Autologous bone grafting is considered as "gold standard" in the alveolar ridge augmentation techniques. In situ onlay grafting uses grafts adjacent to edentulous sites without a separate donor site. Several studies have revealed the satisfactory short-term performance of this less invasive modified technique, but no information is available of stability of alveolar ridge reconstructed by in situ onlay grafting and implant performance after occlusal loading in a mid-term follow-up. This study is to retrospectively evaluate the radiographic and patient reported outcomes (PROMs) of a modified onlay grafting technique and the subsequent implantation in anterior maxilla using in situ grafts without a second bone harvesting region. A total of 83 patients contributed 119 edentulous deficiency sites, and 104 implants were placed in anterior maxilla. 44 patients received in situ onlay grafting using subnasal grafts and 39 patients received ex situ onlay grafting using mandibular symphysis grafts. Alveolar ridge height and multileveled widths were assessed using cone-beam computed tomography (CBCT) prior grafting and at five subsequent time points. Clinical parameters and PROMs were evaluated with a visual analog scale (VAS) during the follow-up. Approximately 6months after onlay grafting, dental implants were placed followed by fixed prosthetic rehabilitation. Implant survival and success rates were assessed with a mean follow-up of 42.90months. The horizontal bone resorption at cervical level after 1-year occlusal loading of in situ group (1.73% ± 1.29%) was lower than that of ex situ (3.85% ± 1.50%) group (P = 0.04). No other significant difference regarding bone resorption was found. The patient reported pain scores at 7days after surgery of in situ group (2.43 ± 1.17) was lower than that of ex situ group (3.47 ± 2.08, P = 0.02). No implant loss was observed. The implant success rates were 96.36% in in-situ group and 97.96% in ex-situ group. Within the limitations of the present retrospective study, the findings suggest that in situ onlay grafting may be a promising approach for reconstructing the anterior maxillary alveolar ridge and facilitating subsequent implant placement. These preliminary results are hypothesis-generating and warrant further validation through prospective, long-term investigations. This study was retrospectively registered in Chinese Clinical Trial Registry (Registration number: ChiCTR2400083954, Registration date: 2024-05-08).

To describe and demonstrate techniques for obtaining lateral and dorsoventral diagnostic skull radiographs and how to apply objective reference lines for the evaluation of acquired dental disease in the domestic rabbit. Domestic rabbits. Rabbits should be heavily sedated or lightly anesthetized to allow for radiographic positioning. Standard radiograph views include lateral and dorsoventral views. Radiographs should be assessed for straightness. In the lateral view, the tympanic bulla and the rami of the mandible should completely overlap by at least 90%. In the dorsoventral view, the mandibular symphysis should overlap the nasal bone, the maxillary incisors should be separated and well-defined, the zygomatic arches should be symmetrical, and the temporal mandibular joints should be partially to completely obscured medially by the rami of the mandible. Diagnostically positioned skull radiographs can be utilized to apply objective anatomical reference lines to diagnose and monitor acquired dental disease in domestic rabbits. Obtaining diagnostic skull radiographs is a simple procedure that can be performed in nearly every veterinary hospital. Skull radiographs are invaluable in providing clinicians with information about intra- and extraoral disease in pet rabbits.

Objective: Mandibular size and foraminal anatomy vary from population to population because they provide passage to important anatomical structures that have great importance during clinical procedures. Through a comprehensive literature review, we found that no existing morphometric data are available for the Pakistani population. This cross-sectional analysis is performed on 86 dry adult mandibles (from Rawalpindi Medical University) to identify key mandibular dimensions and foraminal positions in a Pakistani sample. Methods: Each mandible was measured twice with digital Vernier calipers (0.01 mm precision). Paired (left vs. right) parameters included mandibular body length, ramus height, and distances from the mandibular foramen to the anterior and posterior borders of the ramus. Unpaired parameters (bicondylar width and bigonial width) were measured across specimens. Morphological variants (e.g., accessory mental foramina) were also observed. Statistical comparison of sides used paired two-tailed t-tests or Wilcoxon signed-rank tests (significance set at p<0.05). Results: Out of 100 mandibles examined, 86 were suitable for analysis. Significant side-to-side differences were found for mandibular body length, the distance from the anterior border to the mandibular foramen, and mandibular notch distance to angle (p<0.05). No accessory mental foramina were observed. Unpaired measurements such as bicondylar width (114.53 ± 5.44 mm), bigonial width (94.47 ± 6.93 mm), and symphysis menti height (28.57 ± 4.45 mm) were recorded. Conclusion: The findings offer population-specific morphometric data on the mandible and foramina in Pakistan and may serve as a reference for anatomical and clinical research. Keywords: Mandible; Mandibular Canal; Population; Anatomy, Cross-Sectional; Pakistan

