statistically, finite element modeling of the affected mandibular ramus showed a positive allometry (a lengthening by about 10% to 12%) and marked anisotropy, presumably reflecting the surgical procedure carried out in that region. For the preoperative and late postoperative means, the configurations were statistically different (P < 0.002), showing a lengthening of the ramus (about 14%) while the unoperated side had a high degree of isotropy. The early and late postoperative configurations were also statistically different (P < 0.002). The operated ramus showed an increase in length (about 15%), but the corpus showed a decrease in size (about 10%) and marked anisotropy that reflected remodeling associated with the surgical procedure. Although mandibular morphology is improved in CFM patients who are surgically treated by an inverted L osteotomy, some relapse is evident due to deficient growth, localized in the mandibular ramus and body of the affected side.
Analysis of Variance↗
Morphometry of paranasal sinus anatomy in chronic rhinosinusitis: a pilot study.
OBJECTIVES: To test the null hypothesis that there is no relationship between anatomical variations around the ostiomeatal complex and a predisposition to chronic rhinosinusitis and to define such variations with increased precision. DESIGN: Case-control study of anatomical variations in diseased and normal sinuses. Eight homologous landmarks defining the ostiomeatal complex were located on coronal computed tomographic scans, and their x and y coordinates were digitized using image analysis. SUBJECTS: Ten patients with unilateral sinus disease and 10 subjects without sinus disease (scanned for facial pain) who were selected retrospectively by case-note analysis. RESULTS: Logistic regression showed that the only significant spatial change predictive of a person with rhinosinusitis was the vertical position of the middle turbinate (P=.04), although this was not confirmed by Wilcoxon testing (P>.10). When examined by sinus, however, the horizontal position of the uncinate process was more laterally placed in persons with rhinosinusitis (P=.01), confirmed on Wilcoxon testing (P=.04), but there was no significant difference when compared with sinuses in persons without rhinosinusitis. CONCLUSIONS: Our findings suggest that there are no anatomical differences within the ostiomeatal complex between patients with and without rhinosinusitis. Patients with rhinosinusitis, however, are more likely to develop it in the side with a more laterally positioned uncinate process. Further studies, with more patients and more advanced techniques, including thin-plate spline analysis, are indicated.
Case-Control Studies↗
An anomalous accessory flexor digiti minimi profundus muscle: a case study.
A well-developed anomalous muscle within the forearm flexor compartment was discovered during a routine cadaveric dissection. The identified muscle originated from the intercompartmental septum on the medial side of the forearm just proximal to the wrist joint and inserted on the proximal phalanx of the fifth digit. When stressed, the tendon of the muscle produced flexion of the metacarpophalangeal joint of the fifth digit. Contiguous muscles, including the flexor digitorum profundus, displayed normal morphology. The muscle appeared to be an accessory belly of flexor digitorum profundus. The combination of an accessory flexor digitorum profundus muscle belly acting on the metacarpophalangeal joint of the little finger has not been previously reported. Based on its origin, insertion, and action we have named this variant accessory flexor digiti minimi profundus. This muscular variant could have clinical relevance, possibly affecting ulnar nerve function and circulation in the hand.
Aged↗
Morphometry of the midfacial complex in subjects with class III malocclusions: Procrustes, Euclidean, and cephalometric analyses.
The purpose of this study was to determine whether the morphology of the midface differed in subjects with a retrognathic midfacial appearance (Class III malocclusions) using a combination of morphometric and cephalometric analyses. After obtaining appropriate consent, lateral cephalographs of 133 children of European-American descent, ages 5-11 years, were compared: 73 had Class III malocclusion, 60 had normal (Class I) occlusion. The cephalographs were traced and subdivided into seven age- and sex-matched groups. Average geometries based upon seven nodes (pterygoid point, PTS; rhinion, RO; posterior nasal spine, PNS; midpalatal point, MPP; anterior nasal spine, ANS; subspinale, A; prosthion, Pr), scaled to an equivalent size, were compared using a Procrustes routine. Euclidean distance matrix analysis (EDMA) was employed to localize differences in morphology. Bivariate analyses on unscaled data utilizing nine linear and six angular measurements were also undertaken. Results from Procrustes and EDMA analyses indicated that although the overall midfacial configurations differed statistically (P < 0.05), only about half of the seven age sub-groups maintained significance. Similarly, only four of the nine linear measures (PNS-MPP, MPP-ANS, A-Pr and PTS-RO) and two of the six angular parameters (PTS-RO-ANS and ANS-A-Pr) tested were significantly different (P < 0.05). Therefore, midfacial morphometric variability and morphological diversity may mask statistical differences. It is concluded that the midface may be the defining craniofacial component in the final appearance of Class III malocclusions compared to other craniofacial components, including the cranial base and mandible.
