Search

Due to the close proximity of the primary teeth with the developing permanent successors, several developmental alterations in the permanent successors have been reported as consequences of traumatic dental injuries to the primary dentition. When they occur at a very young age such trauma could disturb normal tooth development and cause rare anomalies, including sequestration of the permanent tooth germ and odontoma-like malformations. A literature review of case reports with a history of trauma and odontoma formation is discussed in this paper. This paper also includes a case report of a patient, who was 3-years and 5-months old, when she was seen at the University of California, Los Angeles Children's Dental Center for the first time. The grandmother reported that the child was dropped from the father's lap when she was 2 weeks old and suffered head trauma and multiple skull fractures.

Objective This report discusses the clinical relevance of a novel case of an odontoma and transmigrated canine in the setting of florid cemento-osseous dysplasia (COD), hypercementosis and moderate to severe periodontitis in a 66-year-old patient. Background An odontoma may infrequently impede tooth eruption and rarely has been implicated with canine transmigration. COD is a benign fibro-osseous lesion associated with decreased vascularity and poorer surgical intervention. Materials and methods A partially edentulous woman, in no acute distress, underwent clinical and radiographic evaluation in pursuit of comprehensive dental care. Results Radiographic assessment demonstrated multiple occult pathologies of the mandible, including compound odontoma, canine transmigration, florid COD, hypercementosis and moderate to severe periodontitis, a concurrence thought to be previously unreported. Furthermore, the presence of the odontoma and transmigrated canine is apparently the second reported case in the geriatric population. Conclusions The attending clinician should carefully weigh removal of an impacted and transmigrated canine associated with an odontoma in the setting of COD and compromised bone, particularly in older individuals. When surgical intervention is deferred in these clinical situations, patients should continue to be monitored for clinical and radiographic development of pathologic processes.

Developing odontoma is a rare mixed odontogenic tumor that can arise with other odontogenic lesions. The association of COC with ameloblastic fibro‐odontoma is extremely rare. We report an extremely rare case of developing odontoma arising from a calcifying odontogenic cyst in a 17‐year‐old girl., The importance of accurate diagnosis that influence the treatment plan. In this case with accurate diagnosis, conservative treatment was substituted with marginal resection.

Traumatic dental injuries are highly prevalent among preschool children. When occurring at a very young age (prior to the eruption of the primary teeth), such trauma can disturb the normal development of the permanent dentition and, more rarely, affect the primary dentition. This report describes a case of a patient who suffered dentoalveolar trauma at six months of age that caused rare developmental problems in the primary dentition, such as impaction, dilacerations, hypoplasia, and odontoma. Imaging revealed that alterations also occurred in the permanent dentition. This report demonstrates that dentoalveolar trauma prior to complete development of the dentition and even before the eruption of the primary teeth can lead to highly uncommon abnormalities in the primary dentition. Moreover, there may be repercussions in the permanent dentition when the germs of these teeth are injured by the intraosseous displacement of primary teeth.

Gardner syndrome with odontogenic sinusitis is rare but should be suspected in patients with multiple osteomas of the skull and facial bones, excess teeth, impacted teeth, and odontomas. Early diagnosis and treatment of GS may improve prognosis.

Special AT-rich sequence-binding protein 2 (SATB2)-associated syndrome (SAS) is characterized by alterations of SATB2. Its clinical features include intellectual disability and craniofacial abnormalities, such as cleft palate, dysmorphic features, and dental abnormalities. Here, we describe three previously undiagnosed, unrelated patients with SAS who exhibited dental abnormalities, including multiple odontomas. Although isolated odontomas are common, multiple odontomas are rare. Individuals in families 1 and 3 underwent whole-exome sequencing. Patient 2 and parents underwent targeted amplicon sequencing. On the basis of the hg19/GRCh37 reference and the RefSeq mRNA NM_001172517, respective heterozygous mutations were found and validated in Patients 1, 2, and 3: a splice-site mutation (chr2:g.200137396C > T, c.1741-1G > A), a nonsense mutation (chr2:g.200213750G > A, c.847C > T, p.R283*), and a frame-shift mutations (chr2:g.200188589_200188590del, c.1478_1479del, p.Q493Rfs*19). All mutations occurred de novo. The mutations in Patients 1 and 3 were novel; the mutation in Patient 2 has been described previously. Tooth mesenchymal cells derived from Patient 2 showed diminished SATB2 expression. Multiple odontomas were evident in the patients in this report; however, this has not been recognized previously as a SAS-associated phenotype. We propose that multiple odontomas be considered as an occasional manifestation of SAS.

Background Induction of podoplanin by transforming growth factor-β (TGF-β) has been shown in a number of lesions but not in odontogenic tumors (OTs). We evaluated the association between these markers in OTs for the first time and compared their expression among the different neoplasms. Methods Immunohistochemistry using monoclonal antibody against podoplanin and TGF-β was performed on 76 odontogenic cysts and tumors. Spearman's correlation coefficient, Kruskal-Wallis, and Mann-Whitney U tests followed by adjustment with Bonferroni were used for statistical analysis (P Results A significant difference in podoplanin expression was found among the lesions consisting of solid ameloblastomas, adenomatoid odontogenic tumors, ameloblastic fibromas, odontogenic myxomas (OMs), odontogenic keratocysts, and calcifying odontogenic cysts. Significant differences were observed only between OMs and each of the other neoplasms. Podoplanin immunostaining in the connective tissue was absent in most lesions. TGF-β was significantly different among the study sample but not between the lesions in paired comparisons. None of the studied OTs showed significant correlations between podoplanin-TGF-β, in either the epithelium or the stroma. These markers were also descriptively reported in calcifying epithelial odontogenic tumors. Conclusions The inductive effect of TGF-β on podoplanin seems to be limited, if any, in odontogenic lesions. Podoplanin appears to play a role in some aspects of OTs with epithelial or mixed origins. Despite the possible participation of podoplanin in tumorigenesis, it may not necessarily be involved in the aggressive behavior of OTs.

