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Previously, we reported an immediate emergence of new lower jaw input to the anterior forepaw barrel subfield (FBS) in primary somatosensory cortex (SI) following forelimb deafferentation. However, a delay of 7 weeks or more post-amputation results in the presence of this new input to both anterior and posterior FBS. The immediate change suggests pre-existing latent lower jaw input in the FBS, whereas the delayed alteration implies the involvement of alternative sources. One possible source for immediate lower jaw responses is the neighboring lower jaw barrel subfield (LJBSF). We used anatomical tracers to investigate the possible projection of LJBSF to the FBS in normal and forelimb-amputated rats. Our findings are as follows: (1) anterograde tracer injection into LJBSF in normal and amputated rats labeled fibers and terminals exclusively in the anterior FBS; (2) retrograde tracer injection in the anterior FBS in normal and forelimb-amputated rats, heavily labeled cell bodies predominantly in the posterior LJBSF, with fewer in the anterior LJBSF; (3) retrograde tracer injection in the posterior FBS in normal and forelimb-amputated rats, sparsely labeled cell bodies in the posterior LJBSF; (4) retrograde tracer injection in anterior and posterior FBS in normal and forelimb-amputated rats, labeled cells exclusively in ventral posterior lateral (VPL) nucleus and posterior thalamus (PO); (5) retrograde tracer injection in LJBSF-labeled cell bodies exclusively in ventral posterior medial thalamic nucleus and PO. These findings suggest that LJBSF facilitates rapid lower jaw reorganization in the anterior FBS, whereas VPL and/or other subcortical sites provide a likely substrate for delayed reorganization observed in the posterior FBS.

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The soft tissues have a considerable impact on whether the results of facial feminization surgery are favorable. Complications or suboptimal results related to the soft tissue may be due to poor choice of surgical approach, improper execution of the surgical technique, a lack of assistance when resuspending the soft tissues during closure, or deficient readaptation of the overlying soft tissue to the new bone contour. This article identifies the possible poor soft-tissue outcomes that may occur after facial feminization bone surgery, describing strategies to prevent them and treatment alternatives.

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Mammalian dentition exhibits distinct heterodonty, with more simple teeth located in the anterior area of the jaw and more complex teeth situated posteriorly. While some region-specific differences in signalling have been described previously, here we performed a comprehensive analysis of gene expression at the early stages of odontogenesis to obtain complete knowledge of the signalling pathways involved in early jaw patterning. Gene expression was analysed separately on anterior and posterior areas of the lower jaw at two early stages (E11.5 and E12.5) of odontogenesis. Gene expression profiling revealed distinct region-specific expression patterns in mouse mandibles, including several known BMP and FGF signalling members and we also identified several new molecules exhibiting significant differences in expression along the anterior-posterior axis, which potentially can play the role during incisor and molar specification. Next, we followed one of the anterior molecules, SATB2, which was expressed not only in the anterior mesenchyme where incisor germs are initiated, however, we uncovered a distinct SATB2-positive region in the mesenchyme closely surrounding molars. Satb2-deficient animals demonstrated defective incisor development confirming a crucial role of SATB2 in formation of anterior teeth. On the other hand, ectopic tooth germs were observed in the molar area indicating differential effect of Satb2-deficiency in individual jaw regions. In conclusion, our data provide a rich source of fundamental information, which can be used to determine molecular regulation driving early embryonic jaw patterning and serve for a deeper understanding of molecular signalling directed towards incisor and molar development.

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The vascularized periosteal free flap transposes a non-irradiated soft tissue with neoangiogenesis, bone induction, and osteogenesis qualities. A surgical technique using a humeral periosteal free flap is described for the treatment of recurrent osteoradionecrosis of the lower jaw. The humeral periosteal free flap is a technique associated with low morbidity. The procedure described avoids sacrificing major vessels as seen in other common flap procedures. Hence, this revascularization approach is equivalent to a prevention technique that should be considered early in the development of osteoradionecrosis to avoid further damage and challenging reconstruction.

