Topic:Mandible
The mandible in horses is the lower jawbone, essential for mastication and articulation with the skull. It comprises two halves that fuse at the mandibular symphysis and supports the lower teeth, playing a key role in the horse's ability to graze and process food. The mandible also provides attachment sites for muscles involved in chewing and facial expressions. Research on the equine mandible often focuses on its anatomy, development, and the impact of various dental and skeletal disorders. This page compiles peer-reviewed research studies and scholarly articles that investigate the structure, function, and clinical implications of the mandible in equine health and management.
Prevalence and Distribution of Lesions in the Nasal Bones and Mandibles of a Sample of 144 Riding Horses. Restrictive nosebands are used in equestrian sports to hold the bit in place and reduce mouth-opening, a response that can attract penalties in some sports and is thought to reduce the rider's control of the horse. Sustained pressure from such tightly fitted (restrictive) nosebands denies normal behaviour and thus, causes frustration and distress that can jeopardise horse welfare. It also may push the cheek against the molar teeth, compress soft tissues including blood vessels and nerves, and possibly induce chronic changes to underlying bone. This study of mature cavalry horses (n = 144) was ...
Complications Following Mandibular Cheek Tooth Extraction in 20 Horses. The objectives of this retrospective study were to describe the prevalence and characteristics of post-operative complications that occur following equine mandibular cheek tooth extractions and to assess for possible associated risk factors. Clinically significant post-extraction complications necessitating repeat referral developed following 20/302 (6.6%) mandibular cheek tooth extractions. Horses developing complications were younger than the overall population having mandibular cheek teeth extractions and the most commonly affected teeth were the Triadan 07 s and 09 s. Alveolar sequestratio...
Arthroscopic approach and intra-articular anatomy of the equine discomandibular joint compartment of the temporomandibular joint. To develop an arthroscopic approach to the discomandibular joint (DMJ), the ventral compartment of the temporomandibular joint (TMJ) of the horse. Methods: Experimental study. Methods: Nine cadaveric equine heads and two live horses. Methods: A 2.5-mm 30° arthroscope was used to explore the DMJ after joint distension. The first portal was created caudally, allowing placement of a rostral portal under visual guidance. Nasotracheal intubation of the live horses allowed mandibular manipulation, which is required for complete visualization of the joint. Results: A novel injection technique allowe...
Transcutaneous Lateral Alveolar Ostectomy for Standing Surgical Extraction of Mandibular First Molar in an 8-Year-Old Miniature Horse. An 8-year-old, 125 kg (275 lb) female miniature horse was evaluated for a persistently thickened left mandible and cutaneous fistula. Pulp horn defects were identified in pulp horns 1 and 3 of tooth 309 and occlusal pulp exposure was detected with a dental explorer. Radiography of the left mandibular dental quadrant revealed changes consistent with apical infection of tooth 309. Following the failure of oral extraction, a standing surgical approach was taken for transcutaneous lateral alveolar ostectomy and extraction. Roots were sectioned at the level of the furcation and elevated from the su...
The case of an arctic wild ass highlights the utility of ancient DNA for validating problematic identifications in museum collections. Museum collections are essential for reconstructing and understanding past biodiversity. Many museum specimens are, however, challenging to identify. Museum samples may be incomplete, have an unusual morphology, or represent juvenile individuals, all of which complicate accurate identification. In some cases, inaccurate identification can lead to false biogeographic reconstructions with cascading impacts on paleontological and paleoecological research. Here, we analyzed an unusual Equid mandible found in the Far North of the Taymyr peninsula that was identified morphologically as Equus hemionu...
Description of the D4/D4 genotype in Miniature horses with dwarfism. Four causative mutations (D1, D2, D3*, and D4) of chondrodysplastic dwarfism have been described in the equine () gene. Homozygotes for one of these mutations and heterozygotes for any combination of these mutations exhibit the disproportionate dwarfism phenotype. However, no case description of homozygotes for D4 (D4/D4) has been reported in the literature, to our knowledge. We report 2 Miniature horses with the genotype D4/D4 in the gene. Clinically, the 2 dwarfs had a domed head that was large compared to the rest of the body, mandibular prognathism, and short and bowed limbs, mainly in t...
Diagnostic imaging of a basihyoid bone fracture and partial avulsion of the medial pterygoid muscle in a horse. A 3-year-old gelding was presented for further evaluation and treatment of a swelling over the left mandible and inability to eat and drink. Radiographs of the mandible were unremarkable. Computed tomography (CT) of the head demonstrated a fracture of the basihyoid bone and partial avulsion of the medial pterygoid muscle. Ultrasound examination was performed to establish a baseline and confirmed the fracture. The gelding was managed conservatively, recovered uneventfully, and was able to return to training after 4 months of rest. Key clinical message: Computed tomography and ultrasonography in...
