The maxilla is one of the primary bones forming the upper jaw in horses, playing a significant role in the dental and skeletal structure of the equine head. It provides support for the upper teeth, including the incisors and cheek teeth, which are essential for the horse's ability to graze and process food. The maxilla also contributes to the formation of the nasal cavity and the orbit, influencing respiratory and visual functions. Anatomical variations and conditions affecting the maxilla, such as fractures, dental malocclusions, and sinusitis, can have implications for a horse's health and performance. This page compiles peer-reviewed research studies and scholarly articles that explore the anatomy, pathology, and clinical management of maxillary conditions in horses.
Borowska M, Jasiński T, Gierasimiuk S, Pauk J, Turek B, Górski K, Domino M.Dental diagnostic imaging has progressed towards the use of advanced technologies such as 3D image processing. Since multidetector computed tomography (CT) is widely available in equine clinics, CT-based anatomical 3D models, segmentations, and measurements have become clinically applicable. This study aimed to use a 3D segmentation of CT images and volumetric measurements to investigate differences in the surface area and volume of equine incisors. The 3D Slicer was used to segment single incisors of 50 horses' heads and to extract volumetric features. Axial vertical symmetry, but not horizon...
Singleton C, Manchella S, Nastri A.The aim of this study was to examine the pattern of equine-related maxillofacial trauma that required operative treatment in patients who presented to a level-one trauma centre in Melbourne between 2011 and 2016. A total of 28 patients (16 female and 12 male, median (range) age 31 (16-76) years) were identified from a database of all operatively managed maxillofacial trauma cases, and data were collected on demographics, mechanisms and patterns of injury, and management. The most common mechanism was kicking (n=16), which was also the most likely to result in multiple injuries. Half the patien...
Szulakowski M, Mageed M, Steinberg T, Winter K, Gerlach K.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...
Morgan RE, Fiske-Jackson AR, Hellige M, Gerhauser I, Wohlsein P, Biggi M.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...
Domanska-Kruppa N, Venner M, Bienert-Zeit A.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...
Nottrott K, Guio C, Schramme M.We report an unusual case of a young Quarter Horse with a large dental fracture fragment displaced into the maxillary sinus, leaving an oroantral communication that caused food impaction and metaplastic calcification in the sinus and facial deformation with cutaneous fistulation. Oral extraction of a remaining tooth fragment from its alveolus was succeeded by a maxillary sinusotomy for removal of the abnormal sinus contents. Since the oroantral fistula did not heal spontaneously following the placement of a silicone dental prosthesis, minimally invasive transbuccal and transnasal endoscopic ap...
Dixon PM, Hawkes C, Townsend N.The vast majority of equine oral procedures are dental-related and, unless great care is taken, almost all such procedures have the potential to cause marked short- or long-term damage to other oral structures. This review of the more common complications of oral surgery begins at the rostral oral cavity with procedures of the incisors, and then moves caudally to deal with complications related to procedures of wolf teeth and cheek teeth, including salivary duct disruption and dental sinusitis. Finally, complications associated with maxillary and mandibular fractures are discussed.
Vlaminck LE, Steenhault M, Maes D, Huys L, Gasthuys F.This study investigated the placement of an intra-alveolar prosthesis of bone substitute on gingival/periodontal health in 5 ponies following repulsion of cheek teeth 108 and 208. In each pony, one randomly chosen alveolus was allowed to heal by second intention while the other was filled with a non-resorbable, biocompatible bone substitute. At 6, 12 and 24-months after surgery, both maxillary arches were evaluated for wear abnormalities and for gingival health using a periodontal scoring system. Recorded changes included development of overgrowths on mandibular cheek teeth, widening of maxill...
Bush JM, Fredrickson RL, Ehrhart EJ.In horses, osteosarcoma is a rare tumor, with the majority of reported cases occurring in the head, and, more specifically, in the mandible of young horses. The following report documents 8 cases of equine osteosarcoma, the majority occurring in male horses aged 7 years or older with a lack of metastasis identified in any horse. Six arose in the maxilla or mandible and one in the proximal tibia. The predominant subtype was fibroblastic osteosarcoma with fewer osteoblastic type tumors. All had osteoid and most had a chondromucinous matrix. Surgical excision was attempted in the majority of case...
Brounts SH, Hawkins JF, Lescun TB, Fessler JF, Stiles P, Blevins WE.Two horses were admitted for evaluation of mandibular swelling (horse 1) or maxillary distortion (horse 2). Both horses had radiographic evidence of tumors of dental origin that had the appearance of a compound odontoma. Extensive surgical resection was performed for treatment. Horse 1 was treated with 1-stage surgical resection, but an iatrogenic fracture occurred during surgery, which was managed successfully with a type I external fixator and extraoral alimentation. Horse 2 was treated in multiple stages to remove all portions of the tumor. To manage an extensive orosinal fistula, a custom-...