Cephalometry↗
Procrustes, Euclidean and cephalometric analyses of the morphology of the mandible in human Class III malocclusions.
The role of mandibular phenotype in the development of Class III malocclusion remains unclear. The purpose of this study was to determine whether the form of the mandible differed between prepubertal individuals with Class I and Class III malocclusions. Lateral cephalographs of 73 children of European-American descent aged between 5-11 years with Class III malocclusion were compared to those of 60 counterparts with a normal, Class I molar occlusion. The cephalographs were traced and checked, and eight homologous mandibular landmarks were digitized. Average mandibular geometries, scaled to an equivalent size, were generated using Procrustes superimposition. Euclidean distance matrix analysis (EDMA) was undertaken to corroborate the Procrustes analysis, and bivariate analysis utilizing eight linear and five angular measurements was also performed. Residuals and F-values from Procrustes analysis indicated that mandibular configurations differed statistically for Class I and Class III types. EDMA confirmed that the Class I and Class III geometries were significantly different, revealing that the greatest differences in morphology arose in the anterior-most mandibular regions. As well, most variables showed statistically significant differences when the Class I and Class III mandibular types were compared. When the sample was subdivided into seven age- and sex-matched groups, nearly all age-based comparisons were significantly different. It is concluded that the morphology of the mandible differs in individuals with Class III malocclusions when compared to the normal Class I configuration, and that these alterations may indicate dichotomous postnatal mandibular ontogeny.
Cephalometry↗
Mandibular morphology in subjects with Class III malocclusions: Finite-element morphometry.
The absence of physical restraint may be associated with a mandibular allometry that contributes to mandibular prognathism. Cephalographs of 73 prepubertal children of European American descent with untreated Class III malocclusions were traced and eight mandibular landmarks digitized. The resulting eight-noded geometries were normalized, and the mean Class III geometry compared with the equivalent Class I average. Procrustes analysis established statistical difference (p < 0.05) between these mean configurations. A color-coded finite-element (FEM) analysis was used to localize differences in morphology. Comparing Class III and normal mandibular configuration for changes in size, FEM revealed positive allometry of the mandibular corpus and around supramentale (15% increase in size), with reductions (30%) between the incisor alveolus and menton. For changes in shape, mandibular configurations were predominantly isotropic, with the exception of the anisotropic anterior region in the Class III subjects. Incremental growth differences are consistent with the view that the absence of physical restraint is associated with mandibular prognathism.
Case-Control Studies↗
Cleft palate formation in fetal Br mice with midfacial retrusion: tenascin, fibronectin, laminin, and type IV collagen immunolocalization.
OBJECTIVE: This study tested the hypothesis that altered craniofacial morphology does not affect the expression of extracellular matrix (ECM) molecules such as fibronectin (FN), laminin (LN), type IV collagen, and tenascin-C (TN) but is associated with failure of palatal shelf elevation and fusion concomitant with cleft palate formation. DESIGN: To test this hypothesis, a comparative immunohistological analysis of FN, LN, type IV collagen, and TN was undertaken on brachyrrhine (Br/Br) mice and normal (+/+) fetuses during secondary palate formation. Normal and Br/Br fetuses were collected at gestational days E13 and E14 (representing prefusion stages) and E15 and E18 (representing postfusion stages). Cryostat palatal sections (8 microm) were postfixed in methanol, washed, and stained with primary antibody. All sections were washed and coated with secondary antibody (swine-anti-rabbit IgG) and mounted with citifluor. RESULTS: Immunohistological analysis showed that LN and type IV collagen were located near the presumptive medial epithelial seam (MES) or edge (MEE) in +/+ or Br/Br fetuses, respectively. Fibronectin showed a homogeneous distribution at all stages in both groups of mice. In contrast, TN became localized below the presumptive MES or MEE in both groups of mice at E14. In +/+ animals at E15, TN dissipated and became confined to the oral basement membrane by E18. At E15 and E18 in cleft Br/Br mutants, TN stained beneath the MEE. CONCLUSION: Although the distributions of ECM molecules are similar during normal and cleft palatogenesis, differences in TN expression are associated with cleft palate formation.
