Load transfer across a mandible during a mastication cycle: The effects of odontogenic tumour.

The extent to which load transfer in a diseased mandible with odontogenic tumour might influence the potential risk of pathological fracture has scarcely been investigated. The study sought to investigate the quantitative deviations in load transfer across healthy and cancer-affected (diseased) mandibles having odontogenic tumours. The effect of size of the tumours (small: 9 mm diameter, large: 19 mm diameter), and variation in bone mechanical (elastic) properties of the mandible on load transfer in cancer-affected mandibles during a mastication cycle have been investigated. Based on patient-specific computed tomography-scan datasets, detailed three-dimensional finite element models of healthy and diseased mandibles were developed. High stresses of 25-30 MPa and strains ∼700 µÎµ were observed in the healthy mandible during the right molar bite. However, marginal deviations were observed in principal stress distributions in the diseased mandibles with small- and large-sized tumours, as compared to the healthy mandible. Maximum principal strains of ∼1474 µÎµ were found in the body region adjacent to the symphysis region for small-sized tumour. Whereas for large-sized tumour, maximum strains of ∼2700 µÎµ were observed in the right buccal regions. Reduction in Young's modulus due to different stages of odontogenic tumours had a localised effect on the principal stress distributions, but triggered an abrupt increase in the principal tensile strains. It appears that there is a potential risk of pathological fracture for large-sized odontogenic tumour, owing to high tensile stresses and strains.

Effect of the sonic hedgehog inhibitor GDC-0449 on an in vitro isogenic cellular model simulating odontogenic keratocysts.

Odontogenic keratocysts (OKCs) are common cystic lesions of odontogenic epithelial origin that can occur sporadically or in association with naevoid basal cell carcinoma syndrome (NBCCS). OKCs are locally aggressive, cause marked destruction of the jaw bones and have a propensity to recur. PTCH1 mutations (at ∼80%) are frequently detected in the epithelia of both NBCCS-related and sporadic OKCs, suggesting that PTCH1 inactivation might constitutively activate sonic hedgehog (SHH) signalling and play a major role in disease pathogenesis. Thus, small molecule inhibitors of SHH signalling might represent a new treatment strategy for OKCs. However, studies on the molecular mechanisms associated with OKCs have been hampered by limited epithelial cell yields during OKC explant culture. Here, we constructed an isogenic PTCH1R135X/+ cellular model of PTCH1 inactivation by introducing a heterozygous mutation, namely, c.403C>T (p.R135X), which has been identified in OKC patients, into a human embryonic stem cell line using the clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated 9 (Cas9) system. This was followed by the induction of epithelial differentiation. Using this in vitro isogenic cellular model, we verified that the PTCH1R135X/+ heterozygous mutation causes ligand-independent activation of SHH signalling due to PTCH1 haploinsufficiency. This activation was found to be downregulated in a dose-dependent manner by the SHH pathway inhibitor GDC-0449. In addition, through inhibition of activated SHH signalling, the enhanced proliferation observed in these induced cells was suppressed, suggesting that GDC-0449 might represent an effective inhibitor of the SHH pathway for use during OKC treatment.

Primordial odontogenic tumor: Subepithelial expression of Syndecan-1 and Ki-67 suggests origin during early odontogenesis.

Primordial odontogenic tumor (POT) is composed of variably cellular myxoid connective tissue, surrounded by cuboidal to columnar odontogenic epithelium resembling the inner epithelium of the enamel organ, which often invaginates into the underlying connective tissue. The tumor is delimited at least partially by a thin fibrous capsule. It derives from the early stages of tooth development. Syndecan-1 is a heparan sulfate proteoglycan that has a physiological role in several cellular functions, including maintenance of the epithelial architecture, cell-to-cell adhesion and interaction of cells with extracellular matrix, and with diverse growth factors, stimulating cell proliferation. Ki-67 is considered the gold standard as a cell proliferation marker. The aim of this study was to examine the expression of Syndecan-1 and Ki-67 proliferation index in POT and normal tooth germs to better understand the biological behavior of this tumor. Results showed that Syndecan-1 was more intensely expressed in subepithelial mesenchymal areas of POT, in a pattern that resembles the early stages of tooth development. The cell proliferation index (4.1%) suggests that POT is a slow growing tumor. Syndecan-1 expression in tooth germs in late cap and early bell stages was similar to POT, showing immunopositivity in subepithelial mesenchymal condensed areas. The immunohistochemical findings showed a pattern in which the population of subepithelial mesenchymal cells exhibited greater proliferative activity than the central portion of the dental papilla.

