Cystic Conditions of the jawbones: A Review of Early Classification Systems.

Cystic conditions of the jawbones were recognized long before the establishment of the American Academy of Oral Pathology (AAOP) in 1948, but it was around this time when they were studied, characterized, and classified. The history of the classification systems implemented by oral pathologists to study the cystic conditions of the maxillary bones is intimately related with the birth of oral and maxillofacial pathology as a specialty of dentistry. The purpose of this paper is to review the early classification systems proposed for the cystic conditions of the jawbones.

Diagnostic capability of artificial intelligence tools for detecting and classifying odontogenic cysts and tumors: a systematic review and meta-analysis.

OBJECTIVE: To evaluate the diagnostic capability of artificial intelligence (AI) for detecting and classifying odontogenic cysts and tumors, with special emphasis on odontogenic keratocyst (OKC) and ameloblastoma. STUDY DESIGN: Nine electronic databases and the gray literature were examined. Human-based studies using AI algorithms to detect or classify odontogenic cysts and tumors by using panoramic radiographs or CBCT were included. Diagnostic tests were evaluated, and a meta-analysis was performed for classifying OKCs and ameloblastomas. Heterogeneity, risk of bias, and certainty of evidence were evaluated. RESULTS: Twelve studies concluded that AI is a promising tool for the detection and/or classification of lesions, producing high diagnostic test values. Three articles assessed the sensitivity of convolutional neural networks in classifying similar lesions using panoramic radiographs, specifically OKC and ameloblastoma. The accuracy was 0.893 (95% CI 0.832-0.954). AI applied to cone beam computed tomography produced superior accuracy based on only 4 studies. The results revealed heterogeneity in the models used, variations in imaging examinations, and discrepancies in the presentation of metrics. CONCLUSION: AI tools exhibited a relatively high level of accuracy in detecting and classifying OKC and ameloblastoma. Panoramic radiography appears to be an accurate method for AI-based classification of these lesions, albeit with a low level of certainty. The accuracy of CBCT model data appears to be high and promising, although with limited available data.

Expression of cell cycle and apoptosis-related proteins in ameloblastoma and keratocystic odontogenic tumor.

Tumors arising from epithelium of the odontogenic apparatus or from its derivatives or remnants exhibit considerable histologic variation and are classified into several benign and malignant entities. A high proliferative activity of the odontogenic epithelium in ameloblastoma (AM) and keratocystic odontogenic tumor (KCOT) has been demonstrated in some studies individually. However, very few previous studies have simultaneously evaluated cell proliferation and apoptotic indexes in AM and KCOT, comparing both lesions. The aim of this study was to assess and compare cell proliferation and apoptotic rates between these two tumors. Specimens of 15 solid AM and 15 KCOT were evaluated. The proliferation index (PI) was assessed by immunohistochemical detection of Ki-67 and the apoptotic index (AI) by methyl green-pyronin stain. KCOT presented a higher PI than AM (P < .05). No statistically significant difference was found in the AI between AM and KCOT. PI and AI were higher in the peripheral cells of AM and respectively in the suprabasal and superficial layers of KCOT. In conclusion, KCOT showed a higher cell proliferation than AM and the AI was similar between these tumors. These findings reinforce the classification of KCOT as an odontogenic tumor and should contribute to its aggressive clinical behavior.

Odontogenic keratocyst: a case report and review of an old lesion with new classification.

The odontogenic keratocyst (OKC) is distinctive among jaw cysts given its tendency toward recurrence and aggressive clinical behavior. This paper presents a well-documented case of OKC and a review of the diagnostic features, treatment modalities and new evidence supporting the reclassification and renaming of this unique pathologic process.

Should the solid variant of odontogenic keratocyst and keratoameloblastoma be classified as the same entity? A clinicopathological analysis of nine cases and a review of the literature.