Scintigraphic evaluation of cheek teeth in clinically sound horses. Dental disorders are one of the top-ranking clinical domains in equine practice. Scintigraphy has emerged as a useful diagnostic imaging modality for equine dental diseases. There is a paucity of the normal scintigraphic uptake and its correlation with age. This prospective, cross-sectional, descriptive and pilot-designed study aimed to describe the radioisotope uptake (RU) patterns of the reserved crown and periodontal bone of the maxillary and mandibular cheek teeth (CT) in clinically sound horses and to evaluate the age effect on RU. For this purpose, 60 horses that underwent a bone scintig...
Equine odontogenic tumors: Clinical presentation, CT findings, and outcome in 11 horses. Odontogenic tumors present as locally invasive, slow growing, firm swellings on the face. They are rare in all species and are characterized histologically by the degree of differentiation and dental tissue of origin. Radiographic appearance is not pathognomonic for these lesions. Computed tomographic (CT) examination allows exact determination of tumor extension and aggressiveness. The objectives of this retrospective, case series study were to describe the clinical presentation, CT characteristics, and outcome in horses with histologically confirmed odontogenic tumors, and to identify imagin...
Ultrasound-Guided Inferior Alveolar Nerve Block in the Horse: Assessment of the Extraoral Approach in Cadavers. Blinded techniques to desensitize the inferior alveolar nerve (IAN) include intraoral, angled, and vertical extraoral approaches with reported success rates of 100%, 73%, and 59%, respectively. It has not been determined whether an ultrasound-guided extraoral approach is feasible. Further, the fascicular nature of the inferior alveolar and lingual nerves of the horse has not been described. The objectives of this study were to describe a low-volume ultrasound-guided vertical extraoral inferior alveolar nerve block technique and to describe the fascicular nature of these nerves. An ultrasound-g...
Influence of plate type and placement on the immobilization of bilateral equine mandibular osteotomies: Ex vivo study. To determine the influence of plate fixation (locking or dynamic compression) and the site of application (ventral [V] or ventrolateral [VL]) on the resistance to bending of transverse mandibular fractures. Methods: Ex vivo, simple randomized study. Methods: Mandibles harvested from adult equine cadavers (n = 18). Methods: Bilateral osteotomies were created 1 cm caudal to the mental foramen and perpendicular to the long axis of each mandible. Mandibles were fixed with 1 of 3 methods: (1) VL dynamic compression plate (DCP), (2) V-DCP, or (3) VL locking compression plating (LCP). Construct...
Management of an extensive equine juvenile ossifying fibroma by rostral mandibulectomy and reconstruction of the mandibular symphysis using String of Pearls plates with cortical and cancellous bone autografts. To describe a surgical technique for rostral mandibulectomy and reconstruction of the mandibular symphysis. Methods: Case report. Methods: One 5-month-old warmblood cross filly. Methods: A preoperative diagnosis of a juvenile ossifying fibroma was made on the basis of clinical appearance and was later confirmed via histology. The tumor was large, rapidly growing and extending to the caudal aspect of the mandibular symphysis. Computed tomography was performed for surgical planning. The tumor was excised by performing a mandibulectomy caudal to the symphysis. The mandibular symphysis was reconst...
Treatment of class 2 malocclusion by corrective osteotomy using two short locking compression plates. To describe a symphyseal osteotomy stabilised with two short locking compression plates (LCPs) for treatment of class 2 malocclusions. Methods: Case series. Methods: Five horses (age range 8 months to 5¾ years) with overjets and/or overbites ranging from 6 to 32 mm and from 0 to 60 mm, respectively, were treated by osteotomy through the caudal third of the mandibular symphysis, cranial to the interdental space. After cranial distraction and ventral rotation of the rostral part of the mandible, two short (5/6 hole), bent 3.5 mm LCPs were applied ventro-laterally and secured with two or three l...
Diffusion of charged and uncharged contrast agents in equine mandibular condylar cartilage is not affected by an increased level of sugar-induced collagen crosslinking. Nutrition of articular cartilage relies mainly on diffusion and convection of solutes through the interstitial fluid due to the lack of blood vessels. The diffusion is controlled by two factors: steric hindrance and electrostatic interactions between the solutes and the matrix components. Aging comes with changes in the cartilage structure and composition, which can influence the diffusion. In this study, we treated fibrocartilage of mandibular condyle with ribose to induce an aging-like effect by accumulating collagen crosslinks. The effect of steric hindrance or electrostatic forces on the d...
