Relation between Metopic Suture Persistence and Frontal Sinus Development

The frontal bone develops as two halves, which further unite in a single bone by the closure of the mid-sagittal metopic suture, typically by the end of the first postnatal year. The frontal sinus begins to expand into the orbital and vertical plates of the frontal bone postnatally and reaches the level of the nasion by the fourth year of age. At this time, the metopic suture is usually entirely closed. However, in the cases of failed closure of the metopic suture, its relationship to the frontal sinus development is still obscure. Here, we review the relevant literature and discuss the frontal bone development and maturation, from the viewpoint of the frontal sinus pneumatization in relation to the metopic craniosynostosis and failed closure of the metopic suture. The peculiar to the metopic skulls frontal bone configuration is rather an expression of the underlying neural mass demands than a consequence of the metopic suture persistence. Furthermore, the persistent metopic suture is frequently associated with a frontal sinus underdevelopment. It seems that the metopic suture does not inhibit the frontal sinus pneumatization itself, but rather both traits are an expression or an aftereffect of a certain condition during the early development

A CT-study of the Cranial Suture Morphology and its Reorganization during the Obliteration

Obliteration of the cranial sutures is an age-dependent process. Its premature occurrence (craniosynostosis) causes different craniofacial deformations, dependent on the affected suture(s). The understanding of the suture morphology and the remodeling processes during the obliteration is essential for early diagnosis and treatment of the premature closure. This study aimed to investigate the morphology of open and obliterated sutures and to perform comparison analysis on the 3D images obtained by both industrial and medical computed tomography (CT) systems with various resolutions. A segment of the sagittal suture of dry skulls of known age and sex was scanned using Nikon XTH 225, an industrial CT system, developed by Nikon Metrology. The same section of the sagittal suture was observed on patients undergoing CT scanning with a multislice system Toshiba Aquilion 64 with 0.5 mm slice thickness. For 3D visualization, VGStudioMax 2.2 were used. The suture morphology was observed in coronal section on sequential 2D slices. Micro-CT (μCT) scanning of dry skulls enabled calculation of the morphometric parameters and visualization of the microarchitecture of the suture and its reorganization during the obliteration, unlike the CT imaging of patients, where the sutures were scarcely discernable. In the entirely open sections of the suture the bone edges were separated by a gap of various widths. As the obliteration proceeded, the gap gradually reduced and the bone edges got into a contact. In the fi nal stages, the traces from the contact faded away and the sutural area became a homogenous structure of increased integrity. The μCT scanning of dry bones is a powerful non-destructive technique for examination of the suture morphology. Remodeling of the suture during the obliteration leads to gradually diminishing of the gap between the bone edges to their entire coalescence

A Geometric Morphometric Study on Sexual Dimorphism in Viscerocranium

The level of sexual dimorphism manifested by human bones is an important factor for development of effective sex estimation methods. The aim of the study was to investigate the sexual dimorphism in the size and shape of the viscerocranium using geometric morphometric techniques. It also aimed to explore the sex differences in distinct viscerocranial regions and to establish the most dimorphic region with regard to size and shape. Computed tomography images of 156 males and 184 females were used in the study. Three-dimensional coordinates of 31 landmarks were acquired. Five landmark configurations were constructed from the viscerocranium and its orbital, nasal, maxillary, and zygomatic region. Generalized Procrustes superimposition, principal component analysis, and discriminant analysis were applied to each configuration. The significance of the sex differences in size and shape was assessed and significant differences were found in all configurations. The highest accuracy was obtained from both shape and size of the whole viscerocranium. Based on size only, the highest accuracy was achieved by the nasal region. The accuracy based on shape was generally low for all configurations, but the highest result was attained by the orbital region. Hence, size is a better sex discriminator than shape