M2-polarized macrophages in keratocystic odontogenic tumor: relation to tumor angiogenesis.

The purpose of this study was to evaluate the presence of M2-polarized macrophages and their relationships to angiogenesis in keratocystic odontogenic tumor (KCOT). M2-polarized macrophages were detected in KCOT samples by immunohistochemistry and immunofluorescence. Meanwhile, microvessel density measured with antibody against CD31 was closely correlated with the presence of M2-polarized macrophages. In addition, macrophage colony-stimulating factor (M-CSF) significantly contributed to the activation of M2-polarized macrophages. Moreover, the results of in vitro wound healing, cell migration and tube formation assays further revealed the pro-angiogenic function of M2-polarized macrophage-like cells. This function might be associated with secretion of angiogenic cytokines, such as vascular endothelial growth factor (VEGF), transforming growth factor-ß (TGF-ß) and matrix metalloprotein-9 (MMP-9). This study demonstrates for the first time that M2-polarized macrophages are prevalent in KCOT, and their presence is dependent on M-CSF expression. More importantly, these tumor-supportive cells can also promote tumor angiogenesis by secreting angiogenic cytokines.

Tratamiento conservador de tumor epitelial odontogénico calcificante asociado al canino inferior retenido: relato de caso clínico / Conservative treatment of a calcifying epithelial odontogenic tumour associated with an impacted mandibular canine: A case report

El tumor epitelial odontogénico calcificante corresponde a menos de 1% de todos los tumores odontogénicos de origen ectodérmica, afectando principalmente la región posterior de la mandíbula, relacionada muchas veces a un diente molar retenido. En este artículo son realizadas las consideraciones en relación a las características clínicas, radiográficas, histopatológicas y sobre las modalidades de tratamiento del tumor epitelial odontogénico calcificante por medio de una revisión de literatura, siendo relatado la asociación de un tumor de este tipo a un canino inferior retenido, en un paciente de género masculino, de 32 años de edad, tratado de forma conservadora y en el cual no se observó recurrencia de la lesión después de 5 años de acompañamiento(AU)

The calcifying epithelial odontogenic tumour is a rare benign odontogenic neoplasm that accounts for approximately 1% of all odontogenic tumours. They are mainly located in the premolar/molar mandibular region, and are associated with an unerupted molar tooth. We present a literature review of the clinical, radiographic, pathological findings and treatment options of the calcifying epithelial odontogenic tumour, as well as describing the case of an calcifying epithelial odontogenic tumour associated with an impacted right mandibular in a 32-year-old male patient, who was treated conservatively, without no sign of recurrence of the lesion after five years(AU)

Odontoblasts in odontogenic tumors.

Odontoblasts are secretory cells displaying epithelial and mesenchymal features, which exist in a monolayer at the interface between the dentin and pulp of a tooth. During embryogenesis, these cells form a dentin shell and throughout life continue to produce dentin while, also acting as sensor cells helping to mediate tooth sensitivity. In this process, odontoblasts are forced to migrate inwards, resulting in an ongoing loss of pulp volume. Correspondingly, there is also a decrease in the surface area of the dentin which supports the odontoblast cell layer. As these events transpire, odontoblasts maintain a tightly controlled monolayer relationship to each other as well as to their dentin substrate. Stability is maintained laterally by epithelial attachment structures and transversely by complex cytoplasmic extensions into the supporting dentin. As a result, it is not possible for the layer to buckle to relieve the mechanical stresses, which develop during the inward migration. A theoretical consequence of this distinctive self-generated niche is the development of long term compressive stresses within the odontoblast population. We present a mechanobiology model, which causally relates the increase in cellular compressive stresses to contact inhibition of proliferation. We link this hypothesis to the observation that there are no reports of pulpal odontoblasts showing neoplasia or acquisition of changes suggestive of a pre-neoplastic phenotype.

Malignant transformation of keratocystic odontogenic tumor: two case reports.