Purpose To integrate the available data published to date on ameloblastic fibromas (AF) and ameloblastic fibrosarcomas (AFS) into a comprehensive analysis of their clinical/radiological features. Methods An electronic search was undertaken in July 2017. Eligibility criteria included publications having enough clinical, radiological and histological information to confirm a definite diagnosis. Results A total of 244 publications (279 central AF tumours, 10 peripheral AF, 103 AFS) were included. AF and AFS differed significantly with regard to the occurrence of patients’ mean age, bone expansion, cortical bone perforation and lesion size. Recurrence rates were as follows: central AF (19.2%), peripheral AF (12.5%), AFS (all lesions, 35%), primary (de novo) AFS (28.8%) and secondary AFS (occurring after an AF, 50%). Larger lesions and older patients were more often treated by surgical resections for central AF. Segmental resection resulted in the lowest rate of recurrence for most of the lesion types. AFS treated by segmental resection had a 70.5% lower probability to recur (OR 0.295; P = .049) than marginal resection; 21.3% of the AFS patients died due to complications related to the lesion. Conclusions Very long follow-up is recommended for AF lesions, due to the risk of recurrence and malignant change into AFS. Segmental resection is the most recommended therapy for AFS.

Supernumerary teeth are teeth that are present in addition to normal teeth. Although several hypotheses and some molecular signalling pathways explain the formation of supernumerary teeth, but their exact disease pathogenesis is unknown. To study the molecular mechanisms of supernumerary tooth‐related syndrome (Gardner syndrome), a deeper understanding of the aetiology of supernumerary teeth and the associated syndrome is needed, with the goal of inhibiting disease inheritance via prenatal diagnosis. We recruited a Chinese family with Gardner syndrome. Haematoxylin and eosin staining of supernumerary teeth and colonic polyp lesion biopsies revealed that these patients exhibited significant pathological characteristics. APC gene mutations were detected by PCR and direct sequencing. We revealed the pathological pathway involved in human supernumerary tooth development and the mouse tooth germ development expression profile by RNA sequencing (RNA‐seq). Sequencing analysis revealed that an APC gene mutation in exon 15, namely 4292‐4293‐Del GA, caused Gardner syndrome in this family. This mutation not only initiated the various manifestations typical of Gardner syndrome but also resulted in odontoma and supernumerary teeth in this case. Furthermore, RNA‐seq analysis of human supernumerary teeth suggests that the APC gene is the key gene involved in the development of supernumerary teeth in humans. The mouse tooth germ development expression profile shows that the APC gene plays an important role in tooth germ development. We identified a new mutation in the APC gene that results in supernumerary teeth in association with Gardner syndrome. This information may shed light on the molecular pathogenesis of supernumerary teeth. Gene‐based diagnosis and gene therapy for supernumerary teeth may become available in the future, and our study provides a high‐resolution reference for treating other syndromes associated with supernumerary teeth.

Primordial odontogenic tumor (POT) is a rare lesion in the jaw which has been included as a new entity of benign mixed epithelial and mesenchymal odontogenic tumour in the latest World Health Organization (WHO) classification (2017). Only seven cases have been reported. It typically occurs in the posterior mandible. We report an additional case of POT in the maxilla of an 8-year-old girl presenting with an asymptomatic buccal enlargement. A well-defined, unilocular, radiolucent lesion was observed radiographically. Histologically, the tumor was mostly composed of loose fibrous connective tissue resembling dental papilla and a single layer of columnar epithelium covering the periphery of the tumor. In part, cords or nests of epithelium were present in the mesenchyme close to the periphery. Nestin, a marker of odontogenic ectomesenchyme, was positive in the mesenchymal tumor cells. We finally diagnosed the lesion as POT considering the possibility of other odontogenic tumors like ameloblastic fibroma or developing odontoma as a differential diagnosis. The patient shows no recurrence after 16 months. This case is the first report from Japan using this novel diagnosis POT after it was recognized and defined in the latest WHO classification.

The calcifying epithelial odontogenic tumour (CEOT), or Pindborg tumour, is a rare, benign odontogenic tumour. CEOT is usually asymptomatic and an incidental radiological finding, often presenting as a mandibular radiolucency with flecks of calcific material. We report an unusual case of CEOT in the left posterior maxilla of a 46-year-old male that was associated with an unerupted tooth. The tumour in this case caused non-specific sinus symptoms and appeared radiographically similar to an odontoma or ossifying fibroma due to its dense calcific contents. Diagnosis was confirmed histologically following surgical removal of the lesion, which showed classic CEOT histomorphology. We report this case to highlight the unusual clinico-radiologic presentation and illustrate the diagnostic difficulties that can occur with radiolucent and/or radiopaque lesions in the jaws.

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.

Odontogenic myxofibroma represents a rare slow-growing benign neoplasm, which usually occurs in the second and third decades of life and rarely in children or adults over 50 years of age. Myxomas in general represent from 2.3% to 17.7% of all odontogenic tumors, and myxofibromas represent a small number of all myxomas. Limited evidence is present in literature regarding the cytological diagnosis of odontogenic myxoma/myxofibroma. We hereby report the cytomorphological features of a histologically confirmed case of odontogenic myxofibroma and the pitfalls of the cytological diagnosis. A painless jaw swelling in a young boy was aspirated. Scanty mucoid material was obtained. Cytology Smears were moderately cellular and showed a population comprising predominantly of singly scattered plump to fusiform cells with bipolar cytoplasmic processes showing mild to moderate atypia embedded within dense myxoid matrix and another population of cells arranged in clusters. Case was interpreted as low grade mesenchymal tumor. Subsequent biopsy confirmed it as odontogenic myxofibroma arising in a odontogenic keratocyst. Precise interpretation of intraosseous jaw lesions FNAC may not always be possible, but an attempt should be made to broadly classify the lesion as an inflammatory lesion, cystic lesion, giant cell lesion, fibro-osseous lesion or as an odontogenic tumor. If dual population of odontogenic epithelium and mesenchymal cells embedded in myxoid matrix are identified in such aspirates, a possibility of myxoid odontogenic tumor may be suggested. Triple correlation of cytological, clinical and radiological findings can guide the surgeon for taking appropriate therapeutic decisions.

