Morphometric analysis of prenatally exposed children to anticonvulsant drugs

OBJECTIVE: To evaluate the morphometric effect of prenatal exposure to phenytoin, phenobarbital and carbamazepine on the shape of the maxilla the posterior and overall cranial base. MATERIAL AND METHODS: Sample selection: This study is a retrospective analyses of lateral cephalograms of 67 (Phenobarbital =21, Phenytoin=21, Carbamazepine=25) children age 6 to 16 who had been exposed prenatally to one of these drugs and compared to a control group of 44 unexposed children of the same age. Cephalometric films were digitized and anatomical landmarks identified by a single investigator. Landmarks were chosen to outline the maxilla, the posterior and overall cranial base. Morphometric analysis including Procrustes superimposition was used to compare the exposed children to the control group. Principal components analysis (PCA) and MANOVA tests were performed to determine the differences between the two groups. RESULTS: The superimposed average showed a significant difference between the two groups. In the exposed group, the anterior cranial base was vertically shorter. Glabella was more inferior and anterior relative to nasion, and the nasal tip was more superior and posterior. Orbitale was more inferior and posterior, suggesting a more posterior articulation with maxilla. The posterior cranial base was vertically taller and sagittally shorter. Also in the exposed group, the maxilla was vertically shorter. CONCLUSION: These results demonstrate a shorter, retrusive maxilla that articulates more posteriorly with a shorter anterior cranial base, confirming the midface hypoplasia of traditional anticonvulsant facies

Covariance patterns between ramus morphology and the rest of the face: A geometric morphometric study

OBJECTIVE The growth and development of the mandible strongly depend on modeling changes occurring at its ramus. Here, we investigated covariance patterns between the morphology of the ramus and the rest of the face. METHODS Lateral cephalograms of 159 adults (55 males and 104 females) with no history of orthodontic treatment were collected. Geometric morphometrics with sliding semi-landmarks was used. The covariance between the ramus and face was investigated using a two-block partial least squares analysis (PLS). Sexual dimorphism and allometry were also assessed. RESULTS Differences in the divergence of the face and anteroposterior relationship of the jaws accounted for 24.1% and 21.6% of shape variation in the sample, respectively. Shape variation was greater in the sagittal plane for males than for females (30.7% vs. 17.4%), whereas variation in the vertical plane was similar for both sexes (23.7% for males and 25.4% for females). Size-related allometric differences between the sexes accounted for the shape variation to a maximum of 6% regarding the face. Regarding the covariation between the shapes of the ramus and the rest of the face, wider and shorter rami were associated with a decreased lower anterior facial height as well as a prognathic mandible and maxilla (PLS 1, 45.5% of the covariance). Additionally, a more posteriorly inclined ramus in the lower region was correlated with a Class II pattern and flat mandibular plane. CONCLUSIONS The width, height, and inclination of the ramus were correlated with facial shape changes in the vertical and sagittal planes

Craniofacial growth and development in modern humans and Neanderthals

This thesis assesses craniofacial growth, development and the dynamics of developmental interactions among cranial regions in modern humans and Neanderthals. To these ends, virtual segmentation, landmarking and Geometric Morphometrics (GM) are applied to an ontogenetic series of the whole crania of 68 H. sapiens and 12 H. neanderthalensis. First, the ontogenetic shape and form changes in the cranial vault, base and face are explored, and the locations and magnitudes of these changes are discussed. Secondly, allometric scaling is tested for differences among different age classes in the three regions of the cranium. In addition, the degree of covariation among these and how it changes over time is investigated.The study then focuses on interactions among facial regions. First, similar analyses as those used in the study of the cranium are applied to compare growth, development and covariation among parts of the face in different age classes. Additionally, a sample of 227 modern humans from 0 to 6 years of age is analysed using path analysis, to investigate the cascade of interactions and relative contributions of soft tissue and skeletal elements to the overall growth and development of the face. Last, the facial morphology of H. sapiens is compared to that of H. neanderthalensis and their ontogenetic trajectories are tested for divergence. Novel method registration-free colour maps are used to visualise regional changes during growth and development and to compare the morphologies of the two species. Covariation among facial elements is also compared to assess potential differences in developmental interactions. In modern humans, the results show that allometry and covariation change significantly among age classes and between cranial regions during ontogeny and that covariation is stronger in younger subadults than in older subadults and adults. Among modern humans, significantly divergent trajectories are observed between age classes during ontogeny in all three cranial regions. In the modern human face, allometric scaling also differs among age stages in each region. Interestingly, covariation among facial regions becomes progressively non-significant with time, with the exception of those including the nose and maxilla. Path analysis in modern humans shows a large contribution of the proxy used for nasal septum to the overall facial development. Soft tissues contribute only locally to the development of some skeletal elements of the face. Major aspects of the differences between adult modern humans and Neanderthals are already present in the youngest individuals. However, additional differences arise through differences in the degree of change in facial size and significantly divergent allometric trajectories. Analyses of covariation among Neanderthal facial regions suffer from small sample size but, where significant, suggest that the interactions among cranial components are similar to those in modern humans, with some differences