INTRODUCTION: Keratocystic odontogenic tumors (KCOTs) are cystic tumours originating from the dental lamina of the maxilla and mandible that are lined with keratinized epithelium. While benign, they can be locally destructive and have a high recurrence rate despite treatment. Rarely, KCOTs may undergo malignant transformation into Primary Intraosseous Squamous Cell Carcinoma (PIOSCC). CASE REPORT: This study reports the clinical findings, radiological scans and histopathology of 2 patients with KCOTs that underwent malignant transformation into PIOSCC. DISCUSSION: A comprehensive literature review was performed to similar reports documenting the malignant transformation of KCOTs. The potential for KCOTs to undergo malignant change should prompt oral maxillofacial surgeons and otolaryngologists to exercise a high index of suspicion when treating these lesions. Patients persisting with unresolved disease after treatment should be investigated for malignant transformation. Detailed histopathological examination of KCOT specimens is recommended to detect small foci of SCC which may be present in the epithelium.

Solución del caso 39. Tumor odontogénico epitelial calcificante (tumor de pindborg) / Solution to case 39. Calcifying epithelial odontogenic tumor (pindborg tumor)

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Imuno-expressão da metalotioneída em cistos e tumores odontogênicos / Metallothionein immunoexpression in odontogenic cysts and in odontogenic tumours

Cistos e tumores odontogênicos são lesões originadas dos tecidos que formam os dentes e apresentam diferentes comportamentos biológicos. A metalotioneíra (MT) é relacionada à homeostase de metais, regulação da diferenciação e proliferação celular e inibição da apoptose. Com relação aos cistos e tumores odontogênicos, a MT poderia ter um papel na regulação da diferenciação e proliferação celuar e na inibição da apoptose, refletindo no comportamento biológico. Os objetivos são avaliar e comparar a expressão da MT entre: 1) cistos odontogêncios e tumor odontogênico ceratocístico (TOC); 2) TOC associados à Síndrome do Carcinoma Basocelular Nevóide (SCBN) e não associados; 3) tumores odontogênicos benignos. Objetivou-se também correlacionar a imuno-expressão da MT com a proliferação celular e com a inflamação. A amostra incluiu cisto radicular (CR), cisto dentígero (CD), TOC (primário associado ou não à (SCBN), cisto odontogênico ortoceratinizado (COO), ameloblastoma sólido (ABS), tumor odontogênico escamoso (TOE), tumor odontogênico adenomatóide (TOA), tumor odontogênico cístico calcificante (TOCC) e tumor odontogênico epitelial calcificante (TOEC). Foi realizada imunoistoquímica para MT, Ki-67 e PCNA...

Midkine expression correlating with growth activity and tooth morphogenesis in odontogenic tumors.

Midkine (MK; a low molecular weight heparin-binding growth factor) is a multifunctional cytokine. MK plays a role in morphogenesis of many organs including teeth through epithelial-mesenchymal interactions. We immunohistochemically examined MK expression in various human odontogenic tumors. There was no difference in positive rate and intensity of MK between benign odontogenic tumors and their malignant counterparts. Ameloblastoma showed MK localization in the peripheral columnar cells in budding processes from the parenchyma, which frequently expressed proliferating cell nuclear antigen. MK was also preferentially expressed in keratinized cells in acanthomatous ameloblastoma and keratocystic odontogenic tumor. In odontogenic mixed tumors except for odontoma, intense immunoreactivity to MK was found in epithelial follicles, the surrounding odontogenic ectomesenchymal tissue, and the basement membrane between them. Intensity in the odontogenic ectomesenchyme decreased in relation to distance from the epithelial follicles. No expression was found in tumor cells associated with production of dental hard tissues in odontogenic mixed tumors including odontoma. These findings suggested that MK is involved in the reciprocal interaction between odontogenic epithelium and odontogenic ectomesenchymal tissue in areas without dental hard tissue formation in odontogenic mixed tumors. Coexpression of MK and proliferating cell nuclear antigen was also observed in epithelial follicles and highly cellular nodules in the ectomesenchyme of odontogenic mixed tumors. MK is considered to mediate growth activity of odontogenic tumors and cell differentiation of odontogenic mixed tumors through molecular mechanisms similar to those involved in morphogenesis of the tooth.

Ameloblastoma and adenomatoid odontogenic tumor: the role of alpha2beta1, alpha3beta1, and alpha5beta1 integrins in local invasiveness and architectural characteristics.

