The early tetrapod Eoherpeton watsoni is known from the mid- to late Carboniferous (late Viséan to Namurian, approximately 346–313 Ma) of Scotland. The holotype is made up of a nearly complete but crushed skull with postcranial fragments. The skull anatomy of Eoherpeton was first described over 40 years ago; however, many details are obscured due to deformation of the specimen, including internal bone surfaces, the palatal bones and dentition, and suture morphology. Most phylogenetic analyses place Eoherpeton as an embolomere/reptilomorph on the lineage leading to amniotes, making it a key taxon for understanding anatomical changes during the fish-tetrapod transition. In this paper, we scanned the holotype using micro-computed tomography and digitally prepared the specimen. Based on these data, we present a revised description of the skull, including sutural morphology, that supplements and amends previous descriptions. New anatomical findings include the presence of a previously unknown tooth-bearing vomer, additional information on the shape of the basipterygoid processes and jaw joint, the ability to visualise the full extent of the pterygoid, and confirmation of the arrangement of the coronoid series. We also note the size of the pterygoid flange, which is larger than previously described for Eoherpeton. The pterygoid flange is widely considered to be characteristic of amniotes and serves as the origin of the medial pterygoideus muscle. The differentiation of the adductor muscles and appearance of medial pterygoideus are thought to have permitted a static pressure bite in amniotes, potentially resulting in greater bite forces and increased dietary range. Thus, the presence and extent of the pterygoid flange in Eoherpeton suggests this feature (and associated changes in feeding mechanism) may have evolved earlier than previously thought. Finally, the skull was digitally repaired and retrodeformed to create a new, hypothetical three-dimensional reconstruction of the skull of Eoherpeton.

Each piece of data is valuable for unearthing the earliest history of tetrapod origin. Despite frequently incomplete preservation, each skeletal element provides important information on the morphology, phylogeny and faunistic diversity of early tetrapodomorphs. We describe here new and earlier collected material from the fossil vertebrate site Yam-Tesovo on the Oredezh River (Leningrad Region, northwestern Russia) in the deposits of the Yam-Tesovo Formation within the Amata Regional Stage (?lowermost Frasnian, Upper Devonian). Upon similarity of their dermal ornamentation, two mandibular fragments are suggested to belong to the new tetrapodomorph taxon Rubrognathuskuleshovi n. gen. et sp. This species demonstrates a general ‘elpistostegalian' morphological pattern with some early tetrapod characters. The new taxon is characterised by an almost closed intercoronoid fossa, a prearticular that is strongly convex in section and bearing small teeth along its dorsal margin, low vertical coronoid laminae and coronoid fangs that enter the coronoid tooth row. The mandibular canal runs partly in open groove or opens to the surface by a row of large pores. The dermal ornament consists of a network of small ridges forming tubercles in the nodes. The postfrontal assigned to Tetrapodomorpha shows a ‘tetrapod-like' pits-and-ridges sculpturing and a supraorbital ridge characteristic of early tetrapods as well as ‘elpistostegalians'. Its long posterolateral bone margin demonstrates a lateral projection similar to that in Tiktaalik and unknown in other ‘elpistostegalians' and early tetrapods. An unusually flattened vomer is doubtfully related to the tetrapodomorph genus Livoniana Ahlberg, Lukševičs & Mark-Kurik, 2000, based upon characteristic multiple tooth rows. Teeth in rows decrease labially and show no clearly enlarged fang pairs. New finds of the last two decades present the earliest records of some tetrapod characters in non-limbed tetrapodomorphs. This challenges previous hypotheses on the origin of tetrapods.

Asymmetries are found in every living being. A non-symmetrical structure is not necessarily pathological. Why then, is the diagnosis of asymmetry relevant for us as practitioners? In orthodontics, we can anticipate difficulties with treatment if we are well informed about the principles of symmetry and thoroughly familiar with craniofacial growth.

Severe mandibular asymmetry is relatively rare, appears early and becomes apparent at first sight to the practitioner. We find it associated with syndromes in patients for whom early multidisciplinary treatment is indicated.

Dyssymetry is a defect rather than an absence of symmetry. It is a mild form of asymmetry where the line between pathological and nonpathological is still unclear. The face can present different types of dyssymmetries including the whole gamut ranging from dental imbalance to imbalances of the jaws to cranial imbalances, each with its own signature that leaves its characteristic mark on the face. When dealing with mandibular laterodymorphias, the diagnosis must be made early in order to initiate an individualized treatment plan. We are providing some summary fact sheets that make it possible for the practitioner to clearly distinguish between the principal mandibular anomalies.

Researchers conduct their studies of the mandible by placing it in the “exploitable” framework of systemic biology. They investigate an anomaly of its development, promandibulia, or mandibular prognathism, within this context, by studying molecular and cellular reactions at the level of their constitutive elements and their integration during the course of mandibular development. Here we propose a new etiological and therapeutic approach for this malformation.

The morphological particularities of the posteriorly rotated mandible, first described by A. Björk, may correspond to extremely variable clinical situations. We can derive important information by analyzing the forms and proportions of different mandibular entities. This article proposes to illustrate the most frequently encountered situations by describing a number of cases of posterior rotation and by explaining how Delaire’s architectural analysis can be used in clinical practice.