Odontogenic neoplasms are locally invasive oral tumors in dogs. The purpose of this retrospective study was to describe CT characteristics for varying histopathologic types of canine odontogenic neoplasms. A board-certified veterinary radiologist who was unaware of histologic findings reviewed and scored imaging studies. A total of 29 dogs were included in the study. Twenty-three of these dogs had concurrent dental radiographs. The most common CT characteristics for all tumor types were a direct association with or in the region of multiple teeth in 96.4% (27/28), contrast enhancement in 96.3% (26/27), alveolar bone lysis in 93.1% (27/29), and mass-associated tooth displacement in 85.2% (23/27). Mass-associated cyst-like structures were identified in 53.6% (15/28) and were only present in tumors containing odontogenic epithelium. Canine acanthomatous ameloblastomas (n = 15) appeared as extra-osseous (10/15) or intra-osseous (5/15) masses. Intra-osseous canine acanthomatous ameloblastomas were more likely to have mass-associated cyst-like structures and were subjectively more aggressive when compared with extra-osseous canine acanthomatous ameloblastomas. Amyloid-producing odontogenic tumors (n = 3) had subjectively uniform CT imaging characteristics and consisted of round soft tissue and mineral attenuating masses with multiple associated cyst-like structures. Fibromatous epulides of periodontal ligament origin (n = 4) were contrast enhancing extra-osseous masses that were rarely referred for CT examinations and 25% (1/4) were not visible with CT. Other odontogenic tumors were less represented or had more variable CT imaging characteristics. Mass-associated tooth destruction was appreciated more often with dental radiographs and extra-oral tumor extension was identified more often with CT.

Dense in dente, also known as dense invaginatus or dilated odontoma, is a developed malformed tooth and usually does not pose a diagnostic challenge. Described here is a unique case in which a rootless type III dense in dente (dilated odontoma) between the lower deciduous molars in a 2-year-old girl emerged through the gingiva mimicking a peripheral developing odontoma. At the time of examination, neither anchored in bone nor associated with an underlying un-erupted tooth. The small size, the superficial position in the growing mandible, the absence of the overlying bone and the physiologic eruptive movement of the neighbouring teeth may predispose the present rootless dense in dente to erupt in the gingiva.

Oral Diseases (2012) 18, 756–762 Objectives: An odontoma, which shows proliferating odontogenic epithelium and mesenchymal tissue, is one of the most common odontogenic tumors encountered. These are commonly found in tooth-bearing regions, although the etiology remains unknown. There are no previous reports of an established line of immortalized human odontoma cells. Methods: Using odontoma fragments obtained from a girl treated at our department, we established an immortalized human odontoma cell line and investigated cell morphology, dynamic proliferation, the presence of contamination, and karyotype. Moreover, cell characterization was examined using osteogenic and odontogenic markers. Results: We successfully established a mesenchymal odontoma cell (mOd cells). The cells were found to be fibroblastic and had a high level of telomerase activity. Cell growth was confirmed after more than 200 population doublings without significant growth retardation. mOd cells expressed mRNA for differentiation markers, including collagen type I (COLI), alkaline phosphatase, bone sialoprotein, osteopontin, osteocalcin, cementum-derived protein (CP-23), dentin sialophosphoprotein (DSPP), and distal-less homeobox 3 (DLX3), as well as bone morphogenetic proteins (BMPs). In addition, they showed a high level of calcified nodule formation activity in vitro. Conclusions: We successfully established a cell line that may be useful for investigating the mechanisms of normal odontogenesis as well as characteristics of odontoma tumors.

Screening for expression of amelogenesis-related proteins represents a powerful molecular approach to characterize odontogenic tumors and investigate their pathogenesis. In this study, we have examined the presence and distribution of odontogenic ameloblast-associated protein (ODAM), amelotin (AMTN), ameloblastin (AMBN), and amelogenin (AMEL) by immunohistochemistry in samples of adenomatoid odontogenic tumor (AOT), calcifying epithelial odontogenic tumor (CEOT), developing odontoma, ameloblastoma, calcifying cystic odontogenic tumor (CCOT), ameloblastic fibroma (AF), myxoma, odontogenic fibroma (OF), and reduced enamel epithelia (REE). Positive results were obtained in those tumors with epithelial component, except for AF, OF, and ameloblastoma. ODAM was found around mineralized structures (dystrophic calcifications) and CEOT's amyloid, whereas AMTN stained the eosinophilic material of AOTs. The CCOT transitory cells to ghost cells were strongly positive with all proteins except AMEL, and the REE as well as odontomas showed immunoexpression for ODAM, AMTN, AMBN, and AMEL similar to those found in normal rat tooth germs. Based on these results, some histopathogenetic theories were formulated.

This work was supported by the grants from the National Research Foundation of Korea (NRF) grant funded by the Korea government (MEST) (No. 2009-0066366) to Pill-Hoon Choung.

Fine-needle aspiration cytology of a case of ameloblastic fibrosarcoma (AFS), an unusual odontogenic tumor related to ameloblastoma (AB), was performed in a 25-year-old female with a 1 cm swelling in the left lower orbital region along with involvement of zygomatic region. Aspiration of the tumor yielded a cellular sample composed predominantly of mesenchymal element and few clusters representing epithelial component showing tall columnar cells with peripheral palisading. Detailed cytomorphological features of AFS are discussed along with differential diagnosis from other tumors such as AB, desmoplastic AB, odontogenic fibroma, ameloblastic fibrodentinoma and ameloblastic fibro-odontoma, ameloblastic fibroma.