Bone-anchored maxillary protraction (BAMP) has been increasingly used to correct midface deficiency and Class III malocclusion in patients with unilateral cleft lip and palate (UCLP). However, its three-dimensional (3D) effects on the mandible remain insufficiently explored. To quantitatively assess 3D mandibular displacement and remodelling, glenoid fossa adaptations, and joint space changes following BAMP treatment in patients with UCLP. A longitudinal cohort of 26 patients with UCLP between ages 11-12 years was evaluated. CBCT scans were obtained before (T0) and after approximately 1.5 years of BAMP therapy (T1). 3D surface models were superimposed using three registration methods: anterior cranial base, mandibular symphysis and condylar head. Joint spaces (superior, anterior, posterior, medial) were measured on CBCT slices. The mean age of the cohort at T0 was 11.5 ± 0.5 years (range: 10.8-12.4 years), and at T1 was 13.2 ± 0.6 years (range: 11.3-14.3 years). The average treatment duration was 1.7 ± 0.4 years. Measurement reliability was moderate to good (ICC: 0.72-0.90). Significant posterior glenoid fossa remodelling was observed, characterised by anterior bone apposition and posterior resorption (both 0.95 ± 0.08 mm; p < 0.01). The mandible showed displacement in the vertical (2.11 ± 0.12 mm), posterior (1.06 ± 0.10 mm) and lateral (0.83 ± 0.09 mm) directions (p < 0.01). Remodelling along the posterior ramus showed greater change at the gonion (1.18 ± 0.07 mm) than at the condylar notch (0.52 ± 0.06 mm) (p < 0.01), resulting in a mild reduction in gonial angle. Morphological changes in the condylar head were minimal (< 0.30 mm), and alterations in joint spaces were negligible (< 0.20 mm). BAMP therapy was associated with measurable mandibular and glenoid fossa adaptations, particularly in the posterior regions, while maintaining condylar and joint space stability. These findings suggest that BAMP treatment may help influence maxillomandibular growth and improve midfacial deficiency without adversely affecting normal mandibular development. 201700423/The Netherlands National Trial Register (TC 6559).

Objective: The aim of this study is to investigate the potential of mandibular symphysis and mental trigone morphometry in determining sex in the Turkish population and to evaluate the performance of machine learning algorithms in sex prediction. Methods: Computed tomography (CT) scans of 350 adult individuals (191 males, 159 females) were retrospectively analyzed. Eleven morphometric parameters were measured from midsagittal and three-dimensional reconstructions of the mandible. Sex differences were assessed using independent t-test or Mann–Whitney U test, with ROC curve analysis performed to determine discriminatory accuracy and optimal cut-off points. ML models (SVM, KNN, Naïve Bayes, Logistic Regression, Random Forest, and XGBoost) were implemented in R. The dataset was split into 70% training and 30% testing sets, with 5-fold cross-validation and grid search applied for model optimization. Performance metrics included accuracy, sensitivity, specificity, F1-score, and AUC. Results: Ten of the eleven morphometric variables differed significantly between sexes (p