Smith GA, Scherzer DJ, Buckley JW, Haley KJ, Shields BJ.Ninety-six children were admitted during a 9-year period to a pediatric level 1 trauma center for treatment of farm-related injuries. The age range was from 6 weeks to 17 years (median, 7.5 years; mean, 7.6 years; standard deviation, 4.4). Thirty-nine patients (40.6%) had an animal-related injury, including 36 children (37.5%) who had an injury associated with a horse. Amish children had an increased risk of horse-related injury when compared with non-Amish children (p=0.04; RR=2.09, 95% CI: 1.18<RR<3.70). Thirty-seven patients (38.5%) had farm machinery-related injuries, including 14 ch...
MacGillivray KC, Graham TD, Parente EJ.A 2-year-old male Thoroughbred was evaluated for multiple firm, raised nodules of the maxilla and mandible that had been present since 6 months of age. The horse was evaluated as a yearling with a final histologic diagnosis of fibrosarcoma. As a 2-year-old, the colt made a loud upper airway sound and was agitated after strenuous exercise. Results of upper airway endoscopy indicated severe narrowing of the nasal passages and pharynx with normal resting function. Radiography revealed multiple circular bony lesions in the mandible, maxilla, multiple long bones, and cervical vertebrae. Biopsy spec...
Boutros CP, Koenig JB.The 3rd maxillary molar is a difficult tooth to remove by extraction or repulsion. A combined frontal and maxillary approach provides good exposure for repulsion of this tooth, debridement of the sinuses, and placement of an alveolar seal. The improved exposure should minimize operative difficulties and postoperative complications.
Dixon PM, Tremaine WH, Pickles K, Kuhns L, Hawe C, McCann J, McGorum BC, Railton DI, Brammer S.Of 400 horses referred because of equine dental disease, 162 suffered from primary apical infections of their cheek teeth (CT), including 92 with maxillary CT infections and 70 with mandibular CT infections. Maxillary swellings and sinus tracts were more common (82 and 26% incidence, respectively) with infections of the rostral 3 maxillary CT, than with infections of the caudal 3 maxillary CT (39 and 5% incidence, respectively). Nasal discharge was more commonly present with caudal (95%) than rostral (23%) maxillary CT infections. Mandibular CT apical infections commonly had mandibular swellin...
Tudor RA, Ramirez O, Tate LP, Gerard MP.A 1-month-old male American Paint Horse was evaluated for a hard swelling on the right side of the maxillary region. On radiographs there was a large, expansile outpouching of the right maxillary bone between the second and third premolar teeth. Computed tomography further characterized the expansile lesion to have a soft tissue component and to originate in the region of a caudal maxillary tooth. Surgical reconstruction of the defect was unsuccessful and the animal was euthanetized. Based on failure to find histopathologic evidence of a neoplasm or cyst, the diagnosis was a congenital malform...
Henninger RW, Beard WL, Schneider RK, Bramlage LR, Burkhardt HA.To compare fracture locations, repair methods, complications, and outcomes of horses with fractures of the rostral portions of the mandible and maxilla. Methods: Retrospective study. Methods: 89 horses with fractures of the rostral portions of the mandible and maxilla. Methods: Medical records and radiographs were reviewed. Fractures were categorized by fracture location and stability. Postoperative complications and long-term outcome were determined by clinical examination and telephone interviews with horse owners. Results: 4 fracture types were recognized. Fractures involving just the alveo...
Teifke JP, Schmidt E, Traenckner CM, Bauer C.Therapy resistant swellings of the maxillary region and unilateral nasal discharge in older horses are mainly thought to be consequences of neoplasias of the oral cavity, especially of the gingiva and the teeth, or to develop from tumours of the nasal cavity. We report an unilateral swelling of the left nasal and buccal region in a 13-year-old gelding, which was accompanied by an aggressive destruction of involved osseous tissue due to a severe proliferative granulomatous inflammation. The granuloma was caused by the nematode Halicephalobus (syn. Micronema) deletrix. This nematode infection is...
Freestone JF, Seahorn TL.Nutritional secondary hyperparathyroidism is associated with horses that are fed diets with an imbalance of calcium and phosphorus or diets containing oxalates. Clinical signs include a shifting lameness, with tenderness of the joints, reluctance to move, or a stiff, stilted gait. Some horses may have broadening of the nasal bones, enlargement of the maxilla and/or the mandible, or a ridge over the nasal bones. Diagnosis may include physical examination findings; analysis of feed; and clinical pathologic data, which may include normocalcemia, normal to increased serum phosphorus, and increased...