Animals↗
Craniofacial heterogeneity of prepubertal Korean and European-American subjects with Class III malocclusions: procrustes, EDMA, and cephalometric analyses.
The purpose of this study is to determine whether there is a difference in craniofacial morphology in subjects of diverse ethnic origin with untreated Class III malocclusions, and thus to examine the validity of using similar therapeutic protocols in their orthodontic management. Lateral cephalographs of 142 Korean and European-American children aged 5 to 11 years were traced, and homologous cranial, midfacial, and mandibular landmarks were digitized. Procrustes analysis and Euclidean Distance Matrix Analysis (EDMA) were performed to identify size-corrected differences of the three craniofacial configurations, and bivariate analysis to determine statistical differences between 42 cephalometric parameters. Procrustes analysis indicated statistical significance for each configuration of landmarks; these results were confirmed by EDMA and cephalometry. Korean children appear to develop Class III malocclusions because of smaller anterior cranial base and midfacial dimensions, exacerbated by a large and less favorable mandibular morphology. Therefore, morphologic diversity of craniofacial components, presumably due to heterochrony during development, contributes to distinctive facial profiles associated with Class III malocclusions. Ethnic heterogeneity may need to be taken into account in the orthodontic management of Class III malocclusions.
Analysis of Variance↗
Glycosaminoglycan biosynthesis during 5-fluoro-2-deoxyuridine-induced palatal clefts in the rat.
The biosynthesis and hydration of glycosaminoglycans (GAG) has been implicated in the generation of palatal shelf-elevating force(s) in mammals, although the nature of the palatal shelf extracellular matrices during cleft palate formation remains poorly understood. This study quantifies the GAG composition in the palatal shelves of Wistar rat fetuses at various periods of palatogenesis where clefts were induced experimentally using 5-fluoro-2-deoxyuridine (FUDR). For both normal and cleft palatal shelves, hyaluronan, heparan sulphate and chondroitin-4-sulphate were detected but not dermatan sulphate or chondroitin-6-sulphate. Throughout the period of cleft development studied, the total amount of GAG was significantly decreased (by approx. 30%) compared with normal development, this decrease being particularly marked at a time equivalent to post-elevation during normal development (approx. 75%). Furthermore, and unlike normal palatogenesis, no significant differences were recorded between the anterior and posterior parts of the palatal shelves during cleft formation. As for normal palatogenesis, however, the percentages of each GAG were not altered at any stage. The findings are consistent with the view that suppression of GAG biosynthesis is related to the development of cleft palate in FUDR-treated rat fetuses and can therefore be interpreted as providing evidence of a role for the mesenchymal glycoconjugates in shelf elevation during normal palatogenesis.
Animals↗
Spline analysis of the mandible in human subjects with class III malocclusion.
This study determines deformations that contribute to a Class III mandibular morphology, employing thin-plate spline (TPS) analysis. A total of 133 lateral cephalographs of prepubertal children of European-American descent with either a Class I molar occlusion or a Class III malocclusion were compared. The cephalographs were traced and checked, and eight homologous landmarks on the mandible were identified and digitized. The datasets were scaled to an equivalent size and subjected to statistical analyses. These tests indicated significant differences between average Class I and Class III mandibular morphologies. When the sample was subdivided into seven age and sex-matched groups statistical differences were maintained for each group. TPS analysis indicated that both affine (uniform) and non-affine transformations contribute towards the total spline, and towards the average mandibular morphology at each age group. For non-affine transformations, partial warp 5 had the highest magnitude, indicating large-scale deformations of the mandibular configuration between articulare and pogonion. In contrast, partial warp 1 indicated localized shape changes in the mandibular symphyseal region. It is concluded that large spatial-scale deformations affect the body of the mandible, in combination with localized distortions further anteriorly. These deformations may represent a developmental elongation of the mandibular corpus antero-posteriorly that, allied with symphyseal changes, leads to the appearance of a Class III prognathic mandibular profile.