The solid variant of odontogenic keratocyst (SOKC) is an extremely rare odontogenic lesion, which remains poorly defined even in the 2017 World Health Organization odontogenic tumour classification. It is difficult to distinguish between SOKC and so called keratoameloblastoma (KAB), both rare lesions that have similarities in clinical, histological and biological characteristics. Here, we report clinicopathological data and results of molecular analysis of nine cases with a literature review. First, they were compared to previously reported cases of SOKC and/or KAB, and many overlaps were found in clinical and pathological characteristics. Second, we performed PCR analysis for BRAF V600E mutation. Although ameloblastoma-like epithelia were often encountered, none exhibited BRAF V600E mutation, which has been reported to occur frequently in ameloblastomas but not in odontogenic keratocysts (OKCs). One of two cases of SOKC in the present series from which fresh frozen tissue specimens were available was found to harbour PTCH1 mutations, indicating that these were more likely to be a subtype of OKC. Moreover, we also examined the differences between SOKC and primary intraosseous carcinoma (PIOC) with regard to the expression of cytokeratins (pan-CK, CK5/6, CK7, CK8/18, CK10, CK14 and CK19), p53 and Ki-67. The proportions of p53-and Ki-67-positive cells were significantly higher in PIOC than in SOKC. These findings suggest that immunostaining for p53 and Ki-67 would be useful to differentiate between SOKC and PIOC. We also conducted a review of SOKC and KAB cases reported in the English language literature.

Reclassification of odontogenic keratocyst as tumour. Impact on the odontogenic tumours prevalence.

AIM: The aim of this study was to establish the impact of the redefinition and reclassification of odontogenic keratocyst (OKC) as a tumour on the prevalence of odontogenic tumours (OT). METHODS: We revised 15 435 files of a teaching head and neck histopathology service in the time period from January 1981 to December 2008 and 478 cases of OT were selected. The 342 cases from 1981 to 2004 were classified according 1992 to the World Health Organization (WHO)-classification (excluding keratocystic OT) while the 136 cases from 2005 onwards were classified according to the 2005 WHO-classification (including keratocystic OT). Age and gender were obtained from medical records. The frequency distribution and prevalence of OT from each periods of time were compared. A chi-square test was performed (P < 0.05 95% confidence interval). RESULTS: The prevalence of OT increases 92% in the 2005-2008 period; from 2.6% (1981-2004 period) to 5% (2005-2008 period) (P 0.000).The most frequent OT in the 1981-2004 period was odontoma (45% of all OT) while in the 2005-2008 period was Keratocystic Odontogenicv Tumour (38.9%). CONCLUSIONS: The redefinition of OKC as a tumour produced an increase in the frequency and prevalence of OT.

[Risk factors for recurrence of maxillary odontogenic keratocysts]. / Les facteurs de risque de récidive des kératokystes odontogéniques des maxillaires.

PURPOSE: The odontogenic keratocyst is a benign tumor with a high recurrence rate and aggressive behavior. We analyzed the risk factors for recurrence of odontogenic keratocysts and compared our results to published ones. PATIENTS AND METHODS: Thirty-two patients (36 odontogenic keratocysts) were treated in our department between 1996 and 2006. We retrospectively analyzed recurrence according to anatomoclinic, histopathological, and prognostic parameters. RESULTS: The patients' mean age was 41 years. The sex ratio was 1.28 with male predominance. The mandible was the most common site (30 cases). The most common radiological finding was a unilocular cyst in 75 % of cases. The primary treatment was conservative surgery for all patients. Twelve recurrences were observed in eight patients between 2 and 10 years of follow-up. All recurrences occurred in the mandible with 41 % in the angle and ramus. Multilocular cysts recurred in 55 % of cases, unilocular in 11 %. The recurrence rate of orthokeratocysts was 40 %. The presence of satellite cysts and extension to soft tissues were associated with a high rate of recurrence (60 %). Sixty-six percent of infected cysts recurred and among these, eight were enucleated in several fragments. DISCUSSION: The recurrence rate of odontogenic keratocysts is higher in case of mandibular posterior region localization and multilocular keratocysts. This might be explained by the difficult surgical accessibility. Some histological findings including the presence of satellite cysts and orthokeratocysts are associated with a higher recurrence rate. Cyst infection and treatment modalities influence the recurrence rate.

