Prevalence of BRAF p.V600E and Detection Methods in Benign Mixed and Malignant Odontogenic Tumors: A Systematic Review.

BACKGROUND: The BRAF p.V600E genetic variant facilitates the pathogenesis of various tumors by triggering tumor proliferation and progression. The aim of this study was to analyze the prevalence of BRAF p.V600E in benign mixed epithelial and mesenchymal and malignant odontogenic tumors. In addition, we discussed the different detection methods used to assess for aberrant BRAF. METHODS: This systematic review followed the PRISMA guidelines and was registered in Prospero (CRD42023445689). A comprehensive search of the PubMed/MEDLINE, Scopus, Web of Science, and Embase electronic databases was performed to answer the question "What is the prevalence of the BRAF p.V600E mutation in benign mixed and malignant odontogenic tumors?" The methodological quality of the selected studies was assessed using the JBI's Critical Appraisal Tool. RESULTS: Initially, 387 records were identified, but only 11 articles met the inclusion criteria. A total of 70 patients with benign mixed epithelial and mesenchymal odontogenic tumors and 63 with malignant odontogenic tumors were included in the analysis. We found that the BRAF p.V600E mutation had a prevalence of 31.42% in mixed tumors and 26.98% in malignant odontogenic tumors. Moreover, immunohistochemistry showed high concordance with DNA-based molecular methods. CONCLUSION: In general, the BRAF p.V600E variant exhibited a prominent prevalence in mixed and malignant odontogenic tumors. However, most of the findings are based on small cohorts of patients and further studies with larger cohorts are needed.

Odontogenic tumours in a Chilean population: a retrospective study of 544 cases based on 2022 WHO classification

Background: Odontogenic tumours are infrequent lesions. Studies on the frequency of odontogenic tumours from Latin America are scarce. This work aimed to determine the relative frequency of odontogenic tumours in a Chilean population using the 2022 World Health Organization classification. Material and Methods: This is a case series retrospective study. We reviewed 35,530 samples from 1975 to 2022 from the Oral Pathology Referral Institute and the Pathological Anatomy Service, Faculty of Dentistry, University of Chile. We utilized the 2022 World Health Organization classification for histological typification. Results: According to 2022 World Health Organization classification, 544 odontogenic tumours were confirmed. The most frequent odontogenic tumours were: odontoma (n=241; 44.3%), ameloblastoma (n=109; 20.0%) and cemento-ossifying fibroma (n=71; 13.1%). Benign odontogenic tumours corresponded to 538 cases (98.9%) and malignant tumours were only six cases (1.1%). Conclusions: In our population, odontoma was the most frequent odontogenic tumour followed by ameloblastoma and cemento-ossifying fibroma. Malignant odontogenic tumours were very rare. The results of this study are similar to reports from America, but there are some differences concerning the data from Africa and Asia. (AU)

Odontogenic tumours in a Chilean population: a retrospective study of 544 cases based on 2022 WHO classification.

BACKGROUND: Odontogenic tumours are infrequent lesions. Studies on the frequency of odontogenic tumours from Latin America are scarce. This work aimed to determine the relative frequency of odontogenic tumours in a Chilean population using the 2022 World Health Organization classification. MATERIAL AND METHODS: This is a case series retrospective study. We reviewed 35,530 samples from 1975 to 2022 from the Oral Pathology Referral Institute and the Pathological Anatomy Service, Faculty of Dentistry, University of Chile. We utilized the 2022 World Health Organization classification for histological typification. RESULTS: According to 2022 World Health Organization classification, 544 odontogenic tumours were confirmed. The most frequent odontogenic tumours were: odontoma (n=241; 44.3%), ameloblastoma (n=109; 20.0%) and cemento-ossifying fibroma (n=71; 13.1%). Benign odontogenic tumours corresponded to 538 cases (98.9%) and malignant tumours were only six cases (1.1%). CONCLUSIONS: In our population, odontoma was the most frequent odontogenic tumour followed by ameloblastoma and cemento-ossifying fibroma. Malignant odontogenic tumours were very rare. The results of this study are similar to reports from America, but there are some differences concerning the data from Africa and Asia.

Peripheral ameloblastoma: case report and our experience 20 years.