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OBJECTIVE: Aim: Optimization of the clinical and diagnostic examination algorithm of patients with cross bite, aggravated by cranio-mandibular dysfunction and postural disorders. PATIENTS AND METHODS: Materials and Methods: 22 patients aged 13-16 years with cross bite with displacement of the lower jaw were examined. The first group consisted of 15 people with a right-sided displacement of the lower jaw, the second - 7 patients with a left-sided one. The condition of the musculoskeletal system was assessed by the position of the head, shoulders, shoulder blades, back (curvature of the spine), legs, chest shape, and abdomen. To determine the state of stability of the body in space, posturological and kinesiological tests were performed. The location of TMJ elements was evaluated on orthopantomograms. Statistical processing of the material was carried out with the help of the "Excel" license package. RESULTS: Results: 63.64% of patients with a cross bite have disorders of the musculoskeletal system: scoliotic posture - 40.91% and scoliosis - 22.73%. TMJ dysfunction was detected in all examined patients. It was established that the anatomical and topographic features of the joint elements depend on the side of the lower jaw displacement. CONCLUSION: Conclusions: The functional imbalance of all structural elements of the musculoskeletal system and the cranio-mandibular complex determined during the research proved the need to optimize the clinical-diagnostic algorithm: consultation of a traumatologist-orthopedic doctor, X-ray examination of TMJ, conducting posturological tests.

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BACKGROUND: The study examines a sample of patients presenting for viscerocranial computer tomography that does not display any apparent signs of asymmetry, assesses the three-dimensional congruency of the mandibular ramus, and focuses on differences in age and gender. METHODS: This cross-sectional cohort study screened viscerocranial CT data of patients without deformation or developmental anomalies. Segmentations were obtained from the left and right sides and superimposed according to the best-fit alignment. Comparisons were made to evaluate three-dimensional congruency and compared between subgroups according to age and gender. RESULTS: Two hundred and sixty-eight patients were screened, and one hundred patients met the inclusion criteria. There were no statistical differences between the left and right sides of the mandibular ramus. Also, there were no differences between the subgroups. The overall root mean square was 0.75 ± 0.15 mm, and the mean absolute distance from the mean was 0.54 ± 0.10 mm. CONCLUSION: The mean difference was less than one millimetre, far below the two-millimetre distance described in the literature that defines relative symmetry. Our study population displays a high degree of three-dimensional congruency. Our findings help to understand that there is sufficient three-dimensional congruency of the mandibular ramus, thus contributing to facilitating CAD-CAM-based procedures based on symmetry for this specific anatomic structure.

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Xanthogranulomatous inflammation (XGI) is an uncommon type of chronic inflammation and is histologically characterized by foamy histiocytes and giant cells. The most common sites of occurrence are kidneys and gallbladder. The etiology remains controversial. Involvement of the lower jaw bone is rare. In this study, we report a case of XGI presenting in the lower jaw.

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OBJECTIVE: To assess the prevalence and quantitative characteristics of skeletal asymmetries of the body and lower jaw branches in three-dimensional space. MATERIALS AND METHODS: Using depersonalized data archive, of 400 CBCT scans, forty studies were picked randomly. Patients aged 25 to 35 years participated in research, no history of maxillofacial reconstructive surgery; gender, race, and facial anomaly were ignored. Three experienced doctors, independently, identified 15 reference points on radiographic images of AUTOPLAN software. Expert consensus found in the orientation determination. Six planes and eight points were constructed, using Math algorithms and the Python OOP; body and branches of the lower jaw length measurements performed and processed automatically. RESULTS: The study identified symmetry, using a method for determining parameters of the lower jaw in 3D space (Priority Reference No.2023100466 at 10.01.2023), modern dentistry research method. Both sides of data obtained shown asymmetry of the body and branches of the lower jaw occurred in 45% (18 people) and 67.5% (27 people) of cases. Forty percent of cases were noted with Mild asymmetry of the lower jaw body (16 people), moderate asymmetry noted in 5% (2 people). These parameters were 57.5% for branches, (23 people) and 10% (4 people). Combined form of anomaly observed in 37.5% (15 people) of cases, among which 12 people (75%) showed adaptive compensation of anomalies, which requires further investigation on a larger number of patients. CONCLUSION: Lower body jaw asymmetry is prevalent (80%). Patients with moderate and serious anomaly form appeared in 15% of cases.