Keratocystic odontogenic tumour: reclassification of the odontogenic keratocyst from cyst to tumour.

The purpose of this paper is to review the features and behaviour of the odontogenic keratocyst (OKC), now officially known as the keratocystic odontogenic tumour (KCOT); to analyze a series of histologically confirmed KCOT cases; and to review and discuss the redesignation of KCOT and the implications for treatment. Redesignation of the OKC as the KCOT by the World Health Organization (WHO) is based on the well-known aggressive behaviour of this lesion, its histology and new information regarding its genetics. Abnormal function of PTCH, a tumour suppressor gene, is noted to be involved in both nevoid basal cell carcinoma syndrome and sporadic KCOTs. Normally, PTCH forms a receptor complex with the oncogene SMO for the SHH ligand. PTCH binding to SMO inhibits growth-signal transduction. SHH binding to PTCH releases inhibition of the signal transduction pathway. If normal functioning of PTCH is lost, the proliferation-stimulating effects of SMO are permitted to predominate. A review of the literature was conducted and results were tabulated to determine whether treatment modality is related to recurrence rate. More aggressive treatment - resection or enucleation supplemented with Carnoy"s solution with or without peripheral ostectomy - results in a lower recurrence rate than enucleation alone or marsupialization. Notably, the recurrence rate after marsupialization followed by enucleation is not significantly higher than that following the so-called aggressive modalities. Our case series consists of 21 patients treated for KCOTs. Results were organized to demonstrate recurrence as it relates to size of lesion and time since treatment and incidence as it relates to patient age and location in the jaws. In our series, the average KCOT surface area measured radiographically was 14 cm2. Most lesions were within the 0-15 cm2 range and lesions in this range resulted in the greatest number and proportion of recurrences. The recurrence rate of 29% in our case series was consistent with previously established data; all recurrences occurred within 2 years post-intervention. The incidence of primary lesions was highest in the age group 70-79 years; most lesions occurred in the posterior mandible. WHO"s reclassification of the OKC as the KCOT based on behaviour, histology and genetics underscores the aggressive nature of the lesion and should motivate clinicians to manage the disease in a correspondingly aggressive manner. The most effective interventions for the KCOT are either enucleation with Carnoy"s solution, or marsupialization with later cystectomy. Future treatment may involve molecular-based modalities, which may reduce or eliminate the need for aggressive surgical management.

[Odontogenic cysts]. / Odontogene Kieferzysten.

Odontogenic cysts form a group of diseases whose origin is linked to the persistence of epithelium resulting from the complex embryonic development of the teeth and jaws within the connective tissue. Inflammatory reactions of the surrounding area of the persisting odontogenic epithelium accompany epithelium proliferation, which leads to the development of a gradually expanding cavity that supersedes the surrounding structure. The correlation between activity of the inflammatory reaction and the development of the epithelial proliferation results in a relatively broad variation of histological features of the cyst wall. Since classification of cyst forms depends on their topographical features, clinical information on the classification of variations is urgently needed. For the classification of their clinical course of development and, in particular, in order to differentiate them from cystic odontogenic tumors of the jaw region, a histological examination of cyst wall tissue is necessary, all the more so since the development of a carcinoma deriving from the odontogenic epithelium has only been described in very few cases.

The World Health Organization Classification of Odontogenic Lesions: A Summary of the Changes of the 2017 (4th) Edition.

The 4th edition of the World Health Organization (WHO) Classification of Head and Neck Tumors was published in January 2017. The edition serves to provide an updated classification scheme, and extended genetic and molecular data that are useful as diagnostic tools for the lesions of the head and neck region. This review focuses on the most current update of odontogenic cysts and tumors based on the 2017 WHO edition. The updated classification has some important differences from the 3rd edition (2005), including a new classification of odontogenic cysts, 'reclassified' odontogenic tumors, and some new entities.

Odontogenic cysts: analysis of 2,944 cases in Chile.

