Clinicopathological evaluation of 164 dental follicles and dentigerous cysts with emphasis on the presence of odontogenic epithelium in the connective tissue. The hypothesis of "focal ameloblastoma"

Correlation Between Radiographic and Histopathologic Findings Associated with Unerupted Teeth in Dogs

An association between unerupted teeth and dentigerous cysts is well known,^{1- 4} however little is known about the presence of disease and histopathologic changes in unerupted teeth without radiographic evidence of cyst formation. Forty-two dogs representing 25 breeds, ranging in age from 5 months to 12 years were selected based on radiographic evidence of an unerupted tooth or teeth, either as a primary complaint or incidental finding. Dogs meeting the study criteria were presented to a private dental referral practice within a period of eighteen months from December 2016 through May 2018. Patients were treated with conservative en bloc resection of the unerupted tooth and overlying bone as well as debridement of any cystic structure and biopsy of the samples collected. Radiographs were evaluated using criteria previously established to assess for evidence of a cyst.^{1, 5- 7} A total of 68 unerupted teeth were identified; 63 (92.7%) were mandibular first premolar teeth. Of the 63 unerupted mandibular first premolar teeth, 28 (44.4%) had radiographic evidence of a cystic structure. Histopathology revealed that 21 of 28 (75.0%) had evidence of non-keratinizing stratified squamous epithelium consistent with a cyst lining. Of the remaining 35 of 63 (55.6%) mandibular first premolar teeth with no radiographic evidence of a cyst, 27 (77.1%) had no histologic evidence of epithelium associated with the impacted tooth. Notably however, the remaining 8 of 35 (22.9%) unerupted teeth without radiographic evidence of a cyst did have histologic evidence of non-keratinizing stratified squamous epithelium associated with the impacted tooth.

Quiste dentígero. Revisión de la literatura y reporte de caso

Introducción: el quiste dentígero, también conocido como quiste folicular, es la segunda forma más habitual de los quistes de la región maxilar después del quiste radicular. Tiene una incidencia del 20% con respecto a todos los quistes odontogénicos y se encuentra más en el género masculino entre los 20-40 años. El manejo conservador en lesiones quísticas de gran tamaño es indispensable para evitar defectos óseos o daño a estructuras vecinas. Sin embargo, en lesiones de menor tamaño, la enucleación continúa siendo el tratamiento de elección. Objetivo: presentar un caso clínico de un quiste dentígero y hacer una revisión de la literatura actualizada. Caso clínico: paciente masculino de 23 años que presentó aumento de volumen en zona geniana derecha y, además, en su ortopantomografía se observó una lesión en el sector de los incisivos superiores. Se realizó enucleación de la lesión, cuyo diagnóstico histológico previo fue quiste dentígero y posteriormente se obtiene una correcta regeneración ósea tras un año de seguimiento Conclusión: el manejo del quiste dentígero es variado: puede ir desde la enucleación quirúrgica hasta la descompresión y marsupialización del mismo. No obstante, todos los tratamientos actuales se basan en contrarrestar los factores de expansión quística que permiten a esta lesión alcanzar grandes tamaños intraóseos y poder causar desde rizolisis de dientes adyacentes hasta una asimetría facial como sucedió en este caso clínico.  

Development of head and neck pathology in Europe

This review gives a brief history of the development of head and neck pathology in Europe from a humble beginning in the 1930s to the explosive activities the last 15 years. During the decades before the introduction of immunohistochemistry in the 1980s, head and neck pathology grew as a subspeciality in many European countries. In the late 1940s, the Institute of Laryngology and Otology with its own pathology laboratory was founded in London, and in 1964 the World Health Organization (WHO) International Reference Centre for the Histological Classification of Salivary Tumours was established at the Bland-Sutton Institute of Pathology, also in London. International collaboration, and very much so in Europe, led to the publication of the first WHO Classification of Salivary Gland Tumours in 1972. In the 1960s, a salivary gland register was organised in Hamburg and in Cologne the microlaryngoscopy was invented enabling microscopic endoscopic examination and rather shortly afterwards a carbon dioxide laser attached to the microscope became established and laryngeal lesions could be treated by laser vaporisation. During the last three decades, the use of immunohistochemistry supplemented with cytogenetic and refined molecular techniques has greatly facilitated the pathological diagnostics of head and neck lesions and has had a huge impact on research. Collaboration between different European centres has drastically increased partly due to establishment of scientific societies such as the Head and Neck Working Group (HNWG) within the European Society of Pathology and the International Head and Neck Scientific Group (IHNSG). A very large number of European pathologists have contributed to the 2nd, 3rd and 4th WHO books, and are involved in the upcoming 5th edition. Accredited educational meetings and courses are nowadays regularly arranged in Europe. Numerous textbooks on head and neck pathology have been written and edited by European pathologists. The increased collaboration has created larger series of tumours for research and new entities, mainly defined by their genetic abnormalities, are continuously emerging from Europe, particularly regarding salivary gland neoplasms and "undifferentiated" sinonasal tumours. These findings have led to a better and more precise classification and open the possibilities for new treatment strategies.