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Mandibular fractures are one of the most frequently observed injuries within craniofacial region mostly due to tumor-related problems and traumatic events, often related to non-linear effects like impact loading. Therefore, a validated digital twin of the mandible is required to develop the best possible patient-specific treatment. However, there is a need to obtain a fully compatible numerical model that can reflect the patients' characteristics, be available and accessible quickly, require an acceptable level of modeling efforts and knowledge to provide accurate, robust and fast results at the same time under highly non-linear effects. In this study, a validated simulation methodology is suggested to develop a digital twin of mandible, capable of predicting the non-linear response of the biomechanical system under impact loading, which then can be utilized to design treatment strategies even for multiple fractures of the mandibular system. Using Computed Tomography data containing cranial (skull) images of a patient, a 3-dimensional mandibular model, which consists cortical and cancellous bones, disks and fossa is obtained with high accuracy that is compatible with anatomical boundaries. A Finite Element Model (FEM) of the biomechanical system is then developed for a three-level validation procedure including (A) modal analysis, (B) dynamic loading and (C) impact loading. For the modal analysis stage: Free-free vibration modes and frequencies of the system are validated against cadaver test results. For the dynamic loading stage: Two different regions of the mandible are loaded, and maximum stress levels of the system are validated against finite element analyses (FEA) results, where the first loading condition (i) transfers a 2000 N force acting on the symphysis region and, the second loading condition (ii) transfers a 2000 N force acting on the left body region. In both cases, equivalent muscle forces dependent on time are applied. For the impact loading stage: Thirteen different human mandibular models with various tooth deficiencies are used under the effects of traumatic impact forces that are generated by using an impact hammer with different initial velocities to transfer the impulse and momentum, where contact forces and fracture patterns are validated against cadaver tests. Five different anatomical regions are selected as the impact site. The results of the analyzes (modal, dynamic and impact) performed to validate the digital twin model are compared with the similar FEA and cadaver test results published in the literature and the results are found to be compatible. It has been evaluated that the digital twin model and numerical models are quite realistic and perform well in terms of predicting the biomechanical behavior of the mandible. The three-level validation methodology that is suggested in this research by utilizing non-linear FEA has provided a reliable road map to develop a digital twin of a biomechanical system with enough confidence that it can be utilized for similar structures to offer patient-specific treatments and can help develop custom or tailor-made implants or prosthesis for best compliance with the patient even considering the most catastrophic effects of impact related trauma.

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The mandible of turtles is rich in osteological characters that are relevant for systematic purposes. Shape variation additionally reflects upon various feeding strategies and are thus informative for the palaeoecological interpretation of extinct species based on fossils. The mandibular anatomy of non-baenid paracryptodires has so far been undescribed. Based on digital segmentation of a computed tomography scan, I herein describe the mandible of the pleurosternid paracryptodire Glyptops ornatus. This taxon has a slender and gracile jaw, with weakly developed muscle attachment sites for adductor muscles (i.e., adductor fossa, coronoid process, and retroarticular process) and strongly reduced triturating ridges. These features are typical for suction-feeding aquatic hunters, thereby contrasting with the robust, durophagous-adapted mandibles of many baenid or compsemydid paracryptodires. In addition, the mandible of G. ornatus is characterized by the presence of a large splenial with a dorsal splenial-dentary contact, the presence of a splenial foramen, and the strong reduction of the foramen dentofaciale majus and the absence of a posterior intermandibular foramen.