INTRODUCTION: Odontogenic cysts constitute a group of frequent intraosseous lesions characteristic in the maxillary bones and one of the main causes of the destruction of these bones. In Chile there are no retrospective studies of these lesions as a whole. OBJECTIVE: The purpose of this study is to determine the frequency of these lesions in so far as they were diagnosed and registered in the Referral Institute for Oral Pathology (IREPO) of the University of Chile in two age groups as well as to analyze and to compare the data obtained with the data published in previous studies. MATERIAL AND METHOD: We studied the records from IREPO of the University of Chile for the period between 1976 and September, 2004; and we determined the frequency according to age, gender and site of each of these lesions. We compare two age groups: younger than or equal to 15 years old and older than 15 years old. Those cases in which the information did not suffice for the purposes of analysis were not considered. All the histological slides were reclassiffed according to the diagnostic criteria included in the Histological Typification of the World Health Organization. RESULTS: We found 2.944 odontogenic cysts (OC), of which 1.935 (65.7%) were inflammatory cysts and 1.009 were developmental cysts. Out of this total, there were 1.554 cysts (52.8%) in men and 1.390 (47.2%) in women. The most frequent cysts were 1.494 radicular cysts (50.7%), 546 dentigerous cysts (18.5%), 421 keratocysts (14.3%) and 328 residual cysts (11.1%). These four varieties represent 94.7% of the OC , that is, 2789 cases. In the population younger than or equal to 15 years of age the developmental cysts (354 cases) are more frequent than the inflammatory cysts (155 cases), the most frequent being dentigerous cysts (240 cases).

Presencia de lesiones quísticas en sacos pericoronarios de terceros molares mandibulares / Presence of cystic lesions in pericoronary sacs of mandibular third molars

Introducción: a pesar de que un tercer molar no erupcionado repre- senta un riesgo de formación quística, la práctica clínica desestima el análisis histopatológico de los folículos de dichos molares. Objetivo: identificar la frecuencia de lesiones quísticas en los sacos pericoronarios de terceros molares mandibulares. Material y métodos: estudio des- criptivo, transversal, analítico y observacional, en donde se incluyeron sacos pericoronarios de terceros molares mandibulares para su análisis histopatológico, descripción de características clínico-radiográficas y su asociación con la presencia de cambios histológicos o lesiones quís- ticas. Resultados: se incluyeron 48 muestras de sacos pericoronarios, la histopatología de los sacos pericoronarios mostró que 83.3% tenían algún tipo de alteración: 13 quistes paradentales (27.1%), cuatro quistes dentígeros (8.3%), 12 folículos hiperplásicos (25.0%) y 11 folículos inflamados (22.9%). La presencia de lesiones quísticas en la población fue de 35.4%. Se detectó asociación estadísticamente significativa entre el sexo y la presencia de lesiones quísticas (p = 0.039) y entre el nivel de erupción y la presencia de cambios histológicos (p = 0.046). Con- clusiones: la frecuencia de lesiones quísticas o cambios histológicos en folículos de terceros molares mandibulares es alta, principalmente en molares parcialmente erupcionados o submucosos y sin importar la ausencia de sintomatología o alteraciones radiográficas (AU))

Introduction: although a non-erupted third molar represents a risk of cystic formation; clinical practice rejects the histopathological analysis of the follicles of said molars. Objective: identify the frequency of the histopathological changes in pericoronary sacs of mandibular third molars. Material and methods: descriptive cross- sectional, observational and analytic study, where pericoronary sacs of mandibular third molars were included for histopathological analysis, description of clinical-radiographic characteristics and their association with the presence of histological changes or cystic lesions. Results: 48 samples of pericoronary sacs were included, the histopathology of the pericoronary sacs showed 83.3% had some type of alteration: 13 paradental cysts (27.1%), four dentigerous cysts (8.3%), 12 hyperplastic follicles (25.0%) and 11 inflamed follicles (22.9%). The presence of cystic lesions in the population was 35.4%. A statistically significant association was detected between sex and the presence of cystic lesions (p = 0.039); and between the level of eruption and the presence of histological changes (p = 0.046). Conclusions: the frequency of cystic lesions or histological changes in mandibular third molar follicles is high, mainly in partially erupted or submucosal molars and regardless of the absence of symptoms or radiographic alterations (AU)

Bi-maxillary dentigerous cyst in a non-syndromic child - review of literature with a case presentation.