Summary. Odontomes associated with primary teeth are rare. This report describes two cases of compound odontome associated with impacted maxillary primary central incisors in patients aged 1 year 8 months and 1 year 2 months, the latter being the youngest to have been reported with the condition. The odontomes were removed under local anaesthesia. Histological examination revealed immature dental tissues in both cases, but no evidence of root formation. Case 1 revealed ‘ghost cells’ within the enamel epithelium. The impacted incisors erupted following removal of the odontomes; in Case 2 the crown had an unusual ridge on its labial surface, extending from the gingival margin to a few millimetres from the incisal edge. Resume. Les odontomes associes aux dents temporaires sont rares. Cette etude decrit deux cas d'odontomes complexes, associes a des incisives centrales maxillaires temporaires non evoluees, chez deux sujets âges de 1 an 8 mois et 1 an 2 mois, ce dernier etant le plus jeune cas rapporte dans la litterature. Les odontomes furent extraits sous anesthesie locale. l'examen histologique a montre des tissus dentaires immatures dans les deux cas, mais aucune formation radiculaire. Le cas 1 montrait des ‘cellules fantomes’ dans l'epithelium de l'email. Les incisives retenues ont fait leur eruption apres suppression des odontomes; dans le cas 2, la couronne avait une crete inhabituelle sur la surface labiale, s'etendany du bord gingival a quelques millimetres du bord incisif. Zusammenfassung. Odomtome sind selten im Milchgebiss. In dieser Arbeit werden 2 Falle von Odomtome beschrieben im Zusammenhang mit impaktierten zentralen oberen Schneidezahne bei 2 Patienten im Alter von 1 Jahr 8 Monate und von 1 Jahr und 2 Monate. Die Odomtome wurden entfernt, histologisch fand man unreifes Zahngewebe ohne Wurzelbildung. Im ersten Fall fand man ‘Ghost’ Zellen im Schmelzepithelium. Nach Entfernung der Odomtome brachen die inpaktierten Zahne durch. Im zweiten Fall fand man eine unubliche Vorwolbung auf der Gingiva bis fast an der Inzisalen Kante reichend. Resumen. Los odontomos asociados a la denticion temporal son raros. Este articulo describe dos casos de odontomas compuestos asociados a incisivos centrales temporales impactados en pacientes de 1.8 y 1.2 anos. El de 1.2 anos es el mas joven reportado en la literatura. Los odontomas fueron removidas bajo anestesia local. El examen histologico revelo tejido dental inmaduro en ambos casos, pero no hubo evidencia de formacion radicular. El Caso i revelo ‘celulas fantasmas’ dentro del epitelio del esmalte. Los incisivos impactados erupcionaron despues de la remocion de los odontomas. En la Caso 2, la corona mostro un reborde inusual en la superficie vestibular extendiendose desde el margen gingival hasta unos milimetros del borde incisal.

Summary Complex odontomas are rare odontogenic tumours in horses comprised of a combination of mesenchymal and epithelial tissues. Examination, radiographic and histopathological findings in this patient all represent the typical behaviour of a complex odontoma. Oral tumours in horses may have treatment limitations due to tumour size and location. Similar to treatment in other species, surgical enucleation was curative for this type of tumour.

OBJECTIVE: To report a case of lateral periodontal cyst (LPC) with marked melanin pigmentation in a 38-year-old Black male and to discuss the phenomenon of melanin pigmentation in odontogenic cysts and tumors. RESULTS: Histologically, the epithelial lining of the LPC contained an abundant amount of melanin granules throughout the entire epithelium. Ultrastructurally, epithelial cells contained mature melanosomes (stage IV melanosomes). Melanophages containing aggregates of melanosomes were identified in the connective tissue cyst wall. Perusal of the literature revealed that melanin pigmentation in odontogenic lesions is uncommon. Melanin has been reported in calcifying odontogenic cyst (18 cases), odontogenic keratocyst (8 cases), adenomatoid odontogenic tumor (3 cases), ameloblastic fibroma (3 cases), odontoma (2 cases), and amelobastic fibro-odon-toma, odonto-ameloblastoma, and odontogenic fibroma (I case each). CONCLUSIONS: Almost all pigmented odontogenic lesions occurred in Blacks and Asians; they are almost non-existent in Whites. Thus, racial pigmentation probably plays an important role in such lesions.

Background and aims: The odontoma is the most common benign tumor of odontogenic origin, characterized by mixed histological features and diverse clinical presentation. The purpose of this study was to review clinicopathologic features of odontomas arising from oral and maxillofacial area in Korean patients. Methods: Sixty cases of odontoma were analyzed for their prevalence, clinical and pathological findings. Results: Clinical symptoms showed delayed eruption (n = 9) of either the deciduous or permanent tooth, intra- or extra-oral swelling (n = 27), pain (n = 6), but 18 cases had no subjective symptoms. Seventy percent of the odontomas were associated with unerupted teeth. The location of the tumor was maxilla in 55% and mandible in 45% of cases. There were 55% in the anterosuperier sector and 25% in the posteroinferior zone, while the rest in the upper molar region. Compound odontoma was more common (60%) than complex odontoma. Compound odontoma showed a mean age of 18.5 years, in the incisor/canine area of the maxilla, and smaller tumors (5–30 mm) with unilocular and multiple radio-opaque miniteeth surrounded by defined radiolucency. The complex odontoma showed a mean age of 30.1 years, in the first and second molar of the mandible, and larger tumors (10–60 mm) with unilocular undistinguished radio-opaque mass surrounded by radiolucent zone and a distinct radio-opaque border. Conclusions: The clinicopathologic pattern of odontomas can be divided into compound and complex odontomas, while the definitive diagnosis of odontomas was based on the pathological examination after surgical removal of the tumor.