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OBJECTIVE: Aim: The aim of the study was to reveal the peculiarities of reparative osteogenesis in experimental lower jaw defect under the conditions of hydroxyapatite-containing osteotropic material application and electrical stimulation. PATIENTS AND METHODS: Materials and Methods: An experiment was conducted on 48 mature male rats of the WAG population. All animals were divided into 4 groups (12 animals in each group). Group 1 included rats that were not subjected to any manipulations. Group 2 included rats that were modeled with a perforated defect of the lower jaw body. Group 3 included rats that were modeled with a perforated defect similar to group 2, the cavity of which was filled with synthetic bone graft "Biomin GT" (RAPID, Ukraine). Group 4 included animals that were modeled with a perforated defect similar to groups 2-3, the cavity of which was filled with synthetic bone graft "Biomin GT". In animals of group 4, a microdevice for electrical action was implanted subcutaneously in the neck area on the side of the simulated bone defect. Morphological and statistical methods were used. RESULTS: Results: The research carried out by the authors proved that the use of the above-mentioned bone replacement material helps to increase the regenerative potential of the bone tissue of the lower jaw, but does not lead to the formation of a full-fledged bone regenerate, as evidenced by the results of the morphometry of the regenerate (the specific volume of lamellar bone tissue accounted for 54.9%); disordered localization of bone beams, which were characterized by reduced signs of mineralization; the presence in connective, osteogenic fibroreticular and lamellar bone tissues the encapsulated bone graft granules with the presence of inflammatory cell infiltration. In cases the combined use of synthetic bone graft "Biomin GT" and electrical stimulation, the authors noted more intensive reparative osteogenesis processes in the bone defect of the lower jaw compared to cases when only one bone graft was used, but they also did not lead to the formation of a full-fledged bone regenerate. CONCLUSION: Conclusions: The experimental and morphological study conducted by the authors proved that the use of hydroxyapatite-containing osteotropic material ("Biomin GT"), especially in cases of its combined use with electrical stimulation, significantly activates reparative osteogenesis in the bone defect of the lower jaw, which does not lead to the formation of a full-fledged bone regenerate.

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Craniofacial development is orchestrated by transcription factor-driven regulatory networks, epigenetic modifications, and signaling pathways. Signaling molecules and their receptors rely on endo-lysosomal trafficking to prevent accumulation on the plasma membrane. ESCRT (Endosomal Sorting Complexes Required for Transport) machinery is recruited to endosomal membranes enabling degradation of such endosomal cargoes. Studies in vitro and in invertebrate models established the requirements of the ESCRT machinery in membrane remodeling, endosomal trafficking, and lysosomal degradation of activated membrane receptors. However, investigations during vertebrate development have been scarce. By ENU-induced mutagenesis, we isolated a mouse line, Vps25ENU/ENU, carrying a hypomorphic allele of the ESCRT-II component Vps25, with craniofacial anomalies resembling features of human congenital syndromes. Here, we assessed the spatiotemporal dynamics of Vps25 and additional ESCRT-encoding genes during murine development. We show that these genes are ubiquitously expressed although enriched in discrete domains of the craniofacial complex, heart, and limbs. ESCRT-encoding genes, including Vps25, are expressed in both cranial neural crest-derived mesenchyme and epithelium. Unlike constitutive ESCRT mutants, Vps25ENU/ENU embryos display late lethality. They exhibit hypoplastic lower jaw, stunted snout, dysmorphic ear pinnae, and secondary palate clefting. Thus, we provide the first evidence for critical roles of ESCRT-II in craniofacial morphogenesis and report perturbation of NOTCH signaling in craniofacial domains of Vps25ENU/ENU embryos. Given the known roles of NOTCH signaling in the developing cranium, and notably the lower jaw, we propose that the NOTCH pathway partly mediates the craniofacial defects of Vps25ENU/ENU mouse embryos.

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For patients with gender dysphoria, gender-affirming surgery of the face has been shown to vastly improve quality of life. The mandible is one area of the face that has distinct feminine and masculine presentations. This article will review gender-affirming surgery of the lower jaw, both for feminization and masculinization. Techniques for bony contouring and soft tissue manipulation will be discussed.