Weber A, Ligthelm AJ, Verstraete FJ.An 8-year-old Hannoverian horse developed a swelling of the maxilla caused by a tumour of the hard palate. On histological examination the tumour was diagnosed as a primary intra-osseous carcinoma of the maxilla, a rare odontogenic tumour not previously described in the horse.
Morgan RE, Fiske-Jackson AR, Hellige M, Gerhauser I, Wohlsein P, Biggi M.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...
Singleton C, Manchella S, Nastri A.The aim of this study was to examine the pattern of equine-related maxillofacial trauma that required operative treatment in patients who presented to a level-one trauma centre in Melbourne between 2011 and 2016. A total of 28 patients (16 female and 12 male, median (range) age 31 (16-76) years) were identified from a database of all operatively managed maxillofacial trauma cases, and data were collected on demographics, mechanisms and patterns of injury, and management. The most common mechanism was kicking (n=16), which was also the most likely to result in multiple injuries. Half the patien...
Bush JM, Fredrickson RL, Ehrhart EJ.In horses, osteosarcoma is a rare tumor, with the majority of reported cases occurring in the head, and, more specifically, in the mandible of young horses. The following report documents 8 cases of equine osteosarcoma, the majority occurring in male horses aged 7 years or older with a lack of metastasis identified in any horse. Six arose in the maxilla or mandible and one in the proximal tibia. The predominant subtype was fibroblastic osteosarcoma with fewer osteoblastic type tumors. All had osteoid and most had a chondromucinous matrix. Surgical excision was attempted in the majority of case...
Henninger RW, Beard WL, Schneider RK, Bramlage LR, Burkhardt HA.To compare fracture locations, repair methods, complications, and outcomes of horses with fractures of the rostral portions of the mandible and maxilla. Methods: Retrospective study. Methods: 89 horses with fractures of the rostral portions of the mandible and maxilla. Methods: Medical records and radiographs were reviewed. Fractures were categorized by fracture location and stability. Postoperative complications and long-term outcome were determined by clinical examination and telephone interviews with horse owners. Results: 4 fracture types were recognized. Fractures involving just the alveo...
Teifke JP, Schmidt E, Traenckner CM, Bauer C.Therapy resistant swellings of the maxillary region and unilateral nasal discharge in older horses are mainly thought to be consequences of neoplasias of the oral cavity, especially of the gingiva and the teeth, or to develop from tumours of the nasal cavity. We report an unilateral swelling of the left nasal and buccal region in a 13-year-old gelding, which was accompanied by an aggressive destruction of involved osseous tissue due to a severe proliferative granulomatous inflammation. The granuloma was caused by the nematode Halicephalobus (syn. Micronema) deletrix. This nematode infection is...
MacGillivray KC, Graham TD, Parente EJ.A 2-year-old male Thoroughbred was evaluated for multiple firm, raised nodules of the maxilla and mandible that had been present since 6 months of age. The horse was evaluated as a yearling with a final histologic diagnosis of fibrosarcoma. As a 2-year-old, the colt made a loud upper airway sound and was agitated after strenuous exercise. Results of upper airway endoscopy indicated severe narrowing of the nasal passages and pharynx with normal resting function. Radiography revealed multiple circular bony lesions in the mandible, maxilla, multiple long bones, and cervical vertebrae. Biopsy spec...
Smith GA, Scherzer DJ, Buckley JW, Haley KJ, Shields BJ.Ninety-six children were admitted during a 9-year period to a pediatric level 1 trauma center for treatment of farm-related injuries. The age range was from 6 weeks to 17 years (median, 7.5 years; mean, 7.6 years; standard deviation, 4.4). Thirty-nine patients (40.6%) had an animal-related injury, including 36 children (37.5%) who had an injury associated with a horse. Amish children had an increased risk of horse-related injury when compared with non-Amish children (p=0.04; RR=2.09, 95% CI: 1.18<RR<3.70). Thirty-seven patients (38.5%) had farm machinery-related injuries, including 14 ch...
Brounts SH, Hawkins JF, Lescun TB, Fessler JF, Stiles P, Blevins WE.Two horses were admitted for evaluation of mandibular swelling (horse 1) or maxillary distortion (horse 2). Both horses had radiographic evidence of tumors of dental origin that had the appearance of a compound odontoma. Extensive surgical resection was performed for treatment. Horse 1 was treated with 1-stage surgical resection, but an iatrogenic fracture occurred during surgery, which was managed successfully with a type I external fixator and extraoral alimentation. Horse 2 was treated in multiple stages to remove all portions of the tumor. To manage an extensive orosinal fistula, a custom-...