Background: Calcifying odontogenic cyst was described first by Gorlin et al. in 1962; since then several hundreds of cases had been reported. In 1981, Praetorius et al. proposed a widely used classification. Afterwards, several authors proposed different classifications and discussed its neoplastic potential. The 2005 WHO Classification of Odontogenic Tumours re-named this entity as calcifying cystic odontogenic tumour (CCOT) and defined the clinico-pathological features of the ghost cell odontogenic tumours, the CCOT, the dentinogenic ghost cell tumour (DGCT) and the ghost cell odontogenic carcinoma (GCOC). Methods: The aim of this paper was to review the clinical-pathological features of 122 CCOT, DGCT and GCOC cases retrieved from the files of the oral pathology laboratories from 14 institutions in Mexico, South Africa, Denmark, the USA, Brazil, Guatemala and Peru. It attempts to clarify and to group the clinico-pathological features of the analysed cases and to propose an objective, comprehensive and useful classification under the 2005 WHO classification guidelines. Results: CCOT cases were divided into four sub-types: (i) simple cystic; (ii) odontoma associated; (iii) ameloblastomatous proliferating; and (iv) CCOT associated with benign odontogenic tumours other than odontomas. DGCT was separated into a central aggressive DGCT and a peripheral non-aggressive counterpart. For GCOC, three variants were identified. The first reported cases of a recurrent peripheral CCOT and a multiple synchronous, CCOT are included. Conclusions: Our results suggest that ghost cell odontogenic tumours comprise a heterogeneous group of neoplasms which need further studies to define more precisely their biological behaviour.

Aim. To survey the paediatric oral lesions in Thailand. Design. Biopsy records over a 15-year period (1990–2004) were retrieved from the files of the Department of Oral Pathology, Faculty of Dentistry, Chulalongkorn University. Paediatric cases with an age of 16 years or younger were selected. The age of the patients was divided into three groups according to the dentition period. The lesions were classified into three categories: inflammatory/reactive lesions, cystic lesions, and tumour/tumour-like lesions. Results. From a total of 8314 oral biopsies, 1251 cases (15.05%) were in the paediatric population. The greatest number of lesions fell into the cystic category, followed closely by the inflammatory/reactive category and tumour/tumour-like category, respectively. The top ten most frequently encountered lesions in the present study were dentigerous cyst, mucocele, pyogenic granuloma, ameloblastoma, radicular cyst, odontoma, odontogenic keratocyst, irritation fibroma (focal fibrous hyperplasia), fibrous dysplasia, and osteomyelitis. The majority of lesions were found in the mixed dentition period (49.24%). There was no statistical difference in the occurrence between genders in this study. Conclusions. The present study shows an almost similar trend to previous studies except in the ranking among and within categories. These differences may be attributable to the nature of the population studied and because Chulalongkorn University is a major referral centre.

BACKGROUND: Although it has been reported that ghost cells are present in odontomas, the generation mechanism of these cells is unclear. To evaluate the presence of ghost cells and involvement of the Wnt signaling pathway, we examined the expression of hard keratins, b-catenin and Lef-1 in odontomas. METHODS: Sixty-nine cases of odontoma were examined immunohistochemically with the use of antibodies against human hair proteins, b-catenin and Lef-1. RESULTS: Expression of hard keratins was found only in the cytoplasm of ghost cells in 46 (66.7%) of the 69 odontomas. Compound odontomas (78.8%) showed a higher incidence of ghost cells than complex odontomas (29.4%). Histopathologically, ghost cells were found within odontogenic epithelium adjacent to immature enamel and in the centre of Liesegang-ring-like calcified materials. Expression of b-catenin and Lef-1 was observed in the cytoplasm and nucleus of odontogenic epithelial cells adjacent to the ghost cells in immature odontomas. CONCLUSION: These findings suggest that odontoma is a hard keratin-expressing tumor-like lesion, and that the Wnt signaling pathway may be involved in the formation of ghost cells in odontomas. J Oral Pathol Med (2007) 36: 400–4

Background. A 7-year old boy was referred with retained maxillary right primary central and lateral incisors. Radiographic exam revealed a large calcified radio-opaque mass overlying the roots of these primary teeth preventing the permanent teeth from erupting. Case Report. The purpose of this paper is to describe the pre-operative use of multi-directional cross-sectional tomography in establishing the relationship between a large complex odontome that was preventing the eruption of a maxillary permanent central incisor. Conclusion. Low dose, multi-directional cross-sectional tomography was beneficial in visualisation of the precise relationship between the large complex odontome and the unerupted permanent incisor. This allowed correct judgement of the position on the odontome prior to its surgical removal.

Ultrastructural observation was performed on a calcifying odontogenic cyst (COC) associated with an odontoma and arising in the right mandibular region of an 8-year-old Japanese boy. Four types of cells were identified in the epithelial layer of the COC. The basal cells were low columnar in shape and contained some intracellular organelles. They were attached to the neighboring cells with a few desmosomes and resembled inner enamel epithelium of the normal enamel organ. The stellate reticulum-like cells, polygonal in shape, possessed desmosomes and many cytoplasmic projections. Some intracellular organelles and a few bundles of tonofilaments were observed in the cytoplasm. The light oval cells that were pale staining with toluidine blue contained dilated membranous organelles and many relatively evenly distributed tonofilaments. These cells were usually scattered in the vicinity of the focal accumulations of ghost cells, and the cell membrane was discontinuous in parts. The ghost cells contained many bundles of tonofilaments that were 60-240 nm in diameter and arranged in various directions. No intact intracellular organelles were noted in the cytoplasm. They were attached to the neighboring ghost cells with some desmosomes and their cell membrane was discontinuous in parts. A variety of vesicles, 90-450 nm in diameter, were scattered among the tonofilament bundles. Some of these contained needle-like crystals that were considered to be initial calcification sites in ghost cells. These vesicles presented morphological similarities to matrix vesicles, and it is therefore suggested that matrix vesicle-like structures are deeply involved with initiation of calcification of ghost cells in COC.