Age Factors↗
Localisation of deformations of the midfacial complex in subjects with class III malocclusions employing thin-plate spline analysis.
This study determines deformations of the midface that contribute to a class III appearance, employing thinplate spline analysis. A total of 135 lateral cephalographs of prepubertal children of European-American descent with either class III malocclusions or a class I molar occlusion were compared. The cephalographs were traced and checked, and 7 homologous landmarks of the midface were identified and digitised. The data sets were scaled to an equivalent size and subjected to Procrustes analysis. These statistical tests indicated significant differences (P < 0.05) between the averaged class I and class III morphologies. Thinplate spline analysis indicated that both affine and nonaffine transformations contribute towards the total spline for the averaged midfacial configuration. For nonaffine transformations, partial warp 3 had the highest magnitude, indicating the large scale deformations of the midfacial configuration. These deformations affected the palatal landmarks, and were associated with compression of the midfacial complex in the anteroposterior plane predominantly. Partial warp 4 produced some vertical compression of the posterior aspect of the midfacial complex whereas partial warps 1 and 2 indicated localised shape changes of the maxillary alveolus region. large spatial-scale deformations therefore affect the midfacial complex in an anteroposterior axis, in combination with vertical compression and localised distortions. These deformations may represent a developmental diminution of the palatal complex anteroposteriorly that, allied with vertical shortening of midfacial height posteriorly, results in class III malocclusions with a retrusive midfacial profile.
Cephalometry↗
Thin-plate spline analysis of the cranial base in subjects with Class III malocclusion.
The role of the cranial base in the emergence of Class III malocclusion is not fully understood. This study determines deformations that contribute to a Class III cranial base morphology, employing thin-plate spline analysis on lateral cephalographs. A total of 73 children of European-American descent aged between 5 and 11 years of age with Class III malocclusion were compared with an equivalent group of subjects with a normal, untreated, Class I molar occlusion. The cephalographs were traced, checked and subdivided into seven age- and sex-matched groups. Thirteen points on the cranial base were identified and digitized. The datasets were scaled to an equivalent size, and statistical analysis indicated significant differences between average Class I and Class III cranial base morphologies for each group. Thin-plate spline analysis indicated that both affine (uniform) and non-affine transformations contribute toward the total spline for each average cranial base morphology at each age group analysed. For non-affine transformations, Partial warps 10, 8 and 7 had high magnitudes, indicating large-scale deformations affecting Bolton point, basion, pterygo-maxillare, Ricketts' point and articulare. In contrast, high eigenvalues associated with Partial warps 1-3, indicating localized shape changes, were found at tuberculum sellae, sella, and the frontonasomaxillary suture. It is concluded that large spatial-scale deformations affect the occipital complex of the cranial base and sphenoidal region, in combination with localized distortions at the frontonasal suture. These deformations may contribute to reduced orthocephalization or deficient flattening of the cranial base antero-posteriorly that, in turn, leads to the formation of a Class III malocclusion.
Case-Control Studies↗
Finite element analysis of the cranial base in subjects with Class III malocclusion.
The association between cranial base morphology and Class III malocclusion is poorly understood. This study analyses local shape- and size differences in cranial base configurations of Class I and Class III subjects, employing finite element (FEM) analysis. Seventy-three prepubertal European-American children with Class III malocclusion were compared to their counterparts with a normal, Class I molar occlusion. Lateral cephalographs were traced, checked and subdivided into age- and sex-matched groups. Thirteen points on the cranial base were identified and digitized, providing a geometrical cranial base representation. Average cranial geometries were scaled to an equivalent size and a FEM analysis, capable of depicting and quantifying local shape- and size-change, employed to highlight regionalized, morphological differences. While the anterior cranial base was more homogeneous for shape-change, significant, localized anisotropy in the posterior regions of the cranial base and around sella turcica was evident. For size-change, areas of negative allometry were located posteriorly, but dilations in the mid- and anterior cranial base also were apparent. It is concluded that morphological alterations within the petro-occipital complex accompanied by changes in the sphenoidal and ethmoidal regions induce deviation from a normal cranial base configuration to one associated with deficient orthocephalization and an appearance of Class III malocclusion.
Age Factors↗