BACKGROUND AND AIM: The purpose of this study was to determine the clinical and histological features and treatment of peripheral ameloblastoma. Peripheral Ameloblastoma is a rare benign odontogenic tumor that concerns soft tissue and have a typical extraosseous localization. METHODS: Aim of this work is to show its clinical and histological characters, in order to define some useful information for differential diagnosis with other oral neoformations, comparing literature with our data, collected in ten years of clinical activity of Oral and Maxillofacial Surgery Unit of Policlinico Tor Vergata in Rome. RESULTS: Prognosis of PA is certainly favourable, with a restitutio ad integrum close to 100%. In the period between October 2011 and November 2021, we reported 8 diagnoses of P.A. Medium age of the group with diagnosis of PA was 71,4 y with a SD: 3,65. P.A.'s incidence in our sample of patients was 0,26%. CONCLUSIONS: PA is a benign odontogenic tumor that requires a careful diagnosis, a complete surgical eradication and adequate follow up, because malignant evolution is rare but possible.

A retrospective study of the malignant change of odontogenic keratocyst.

The odontogenic keratocyst (OKC) is a common cystic lesion of the maxilla and mandible. Squamous cell carcinoma (SCC) arising from OKC or dysplasia occurring in OKC is rare. This study aimed to explore the incidence and clinical features of the dysplasia and malignant transformation of OKC. In this study, 544 patients diagnosed with OKC were collected. Among them, 3 patients were diagnosed as SCC arising from OKC, and 12 patients were diagnosed as OKC with dysplasia. The incidence was calculated. Clinical features were analyzed by chi-square test. In addition, a representative case reconstructing mandible with vascularized fibula flap under general anesthesia was reported. And cases reported before were reviewed. The incidence of the dysplasia and malignant transformation of OKC, which are highly associated with the clinical features of swelling and chronic inflammation, is about 2.76%. But the relevance between the dysplasia and malignant transformation and age, gender together with pain is not statistically high. All in all, the clinical features of swelling and chronic inflammation can be considered as characteristics of the dysplasia and malignant transformation of OKC. Although the pain isn't statistically relevant, it may be a dangerous clew. Also, combined with earlier literatures, the dysplasia and malignant transformation of OKC shows unique features of radiographs and histopathology.

Prevalence of oral and maxillofacial lesions in children and adolescents at a regional Brazilian oral pathology service: a retrospective study and the relevant literature review.

PURPOSE: This study assessed the prevalence of maxillofacial lesions in children, i.e., 0-9 years, and adolescents, i.e., 10-19 years, in a Brazilian Oral Pathology Service and compared results with available literature. METHODS: Clinical and histopathological records from January 2007 to August 2020 were analysed and a literature review investigating maxillofacial lesions in paediatric populations was also performed. RESULTS: Overall, "reactive salivary gland lesions" and "reactive connective tissue lesions" were the most prevalent group of soft tissue lesions, affecting children and adolescents equally. From these, mucocele and pyogenic granuloma were the most prevalent histological diagnoses, respectively, regardless of age. These findings were consistent with the 32 studies included. Considering intraosseous lesions, "odontogenic cysts" and "periapical inflammatory lesions" were the most prevalent groups, with no relevant differences between age groups, except for the odontogenic keratocyst, which was more prevalent in adolescents. Moreover, several odontogenic tumours, such as ameloblastic fibroma and odontogenic myxoma, were significantly more prevalent in children. CONCLUSION: Most maxillofacial lesions presented a similar prevalence between children and adolescents. Reactive salivary gland lesions and reactive connective tissue lesions were the prevailing diagnostic categories, regardless of age. Some odontogenic tumours and the odontogenic keratocyst showed significantly different frequencies across these age groups.

Histopathological diagnosis in pediatric stomatology: A 43-year retrospective study of 1,480 cases from a Brazilian institution.

OBJECTIVES: the aim of this study was to analyze the prevalence of histopathological diagnoses in oral biopsied tissues obtained from a Brazilian pediatric population. METHODS: an analytical, cross-sectional retrospective study was performed with biopsy files of patients ≤14 years of age from a Brazilian oral pathology laboratory over a 43-year period. Data included sex, age, location, and diagnoses. The prevalence was calculated by means of relative frequency. Associations between sex, age groups and diagnoses were verified with Pearson's chi-square test. RESULTS: from 19,456 oral biopsies, 1480 (7.6%) were obtained from patients aged ≤14 years. Most children were 10-14 years of age (60.1%) and females (55.1%), with an overall M:F of 1:1.2. Children aged 0-9 years and males had a higher frequency of lesions of the oral mucosa, whilst the 10-14 year age group showed a higher frequency of cysts, odontogenic tumors, and salivary gland lesions. The latter was also significantly higher in females. Samples consisted mostly of soft tissue lesions (53%) obtained from the lower lip (30.7%). Intraosseous lesions showed a slight predilection for the mandible (21.2%). Salivary gland lesions (28.8%) was the most common diagnostic category, followed by reactive lesions (18.8%), and cysts (16.1%). Mucocele (33.5%), dentigerous cyst (6.7%), and fibrous hyperplasia (5.9%) were the top three histopathological diagnoses. Malignant lesions affected only 0.9% of this population. CONCLUSION: our results were similar to other retrospective studies. Due to the low frequency of oral biopsies in children, data on the prevalence of oral pathology in this population might aid in the clinical and histopathologic diagnoses.

