Immunohistochemical observations on a possible ameloblastic fibro-odontoma

Higher immunoexpression of CK14 from the Wnt-1/β-catenin pathway in the development of odontomas

Tooth development depends on a series of reciprocal signaling interactions between the oral epithelium and ectomesenchyme. This study aimed to investigate the role of CK14, a protein involved in Wnt-1/β-catenin signaling, in odontogenesis and the development of odontomas. This cross-sectional, retrospective, immunohistochemical study analyzed 30 compound odontomas, 30 complex odontomas, and 17 tooth germs. Higher immunoexpression of CK14 was observed in odontogenic epithelial cells of tooth germs (p < 0.001) and odontogenic epithelial cells of odontomas (p < 0.001). There was higher immunoexpression of Wnt-1 and β-catenin proteins in epithelial cells of tooth germs (p = 0.002 and p < 0.001, respectively), as well as in the ectomesenchyme of odontomas (p = 0.003 and p < 0.001, respectively). β-Catenin was moderately and significantly correlated with CK14 in the membrane of reduced enamel epithelial cells in odontomas (p = 0.007). Higher immunoexpression of CK14 was observed in the odontogenic epithelium during the bud and cap stages and lower immunoexpression in the internal enamel epithelium during the bell stage. In odontomas, lower expression of Wnt-1/β-catenin and higher immunoexpression of CK14 were found in odontogenic epithelial cells, especially adjacent to the mineralized material resembling the tooth formed in these lesions.

Analysis of Protein Immunoexpression and Its Interrelationship in the Pathogenesis of Odontomas and Ameloblastic Fibro-Odontomas: A Systematic Review

Odontomas and ameloblastic fibro-odontomas (AFOs) are the result of a developmental anomaly of odontogenic tissues. A literature review of proteins immunoexpressed in odontomas and AFOs was conducted in order to determine which proteins are involved in the pathogenesis of these lesions. AFO was changed to early odontoma in the 2017 WHO classification and will also be discussed in this article. A literature search was performed in the following electronic databases: PubMed/MEDLINE, Web of Science, Scopus, EMBASE, Lilacs, Cochrane Collaboration Library, and Science Direct. The research question was developed according to the population, intervention, comparison, and outcome (PICO) framework: Which proteins are related to the differentiation of odontomas and what is their interrelationship with AFOs? Thirty articles met all inclusion criteria and were selected for this systematic review, totaling 355 cases of odontomas and 43 cases of AFO. Similar immunoexpression was observed in odontomas and AFOs. Immunoexpression of proteins involved in cell differentiation was higher in compound odontomas than in complex odontomas. Proteins involved in histodifferentiation and enamel formation were more frequent in odontomas. The immunoexpression of enamel matrix proteins differs between odontomas and tooth germs, with their persistence being related to the development of odontomas. Compound odontomas exhibit the highest immunoexpression of proteins involved in cellular histodifferentiation and the Wnt/beta-catenin pathway is involved in tumor formation.

Clinical and radiological profile of ameloblastic fibro-odontoma: an update on an uncommon odontogenic tumor based on a critical analysis of 114 cases

Ameloblastic fibro-odontoma is an uncommon benign tumor of the jaws that belongs to the group of mixed odontogenic tumors. The descriptions of its clinical and radiological features in the literature are not always accurate and sometimes even contradictory. The aim of the present study was to critically evaluate their clinical and radiological features as reported in the English-language literature. A total of 114 well-documented cases of ameloblastic fibro-odontomas (103 from publications and 11 of our own new cases) were analyzed. The patients' age ranged from 8 months to 26 years (mean 9.6). There were 74 (65 %) males, with a male-to-female ratio of 1.85:1 (P = 0.001). The mandible was involved in 74 (65 %) cases, and the mandible-to-maxilla ratio was 1.85:1 (P < 0.001). Nearly 80 % of the lesions were located in the posterior region of the jaws, and most (58 %) were in the posterior mandible. Radiographically, most of the lesions were unilocular and only a few (~10 %) were multilocular. Most lesions were mixed radiolucent-radiopaque, and only a few (~5 %) were radiolucent. Almost all lesions (~92 %) were associated with the crown of an unerupted tooth/teeth. This comprehensive analysis of a large number of patients with an uncommon lesion revealed that ameloblastic fibro-odontomas are significantly more common in males and in the mandible, and that multilocular lesions are uncommon. It also revealed that, based on their clinical and radiological features, some of them are probably true neoplasms while others appear to be developing odontomas (hamartomas).