The development of bite force resistance and cranial form in Neanderthals and modern humans

The general aim of the thesis is to understand how biting mechanics interact with cranial form to impact post-natal craniofacial ontogeny in modern humans and Neander-thals. To this end, CT scans of ontogenetic samples of 12 Neanderthal and 63 modern human crania were collected and a series of reconstructions of Neanderthal crania were carried out. Geometric morphometric and multivariate regression approaches were used to create a craniofacial growth model for each species. Using these two models, 3D virtual crania representing the mean adult, juvenile, and infant were extracted in each species. These 6 mean crania were then converted into finite element models and used to conduct two biting simulations: at the right second premolar or second deciduous molar (RP2/RdM2) and right first incisor (RI1), applying the same muscle forces for all models because these are unknown especially for Neanderthals. This study compared modes and magnitudes of deformation, and the distribution and magnitude of tensile and compres-sive strains between the mean infant, juvenile, and adult models within each species and between the two species at each age stage.The morphometric analyses indicate that cranial ontogenetic trajectories differ be-tween modern humans and Neanderthals. The finite element analyses (FEA) in both bit-ing simulations indicate that, within each species, the mean infant juvenile and adult mod-els deform differently. Further, in both biting simulations, the highest strains are localised over similar regions of the cranium; over the anterior maxilla, orbits, and anterior subna-sal surface. Modern humans and Neanderthals deform differently and show differences in the development of biting forces during RI1 and RP2/RdM2 biting simulations at each stage. These findings confirm that modern human and Neanderthal crania have divergent postnatal developmental trajectories and manifest differences in the resistance of masti-catory system loadings throughout life. Differences in modes of deformation and so, strain distributions are considered in light of known differences in craniofacial bone growth remodeling between Neanderthals and modern humans. The findings show some correspondence with the remodeling maps for both species, particularly during RP2/RdM2 biting simulations. They do not falsify the hypothesis that facial remodeling differences arise because of differences in load resistance, and so, in the strain environment during post-natal development. As such, how differences among adult crania arise through post-natal interactions between form and functional loadings merits further investigation through more detailed analyses of a wider range of loading scenarios

Number of Teeth Is Related to Craniofacial Morphology in Humans.

One of the most common dental anomalies in humans is the congenital absence of teeth, referred to as tooth agenesis. The association of tooth agenesis to craniofacial morphology has been previously investigated but remains unclear. We investigated this association by applying geometric morphometric methods in a large sample of modern humans. In line with previous studies, we report here that a reduced teeth number is linked to a less convex profile, as well as to a shorter face. The effects were similar for males and females; they increased as the severity of the tooth agenesis increased and remained unaltered by the inclusion of third molars and of allometry in the analysis. Furthermore, in cases with tooth agenesis only in the maxilla, there was no detectable effect in mandibular shape, whereas maxillary shape was affected independently of the location of missing teeth. The robustness of the present sample along with the shape analysis and the statistical approach applied, allowed for thorough testing of various contributing factors regarding the presence but also the magnitude of effects. The present findings suggest a relationship between number of teeth and overall craniofacial development and have evolutionary implications

Palatal development of preterm and low birthweight infants compared to term infants – What do we know? Part 2: The palate of the preterm/low birthweight infant