The mandible is the largest and strongest bone of the facial skeleton. The mandible has body occurring in 2 halves. Both halves unite together in the midline forming symphysis menti. The inner surface of the body of the mandible is also known as lingual surface. The literature search revealed presence of lingual foramen on the lingual surface of the mandible. The lingual foramen is reported to be present above, below, or lateral to genial tubercles of the mandible. The lingual foramen transmits neurovascular bundle, which may be injured during surgery involving lingual surface of the mandible, including lingual foramen. But the lingual foramen varies in incidence, location and number. So, in absence of detailed information related to lingual foramen may lead to intra- and postoperative complications. Hence, study is important. The aim of the study is to provide detailed information, including incidence, location, and number of lingual foramina. The study was conducted in the department of Anatomy using thirty mandibles. The number and location of lingual foramen were inspected visually and recorded. The incidence was calculated using Microsoft Excel 2021. The varied anatomy of the lingual foramina was correlated with clinical implications. The incidence of lingual foramen was 76.6% with range of 0 to 4. The most common location of this foramen was in the region of premolar teeth. The detailed information about the lingual foramen will be of utmost use to surgeons during placement of dental implants, management of fracture of mandible, and ridge augmentations.

Mandibular fractures (MF) are among the most common facial injuries, with significant implications for patient function and quality of life. There is a lack of comprehensive, multi-institutional studies examining short term outcomes and predictors of early complications after treatment of mandibular fractures. The American College of Surgeons National Surgical Quality Improvement Program database (ACS-NSQIP) was queried for the time period 2008 through 2021 to identify patients who underwent open reduction and internal fixation (ORIF) of MF. We extracted data on comorbidities, preoperative blood values, and 30-day postoperative outcomes regarding the occurrence of complications. A total of n = 2,705 patients (443 females; 2,262 males) with an average age of 35 years and a mean BMI of 25.4kg/m² were analyzed. The most common fracture locations were the mandibular body (42%), angle (22%), and symphysis (16%). Complications occurred in 9.4% of cases, with reoperations and readmissions being the most common general complications. Multivariate analysis revealed site-specific risk profiles: condylar and symphyseal fractures showed higher complication rates, while subcondylar fractures had lower rates. Patients undergoing ORIF without placement in mandibulomaxillary fixation (MMF) had a higher rate of surgical complications. Smoking, weight loss, disseminated cancer history, and higher wound class were independently associated with increased risk of complications. A 30-day postoperative complication rate of nearly 10% emphasizes the need for robust risk stratification and targeted strategies to further improve surgical safety in this challenging patient population. Site-specific risk variations, particularly for symphyseal and condylar fractures, and the higher rate of complication in patients without MMF, underscore the importance of tailored procedural planning. Moreover, identifying smoking and inpatient care as independent risk factors underscores the value of addressing modifiable risks and optimizing care for high-risk patients to improve surgical outcomes.

Morphological diversity of the cetacean mandibular symphysis coincides with novel modes of aquatic feeding – CORRIGENDUM

The mandible is an important component of the facial skeleton, and it possesses outer and inner surfaces. The main feature of the outer surface of the mandible is the presence of the mental foramen, which transmits the mental nerve and vessels. Old literature elaborates the presence of the mandibular incisive foramen on the symphysis menti. But the author of the present study detected a foramen on the mental protuberance that has not been reported so far. Hence study assumes great importance. The aim of the study is to expound on the foramen on the mental protuberance and correlate it with the clinical implications. The study was conducted in the department of Anatomy using 10 intact adult mandibles of unknown age and sex. The mandibles were inspected visually for the presence of the foramen under study. The diameter and distance of this foramen from the inferior border of the mandible were measured by vernier calipers. The 2 foramina were observed in 2 mandibles, constituting 20%. The mean distance of the foramen from the inferior border of the mandible was 1.25mm, and the mean diameter of this foramen was 1mm. The precise knowledge of this foramen and structures transmitted by it will be of utmost use for preoperative and perioperative procedures of oral and maxillofacial surgeries involving the mandible, especially in the inter-foraminal region.