Hemimandibulectomy should be avoided whenever possible, as it results in significant deterioration in quality of life. If hemimandibulectomy is unavoidable, attempts should be made to reconstruct the bone and soft tissue defect by free tissue transfer or a pedicled flap such as a pectoralis major myocutaneous flap. Bony reconstruction may become challenging when oncological safety mandates removal of the vertical ramus or the condyle. Elderly patients and those with significant co-morbidity are not suitable for prolonged microvascular surgery. Oral cancer is a disease of impoverished nations, where most health institutions may not have the infrastructure to offer microvascular reconstruction. The pectoralis major myocutaneous flap, the workhorse for reconstruction of such defects, occasionally has limitations in terms of bulk, limited arc of rotation, shoulder dysfunction etc. Therefore, hemimandibulectomy and primary mucosal closure continues to be a common procedure in developing nations. A simple technique is proposed with which to improve cosmesis following hemimandibulectomy, utilising the locally available muscle remnants. In highly selected patients, the remaining muscles can be approximated to prevent the lateral hollow that is a common but unacceptable sequel to hemimandibulectomy.

Finite Element Modeling was used to compare the efficacy of common screw-plate configurations used for fixation of parasymphyseal fractures of the mandible. Measures of Von Mises stress on the screw bone interface, as well as principal strain in the reduced fracture region, were used in this comparison. This study also explored differences between orthotropic and isotropic modeling practices and compared the effect of mastication forces on both the fractured and intact halves of the mandible. The results of this analysis showed no major differences between configurations from a mechanistic point of view. This suggests that the use of any of the studied screw-plate configurations will not increase chances for post-operative complications. Furthermore, little difference is seen between analyses with either orthotropic or isotropic material properties. The inclusion of orthotropic properties can thus be avoided in future studies with similar boundary and plating conditions. Mastication ipsilateral to the fracture increases Von Mises stress 2 to 4 times, and should be avoided during early healing periods. These recommendations only apply to patients whose fractures mimic the finite-element model.

Aim: To evaluate the impact of positive sleep nasendoscopy, with simultaneous mandibular advancement, on the outcome of mandibular advancement splint therapy in 120 subjects with sleep-related breathing disorders.

Methodology: Overnight polysomnography and sleep nasendoscopy were performed prior to splint therapy. Follow-up sleep studies, with the appliance in situ, were undertaken for those patients with obstructive sleep apnoea. Subjective outcome measures assessed daytime sleepiness and snoring.

Results: One hundred and seven (89 per cent) subjects completed the study. Follow-up sleep studies confirmed the efficacy of treatment, with patients showing a mean reduction in apnoea/hypopnoea index (from 18.9 to 4.9, p<0.001), Epworth sleepiness scale scores (from 11 to seven, p<0.001) and partner-recorded snoring scores (from 14 to eight, p<0.001).

Conclusion: Sleep nasendoscopy, with concomitant mandibular advancement to mimic the treatment effect, could be of prognostic value in determining successful mandibular advancement splint therapy.

Ossifying fibroma is an uncommon benign osteogenic neoplasm arising from cells of the periodontal ligament, typically with a slowly progressive enlargement of the affected bone. The neoplasm sometimes presents with hyperparathyroidism, most of which cases are due to familial parathyroid tumours. We report a rare case of ossifying fibroma of the mandible which showed very rapid growth and presented with primary hyperparathyroidism due to non-familial parathyroid adenoma. Despite improvement of parathyroid dysfunction after removal of the parathyroid adenoma, the tumour continued to grow very aggressively. The case required partial mandibular resection for complete resection of the tumour, and fixation of the remaining mandible with a titanium plate.

A biomechanical approach is used to model the mandibles of extant carnivoran predators (felids, canids, and hyaenids) as beams to gain insight into feeding behaviours. Because bite force applied at any given point along the mandible should be proportional to external dimensions at an analogous location (interdental gaps) on the mandible, patterns of variation in these dimensions will reflect the adaptation of the jaw to specific loads. The mandibular force profiles of extant carnivorans closely reflect particular feeding behaviours. Solitary hunters relying on a powerful canine bite to subdue their prey have a strong mandibular symphysis, while pack hunters delivering shallow bites have a relatively weaker one. Symphyseal shape also gives insight into the feeding behaviour of a predator: (1) a deeper-than-long symphysis indicates that stresses induced by the canine bite (or while cracking bones with the anterior dentition) are more important than those induced by struggling prey; (2) an equidimensional symphysis indicates that the symphyseal region is optimally designed to resist torsional stresses induced during prey capture and/or bone cracking; (3) a longer-than-deep symphysis indicates that stresses related to prey capture are predominant over those induced by the canine bite or while cracking bone. Mandibular force profiles of juvenile carnivorans also reflect documented ontogenetic changes in feeding behaviour. Because variation in mandibular cross-sectional properties are interpretable in terms of documented behaviours among extant predators, mandibular force profiles are developed to gain insight into the feeding behaviour of two extinct predators, Panthera atrox and Canis dirus. Results indicate that the feeding behaviour of P. atrox differed slightly from that of modern lions, as the powerful paws restrained prey more efficiently, while C. dirus hunted in a similar fashion to the gray wolf, although it may not have been an efficient bone cracker. Both extinct predators are inferred to have had a more powerful bite than their extant relatives.

Ewings’ sarcoma involving the facial bones is rare although it is the second most frequent bone malignancy. For the diagnosis a biopsy is needed. Currently the treatment is the combination of chemotherapy and radiotherapy with surgery indicated in only a few instances. We report a case of Ewing’s sarcoma of the mandible and describe its clinicopathologic features and the treatment of this disease.