Ameloblastoma is an odontogenic neoplasm characterized by local invasiveness and a tendency toward recurrence, whereas adenomatoid odontogenic tumor (AOT) is an indolent neoplasm. The objective of the present study was to immunohistochemically analyze the role of alpha2beta1, alpha3beta1, and alpha5beta1 integrins in the cellular events and cell-matrix interactions that occur in these tumors and their consequent repercussions on the architectural arrangement and biologic behavior of these lesions. Paraffin-embedded specimens from 30 ameloblastomas (20 solid and 10 unicystic tumors) and 12 AOTs were submitted to immunohistochemistry using the catalyzed signal amplification system. A difference in the pattern of integrin expression was observed between the various histologic types of ameloblastoma. No significant difference in labeling intensity was observed between unicystic and solid ameloblastomas, but comparison between ameloblastomas and AOT showed a significantly stronger expression of alpha5beta1 integrin in the former (P < .05). Our findings suggest an important role of the integrins studied in the architectural characteristics of ameloblastomas and AOTs and a possible participation of alpha5beta1 integrin in the mechanism of local invasion of ameloblastomas.

Recurrent calcifying epithelial odontogenic tumor of the maxilla: report of a case with cytologic diagnosis.

BACKGROUND: Calcifying epithelial odontogenic tuor (CEOT) occurs rarely in the maxilla and lacks classical clinicoradiologic features. The cytologic features in conjunction with the radiologic picture can be helpful in making a preoperative diagnosis and guiding management. CASE: A young man with a progressively increasing left cheek swelling and proptosis of the left eye was referred for fine needle aspiration cytology. The smears were paucicellular and showed clusters of mildly pleomorphic squamoid cells; abundant, amyloidlike, pink material; and occasional concentric calcification. A provisional diagnosis of CEOT was given and confirmed on histopathology. CONCLUSION: The characteristic cytologic findings in association with radiologic features can help the cytopathologist in rendering a firm preoperative diagnosis of CEOT even at atypical sites such as the maxilla.

Ameloblastic fibroma and related lesions: a clinicopathologic study with reference to their nature and interrelationship.

BACKGROUND: Ameloblastic fibroma (AF) and related lesions constitute a group of lesions, which range in biologic behavior from true neoplasms to hamartomas. The aim of this study was to elucidate the nature and interrelationship of this group of lesions. METHODS: Clinical and pathological studies were undertaken retrospectively on 13 cases of AF and seven cases of ameloblastic fibro-odontoma (AFO). Thirty-three complex odontomas and 33 compound odontomas were also included for comparative purpose. Relevant follow-up data were recorded and the literature was reviewed. RESULTS: The majority of patients with AF (nine cases, 69.2%) were over the age of 22 years with frequent involvement (76.9%) of the posterior mandible. Tumors recurred in four of 11 patients with follow-up information and two recurrent tumors showed malignant transformation. There was no case in this series that could be designated as the so-called ameloblastic fibrodentinoma, apart from one recurrent AF in which further maturation to form only tubular dentin materials was identified. AFO tended to occur at a younger age group with an average of 9.6 years. Recurrence was noted in two of five patients with follow-up data and both recurrent lesions showed limited growth potential and further maturation into a complex odontoma. Significant differences were noted in the age and site distribution between the complex and the compound odontomas. CONCLUSION: Whilst the majority, if not all, of AFs are true neoplasms with a potential to recur and/or of malignant transformation, some, especially those occurred during childhood, could represent the primitive stage of a developing odontoma. Our data also suggests that some AFOs are hamartomatous in nature, representing a stage preceding the complex odontoma.

Malignant odontogenic tumors: a 22-year experience.

OBJECTIVES/HYPOTHESIS: Malignant odontogenic tumors are exceedingly rare and arise from odontogenic epithelial residues and odontogenic cysts in the jaw bones. Odontogenic malignancies have various origins. Some develop directly from the remnants of odontogenic epithelium left after completion of dental development; others may result from malignant transformation of a benign odontogenic cyst or ameloblastoma. These lesions are usually locally aggressive with radical surgery being the primary mode of treatment. Because of their rarity, much of the existing information about malignant odontogenic tumors with regard to their origin, clinicopathological features, biological behavior, and therapeutics is derived from case reports or small series. The study represents one of the largest series of malignant odontogenic tumors compiled in a single institution. STUDY DESIGN: Retrospective 22-year review from an Academic Medical Center. METHODS: Twenty cases of reported malignant odontogenic tumors were diagnosed in the authors' institution between 1981 and 2002. All pathological slides were reviewed to reconfirm diagnosis. Malignancy was confirmed based on the following criteria: histological findings of infiltrative growth, atypical cytological features, and focal necrosis or clear evidence of distant metastatic spread. Patient age, race, sex, treatment and outcome were recorded on chart review. RESULTS: Of the twenty reported cases, only nine were actually found to be malignant tumors on re-evaluation. These consisted of four cases of malignant ameloblastomas, two cases of ameloblastic carcinoma, one case of malignant Pindborg tumor (calcifying epithelial odontogenic tumor), one case of odontogenic ghost cell carcinoma, and one case of squamous cell carcinoma arising in an odontogenic keratocyst. The racial demographics were six Caucasian patients, one African American patient, and two Asian patients; seven men and two women represented the gender distribution. Tumors of six cases were located in the mandible, and of three cases, in the maxilla. All cases were treated with radical surgical excision. Two patients died of their disease, three patients were alive and free of disease, and four patients were lost to follow-up. CONCLUSION: Malignant odontogenic tumors are rare. They require a multidisciplinary team to determine proper treatment. Long-term surveillance is mandatory and is accomplished by routine physical examinations, along with serial radiographic imaging.