Dentigerous cysts are the most common developmental odontogenic cysts of the jaw, which usually occur in the second and third decade of life. It is most frequently associated with impacted mandibular third molar teeth and impacted canines. Bilateral/multiple dentigerous cysts are rare and typically associated with developmental syndromes. Non-syndromic dentigerous cyst occurring bilaterally or involving both arches at the same time is very rare. Here, we discuss the review of literature with a case of unusual occurrence of non-syndromic bi-maxillary dentigerous cysts in a child.

Prevalence profile of odontogenic cysts and tumors on Brazilian sample after the reclassification of odontogenic keratocyst.

PURPOSE: The aim of this study was to evaluate the impact of the reclassification of odontogenic keratocyst (OKC) as a tumor on the prevalence profile of odontogenic cysts (OCs) and odontogenic tumors (OTs). STUDY DESIGN: Two referral Oral and Maxillofacial Pathology services in Brazil were evaluated. All cases diagnosed as OCs or OTs were selected and classified according to the 1992 WHO-classification (cases before 2005 WHO classification of tumors excluding OKC) and the 2005 WHO classification of tumors, going forward including cases of odontogenic keratocyst tumor (KCOT). The frequency and prevalence of OCs and OTs were compared before and after the reclassification. RESULTS: Among 27,854 oral biopsies, 4920 (17.66%) were OCs and 992 (3.56%) were OTs. The prevalence of OTs before 2005 WHO classification of tumors was 2.04%, while the prevalence after 2005 WHO classification was 11.51% (p < 0.0001). Before 2006, the most frequent tumor diagnosed was odontoma with 194 cases (39.67%), and after 2005 WHO classification of tumors the KCOT was the most frequent with 207 cases (41.07%). CONCLUSIONS: The increase in the prevalence of OTs after 2005 WHO is related to the improvement of pathology services and to the inclusion of KCOT in the OTs group.

Reclassification and treatment of odontogenic keratocysts: A cohort study.

The odontogenic keratocyst (OKC) is a recurrent cyst that has been recently reclassified from an odontogenic tumor to an odontogenic cyst. The aim of the present study was to investigate its treatment and address issues related to its association with nevoid basal cell carcinoma syndrome (NBCCS). Lesions from the cohort of patients included in the present study consisted of 40 OKCs, of which 27 lesions were treated by enucleation (GE) and 13 underwent decompression (GD). Complementary treatment occurred in 38 (95%) lesions, of which 10 underwent isolated peripheral ostectomy (GO) and 28 underwent peripheral ostectomy combined with Carnoy's solution (GC). Thirteen lesions were associated with NBCCS (GS), while the others (n=27) were non-syndromic lesions (GnS). The recurrence-free periods (RFP) in the sample groups were compared using the Kaplan-Meier function and log-rank test at a significance level of 5% (p < 0.05) and were used to calculate the cumulative risk of recurrence (CRR) in each postoperative year. During the follow-up period, which had a mean of 43.5 months (range: 12-102 months), six (15%) recurrences were diagnosed. There was no significant difference among the RFP for the compared groups (p > 0.05) or increased CRR for the decompression (15.4%) over five years. Application of Carnoy's solution did not increase the efficacy of the peripheral ostectomy, but was related to a CRR of 0% for the syndromic lesions over five years. Therefore, 1) decompression did not increase the recurrence risk; 2) peripheral ostectomy demonstrated a similar efficacy as the combination with Carnoy's solution; 3) the association of NBCCS did not seem to significantly influence OKC recurrence; and 4) syndromic lesions seem to behave in the same manner as non-syndromic lesions when submitted to complementary treatments.