Background: The aim of this study was to evaluate the correlation between skeletal class and morphological patterns of the mandibular symphysis. Methods: The sample consisted of 90 patients with an average age of 18 years (44 > x > 12). In order to investigate any correlation between skeletal class and morphological patterns of the mandibular symphysis, the following tests were used: Pearson's correlation test, Spearman's test, and the analysis of variance test (ANOVA) followed by Tukey's post hoc HDS test. The significance level was set at 0.050. Results: Pearson's correlation test and ANOVA showed a weak negative correlation between malocclusion and symphyseal height. Therefore, as ANB increases, symphyseal height decreases (r = -0.25, p < 0.01). In addition, a strong positive correlation was found between ANB and IMPA (r = 0.47, p < 0.01). So, as ANB increases, IMPA increases. No statistically significant association was found between symphyseal morphology and IMPA (Spearman's test). Conclusions: The analysis revealed a weak but statistically significant negative correlation between ANB angle and symphysis height, indicating that as sagittal discrepancy increases (higher ANB), the symphysis tends to be shorter (r = -0.25, p < 0.01). A moderate positive correlation was also found between ANB and IMPA (r = 0.47, p < 0.01), suggesting that a more pronounced Class II skeletal pattern is associated with greater incisor proclination. However, no significant relationship was observed between symphysis type (A/B/C) and IMPA. When comparing skeletal classes, Class III subjects displayed significantly greater symphyseal height than Class II subjects (p < 0.001), while Class II subjects showed the highest IMPA values (p < 0.001).

Mandibular fractures are rare in infants under one year of age, accounting for only 0.9%-2.6% of pediatric mandibular injuries. Their infrequency is due to the unique anatomical and developmental features of the infant mandible, including increased bone elasticity and minimal exposure to high-impact trauma. Diagnosis and management are often challenging, particularly given the difficulty in symptom communication, presence of unfused skeletal structures, and developing tooth buds. We described a case of a 3-month-old infant who sustained concurrent fractures of the mandibular symphysis and left condylar head following an accidental fall from a diaper-changing table. Computed tomography revealed a greenstick fracture at the symphysis and a minimally displaced condylar fracture. In consideration of the patient's age, fracture type, and high remodeling capacity, conservative management was selected. Clinical and radiographic follow-up over three months demonstrated excellent bony remodeling without any surgical intervention. There was no functional impairment or developmental delay. This case highlights the substantial remodeling potential of the infant mandible and supports the efficacy of conservative treatment in selected cases. It also underscores the importance of distinguishing true fractures from developmental non-union in the symphyseal region. Long-term follow-up until the completion of mandibular growth remains crucial to detect potential growth disturbances.

ObjectiveThe mandibular symphysis is a donor site for alveolar bone grafting (ABG) in patients with cleft lip and/or palate, offering reduced morbidity. This prospective study evaluated ABG outcomes and donor site regeneration using artificial intelligence (AI)-powered 3-dimensional (3D) tools.DesignProspective study.SettingTertiary-level craniofacial hospital.Patients, ParticipantsTwenty-one patients with cleft lip and alveolus (mean age 12.1 ± 3.2 years), and without syndromes.InterventionsAlveolar bone grafting was performed using mandibular symphysis bone by an experienced surgeon at a single center.Main Outcome MeasuresPre- and one-year postoperative cone-beam computed tomography scans were analyzed using AI-powered 3D tools to assess alveolar bone defect and bone bridge formation in terms of thickness, mediolateral extension, and height. Donor site regeneration was evaluated by shape correspondence analysis comparing pre- and postharvesting morphology. Pulp vitality, mental nerve sensory disturbances, and length of hospital stay were recorded.ResultsAt one-year follow-up, cleft defects were reduced to near-zero in all dimensions. The bone bridge reached mean values of 11.6 ± 3.4 mm buccopalatally, 20.7 ± 2.7 mm mediolaterally, and 14.6 ± 4.2 mm vertically. Donor site regeneration was highly favorable, requiring 2.73 ± 1.3 mm of residual bone formation. All patients were discharged within 24 h, with minimal discomfort and no complications.ConclusionThese findings confirm mandibular symphysis bone as a reliable graft source and support the clinical value of AI-powered 3D approach.