Objective To determine the change in metabolic activity of chondrocytes in osteoarthritic (OA) cartilage, considering regional difference and degree of cartilage degeneration. Methods OA cartilage was obtained from knee joints with end-stage OA, at both macroscopically intact areas and areas with various degrees of cartilage degeneration. Control cartilage was obtained from age-matched donors. Using laser capture microdissection, cartilage samples were separated into superficial, middle, and deep zones, and gene expression was compared quantitatively in the respective zones between OA and control cartilage. Results In OA cartilage, gene expression changed markedly with the site. The expression of cartilage matrix genes was highly enhanced in macroscopically intact areas, but the enhancement was less obvious in the degenerated areas, especially in the upper regions. In contrast, in those regions, the expression of type III collagen and fibronectin was most enhanced, suggesting that chondrocytes underwent a phenotypic change there. Within OA cartilage, the expression of cartilage matrix genes was significantly correlated with SOX9 expression, but not with SOX5 or SOX6 expression. In OA cartilage, the strongest correlation was observed between the expression of type III collagen and fibronectin, suggesting the presence of a certain link(s) between their expression. Conclusion The results of this study revealed a comprehensive view of the metabolic change of the chondrocytes in OA cartilage. The change of gene expression profile was most obvious in the upper region of the degenerated cartilage. The altered gene expression at that region may be responsible for the loss of cartilage matrix associated with OA.

BACKGROUND: The aim of this study was to determinate the relative frequency of odontogenic tumors (OTs) in a Brazilian population and to compare this data with previous reports. METHODS: We reviewed the achieves of 19 123 specimens from oral pathology laboratory of Universidade Federal de Minas Gerais, from 1954 to 2004. Using the criteria of histologic typification published by the World Health Organization in 1992, we classified the OTs. RESULTS: A total of 340 OTs were found. The frequency of OTs comprises 1.78% of all pathologic specimens in our laboratory. The most frequent tumor was ameloblastoma (45.2%), followed by odontomas (24.91%), and myxomas (9.1%). CONCLUSIONS: Odontogenic tumors are uncommon lesions in this Brazilian population and malignant OTs are very rare. The relative frequency of various types of OTs, age, and gender distribution are similar to those reported in African, Asian but not to Chilean and North American series. J Oral Pathol Med (2005) 34: 583–7

This report describes a case of a patient (1 year and 8 months old) with traumatic avulsion of the maxillary right primary central incisor and morphological changes in the germ of the permanent successor. One year after the trauma, an odontoma-like malformation developed. This malformation was removed 6 years after trauma and orthodontic treatment was started. Clinical follow-up and periodic radiographs are necessary after traumatic avulsion of primary teeth to monitor possible sequelae in the permanent successor. An odontoma-like malformation requires a multidisciplinary approach.

A three-month-old, male German shepherd dog was admitted with a facial mass of two months' duration. Clinical examination showed a round mass, 3 cm in diameter, in the left infraorbital area. The upper last premolar deciduous tooth was not erupted. No other abnormalities were detected. Radiological examination revealed a posterior maxillary mass of mixed opacity. The mass was surgically excised. Histopathological examination demonstrated a connective tissue stroma containing foci of irregular enamel and dentine, resembling rudimentary teeth (denticles), surrounded by new bone formation. Morphology and structure of the denticles were also confirmed by scanning electron microscopy. A compound odontoma was diagnosed. One year after surgery, the dog was free of clinical signs.

Retrospective investigations of odontomas in Japanese children and one recurrent case were carried out. Thirty-nine cases of odontoma in 38 children were treated in the Paediatric Dentistry Clinic of Niigata University Dental Hospital between September 1979 and December 2002. The patients consisted of 23 males and 15 females and their ages ranged from 1 year 2 months to 14 years old. The chief complaints were delayed tooth eruption in 19 cases (five: primary teeth, 14: permanent teeth), retention of primary teeth in 11, incidentally found on the radiographic examination in eight cases, and swelling of the jaw in one case. Thirty-four cases (87%) were associated with tooth eruption disturbances. The most frequently affected region was the maxillary anterior region. Treatment consisted of surgical removal of odontomas in all cases, after which if the impacted teeth did not erupt, exposure of the crown and/or orthodontic traction was performed. Pathological diagnoses were compound odontoma in 30 cases, complex odontoma (n = 7), and compound and complex odontoma (n = 2). A retrospective study of the radiographs revealed the developing process of odontomas in four cases and odontoma disturbed tooth eruption since the early uncalcified developing stage. A recurrent case was a boy aged 6 years 5 months in whom the first surgical removal of odontoma was performed at the age of 1 year 8 months. Recurrence of an odontoma is very rare, but in very young children odontomas are in the early developing stages, containing uncalcified portions, so it is important to perform periodical observations until the succedaneous teeth erupt.

The occurrence of odontoma in the primary dentition is uncommon. There are very few reports of non-eruption of a dilacerated primary tooth in the literature. A rare case of compound odontoma in association with an unerupted dilacerated maxillary primary incisor in a young patient is reported. There was also a developing supernumerary tooth in the vicinity of the odontoma. The clinical features and management of these conditions are discussed. The relevant literature is reviewed. A possible causal relationship between odontoma and dilaceration is highlighted.