Freestone JF, Seahorn TL.Nutritional secondary hyperparathyroidism is associated with horses that are fed diets with an imbalance of calcium and phosphorus or diets containing oxalates. Clinical signs include a shifting lameness, with tenderness of the joints, reluctance to move, or a stiff, stilted gait. Some horses may have broadening of the nasal bones, enlargement of the maxilla and/or the mandible, or a ridge over the nasal bones. Diagnosis may include physical examination findings; analysis of feed; and clinical pathologic data, which may include normocalcemia, normal to increased serum phosphorus, and increased...
Domanska-Kruppa N, Venner M, Bienert-Zeit A.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...
Weber A, Ligthelm AJ, Verstraete FJ.An 8-year-old Hannoverian horse developed a swelling of the maxilla caused by a tumour of the hard palate. On histological examination the tumour was diagnosed as a primary intra-osseous carcinoma of the maxilla, a rare odontogenic tumour not previously described in the horse.
Szulakowski M, Mageed M, Steinberg T, Winter K, Gerlach K.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...
Nottrott K, Guio C, Schramme M.We report an unusual case of a young Quarter Horse with a large dental fracture fragment displaced into the maxillary sinus, leaving an oroantral communication that caused food impaction and metaplastic calcification in the sinus and facial deformation with cutaneous fistulation. Oral extraction of a remaining tooth fragment from its alveolus was succeeded by a maxillary sinusotomy for removal of the abnormal sinus contents. Since the oroantral fistula did not heal spontaneously following the placement of a silicone dental prosthesis, minimally invasive transbuccal and transnasal endoscopic ap...
Tudor RA, Ramirez O, Tate LP, Gerard MP.A 1-month-old male American Paint Horse was evaluated for a hard swelling on the right side of the maxillary region. On radiographs there was a large, expansile outpouching of the right maxillary bone between the second and third premolar teeth. Computed tomography further characterized the expansile lesion to have a soft tissue component and to originate in the region of a caudal maxillary tooth. Surgical reconstruction of the defect was unsuccessful and the animal was euthanetized. Based on failure to find histopathologic evidence of a neoplasm or cyst, the diagnosis was a congenital malform...
Boutros CP, Koenig JB.The 3rd maxillary molar is a difficult tooth to remove by extraction or repulsion. A combined frontal and maxillary approach provides good exposure for repulsion of this tooth, debridement of the sinuses, and placement of an alveolar seal. The improved exposure should minimize operative difficulties and postoperative complications.
Dixon PM, Hawkes C, Townsend N.The vast majority of equine oral procedures are dental-related and, unless great care is taken, almost all such procedures have the potential to cause marked short- or long-term damage to other oral structures. This review of the more common complications of oral surgery begins at the rostral oral cavity with procedures of the incisors, and then moves caudally to deal with complications related to procedures of wolf teeth and cheek teeth, including salivary duct disruption and dental sinusitis. Finally, complications associated with maxillary and mandibular fractures are discussed.
Vlaminck LE, Steenhault M, Maes D, Huys L, Gasthuys F.This study investigated the placement of an intra-alveolar prosthesis of bone substitute on gingival/periodontal health in 5 ponies following repulsion of cheek teeth 108 and 208. In each pony, one randomly chosen alveolus was allowed to heal by second intention while the other was filled with a non-resorbable, biocompatible bone substitute. At 6, 12 and 24-months after surgery, both maxillary arches were evaluated for wear abnormalities and for gingival health using a periodontal scoring system. Recorded changes included development of overgrowths on mandibular cheek teeth, widening of maxill...
Dixon PM, Tremaine WH, Pickles K, Kuhns L, Hawe C, McCann J, McGorum BC, Railton DI, Brammer S.Of 400 horses referred because of equine dental disease, 162 suffered from primary apical infections of their cheek teeth (CT), including 92 with maxillary CT infections and 70 with mandibular CT infections. Maxillary swellings and sinus tracts were more common (82 and 26% incidence, respectively) with infections of the rostral 3 maxillary CT, than with infections of the caudal 3 maxillary CT (39 and 5% incidence, respectively). Nasal discharge was more commonly present with caudal (95%) than rostral (23%) maxillary CT infections. Mandibular CT apical infections commonly had mandibular swellin...
Borowska M, Jasiński T, Gierasimiuk S, Pauk J, Turek B, Górski K, Domino M.Dental diagnostic imaging has progressed towards the use of advanced technologies such as 3D image processing. Since multidetector computed tomography (CT) is widely available in equine clinics, CT-based anatomical 3D models, segmentations, and measurements have become clinically applicable. This study aimed to use a 3D segmentation of CT images and volumetric measurements to investigate differences in the surface area and volume of equine incisors. The 3D Slicer was used to segment single incisors of 50 horses' heads and to extract volumetric features. Axial vertical symmetry, but not horizon...