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OBJECTIVE: Aim: To analyze morphometric changes in the structure of bone tissue of the mandibular articular processes and establish their densitometric dependence on the masticatory teeth loss in people of I-II periods of adulthood. PATIENTS AND METHODS: Materials and methods: We analyzed 136 digital CT recordings of human temporomandibular joints. The research subjects were divided into three groups based on the degree of dentition defect acquisition: the first - a limited defect, the second - a final defect, and the third - a preserved dentition (control); by age into two periods of adulthood of postnatal human ontogenesis. Digital statistical analysis of the bone density is presented as M±σ (mean and standard deviation). We compared the experimental groups with the control group using nonparametric statistical analysis. RESULTS: Results: Changes in the vertical dimension of occlusion due to limited masticatory teeth loss acquire variable morphometric features, causing an interrelated process of bone atrophy of the cellular part and the trabecular layer of the mandibular processes. The density of bone tissue of the cortical layer of the articular-fossa quadrant (A-Fh/q) of the articular head of the mandibular process increases on the right with limited defects and decreases with final defects. Indicators of bone densitometry of A-Fh/q on the left is characterized by a decrease with limited defects for individuals of the I-st period of adulthood and an increase in the final defects in the II-nd on the left and right. CONCLUSION: Conclusions: Multifactorial pathomorphological compensatory processes ensure bone density, but with a change in values on the right and a decrease on the left. Morphometric values of trabecular layers, the most vulnerable areas of the neck and base of the mandibular articular processes, indicate the reconstruc¬tion of their bone tissue with limited defects; in the first period of the adulthood, they decrease with a significant predominance on the left.

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Reconstruction of bone defects and maintaining the continuity of the mandible is still a challenge in the maxillofacial surgery. Nowadays, the biomedical research within bone defect treatment is focussed on the therapy of using innovative biomaterials with specific characteristics consisting of the body's own substances. Hydroxyapatite ceramic scaffolds have fully acceptable phase compositions, microstructures and compressive strengths for their use in regenerative medicine. The innovative hydroxyapatite ceramics used by us were prepared using the tape-casting method, which allows variation in the shape of samples after packing hydroxyapatite paste to 3D-printed plastic form. The purpose of our qualitative study was to evaluate the regenerative potential of the innovative ceramic biomaterial prepared using this method in the therapy of the cortical bone of the lower jaw in four mature pigs. The mandible bone defects were evaluated after different periods of time (after 3, 4, 5 and 6 months) and compared with the control sample (healthy cortical bone from the opposite side of the mandible). The results of the morphological, clinical and radiological investigation and hardness examination confirmed the positive regenerative potential of ceramic implants after treatment of the mandible bone defects in the porcine mandible model.

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The right and left mandibular processes derived from the first branchial arch grow toward the midline and fuse to create the rostral tip region of the mandible during mandibular development. Severe and mild cases of failure in this process results in rare median cleft of the lower lip and cleft chin, respectively. The detailed molecular mechanisms of mandibular tip formation are unknown. We hypothesize that the Msx1 gene is involved in mandibular tip development, because Msx1 has a central role in other craniofacial morphogenesis processes, such as teeth and the secondary palate development. Normal Msx1 expression was observed in the rostral end of the developing mandible; however, a reduced expression of Msx1 was observed in the soft tissue of the mandibular tip than in the lower incisor bud region. The rostral tip of the right and left mandibular processes was unfused in both control and Msx1-null (Msx1-/-) mice at embryonic day (E) 12.5; however, a complete fusion of these processes was observed at E13.5 in the control. The fused processes exhibited a conical shape in the control, whereas the same region remained bifurcated in Msx1-/-. This phenotype occurred with 100% penetrance and was not restored at subsequent stages of development. Furthermore, Meckel's cartilage in addition to the outline surface soft tissues was also unfused and bifurcated in Msx1-/- from E14.5 onward. The expression of phosho-Smad1/5, which is a mediator of bone morphogenetic protein (Bmp) signaling, was downregulated in the mandibular tip of Msx1-/- at E12.5 and E13.5, probably due to the downregulated Bmp4 expression in the neighboring lower incisor bud. Cell proliferation was significantly reduced in the midline region of the mandibular tip in Msx1-/- at the same developmental stages in which downregulation of pSmad was observed. Our results indicate that Msx1 is indispensable for proper mandibular tip development.