Functional anatomy of the equine temporomandibular joint: Histological characteristics of the articular surfaces and underlining tissues. It has been assumed that dental conditions cause disorders of the equine temporomandibular joint (TMJ), due to biomechanical overload or aberrant loading. However, the incidence of published TMJ disorders in horses is low and this leads to the question whether the equine TMJ is adapted well to its biomechanical requirements or is able to remodel its articular surfaces in response to modified loading conditions. The aim of this study was to determine the histological characteristics of healthy equine TMJs. The tissue components of the articular surfaces of 10 TMJs obtained from horses without a...
The use of cerclage wire for surgical repair of unilateral rostral mandibular fracture in horses. Fractures of the rostral mandible in horses are the most common type of jaw fractures. The present study was performed for stabilization of rostral mandibular fracture with cerclage wire. In a retrospective case series, six client-owned horses with unilateral mandibular fractures were admitted to our clinic and suffered from a major gingival wound at rostral part of mandible. Rostral mandibular fracture was diagnosed through clinical examination and radiography. Fractured region was repaired by cerclage wire under the effect of general anesthesia and wires were maintained for 6-12 weeks. The r...
Study of the relationship between overjet development and some skull bone measurements in Warmblood foals. Overjet is defined as the projection of the maxillary incisors labial to their antagonists in a horizontal direction. This malocclusion in horses can lead to incorrect dental wear and is aesthetically undesirable. Whether lengthening of the maxilla or shortening of the mandible causes the condition has not yet been determined. Therefore, a measurement technique was developed to investigate the correlations between skull bone measurements in overjet-affected individuals. The position of the incisors in 650 Warmblood foals born in a private German stud was examined at two weeks of age, revealing...
Evaluation of the equine mental foramen block: cadaveric and in vivo injectate diffusion. To describe injectate diffusion for two equine mental foramen block techniques. Methods: Descriptive anatomic study. Methods: A total of 12 equine heads and three live horses. Methods: Equine heads were longitudinally sectioned to create 24 hemi-heads for testing two mental foramen block techniques (T1 and T2) and two injectate volumes (3 and 5 mL) of mixed dye and contrast medium. T1 needles were directed rostrocaudally into the mental foramen for 3 cm, and T2 needles were directed dorsolaterally to ventromedially into the foramen for 1 cm. Hemi-heads were randomly assigned one injection tech...
First Radiological Study of a Complete Dental Ontogeny Sequence of an Extinct Equid: Implications for Equidae Life History and Taphonomy. The sequence of cheek teeth mineralization, eruption, and replacement of an extinct horse species is here documented with radiological techniques for the first time thanks to the exceptional preservation of Hipparion sp. mandibles from Cerro de los Batallones (Madrid Basin, Spain). The sequence of dental ontogeny in mammals provides valuable insights about life history traits, such as the pace of growth, and about the mode of formation of fossiliferous assemblages. We have determined that the order of permanent cheek teeth mineralization and eruption of hipparionine horses is m1, m2, (p2, p3),...
Shape variation and modularity of skull and teeth in domesticated horses and wild equids. In horses, the morphological changes induced by the process of domestication are reportedly less pronounced than in other species, such as dogs or pigs - although the horses' disparity has rarely been empirically tested. We investigated shape differences and modularity of domesticated horses, Przewalski's horses, donkeys and zebras. Mandibular and tooth shape have been shown to be valuable features for differentiating wild and domesticated forms in some mammals. Results: Both mandible and teeth, show a pattern of shape space occupation analogous to that of the cranium, with domesticated horses...
Anatomic analysis of the equine mental foramen and rostral mandibular canal using computed tomography. To characterize the anatomy of the mental foramen and determine associations with age, weight, sex and breed. Methods: Retrospective descriptive study. Methods: Forty-one horses, 0.6-25.2 years and weighing 136-820 kg. Methods: Computed tomography (CT) studies of equine heads performed over 5 years were evaluated in multiplanar and three-dimensional reconstruction. Measurements obtained were positioning of the foramen along the mandible, foramen height and width, foramen-canal angulation and rostral canal mineralization. Exploratory statistical analyses investigated associations between measu...