ABSTRACT Background and Objective The natural physiological structure of the alveolar bone significantly influences the movement of the anterior teeth during orthodontic treatment. This study aimed to assess the alveolar bone thickness (ABT) of mandibular anterior teeth at three levels using Cone Beam Computed Tomography (CBCT) in individuals with different anteroposterior skeletal malocclusions and to explore its relationship with symphysis dimensions. Materials and Methods Sixty CBCT scans were analysed from untreated adult subjects in their naturally compensated state to minimize treatment-related variation. The subjects were divided into three skeletal malocclusion groups (Class I, II, and III). Three labial measurements were recorded at 3 mm and 6 mm from the cementoenamel junction (CEJ), and at the root apex level. Similarly, three lingual measurements were taken at 3 mm and 6 mm from the CEJ, and at the root apex level. . Symphysis dimensions, including height and buccal/lingual width, were also assessed. Statistical analysis included ANOVA, Bonferroni post hoc test and Pearson correlation. Results Class I patients showed significantly greater ABT than Class II and III at specific sites, particularly at 6 mm from the CEJ and apex labially in the mandibular central incisors and 3 mm,6 mm from the CEJ lingually and apex lingually in the mandibular canine. A positive correlation between symphysis dimensions and ABT was found in Class III malocclusions, while Class II malocclusions exhibited a negative correlation. Conclusion Mandibular anterior alveolar bone thickness and symphysis morphology varied significantly across skeletal malocclusions. Class III subjects exhibited reduced labial alveolar support, while Class II subjects showed greater symphysis dimensions. These variations underscore the importance of individualized diagnosis and meticulous planning of incisor movements to minimize iatrogenic effects.

Background:Craniofacial trauma is a major global health concern, most commonly resulting from high-energy impacts such as road traffic accidents. These injuries often involve complex maxillofacial and cranial fractures, leading to functional, neurological, and aesthetic challenges. Objectives:To present a complex case of panfacial trauma with intracranial and ocular involvement, highlighting the staged surgical approach and importance of multidisciplinary management. Results:A 26-year-old male sustained severe craniofacial injuries following a motorcycle accident. Imaging revealed multiple fractures including Le Fort II maxillary fracture, bilateral orbital rim and blow-out fractures, zygomatic tripod fracture, mandibular symphysis fracture, comminuted frontal sinus fractures, and anterior cranial base fracture, along with intracerebral hemorrhage, brain edema, and vitreous hemorrhage. Initial stabilization was achieved with interdental wiring and mandibular arch bar fixation. Definitive management included craniotomy with frontal sinus reconstruction, orbital exploration with scleral repair and hyphema evacuation, and orthopedic procedures for associated toe dislocations. The staged “bottom-to-top and outside-in” approach facilitated restoration of occlusion prior to cranial and orbital reconstruction. Conclusion: This case illustrates the complexity of managing multiregional craniofacial trauma involving the skull base and orbit. Optimal outcomes depend on early imaging, a staged surgical strategy, and close multidisciplinary collaboration between maxillofacial, neurosurgical, ophthalmologic, and orthopedic teams.