Synchronous odontogenic tumors: A systematic review.

This systematic review aimed to incorporate published information about synchronous odontogenic tumors (SOTs) with an analysis of the demographic and clinical characteristics from the cases published in the literature. Case reports and case series of SOT were searched in PubMed, Web of Science, Scopus, and EMBASE. A descriptive statistical analysis was performed. Twenty-eight studies comprising 30 cases of SOTs were included. Considering all cases published, SOTs mostly occurred simultaneously in the maxilla and mandible (n = 19/63.3%). Lesions were bifocal in 13 (43.3% of all the 30 cases) and multifocal in 17 cases (56.7% of all the 30 cases). All SOTs available in the literature presented the same type of lesion, and two of them also involved another different SOT (n = 2/6.7% of all the 30 cases). Out of all published cases, the most frequent SOTs in the literature were odontomas (n = 10/33.3% of all the 30 cases), squamous odontogenic tumors (OTs) (n = 8/26.7% of all the 30 cases), calcifying epithelial OTs (n = 8/26.7% of all the 30 cases), and adenomatoid OTs (n = 2/6.7% of all the 30 cases). Considering all SOTs cases included, the overall recurrence was 13.3%. Inside a subgroup of the lesion, synchronous calcifying epithelial OT presented the highest (25%). Five cases (16.7% of all the 30 cases) had a previously associated syndrome, with two cases of Schimmelpenning syndrome being reported. Among published SOTs, odontomas were the most common. All SOTs available in the scientific literature showed the same type of OT and mainly affected both jaws simultaneously. Only a few of these cases were associated with a syndrome.

Malignant odontogenic tumors. A report of a series of 30 cases and review of the literature.

Malignant odontogenic tumors are rare entities and can arise de novo or from malignant transformation of pre-existing lesions. The aim of the present study was to report 30 cases of malignant odontogenic tumors diagnosed at a single diagnostic center over a 38-year period. MATERIALS AND METHODS: All cases of malignant odontogenic tumors diagnosed between 1980 and 2018 were retrieved from the files of the School of Dentistry, University of Buenos Aires; their frequency and clinical, radiographic, and histopathological features were analyzed. The obtained data were compared with the information reported in the literature. RESULTS: Malignant odontogenic tumors accounted for 2 % of odontogenic tumors and 0.05 % of all oral-maxillofacial diseases. Mean age was 43 years (8 to 87 years). No differences in sex distribution were observed. The most frequent location was the mandible, mostly the posterior mandibular body and the ramus. Odontogenic carcinomas were the most frequent tumors, and primary intraosseous carcinomas were the most common in this group. CONCLUSIONS: This is the largest case series of malignant odontogenic tumors diagnosed at a single center reported in the literature to date. Diagnosis of these tumors is challenging based on their rarity and complexity and relies on careful analysis of the histopathological, clinical, and radiographic features.

Analysis of 55 cases of adenomatoid odontogenic tumor in an Indian population and review of literature

Background: This study reviews the demographic, clinical and radiographic features of adenomatoid odontogenic tumor(AOT) diagnosed in an Indian population over 50 years and also evaluate and compare follicular AOT(F-AOT) and extra-follicular AOT(EF-AOT). Material and Methods: 55 diagnosed cases of AOT from 1971-2020 were studied retrospectively. The data regarding the age, sex, location, variant of AOT, duration, clinical features, radiographic appearance, treatment and recurrence were collected and analysed. Results: Of the 722 odontogenic tumors diagnosed, 7.6% were AOTs with higher prevalence of extra-follicular (67.3%) than follicular (32.7%) variant. All the tumors were intraosseous with a marked predilection for maxilla over mandible, ratio 2:1. The patients mean age was 19.8 years with slightly higher female predilection (male:female ratio - 1:1.5). The anterior region (76.4%) was more frequently affected and entire quadrant was involved in 21.8% cases. Clinically, asymptomatic, slow-growing swelling was seen in 81.8% cases with duration of 15 days to 10 years. Radiographically, AOT appeared as well-corticated radiolucent lesion. Canine was the most commonly impacted tooth. Recurrence was seen in 3 cases. Conclusions: Interestingly, in this series extra-follicular was twice more common than follicular AOT. Few cases involved the entire quadrant or crossed the midline of either jaws.(AU)

Analysis of 55 cases of adenomatoid odontogenic tumor in an Indian population and review of literature.