Dental mesenchymal stromal/stem cells in different microenvironments— implications in regenerative therapy

Current research data reveal microenvironment as a significant modifier of physical functions, pathologic changes, as well as the therapeutic effects of stem cells. When comparing regeneration potential of various stem cell types used for cytotherapy and tissue engineering, mesenchymal stem cells (MSCs) are currently the most attractive cell source for bone and tooth regeneration due to their differentiation and immunomodulatory potential and lack of ethical issues associated with their use. The microenvironment of donors and recipients selected in cytotherapy plays a crucial role in regenerative potential of transplanted MSCs, indicating interactions of cells with their microenvironment indispensable in MSC-mediated bone and dental regeneration. Since a variety of MSC populations have been procured from different parts of the tooth and tooth-supporting tissues, MSCs of dental origin and their achievements in capacity to reconstitute various dental tissues have gained attention of many research groups over the years. This review discusses recent advances in comparative analyses of dental MSC regeneration potential with regards to their tissue origin and specific microenvironmental conditions, giving additional insight into the current clinical application of these cells.

Revisiting the human dental follicle: From tooth development to its association with unerupted or impacted teeth and pathological changes

Dental follicles are involved in odontogenesis, periodontogenesis, and tooth eruption. Dental follicles are unique structures, considering that their remnants can persist within the jawbones after odontogenesis throughout life if the tooth does not erupt. Pathological changes may occur in these tissues as individuals age. The changes range from benign to life threatening. Thus, the assessment of age-related changes in dental follicles associated with unerupted teeth is of paramount importance. In this review, we summarize the physiological roles and changes in dental follicles in odontogenesis, tooth eruption, and aging, in addition to the pathological changes associated with these structures. We encourage investigators to consider this peculiar tissue as a unique model and explore its potential to clarify its importance from the viewpoints of developmental biology, tissue physiology, and pathology.

Diagnóstico de quiste dentígero en sacos foliculares de terceros molares incluídos

Objetivo: establecer el tipo de patología más frecuente asociada a terceros molares incluidos, extraídos en las clínicas de cirugía oral de la Facultad de Odontología de la Universidad Nacional de Colombia y la frecuencia de aparición de quistes dentígeros, rango de edad, sexo y la región anatómica en que predominan. Métodos: se revisaron 17 sacos foliculares de 11 pacientes atendidos en las clínicas de cirugía oral entre agosto del 2018 y febrero 2019. Resultados: se recolectaron 7 biopsias de 5 pacientes masculinos  y 10 de 7 pacientes femeninos, con edades comprendidas entre los 17 a 24 años (media: 20.40), se realizó estudio histopatológico con hematoxilina-eosina, los datos obtenidos se analizaron para determinar frecuencia, edad, sexo y patología asociada. Se encontraron 15 casos que mostraron cambios quísticos diagnosticados como quistes dentígeros y  2 casos diagnosticados como saco folicular. Conclusiones: aunque la muestra es pequeña, este estudio da indicios que los sacos foliculares asociados a terceros molares incluídos están  altamente implicados en la formación de quistes dentígeros.

Evaluación radiográfica de la estabilidad en medidas cefalométricas de pacientes Clase III sometidos a cirugía ortognática bimaxilar*

Objetivo: evaluar cefalométricamente en los planos sagital y vertical la estabilidad de pacientes con maloclusión clase III sometidos a cirugía ortognática bimaxilar. Métodos: estudio longitudinal en 20 pacientes (11 mujeres), con un promedio de 22.5 años y diagnóstico de hipoplasia del tercio medio facial y prognatismo mandibular, tratados con ortodoncia y cirugía ortognática bimaxilar. Se realizaron tres radiografías cefálicas laterales por cada paciente: una previa al procedimiento quirúrgico (T1), otra a los 8 meses posquirúrgicos (T2) y a los 18 meses posquirúrgicos (T3). Se evaluaron los cambios en el plano X y Y en los tres tiempos, realizando las pruebas estadísticas pertinentes con el fin de observar diferencias. Resultados: se encontraron medidas más estables en el maxilar superior en sentido vertical y sagital, mientras que la mandíbula es menos estable a los movimientos quirúrgicos, principalmente en sentido vertical (diferencias estadísticamente significativas p<0.05) Conclusión: la cirugía ortognática bimaxilar en casos de clase III es muy estable (especialmente en el maxilar); dicha estabilidad fue definida solamente con medidas cefalométricas, sin tener en cuenta variables como la función o las características clínicas de los pacientes.