Various surgical options exist for correcting long, hyperprojected chins, including modified genioplasty techniques, pogonion burring, soft tissue rejuvenation, and custom implants. These can be performed as standalone procedures or in conjunction with orthognathic surgery. Among these, lower chin border resection combined with meticulous soft tissue suspension offers a reliable method for enhancing mandibular contour and cervicomental definition. From 2018 to 2024, 24 patients with elongated, protrusive chins underwent genioplasty with symphysis resection and soft tissue suspension. The technique involved segmental resection of the mandibular symphysis, typically extending from the mandibular angle or first molar. Muscle insertions, including platysma and medial pterygoid, were carefully released with electrocautery. The inferior chin periosteum was sutured and repositioned. Contouring of the mandibular edge was achieved using a round bur, followed by precise hemostasis and suspension of the cervical soft tissues, including the platysma. In 14 patients, the genioglossus and digastric muscles were also anchored to the resected symphysis to enhance submental support. Mandibular reductions ranged from 5 to 10 mm. No major complications were observed. All patients expressed high satisfaction with aesthetic and functional outcomes, with a mean FACE-Q score of 96.02. This technique proved particularly valuable in cases where standard advancement or setback genioplasty alone would not sufficiently address vertical excess or soft tissue laxity. Genioplasty with symphysis resection and soft tissue suspension is a safe, reproducible technique for treating long, hyperprojected chins. The integration of soft tissue suspension is critical to optimize cervicomental angle definition and overall facial harmony. Further comparative studies are warranted to refine indications and validate long-term outcomes. (1) Genioplasty with symphysis resection and soft tissue suspension is a safe and effective alternative to conventional techniques for correcting long and prominent chins, offering aesthetic and functional results when standard genioplasty is insufficient. (2) 3D imaging and CAD/CAM surgical guides enhance precision, reduce intraoperative risks, especially nerve injury, and are recommended for complex asymmetric patients and resections exceeding 5 mm. (3) Soft tissue suspension is essential for optimal outcomes. Proper muscular reattachment (mentalis, platysma, digastric, and optionally geniohyoid/genioglossus) reassures long-term soft tissue adaptation and aesthetic results.Level of Evidence IV This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Objective: This study aimed to evaluate and compare the effects of two functional appliances, the Activator (AA) and the Biblock (BA), on mandibular symphysis (MS) morphology in patients with Class II malocclusion. Methods: Records of patients treated at the Department of Orthodontics, Ankara University, between 2011 and 2021 were retrospectively analyzed. Inclusion criteria were mandibular deficiency, optimal growth pattern, and CS2–CS3 cervical maturation stage. Twenty patients treated with the Biblock (10 females, 10 males; mean age: 13.52±1.36 years) were identified. An age- and sex-matched control group of 20 patients treated with the Activator (mean age: 13.78±1.18 years) was selected. Lateral cephalometric radiographs taken before and after treatment were evaluated for angular and linear changes. Intragroup comparisons were performed with paired t-tests, and intergroup comparisons with independent t-tests. Results: The mean treatment duration was 17.39±5.94 months in the BA group and 17.03±4.37 months in the AA group. Both appliances significantly improved Class II malocclusion. Significant anterior MS changes were observed in both groups, except for B-Ida-Idp. Upper MS width remained unchanged, while significant increases occurred in the middle (AA: 0.4±0.5 mm; BA: 0.4±0.5 mm) and lower widths (AA: 0.9±0.2 mm; BA: 0.8 ± 0.7 mm) (P&amp;lt;.005). Intergroup comparisons showed greater reduction in Pg-B-Ida and greater increase in Pg-B in the BA group (P&amp;lt;.05). Conclusion: Functional treatment flattened MS curvature, promoted forward growth of B and Pg points, and altered anterior MS morphology. The effects of AA and BA on MS morphology were largely similar. Keywords: Class II malocclusion, Functional appliance, Biblock, Activator, Mandibular symphysis morphology

IntroductionSymphysis and parasymphysis fractures are common in maxillofacial trauma, requiring precise management to restore form, function, and aesthetics. While Champy’s technique recommends two miniplates - superior and inferior - for optimal stability, placing a superior plate in the canine-premolar region risks damaging dental roots and neurovascular structures. Additionally, the cost of dual plating may be a burden in low-resource settings. This study evaluates the efficacy of a single miniplate at the inferior border, aided by an arch bar as a tension band, for managing these fractures.MethodsThis prospective clinical study included 15 patients presenting with isolated mandibular symphysis or parasymphysis fractures. All fractures were managed using a single 2.5 mm miniplate along the inferior mandibular border, with an arch bar serving as a tension band across the dental arch. Patients were evaluated postoperatively for the incidence of surgical site infection, wound dehiscence, malunion or nonunion, malocclusion, miniplate fracture, and neurosensory deficits. Cost implications related to avoiding the use of a second miniplate were also analyzed. Follow-up was conducted for a minimum of four weeks postoperatively.ResultsThe study observed that single miniplate fixation in combination with an arch bar provided satisfactory clinical outcomes in most cases. There were no significant incidences of postoperative infection, plate fracture, or malocclusion. Neurosensory complications were minimal and comparable to standard dual-plate protocols. Importantly, the reduction in hardware usage translated to lower overall treatment costs, offering a substantial benefit for patients from economically constrained backgrounds.ConclusionSingle miniplate fixation along the inferior border of the mandible, when augmented with a tension band in the form of an arch bar, appears to be a reliable and cost-effective alternative for the management of symphysis and parasymphysis fractures. This technique minimizes iatrogenic risk to adjacent anatomical structures and offers a financially feasible solution, particularly in low-resource settings. Larger randomized controlled studies are recommended to further validate these findings and support broader adoption of this simplified approach in clinical practice.