Recommendation of modified classification for odontogenic carcinomas.

Primary squamous cell carcinoma (SCC) derived from odontogenic epithelium is diagnosed as primary intraosseous carcinoma (PIOC). The term "intraosseous" means the bone marrow spaces. Odontogenic cells, however, exist not only in the bone marrow space but also in the periodontal space and the subepithelial soft tissue space. In our survey for 36 SCC lesions of odontogenic origin, many lesions involved two or all of the three spaces. There was only one lesion which involved the bone marrow space alone. In some cases, the extent of the early lesions was restricted around the tooth or at a part of the alveolar crest. The possibility of a SCC of odontogenic origin arising in the periodontal and the subepithelial soft tissue spaces was suggested. We proposed the term "Odontogenic SCC" to replace "PIOC".

[Radiologic features of desmoplastic ameloblastoma].

OBJECTIVE: To investigate the radiologic features of desmoplastic ameloblastoma. METHODS: The radiologic characteristics of 15 cases desmoplastic ameloblastoma which were diagnosed pathologically were analyzed retrospectively, and compared with solid or multicystic ameloblastoma. RESULTS: Desmoplastic ameloblastoma were mainly located in anterior and (or) premolar region of maxilla and mandible. There existed three features radiologically. 1. unilocular formation containing varying amounts of radiopaque islands or strands material. 2. multilocular destruction containing irregular or line-like radiopaque areas. 3. mixed destruction showing plxiform radiopaque material and unilocular change. Typical microscopic features were irregular and compressed epithelial islands or strands interspersed among dense fibrous connective tissue stroma. CONCLUSIONS: The desmopleatic ameloblastoma is a new type of ameloblastoma and exhibits some special characteristics radiologically and pathologically. It should be differentiated from osteofibroma and odontogenic myxoma.

Un nuevo caso de tumor odontogénico epitelial calcificante / A new case of epithelial calcifying odontogenic tumor

Presentamos un nuevo caso de tumor Pindborg con una evolución muy larga y asintomática, y con un aspecto radiológico poco sospechoso de tumor odontogénico epitelial calcificante. Este caso pasa a engrosar la escasa casuística recogida en la literatura, por su poca incidencia entre los de tumores odontogénicos. Como hechos más destacables debemos mencionar, por una parte, lo atípico de la imagen radiológica y , por otra, su evolución, totalmente concordante entre la abundancia de calcificación y su benignidad (AU)

Fibroma odontogénico cetral: presentación de un caso agresivo y revisión de la literatura / Central odontogenic fibroma: Presentation of an agresive case and literature review

El fibroma odontogénico central es un tumor benigno poco frecuente. Basado en criterios específicos sólo se han descrito unos 100 casos. Revisamos la literatura y presentamos un nuevo caso de fibroma odontogénico de gran tamaño y comportamiento agresivo. El paciente de 24 años de edad presentaba una tumoración de 6 centímetros que afectaba al maxilar izquierdo. El fibroma se extendía al seno maxilar izquierdo, la tuberosidad, fosa nasal, etmoides, región retroorbitaria y paladar duro homolateral presentando una zona central ulcerada en la mucosa oral lo que le daba un aspecto clínico semejante a una neoplasia maligna. Mediante un abordaje intraoral, disección roma y osteotomía resecamos la lesión. El resultado AP fue de fibroma odontogénico con alta actividad proliferava. Tras 48 meses de seguimiento no existen signos de recidiva local (AU)