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Turtles are a charismatic reptile group with a peculiar body plan, which most notably includes the shell. Anatomists have often focused descriptive efforts on the shell and other strongly derived body parts, such as the akinetic skull, or the cervical vertebrae. Other parts of turtle osteology, like the girdles, limbs, and mandibles, are documented with less rigor and detail. The mandible is the primary skeletal element involved in food acquisition and initial food processing of turtles, and its features are thus likely linked to feeding ecology. In addition, the mandible of turtles is composed of up to seven bones (sometimes fused to as little as three) and has thus anatomical complexity that may be insightful for systematic purposes and phylogenetic research. Despite apparent complexity and diversity to the mandible of turtles, this anatomical system has not been systematically studied, not even in search of characters that might improve phylogenetic resolution. Here, we describe the mandibular osteology for all major subclades of extant turtles with the help of digitally dissected 3D models derived from high-resolution computed tomography (µCT) scans of 70 extant species. We provide 31 fully segmented mandibles, as well as 3D models of the mandibular musculature, innervation, and arterial circulation of the cryptodire Dermatemys mawii. We synthesize observed variation into 51 morphological characters, which we optimize onto a molecular phylogeny. This analysis shows some mandibular characters to have high systematic value, whereas others are highly homoplastic and may underlie ecological influences or other factors invoking variation.

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Odontomas are considered to be among the more common odontogenic tumors in the oral cavity. Several authors classify them as hamartomas instead of actual tumors. Odontomes' precise etiology is still unknown. The majority of odontomas are found during routine radiography studies and are asymptomatic. Odontomes typically cause disruptions to the teeth's eruption, most frequently deflection or delayed eruption. Here, the reported study details the surgical management of a mandibular compound odontoma in a patient who presented with a complaint of numbness in his lower jaw.

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OBJECTIVE: Aim: The purpose of the study was to identify the morphological features of reparative osteogenesis in the rats lower jaw under the conditions of using electrical stimulation. PATIENTS AND METHODS: Materials and Methods: An experiment was conducted on 24 mature male rats of the WAG population. Two groups were formed. Group 1 included 12 rats that were modeled with a perforated defect of the lower jaw body. Group 2 included 12 animals that were modeled with a perforated defect similar to group 1. In animals, a microdevice for electrical action was implanted subcutaneously in the neck area on the side of the simulated bone defect (a temporary Videx AG 4 battery; a constant sinusoidal electric current of an unchanging nature 1 milliampere, frequency 30 W). The negative electrode connected to the negative pole of the battery was in contact with the bone defect. The battery and electrode were insulated with plastic heat shrink material. Morphological and statistical methods were used. RESULTS: Results: The positive effect of electrical stimulation on reparative osteogenesis was due to a decrease in the severity of hemodynamic disorders, activation of angiogenesis in granulation tissue, which was one of the components of the regenerate that filled the bone defect, matured and turned into connective tissue; stimulation of the proliferative potential of fibroblastic cells and cells with osteoblastic activity in granulation tissue; increasing the proliferative potential of osteoblastic elements of bone tissue bordering the cavity; stimulation of macrophage cells and processes of cleansing the bone cavity from fragments of a blood clot and alteratively changed tissues; formation of clusters of adipocytes in the loci of connective and granulation tissue of the regenerate; the process of metaplasia of connective tissue into bone tissue; an increase of the foci of hematopoiesis in the intertrabecular spaces of lamellar bone tissue. CONCLUSION: Conclusions: A comprehensive clinical and experimental study conducted by the authors proved that electrical stimulation activates the reparative osteogenesis in the lower jaw, which occurs through direct osteogenesis and does not finish on the 28th day of the experiment.

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The tight fit of the roots of the third molars to the mandibular canal is the main predisposing factor of injury to the inferior alveolar nerve during tooth extraction surgery. Surgical treatment of 92 patients diagnosed with pericoronitis, retention of the third molar of the mandible, close fit of the roots of the third molar to the mandibular canal was performed. Four types of close fit of the roots of the third molars to the mandibular canal were revealed, according to CBCT, OPTG and clinical data. Most cases of paresthesia after the removal of the third molars are associated with an anatomical variation in the structure of the mandibular canal, in which the canal walls are partially formed by the cement of the tooth root. Two variants of postoperative management of the surgical wound are proposed, when an open section of the neurovascular bundle is detected at the bottom of the hole.

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