Immunohistochemical expression of beta-catenin, BMP4 and TGF-beta in odontomas.

Changes in the expression of nuclear ß-catenin are responsible for tumorigenesis. Beta-catenin acts synergistically with the TGF-ß/BMPs pathway. This interaction leads to greater dentin deposition and may explain the differences between distinct tooth morphologies and hamartomas. The aim of this study was to investigate the role of ß-catenin, BMP4 and TGF-ß in the development of odontomas. This cross-sectional, retrospective, immunohistochemical study evaluated 30 compound odontomas, 30 complex odontomas and 17 tooth germs. The results showed that BMP4 and TGF-ß were more immunoexpressed in the ectomesenchyme of complex odontomas (median = 33.7, p < 0.001; median = 76.4, p = 0.002, respectively). Higher immunoexpression of BMP4 and TGF-ß was also observed in the epithelium of tooth germs (median = 2.0, p < 0.001; median = 120.3, p < 0.001, respectively). TGF-ß and BMP4 showed a positive and significant correlation (p < 0.001). Both TGF-ß and BMP4 were positively correlated with nuclear ß-catenin in ectomesenchyme (p = 0.047 and p = 0.023, respectively). Developing teeth exhibited higher concentrations of the proteins studied in odontogenic epithelium, especially during the bud and cap stages. Higher immunoexpression in odontomas occurred mainly in the ectomesenchyme. We therefore suggest that changes in the ectomesenchyme can lead to the development of odontomas.

A spontaneous compound odontoma in an adult Sprague Dawley rat (Rattus norvegicus).

Reports of compound odontomas in rats are very rare. A 14-month-old adult male Sprague Dawley rat was found to have a hard mass associated with the caudal aspect of the left mandible. After 2 weeks of observation, the rat was euthanized due to the mass growing significantly in size and the rat losing >20% of its body weight. Grossly, the mass was well-circumscribed, 3.7 × 3 × 1.2 cm, hard and heterogeneously coloured white, tan and red. The mass was restricted to the mandibular bone and did not involve surrounding subcutaneous tissue. On cut surface, the mass was a similar colour and brittle. Histologically, there were numerous proto-teeth embedded in ossified stroma. Each proto-tooth had a central mesenchyme pulp surrounded by columnar odontoblasts and dentine matrix. The dentine was often bordered by enamel matrix, which was occasionally bounded by ameloblasts. These histological findings were consistent with a compound odontoma. This is the first report of a spontaneous compound odontoma in the caudal mandible of a rat.

REMOVAL OF PSEUDO-ODONTOMAS VIA LATERAL MAXILLOTOMY IN THREE RICHARDSON'S GROUND SQUIRRELS (UROCITELLUS RICHARDSONII).

Pseudo-odontoma can occur in some species with elodont teeth. Pseudo-odontomas affecting maxillary dentition may result in obstruction of the nasal cavities and lead to dyspnea. Effective treatments for the disease in Richardson's ground squirrels (Urocitellus richardsonii) have not yet been established. Three Richardson's ground squirrels exhibiting dyspnea and with maxillary pseudo-odontomas, based on diagnostic imaging, were surgically treated. The animals were placed under general anesthesia, and following excision of skin and subcutaneous tissue at the midpoint of the line connecting the medial canthus and ipsilateral nasal opening, maxillotomy of the incisive bone was performed. The reserve crown of the maxillary incisor tooth was exposed via the maxillotomy site and was sectioned into labial and palatal fragments, and the diseased tooth was completely extracted. In all three cases, dyspnea improved immediately after surgery. In one case, no recurrence was observed 600 d following surgery. These results suggest that the procedure used provides a practical approach for treating maxillary pseudo-odontomas in Richardson's ground squirrels.

Ameloblastic Fibro-Odontoma in a Free-Ranging Rocky Mountain Bighorn Sheep (Ovis canadensis canadensis), Alberta, Canada.

An adult female Rocky Mountain bighorn sheep (Ovis canadensis canadensis) was euthanized because of a large mandibular mass. Histopathology revealed an ameloblastic fibro-odontoma, a rare odontogenic neoplasia.

Complex Odontoma in a Young Captive Reticulated Giraffe (Giraffa camelopardalis reticulata).

Complex odontoma is a rare odontogenic lesion reported in rodents (order: Rodentia) and odd-toed ungulates (order: Perissodactyla), to name a few, and only in bovine animals of the order Artiodactyla. A 3-year-old female giraffe presented with a steadily proliferating, firm mass in the rostral mandible. With further expansion and ulceration of the mass, the general condition of the giraffe deteriorated and it was euthanized. Post-mortem examination revealed greyish-white tissue with an irregular arrangement of yellowish hard tissue arranged in thin plates and intermingled areas of greyish soft tissue. Histologically, irregular proliferated odontogenic epithelium and mesenchyme, dentin, cementum and empty spaces, suggestive of decalcified enamel, were present. These findings are consistent with a diagnosis of complex odontoma, which should be added to the differential diagnoses of oral tissue proliferations in giraffes. To our knowledge, this is the first description of a complex odontoma in a giraffe.