Odontogenic calcified masses were present in the opercula of lower first molars that were delayed in eruption. The masses were relatively small, opaque, white in color with a smooth texture. Histopathological examinations revealed that they contained osteodentin, cementum, and pulp-like components; however, not odontogenic epithelial cells or enameloid. Further, mesenchymal multinucleated giant cells and dysplastic dental matrices were observed in the connective tissues surrounding the masses. These clinical and histopathological findings disagree with the features of pericoronal odontogenic hamartoma lesions, including odontoma, ameloblastic fibroma, and ameloblastic fibro-odontoma. Therefore, we propose to categorize this odontogenic mass as a new variety of hamartoma, eruption mesenchymal calcified hamartoma.

Background: Calcifying odontogenic cyst (COC) is an uncommon odontogenic lesion with few studies describing its immunohistochemical profile and proliferative activity reported in the literature. Methods: Clinical and histological features and immunohistochemical expression of cytokeratins, Mel-CAM (CD146), bcl-2, PCNA and ki-67, in 10 cases of COC were studied. Results: All 10 cases affected the maxilla, eight intraosseous and two peripheral. Five central cases were cystic and three were cystic associated with odontoma, and the two extraosseous showed solid histological pattern; immunohistochemistry was positive for cytokeratins 8, 14, 19, AE1/AE3 and 34bE12 and bcl-2 in all cases, and Mel-CAM in six cases. Proliferative activity was greater in the epithelium of central cystic COC in relation to COC associated with odontoma and peripheral lesions. Conclusion: Calcifying odontogenic cysts showed odontogenic cytokeratin profile and bcl-2 and Mel-CAM expression indicate that these proteins may be involved in the development of COC. There were no recurrences after surgery, irrespective of their proliferative activity.

Neoplasms and tumours related to the odontogenic apparatus may be composed only of epithelial tissue or epithelial tissue associated with odontogenic ectomesenchyme. The immunohistochemical detection of different cytokeratins (CKs) polypeptides and vimentin has made it easier to explain the histogenesis of many epithelial diseases. The present study aimed to describe the immunohistochemical expression of cytokeratins 7, 8, 10, 13, 14, 18, 19 and vimentin in the epithelial components of the dental germ and of five types of odontogenic tumours. The results were compared and histogenesis discussed. All cells of the dental germ were positive for CK14, except for the preameloblasts and secreting ameloblasts, in which CK14 was gradually replaced by CK19. CK7 was especially expressed in the cells of the Hertwig root sheath and the stellate reticulum. The dental lamina was the only structure to express CK13. The reduced epithelium of the enamel organ contained CK14 and occasionally CK13. Cells similar to the stellate reticulum, present in the ameloblastoma and in the ameloblastic fibroma, were positive for CK13, which indicates a nature other than that of the stellate reticulum of the normal dental germ. The expression of CK14 and the ultrastructural aspects of the adenomatoid odontogenic tumour probably indicated its origin in the reduced dental epithelium. Calcifying odontogenic epithelial tumour is thought to be composed of primordial cells due to the expression of vimentin. Odontomas exhibited an immunohistochemical profile similar to that of the dental germ. In conclusion, the typical IF of odontogenic epithelium was CK14, while CK8, 10 and 18 were absent. Cytokeratins 13 and 19 labelled squamous differentiation or epithelial cells near the surface epithelium, and CK7 had variable expression.

Background: Odontogenic tumors are infrequent lesions. Thus, the review of a large number of cases becomes a necessity for both the pathologist and the clinician. Studies on odontogenic tumors have been published in many parts of the world, but there is little information available in the English language literature on the relative frequency of odontogenic tumors in Latin America. The aim of this study was to determine the relative frequency of this heterogeneous group of lesions in a Chilean population, and to compare these data with previous reports. Methods: We reviewed the records of 28,041 specimens from 1975 to 2000 in the Oral Pathology Referral Institute (IREPO), and using the criteria for histological typification published by the World Health Organization in 1992, we reclassified the odontogenic tumors. Results: We confirmed a total of 362 odontogenic tumors. The frequency of odontogenic tumors as a percentage of all pathological specimens in our institute was 1.29%. The most frequent histological type was odontomas (44.7%), followed by ameloblastomas (20.4%) and myxomas (8.8%). Conclusions: Odontogenic tumors are uncommon lesions in the Chilean population and malignant odontogenic tumors are very rare. The relative frequency of various types of odontogenic tumors, as well as the age and gender distribution are similar to those reported in the North American series and different from those found in recently published Asian and African series.

Background: Odontoma-like structures are formed in the jaw bone of osteopetrotic (op/op) mice, which have a congenital deficiency in osteoclastic differentiation due to the absence of functional macrophage colony-stimulating factor (M-CSF). Methods: To clarify the histopathogenesis of tooth malformation and odontoma-like structures, a 2-year postnatal process of development of the op/op mandibular incisor was examined radiologically and histologically. At the same time, extracellular matrix (ECM) remodeling around tooth germs was analyzed immunohistochemically. Results: Abnormal forms of op/op tooth germ were noticeable even at 3 days after birth on a radiogram. Histologically, op/op mice were clearly distinguished by the disappearance of dental follicular space at 3 days. With aging, bone trabeculae, which were not remodeled, penetrated into op/op tooth germs and divided them into several daughter germs, which were recognized as odontomas. In mandibular incisor bodies, the immature ECM components, such as heparan sulfate proteoglycan and tenascin, were preserved diffusely in the dental papilla/pulp, which indicates that maturation of the stroma does not take place in op/op mandibular incisors. Conclusion: The observation suggests that the disturbed morphogenesis of op/op tooth germs is functionally explained by the disordered immunolocalization of ECM molecules, and that the dental follicular space is essential for normal tooth development because it prevents bone penetration into the tooth germs.