Management of ameloblastic fibro-odontoma in a 6-year-old girl preserving the associated impacted permanent tooth

The ameloblastic fibro-odontoma (AFO) is a rare odontogenic tumor that occurs predominantly in children and is generally associated with unerupted teeth. The choice of treatment for this entity is conservative surgery with enucleation and its prognosis is excellent. However, preserving the associated impacted teeth may make complete removal of the lesion difficult and may explain some cases of recurrence. A case of AFO in a 6-year-old girl treated with enucleation and preservation of an impacted lower left first permanent molar is reported. After two years of follow-up, there were no signs of recurrence and complete spontaneous eruption of the preserved tooth was observed. The present report indicates that the degree of involvement of the impacted tooth by AFO is a fundamental aspect to be considered during radiological analysis and surgical assessment. We concluded that preservation of the impacted permanent teeth associated with this tumor should always be considered and carried out with caution, since they are clearly not included in the surgical cavity.

Immunohistochemical expression of neural tissue markers (neuron-specific enolase, glial fibrillary acidic protein, S100 protein) in ameloblastic fibrodentinoma: a comparative study with ameloblastic fibroma

Formalin-fixed paraffin-embedded sections of three cases of ameloblastic fibrodentinoma (AFD) were studied by the avidin-biotin-peroxidase complex method using antibodies against neuron-specific enolase (NSE), glial fibrillary acidic protein (GFAP) and S100 protein and the results were compared with those in ameloblastic fibroma (AF). A striking histopathological characteristic of AFD was the formation of abortive dentin with various degrees of maturation at the epithelial-mesenchymal tissue interface. Central cells of enamel organ-like epithelia with various stages of abortive dentin induction in AFD were generally positive for NSE. Dental lamina-like epithelial cells also showed positive staining in some areas. No cells were positive for NSE in AF. Positive staining for GFAP was observed in the juxta-epithelial mesenchymal tissue of the formation stage of immature dentin with various numbers of entrapped cells in AFD, but GFAP staining was negative in other mesenchymal and epithelial tissues at other stages. In AF, no GFAP-positive cells were found. There were a few S100 protein-positive cells found in the foci of epithelial components in both AFD and AF. Mesenchymal cells showing a dendritic or spindle shape were positive for S100 protein in some areas of AFD and AF. Although such cells in the mesenchymal component of pigmented AFD were more numerous than in non-pigmented AFD and AF, their distribution pattern in the former condition was basically similar to that in the latter. Although the present results, obtained from conventional immunohistochemical procedures, do not directly reflect the expression of neural crest-derived cells in the dentinogenesis of AFD, such results do not disprove the possibility of the expression of neural proteins probably related to neural crest-derived cells in dentinogenesis under certain pathologic conditions in odontogenic mixed tumors. Such a phenomenon may also occur during dentinogenesis in other odontogenic mixed tumors and in normal tooth differentiation, but at an undetectable level.

Advances and new concepts in oral and maxillofacial pathology

New techniques in surgical pathology at the cellular and molecular levels offer the clinician help in determining modalities of treatment of specific diseases. In addition to routine staining, adjunctive tests such as immunohistochemical analysis, and the various methods of evaluating nucleic acid have helped make this possible. The efficacy of fine-needle aspiration biopsy has been enhanced by these diagnostic aids that enable the assessment of information from small amounts of tissue.

Ameloblastic fibro-odontoma: report of two cases

Ameloblastic fibro-odontoma is a rare odontogenic tumour. It affects young people and is usually located in the posterior jaws. Two cases of this tumour are presented: both lesions had produced an asymptomatic swelling. The histology showed the presence of an odontogenic epithelium immersed in a fibrous mesenchyme; dental hard tissues were also present. No recurrences were found after 12 and 4 years from the surgical enucleation of the tumour.