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Facial anatomy
Published in Michael Parker, Charlie James, Fundamentals for Cosmetic Practice, 2022
The mandible is the jawbone (Figure 3.6), and it articulates with the temporal bone at the temporomandibular joint, allowing us to open and close the mouth at our leisure. It is found directly inferior to the maxilla and offers a point of anchorage of our lower teeth. The mandible is a complex bone with multiple discernible anatomical segments, including the body, angle, ramus, condyle and coronoid process. The area at which the two halves of the mandible fuse during development is known as the symphysis menti, located in the midline of the chin. The mandible has two main foramina on each side, the mandibular and mental foramina. The mandibular foramina are located in the middle of each mandibular ramus, and the mental foramina are located just lateral to the chin bilaterally. The mental foramina are of key clinical significance regarding augmentation of the chin with dermal fillers, as with any other facial foramina, due to the risk of avascular necrosis, filler embolisation and neuronal damage of structures exiting them.
Maxillofacial Trauma
Published in Ian Greaves, Keith Porter, Jeff Garner, Trauma Care Manual, 2021
Ian Greaves, Keith Porter, Jeff Garner
Bleeding inside the mouth is often inaccessible to direct pressure, other than biting on a swab. If the general condition of the casualty permits, he or she should be sat up to reduce venous bleeding and to allow blood to escape through the mouth rather than falling to the back of the throat and compromising the airway. Bleeding from the inferior alveolar artery within the mandible is usually controlled by reduction of the mandibular fracture and immobilization. It may be helpful to pass a wire around the teeth on either side of a bleeding mandibular fracture (bridle wire), tightening it to pull the ends of the fracture together; in this case, maxillofacial assistance will be required. Torrential bleeding from the region of the nasopharynx following trauma to the middle third of the facial skeleton is difficult to manage and often signifies a fracture of the skull base. Massive resuscitation may be required.
Oral cavity
Published in Neeraj Sethi, R. James A. England, Neil de Zoysa, Head, Neck and Thyroid Surgery, 2020
Osteoradionecrosis (ORN) of the jaws is one of the most severe chronic side effects of radiotherapy to the head and neck. It occurs in between 5%–10% of patients with oral or oropharyngeal cancer receiving radiotherapy [29,30]. ORN is radiation-induced fibrosis with disturbance of fibroblasts and the combination of osteoblastic death without replication of these cells. The mandible is susceptible to ORN due to the blood supply being limited to a single functional terminal artery (the inferior alveolar artery) [31].
An approach for simultaneous reduction and fixation of mandibular fractures
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2023
Ethan Snyder, Mohamed Trabia, Nir Trabelsi
Bones are composed of an outer cortical bone shell surrounding a cancellous bone interior. The cortical bone shell has a higher density, providing most of the structural stiffness and load bearing for bones, while cancellous bone ensures that the load is evenly distributed (Ott 2018). The mandible tends to be an anomaly in respect to other bones. It has a relatively irregular shape with cavities along the top surface for teeth. Additionally, the thickness of the cortical shell of the mandible varies across its contour of the bone, with an average thickness of approximately 2.5 mm (Batbayar et al. 2019). Modeling mandibular cortical and cancellous bone as a linearly elastic, homogeneous and isotropic material is fairly common, e.g. (Lovald et al. 2010), (Kılınç et al. 2018) since they are easy to implement. However, these models do not accurately represent mandibular bones, whose properties were experimentally found to be a function of direction and location, (van Eijden 2000). Several researchers have used orthotropic material models, e.g. (Kharmanda et al. 2020). However, it may be difficult to use these models accurately due to the irregularity of the mandible.
A model of radiation-induced temporomandibular joint damage in mice
Published in International Journal of Radiation Biology, 2022
Peng Zhang, Lejing Yao, Guoping Shan, Yuanyuan Chen
Radiation-induced injury of the submaxillary joint can result in significant limited jaw mobility or dysphagia in the later stage, and is the most common dose-limiting acute toxicity in head and neck cancer patients receiving radiotherapy (Baudelet et al. 2019). In our Experiment 2 (Full –scale validation study), there are two stages of weight change in the C57BL/6 mouse test group: weight loss in the early stage and weight gain in the middle and late stage. We speculate that the weight loss in early stage is related to the acute radiation response of soft tissue around temporomandibular joint. The early acute phase reaction of radiation will lead to the reduction of food intake and weight loss of mice. After the delivery of the total dose, The early acute phase reaction caused by irradiation will gradually disappear with the help of joint tissue self-healing. The food intake of mice recovered and the weight increased in the subsequent observation period. Nolan MW et al. found that the weight change trend also confirmed this in the prepared mouse radiation oral mucositis model (Nolan et al. 2017). The pathological results showed that the injury of mandible persisted during the observation period. We speculate that unilateral mandibular injury has limitations on the reduction of food intake, or the masticatory function of the skeletal muscle is not lost. But our experiments can not be effectively confirmed at present.
Biomechanical analysis of mandibular defect reconstruction based on a new base-fixation system
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2022
Haipo Cui, Liping Gao, Jing Han, Jiannan Liu
The mandible is located below the face and is the only movable bone of the skull. It is mainly involved in important functions such as chewing, swallowing, occlusion, language, and expression. Partial resection of the mandible becomes clinically necessary due to tumor, trauma, cancer, and other factors. In order to maintain the important functions of the mandible after surgery, it needs to be reconstructed. The ideal state of mandibular reconstruction includes the following three requirements: (i) the appearance of the face should be close to normal after restoration; (ii) dentition and occlusal relationships should be normal; (iii) mastication and the language function should be normal or nearly normal (Ciocca et al. 2012; Azuma et al. 2014; Rubio-Palau et al. 2016). At present, fibula free flap grafting is the most common method for repairing mandibular defects. Hidalgo first used the fibula to repair mandibular defects during surgery in 1989 (Hidalgo 1989). The fibula has gradually become the most common donor area for the repair of large-scale defects of the mandibular bone in clinics due to the following characteristics: the sufficient amount of bone tissue that is resident in the fibula, the dual blood supply of the periosteum and the bone flap, the ability to withstand greater masticatory force, the simple preparation of a bone flap, the easier three-dimensional shaping of a bone flap, and its suitability for the implementation of dental implants (Grohmann et al. 2015).