OBJECTIVE: Odontoma is a comparatively common odontogenic tumor, and it may lead to interference with the eruption of its associated tooth. Odontomas are mostly associated with permanent teeth, and they are rarely associated with deciduous teeth. The purpose of this report is to analyze 107 odontomas and to present a case of complex odontoma associated with a lower deciduous second molar. SUBJECT AND METHODS: The 106 cases were analyzed with regard to the following parameters: age, gender, location, erupted teeth, congenital missing teeth, radiological features, histopathological features and prognosis. RESULTS: Of the 106 cases, 41 were complex odontoma, 62 were compound odontoma, and three were immature odontoma. Compound odontoma had a predilection for the anterior. Complex odontoma occurred more often at the mandible. CONCLUSION: Odontoma located above the tooth crown of lower deciduous molar did not behave clinically different from that associated with permanent tooth. An odontoma could be related with a supernumerary tooth or a missing tooth. If odontomas, which interfered with tooth eruption, were extirpated early, the impacted teeth would probably erupt normally and be normal in shape.

Method and Results: Calcifying odontogenic cysts (COCs) were examined histopathologically and immunohistochemically to characterize the histological and cytological properties of these lesions. Histopathologically, COCs showed thin or thick lining epithelium with ghost cells. COCs were classified according to proliferative type or nonproliferative type lining epithelium, the presence or absence of ameloblastomatous appearance, and the presence or absence of odontoma in the cyst walls. Immunohistochemically, amelogenin protein was expressed chiefly in ghost cells, whereas cytokeratin 19 (CK19) and bcl-2 proteins were expressed chiefly in lining epithelial cells. The proportion of cases positive for bcl-2 protein was slightly higher in COCs with odontoma than in those without odontoma. Lining epithelial cells sporadically showed positive reactions for Ki-67 antigen. Mean Ki-67 labeling index was slightly greater in COCs with proliferative type lining epithelium, COCs with ameloblastomatous appearance of the cyst walls, and COCs with odontoma of the cyst walls than in COCs without these histological features. Our results suggest that ghost cells or lining epithelial cells show ameloblastic cytodifferentiation or odontogenic epithelial characteristics, that bcl-2 protein is associated with survival of lining epithelial cells in COCs, and that high proliferation potential is associated with ameloblastomatous proliferation or combined odontoma. COCs exhibited various histological features with several transitional forms, and immunohistochemical examinations revealed little or no difference in cytodifferentiation and cellular activity among COCs. Conclusion: We conclude that COCs with various histological features have neoplastic potential and may not be separate entities within the same histological spectrum.

A case is presented of a 10-year-old girl, referred for consultation for failure of the maxillary central incisor to erupt. At 18 months, the patient underwent intrusion of the right central primary incisor, which re-erupted several months later. Radiographic examination revealed a complex odontoma-like malformation located next to the floor of the nose, away from the permanent incisors. Clinical examination revealed space loss of the corresponding permanent incisor and severe hypoplasia of the permanent right lateral incisor. Because of its deep location, it was decided not to remove the odontoma, but to recommend yearly radiographic follow up to rule out the development of a dentigerous cyst. This case describes a very rare complication of intrusion of primary incisors and emphasizes the importance of follow up until eruption of the corresponding permanent teeth.

The calcifying odontogenic cyst (COC) presents with diverse hlstologlcal features; thus, several subclasslfl-cations have been proposed. To evaluate the slgnlficance of the various histological features and subtypes of COC from the perspectlve of proliferative activity, the proliferating cell nuclear antigen (PCNA) labellng index (LI; the percentage of positive nuclei) was assessed immunohistochemlcally in 25 cases of COC (21 benign and four malignant). All of the benign cases were of the cystic variety and further subclas-sified into non-proliferative subtype (NPS; four cases); proliferative subtype (PS; eight cases); and COC associated with odontoma (COCaO, nlne cases). The PCNA U of the mallgnant COC (65.2 ± 5.6) was slgnlflcantly higher than that of the benlgn COC (11.6 ± 9.0; P = 0.002). Non-proliferative subtype (6.8 ± 2.8) showed the lowest PCNA LI and PS (17.2 ± 11.2) the highest of among the three subtypes of benign cystic COC (P = 0.028). In nine cases of COCaO, six showed epithelial lining of the non-proliferative type as NPS and the other three had lining wlth proliferative features as PS. The PCNA LI of the latter COCaO group (14.3 ± 6.6) was significantly higher than that of the former (6.1 ± 4.3; P = 0.05), as Seen between PS and NPS. These results demonstrate that PCNA LI is a possible parameter for differentiating mallgnant COC from benign COC and, whatever the subtypes, the proliferative features In the lining are the main factor influencing the prollferatlng actlvity of COC.

Tooth abnormalities occur in microphthalmic (mi/mi) mice. The elongated odontogenic epithelium is interrupted by unresorbed bone at the basal end of the mi/mi incisor, with the epithelium gathered into cell clusters. These clusters develop to odontoma-like masses. To identify the origin of the cell types of these odontoma-like masses, the localization of osteonectin (Osn), osteocalcin (Osc), osteopontin (Osp), matrix Gla protein (MGP) and amelogenin (Am) mRNA in the process of tooth development in mi/mi and +/+ mice was investigated by means of in situ hybridization. Decalcified mandibles of neonatal, 5-, 10-, 14-day-old mice were examined. Osn and Osc mRNA, which localized in osteoblasts and odontoblasts, were also detected in the cells of odontoma-like masses in mi/mi mice. The cells expressing these mRNA were short, columnar and odontoblast-like. Am mRNA was detected in ameloblasts. In mi/mi mice, Am mRNA was also detected in ameloblastic cell clusters, which were formed by the tall columnar cells in the odontoma-like masses. No apparent Osp mRNA expression was detected in the masses. These results indicated that even in odontogenic abnormal cells resulting from physical obstruction in mi/mi mice, the genes that are involved in normal tooth development were still expressed.