Odontomas in Frogs.

Odontomas are variably differentiated, hamartoma-like proliferations of odontogenic epithelium, pulp ectomesenchyme (odontoblasts), and dental matrix. Frogs are polyphyodont and homodont. Their teeth also differ from mammals in that they are restricted to the upper jaw in adults and lack a periodontal ligament and cementum, attaching directly to the underlying bone. Odontomas were identified in an African clawed frog (Xenopus laevis), a false tomato frog (Dyscophus guineti), and a tomato frog of unknown species (Dyscophus sp.). All of the examined odontomas were composed of numerous tooth-like structures comprising an arc of dentinal matrix lined on the convex surface by ameloblasts and on the concave surface by odontoblasts. Masson's trichrome and immunohistochemistry with pan-cytokeratin supported these findings. The pathogenesis of these lesions may be displacement of the dental lamina, which has been shown in research studies to lead to de novo proliferation of dental elements in frogs.

Case Report: An association of the gubernacular canal, supernumerary tooth and odontoma with an impacted canine on cone-beam computed tomography.

This report describes a clinical case of asymptomatic compound odontoma in the anterior left side of the maxilla associated with an impacted canine and supernumerary tooth with a gubernacular canal of a 47- year-old female with no relevant medical history. Cone-beam computed tomography (CBCT) was performed for precise three-dimensional localization of each structure and assessment of their spatial relationship with the associated structures before surgery. The treatment protocol involved surgical enucleation of the odontoma and open extraction of both impacted and supernumerary teeth. The patient had uneventful healing and proceeded with the prosthodontic treatment plan. The dentist should be aware of the probability of a close relationship between the development of odontoma and presence of the gubernacular tract, which could be used as a future radiographic diagnostic criterion of an odontoma. Also, we recommend that more studies be performed in this field to deeply analyze the imaging characteristics of GT and its spatial association with various pathological lesions in the future.

Mixed odontogenic tumors in four young dogs: ameloblastic fibroma and ameloblastic fibro-odontoma.

Ameloblastic fibroma (AF) and ameloblastic fibro-odontoma (AFO) are mixed odontogenic tumors (odontogenic tumors with induction) that are reported only rarely in dogs. These tumors are histologically complex and, to a degree, recapitulate the early stages of tooth development, comprising 2 types of tissue: neoplastic odontogenic epithelium, and induced ectomesenchyme (dental pulp). AFOs are distinguished from AFs by the additional presence of hard dental matrices such as dentin. Herein, we describe the key diagnostic features of AF and AFO in 4 young dogs.

Odontomas in two long-finned ocellaris clownfish ( Amphiprion ocellaris).

Two adult long-finned ocellaris clownfish ( Amphiprion ocellaris) from 2 different aquaculture facilities were examined at the University of Florida, Tropical Aquaculture Laboratory for oral masses. Incisional biopsies were obtained from the masses under anesthesia, and histologic examination revealed both to be odontomas. Most benign odontomas are classified as hamartomas (disorganized proliferations of tissues found normally at the site of origin). Odontomas have previously been reported in wild teleost fish in association with viral infections and pollution.

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 been exposed in utero to the mutagen ENU (N-ethyl-N-nitrosourea), and a naturally occurring lesion in a 2-y-old Appaloosa horse. In order to satisfy the diagnostic criteria for this lesion, mineralized dental matrix in relationship to neoplastic odontogenic epithelium must be identifiable within the OA lesion. This group of odontogenic tumors is differentiated by the degree to which the dental matrix is organized and the relative proportions of pulp ectomesenchyme, odontogenic matrix, and odontogenic epithelium.

Mandibular odontogenic sarcoma (ameloblastic fibrodentinosarcoma) in an aged cat - Short communication.

A 13-year-old male cat presented with an ill-defined mass in the rostral mandible causing destruction and loss of alveolar bone. Microscopically, the mass consisted of cords or islands of benign odontogenic epithelium and a malignant, pleomorphic spindle-shaped cell component with dysplastic dentine formation. Immunohistochemically, neoplastic mesenchymal cells proved to be strongly positive for vimentin and negative for cytokeratins, desmin, actin and S100 protein; the Ki67 proliferation index was high. Morphological and immunohistochemical features largely overlap those reported for ameloblastic fibrodentinosarcoma, an uncommon histologic subtype of odontogenic sarcoma recognised in humans but no reported previously in animals. Ki-67 expression assessment may help to discriminate between malignant and benign forms of odontogenic tumours but the final diagnosis is mainly morphological.

COMPUTED TOMOGRAPHIC FEATURES OF INCISOR PSEUDO-ODONTOMAS IN PRAIRIE DOGS (CYNOMYS LUDOVICIANUS).