Mandibular odontoameloblastoma in a rat and a horse. Odontoameloblastoma (OA) is a mixed odontogenic tumor that is an ameloblastoma with concurrent histologic evidence of odontoma differentiation. As a mixed tumor, OA is a tripartite lesion comprised of neoplastic odontogenic epithelium, induced dental ectomesenchyme (dental pulp), and mineralized dental matrix. Although rare, OA represents a diagnostic conundrum, as it is histologically closely related to 2 other mixed odontogenic tumors: odontoma (complex and compound) and ameloblastic fibro-odontoma. Herein we describe an OA arising from the mandible of a 4-mo-old Fischer 344 rat that had bee...
[Congenital goiter in the neonatal foal. Two case reports. Zwei Fallberichte]. Two cases of an innate hyperplastic goiter in foals as well as the sonographic evaluation of the hyperplastic gland are presented. One foal displayed skeletal deformities in the form of a mandibular prognathism and forelimb contractures in addition to the swollen thyroid gland. Because of a poor prognosis, the animal was euthanized. The second foal was premature and displayed respiratory signs. Under symptomatic therapy, the goiter regressed within a few weeks.
A tall rostral hook in a medieval horse premolar tooth. Development of dental abnormalities due to improper occlusal wear is common among modern domestic horses. This phenomenon often is attributed to jaw conformation. Rostral mandibular hooks may develop in horses with underjet or mandibular prognathism, a condition where the lower jaw protrudes forward, beyond the upper jaw. Less abrasive diet, free of phytoliths and matrix-like plant fibers, also may promote enamel and focal overgrowths of equine dentition. Here we report a rostral mandibular hook in a lower premolar tooth of a medieval horse, found in a spring deposit in Levänluhta, Osthroboth...
Early volumetric changes after vertical augmentation of the atrophic posterior mandible with interpositional block graft versus onlay bone graft: A retrospective radiological study. The aim of this study was to evaluate volumetric and clinical outcomes of atrophic posterior mandibles treated with inlay or onlay bone grafting techniques. Methods: In posterior mandibles, alveolar ridges were treated either with interpositional equine cancellous bone block (inlay group) or with onlay autogenous bone block (onlay group). Bone volumes at baseline and at 4 months after surgery were measured by computed tomography. Results: A total of 20 subjects were enrolled in the present study: 10 in the inlay group and 10 in the onlay group. After surgery, atrophic posterior mandibles showe...
Socket Preservation using Enzyme-treated Equine Bone Granules and an Equine Collagen Matrix: A Case Report with Histological and Histomorphometrical Assessment. To histologically assess the effectiveness of a socket-preservation technique using enzyme-treated equine bone granules as a bone-graft material in combination with an equine collagen matrix as a scaffold for soft-tissue regeneration. Background: Enzyme-treated equine bone granules and equine collagen matrix recently have been developed to help overcome alveolar bone deficiencies that develop in the wake of edentulism. Methods: The patient had one mandibular molar extracted and the socket grafted with equine bone granules. The graft was covered with the equine collagen matrix, placed in a doub...
Conservative Management of Unilateral Fractures of the Mandibular Rami in Horses. To report the outcome of conservative management of unilateral fractures of the mandibular rami in horses. Methods: Retrospective case series. Methods: 24 client-owned horses with unilateral mandibular fractures METHODS: Medical records (January 2000-January 2014) of horses with unilateral mandibular ramus fractures were retrieved. Only conservatively managed horses with follow-up information were included. Follow-up information on clinical outcome was retrieved from the medical records (n=11) or obtained by telephone interviews with the owners or trainers (n=13). Results: Twenty-three horses ...
Functional anatomy of the equine temporomandibular joint: Collagen fiber texture of the articular surfaces. In the last decade, the equine masticatory apparatus has received much attention. Numerous studies have emphasized the importance of the temporomandibular joint (TMJ) in the functional process of mastication. However, ultrastructural and histological data providing a basis for biomechanical and histopathological considerations are not available. The aim of the present study was to analyze the architecture of the collagen fiber apparatus in the articular surfaces of the equine TMJ to reveal typical morphological features indicating biomechanical adaptions. Therefore, the collagen fiber alignmen...
Sialoendoscopy as a treatment for an obstructed mandibular salivary duct in a horse. A 14-year-old Quarter Horse was examined for a draining tract of 8 months' duration on the right mandible that was non-responsive to antibiotic therapy and surgical therapy. Further investigation and subsequent treatment with sialoendoscopy and ultrasonography were performed to relieve an obstruction of plant awns in the mandibular salivary duct. Un cheval Quarter Horse âgé de 14 ans a été examiné pour une fistule purulente d’une durée de 8 mois à la mandibule droite qui ne répondait pas à la thérapie antibiotique et à la thérapie chirurgicale. De nouvelles investigations et le ...