Relative frequency of dentigerous cyst in Iranian population: A 20-year retrospective study

Purpose

Dentigerous cyst (DC) is the most common type of developmental odontogenic cysts which apparently develops via accumulation of fluid between the reduced enamel epithelium and crown of the tooth. The aim of this study is to analyze the frequency of DC in Iranian population.

Materials and Methods

The files of oral pathology, Shahid Beheshti University of Medical Sciences, served as the source of the materials from 1992 to 2012 for this study. All lesions diagnosed as DCs were subjected to microscopic reevaluation. Patient's age, sex, location, and microscopic characteristics were recorded. Based on these data, a descriptive statistical analysis was performed using SPSS 19 software (IBM SPSS Statistics 19, New York, United States) and the results with P < 0.05 were considered as significant.

Results

DC accounted for 34.37% of all odontogenic cysts of the jaws during the 20-year period. The mean age of patients was 24.72 years and most cases are diagnosed in the second and third decades of life. The male-to-female ratio was 1.52. About 73.89% of all lesions had occurred in the mandible and 26.11% in maxilla. DCs showed Vickers and Gorlin (ameloblastomatous) changes in 2.36% of cases. The mean age was significantly lower in the premolar area (P = 0.00).

Conclusion

Age, sex, and location of DCs in Iranian population are similar to previous studies. In addition, the age of occurrence for this lesion in the premolar region was relatively lower than at other sites. Although the risk of ameloblastic change is low, it should be considered as an important issue.

Ability of Oral and Maxillofacial Surgery Residents in Diagnosing Jaw Cysts: A Retrospective 20 Years Study

INTRODUCTION

Diagnosis of odontogenic cysts despite of their benign nature is a critical and challenging problem especially among undergraduate and postgraduate students.

AIM

This study aimed to evaluate the capability of oral and maxillofacial surgery residents in diagnosing odontogenic cysts.

MATERIALS AND METHODS

This cross-sectional study was executed on 312 patient records over the past 20 years since October 1995 till December 2014 in Taleghani Hospital, Tehran, Iran. All recorded data was based on 2005 World Health Organization (WHO) classifications. The differential diagnosis was made by 65 residents based on clinical and paraclinical evaluations established in the charts. Differential diagnoses made by the residents were compared to the histopathological examination as the gold standard for identifying the nature of the cysts. Weighted kappa test was used to show the degree of agreement.

RESULTS

Data extracted from 312 records were analyzed. The mean age of examined patients was 27.6 years. The accuracy of diagnosis among the residents was moderate (k_w=0.5). The diagnosis made by the residents was significantly related to the radiographic view of the cysts (p<0.05). The residents were able to identify odontogenic keratocysts and dentigerous cysts in most cases.

CONCLUSION

There are several factors associated with the occurrence of pathologic odontogenic cysts which could help either the clinician or the pathologist in diagnosing the odontogenic cysts of the jaws. The surgeons should consider these related factors before the final diagnosis and choosing the appropriate treatment plan.

The importance of histopathologic analysis of pericoronal follicles for the early identification of ameloblastomas

The objective of this study was to discuss the importance of performing histopathological examination of pericoronal follicles as a routine procedure, so as to enable the early identification of odontogenic lesions. We describe two clinical cases with histopathological diagnoses of ameloblastomas who did not show clinical or radiographic signs of disease before microscopic examination.

Analysis of the proliferative potential of odontogenic epithelial cells of pericoronal follicles

AIM

To evaluate the proliferative potential and the cell proliferation rate of odontogenic epithelial cells.

MATERIALS AND METHODS

Forty-two cases of pericoronal follicles of impacted third molars were submitted to silver impregnation technique for quantification of argyrophilic nucleolar organizer regions (AgNOR) and immunohistochemical staining for EGFR and Ki-67. For AgNOR quantification, the mean number of active nucleolar organizer regions per nucleus (mAgNOR) and the percentage of cells with 1, 2, 3 and 4 or more AgNORs per nucleus (pAgNOR) were quantified. Ki-67 immunolabeling was quantified, whereas for EGFR, a descriptive analysis of staining patterns (membrane, cytoplasm or membrane + cytoplasm positivity) was performed. We evaluated the reduced epithelium of the enamel organ and/or islands of odontogenic epithelium present in the entire connective tissue.

RESULTS

mAgNOR were 1.43 (1.0-2.42) and were significantly different among pericoronary follicles from upper and lower teeth (p = 0.041). Immunostaining of Ki-67 was negative in all cases. EGFR immunolabeling was found mainly in the cytoplasm and was more intense in islands and cords when compared to reduced epithelium of the enamel organ.

CONCLUSION

Odontogenic epithelial cells of some pericoronal follicles have proliferative potential, suggesting their association with the development of odontogenic lesions.

CLINICAL SIGNIFICANCE

The authors suggest that nonerupted, especially of the lower teeth, should be monitored and if necessary removed.