BACKGROUND: Well-designed clinical studies on the palatal development in preterm and low birthweight infants are desirable because the literature is characterized by contradictory results. It could be shown that knowledge about 'normal' palatal development is still weak as well (Part 1). The objective of this review is therefore to contribute a fundamental analysis of methodologies, confounding factors, and outcomes of studies on palatal development in preterm and low birthweight infants. METHODS: An electronic literature search as well as hand searches were performed based on Cochrane search strategies including sources of more than a century in English, German, and French. Original data were recalculated from studies which primarily dealt with both preterm and term infants. The extracted data, especially those from non-English paper sources, were provided unfiltered for comparison. RESULTS: Seventy-eight out of 155 included articles were analyzed for palatal morphology of preterm infants. Intubation, feeding tubes, feeding mode, tube characteristics, restriction of oral functions, kind of diet, cranial form and birthweight were seen as causes contributing to altered palatal morphology. Changes associated with intubation concern length, depth, width, asymmetry, crossbite, and contour of the palate. The phenomenon 'grooving' has also been described as a complication associated with oral intubation. However, this phenomenon suffers from lack of a clear-cut definition. Head flattening, pressure from the oral tube, pathologic or impaired tongue function, and broadening of the alveolar ridges adjacent to the tube have been raised as causes of 'grooving'. Metrically, the palates of intubated preterm infants remain narrower, which has been examined up to the age of the late mixed dentition. CONCLUSION: There is no evidence that would justify the exclusion of any of the raised causes contributing to palatal alteration. Thus, early orthodontic and logopedic control of formerly orally intubated preterm infants is recommended, as opposed to non-intubated infants. From the orthodontic point of view, nasal intubation should be favored. The role that palatal protection plates and pressure-dispersing pads for the head have in palatal development remains unclear

Influence of isolated cleft palate and palatoplasty on the face

INTRODUCTION: The literature has demonstrated that alterations in craniofacial morphology characterizing individuals with cleft palate are observed in both operated and unoperated patients. OBJECTIVE: This study evaluated the influence of isolated cleft palate and palatoplasty on the face, based on facial analysis. MATERIAL AND METHODS: Lateral facial photographs of the right side of 85 young adult patients with cleft palate were analyzed, of whom 50 were operated on and 35 had never received any previous surgical treatment. The nasolabial angle and zygomatic projection were used to define the maxillary position in the face. Mandibular positioning was classified as Pattern I, II and III. RESULTS: Patients were distributed into 54.12% as Pattern I, 32.94% Pattern II and 12.94% Pattern III. Distribution of facial patterns did not show statistically significant differences between groups (p>;0.05). Although palatoplasty did not influence the facial pattern, the zygomatic projection was vulnerable to plastic surgeries. Twenty-eight percent of the patients in the operated group showed zygomatic deficiency, compared to only 8.5% in the unoperated group. CONCLUSIONS: In patients with isolated cleft palate, palatoplasty may influence negatively the sagittal behavior of the maxilla, according to the zygomatic projection of the face, though without compromising the facial pattern

Palatal development of preterm and low birthweight infants compared to term infants – What do we know? Part 1: The palate of the term newborn

BACKGROUND: The evidence on prematurity as 'a priori' a risk for palatal disturbances that increase the need for orthodontic or orthognathic treatment is still weak. Further well-designed clinical studies are needed. The objective of this review is to provide a fundamental analysis of methodologies, confounding factors, and outcomes of studies on palatal development. One focus of this review is the analysis of studies on the palate of the term newborn, since knowing what is 'normal' is a precondition of being able to assess abnormalities. METHODS: A search profile based on Cochrane search strategies applied to 10 medical databases was used to identify existing studies. Articles, mainly those published before 1960, were identified from hand searches in textbooks, encyclopedias, reference lists and bibliographies. Sources in English, German, and French of more than a century were included. Data for term infants were recalculated if particular information about weight, length, or maturity was given. The extracted values, especially those from non-English paper sources, were provided unfiltered for comparison. RESULTS: The search strategy yielded 182 articles, of which 155 articles remained for final analysis. Morphology of the term newborn's palate was of great interest in the first half of the last century. Two general methodologies were used to assess palatal morphology: visual and metrical descriptions. Most of the studies on term infants suffer from lack of reliability tests. The groove system was recognized as the distinctive feature of the infant palate. The shape of the palate of the term infant may vary considerably, both visually and metrically. Gender, race, mode of delivery, and nasal deformities were identified as causes contributing to altered palatal morphology. Until today, anatomical features of the newborn's palate are subject to a non-uniform nomenclature. CONCLUSION: Today's knowledge of a newborn's 'normal' palatal morphology is based on non-standardized and limited methodologies for measuring a three-dimensional shape. This shortcoming increases bias and is the reason for contradictory research results, especially if pathologic conditions like syndromes or prematurity are involved. Adequate measurement techniques are needed and the 'normal palatal morphology' should be defined prior to new clinical studies on palatal development