The origin and evolution of snakes has been marked by the acquisition of many morphological and functional novelties, one of which is the possession of a highly kinetic skull allowing for the consumption of prey that are often larger than their head diameter. One feature of the iconic wide gape of macrostomate (large-mouthed) snakes is due to changes in the rostral midline where the left and right hemi-mandible come together. Across vertebrates, the two sides of the lower jaw are held together by the mandibular symphysis. In snakes, the two halves of the lower jaw do not fuse and the symphysis remains free, facilitating gape expansion. The symphysis has previously been explored in lizards and crocodiles, where ligamentous fibres and cartilages span the joint. Here, we compared the anatomy of the forming 'free' mandibular symphysis in the corn snake (Pantherophis guttatus) to symphysis development in two lizards, the veiled chameleon (Chamaeleo calyptratus) and the ocelot gecko (Paroedura picta), and an outgroup sauropsid, the chicken (Gallus gallus domesticus). Microcomputed tomography imaging, whole-mount skeletal staining and histology staining confirmed the absence of bone and cartilage fusion at the mandibular symphysis in the corn snake during development, in contrast to the complete fusion of cartilage, but not bone, in both lizards and the fusion of the bone in the chick. Trichrome staining under circular polarised light and whole fast green staining highlighted that, while the symphyseal region was populated by a dense network of collagen fibres, the snake hemi-mandibles were not connected across the rostral region by this fibrous network. Instead, collagen fibres extended backwards and around the snake mental groove to an intermandibular nodule. This nodule attached to the midline dorsally, allowing integration of the movement of the soft and hard tissues. Our analysis highlights the adaptations required to allow extreme lower jaw mobility and independence of the two sides of the jaw as found in macrostomate snakes.

Lingual foramina are present on the inner surface of the anterior portion of body of mandible. These foramina provide passages of neurovascular structures to the mandible. The aim of the study was to identify these foramina if present, as well as their different positions in the anterior mandibular regions. This cross-sectional descriptive study was done on 150 fully ossified dry human mandibles in the department of Anatomy, Mymensingh Medical College, Bangladesh from July 2019 to June 2020. A non-random purposive sampling technique was adopted. Study was carried out by observations only. Lingual foramina were classified into midline position behind the symphysis menti and lateral position to symphysis. Again, in midline, they were grouped into three groups in relation with the position of genial tubercle (mental spine) as supraspinous, interspinous and infraspinous positions. Lingual foramina were present in all samples. In 96.0% samples, foramina were located in midline and rest 4.0% having lateral foramina. In midline position, they were grouped in relation with the mental spine. Among 144 samples, 79.86% foramens were found above the spine (supraspinous), 4.86% foramens found in between the spine (interspinous) and 15.27% foramens found below the spine (infraspinous). Study of these mandibular foramina helps to lower the per and post operative complications such as hemorrhage and hematoma formation in operations like implant placement, autogenous bone graft etc.

For a long time, Monotremata included Mesozoic taxa such as Steropodon and Teinolophos in addition to Cenozoic species. However, fossil discoveries from the Cretaceous revealed a major difference between Cenozoic monotremes and their ancestors, with Cenozoic monotremes being more closely related to each other than to earlier forms, thus forming the crown group of Monotremata described by Chimento et al. (2023). Among living mammals, moles have several morphofunctional parallels with monotremes. These parallels may reflect similar evolutionary trajectories. Our objectives were: to find additional morphological characters to differentiate Monotremata from their ancestors, and to trace possible evolutionary parallels between them and Talpidae. To this end, specimens of monotremes and talpids stored in the collection of the Museu Nacional-UFRJ were evaluated, as well as bibliographical research on the evolution, morphology and fossil record of these groups. Among the non-dental morphological characteristics identified here are the presence of a lateral projection in the anterior portion of the mandible that extends beyond the mandibular symphysis, forming the bony support of the “beak” in living monotremes and the presence of a reinforced shoulder girdle, with several hypertrophied bones and joints not seen in other tetrapods. The swimming method of platypuses, which involves a series of alternating beats of the front limbs, is very similar to that of moles when digging or swimming. Thus, it is possible that, like semi-aquatic moles, monotremes descended from an ancestor with a specialized fossorial lifestyle.