Maxillary incisor pseudo-odontomas are common in pet prairie dogs and can cause progressive respiratory obstruction, while mandibular pseudo-odontomas are rarely clinically significant. The aim of this retrospective cross-sectional study was to describe CT features of maxillary and mandibular incisor pseudo-odontomas vs. normal incisors in a group of pet prairie dogs. All pet prairie dogs with head CT scans acquired during the period of 2013-2015 were included. A veterinary radiologist who was aware of final diagnosis reviewed CT scans and recorded qualitative features of affected and normal incisors. Mean density values for the pulp cavity and palatal and buccal dentin were also recorded. A total of 16 prairie dogs were sampled (12 normal maxillary incisors, 20 confirmed maxillary incisor pseudo-odontomas, 20 normal mandibular incisors, 12 presumed mandibular incisor pseudo-odontomas). Maxillary incisors with confirmed pseudo-odontomas had a significantly hyperattenuating pulp and dentin in the reserve crown and apical zone, when compared to normal maxillary incisors. Pseudo-odontomas appeared as enlargements of the apical zone with a globular/multilobular hyperattenuating mass formation haphazardly arranged, encroaching on midline and growing caudally and ventrally. Presumed mandibular incisor pseudo-odontomas had similar CT characteristics. In 60% of prairie dogs with maxillary incisor pseudo-odontomas, the hard palate was deformed and the mass bulged into the oral cavity causing loss of the palatine bone. The common nasal meatus was partially or totally obliterated in 81.8% of prairie dogs with maxillary pseudo-odontomas. Findings supported the use of CT for characterizing extent of involvement and surgical planning in prairie dogs with pseudo-odontomas.

Campylorrhinus lateralis, Bilateral microphthalmia and odontoma temporalis in an Oldenburg Foal.

An Oldenburg colt with wry nose was autopsied after having lived for only 30 min. It presented cyanotic oral mucosae, underdeveloped eyes and a right-sided temporal osseous mass. The applicable nomenclature for the defects is discussed, and the potential etiopathogenesis is explored by describing the normal embryonic development of the affected body parts.

Extensive Maxillary Odontomas in 2 Dogs.

Two immature male dogs were presented for the treatment of extensive maxillary compound odontomas. In both cases, clinical evaluation and diagnostic imaging revealed extensive lesions invading and displacing anatomical structures of the maxilla. Histopathology confirmed the diagnoses in both cases. One dog was treated with partial rostral maxillectomy, and the other dog was treated with enucleation of the cystic lining and removal of tooth-like structures through a lateral rhinotomy utilizing an intraoral approach. This report illustrates the growth potential of maxillary compound odontomas in 2 dogs and highlights their subclinical appearance and excellent prognosis despite their extensive nature.

Elodontoma in Two Guinea Pigs.

Elodontoma was diagnosed in two pet guinea pigs, one involving a maxillary premolar tooth and the other affecting a mandibular incisor tooth. Diagnostic imaging, including radiographs, computed tomography, and oral endoscopy was performed in order to quantify dental disease. Diagnostic imaging was also used to guide treatment of acquired dental disease, which included intraoral restoration of normal occlusal plane and tooth extraction using an extraoral approach. These are the first histologically confirmed cases of elodontoma in guinea pigs.

Occurrence of tumour (odontoma) in marine fish Sphyraena jello from the southeast coast of India.

We examined the occurrence of odontoma in the marine fish Sphyraena jello sourced from 3 different landing centers (Cuddalore, Parangipettai and Nagapattinam) in Tamil Nadu (southeast India). A total of 19783 fishes were examined for odontoma presence, of which 2393 were affected with odontoma. The overall prevalence was 12.1% among the 3 stations. Fish landed at Parangipettai showed the highest peak prevalence of odontoma (16.8%) during the pre-monsoon, followed by Nagapatinam (9.1%) during summer 2011. The tumour lengths in premaxilla, supermaxilla and dentary bone were 1.1-3.6, 1.4-5.9 and 1.2-4.1 cm, respectively, and tumour widths were 0.3-1.9, 0.7-3.1 and 0.5-1.9 cm. Higher prevalence (0.206%) of tongue tumour along with odontoma was observed at Nagapattinam whereas it was lower (0.162%) at Cuddalore. Odontoma histopathology showed dense fibrous tissue with fine teeth roots. TEM analysis showed virus-like particles associated with odontoma. Radiography of the odontoma showed that the tumour masses were bony in nature and tissues were merged with upper and lower jaw.

Pharyngeal odontoma in an adult walleye (Sander vitreus).

An adult walleye (Sander vitreus) was submitted to Cornell University for evaluation of a hard pale-tan pharyngeal mass attached to the gill arches. Dozens of hard white conical structures radiated from the surface. Microscopically, conical structures were identified as denticles and rested on plates of dysplastic orthodentine, cementum, and acellular bone. A diagnosis of compound odontoma was made based upon the presence of proliferative epithelial and mesenchymal odontogenic tissues that recapitulated tooth structures normally present on gill rakers. Odontomas are classified as hamartomas and typically develop in immature diphyodont mammals. The pharyngeal location and lifelong regeneration of teeth in fish, however, both qualify the present diagnosis in the pharyngeal region of an adult teleost. Ontogenic and morphologic differences between mammalian and piscine dentition and differentials for tooth-bearing tumors in fish are presented within the context of a developmental anomaly.