BACKGROUND: This study reviews the demographic, clinical and radiographic features of adenomatoid odontogenic tumor(AOT) diagnosed in an Indian population over 50 years and also evaluate and compare follicular AOT(F-AOT) and extra-follicular AOT(EF-AOT). MATERIAL AND METHODS: 55 diagnosed cases of AOT from 1971-2020 were studied retrospectively. The data regarding the age, sex, location, variant of AOT, duration, clinical features, radiographic appearance, treatment and recurrence were collected and analysed. RESULTS: Of the 722 odontogenic tumors diagnosed, 7.6% were AOTs with higher prevalence of extra-follicular (67.3%) than follicular (32.7%) variant. All the tumors were intraosseous with a marked predilection for maxilla over mandible, ratio 2:1. The patients mean age was 19.8 years with slightly higher female predilection (male:female ratio - 1:1.5). The anterior region (76.4%) was more frequently affected and entire quadrant was involved in 21.8% cases. Clinically, asymptomatic, slow-growing swelling was seen in 81.8% cases with duration of 15 days to 10 years. Radiographically, AOT appeared as well-corticated radiolucent lesion. Canine was the most commonly impacted tooth. Recurrence was seen in 3 cases. CONCLUSIONS: Interestingly, in this series extra-follicular was twice more common than follicular AOT. Few cases involved the entire quadrant or crossed the midline of either jaws.

Hybrid odontogenic lesions: A systematic review of 203 cases reported in the literature.

BACKGROUND: Hybrid odontogenic lesions combine histopathological characteristics of two or more odontogenic cysts and/or tumours. The aim of this study was to evaluate the available data on hybrid odontogenic lesions (HOL) and to analyse their epidemiological/clinical features and biological behaviour. METHODS: An electronic search was done in January 2021 using multiple databases. Eligibility criteria encompassed publications with sufficient clinical and histological information to confirm the tumours' diagnoses. RESULTS: A total of 147 articles were included in this study, comprising 203 cases. Calcifying odontogenic cyst associated with odontoma (COC/OD) (37/18.2%) was the most common HOL. Females were more affected with a mean age of 24.9 years. Lesions presented as asymptomatic swellings, with a mean evolution time of 8.2 months (0.3-96), and mean tumour size of 4.8 cm (0.3-7). Radiographic aspects frequently showed radiolucent (139/68.4%) and unilocular (52/25.6%) images with well-defined limits (48/23.6%). The lesions mostly affected mandibular pre-molars (69/34%) and mandibular molars (69/34%) regions. Enucleation (89/43.8%) and surgical excision (59/29%) were the most common treatment modalities. The mean follow-up time was 33.8 months (0.5-216 months) and recurrences were observed in four cases (1.9%), all of which were central odontogenic fibroma associated with central giant cell granuloma (COF/CGCG). CONCLUSION: COC/OD is the most common HOL and recurrence is a rare event, being usually associated with the diagnosis of COF/CGCG.

Clinical and demographic characteristics of adenomatoid odontogenic tumors: analysis of 116 new cases from a single center.

INTRODUCTION: The adenomatoid odontogenic tumor is a relatively uncommon odontogenic neoplasm representing about 4.7% of all odontogenic tumors. OBJECTIVE: The aim of this study was to determine the demographic and clinical profile of the adenomatoid odontogenic tumors in a Sri Lankan population. METHODS: Data gathered from the cases received for a period of 38 years from the Department of Oral Pathology, Faculty of Dental Sciences, University of Peradeniya. Request forms, biopsy reports and electronic data base of the department were used to obtain relevant information. Demographic data including age, gender and location of the tumor were included in the analysis. RESULTS: Out of 116 cases of adenomatoid odontogenic tumor, the mean age was 21.02 ±â€¯11.24. It occurs more fre quently in the second decade of life, more prevalent in females, most often associated with the maxilla, predominantly affecting anterior jaw bones and presenting mostly in the right side of the jaw bone. The results from the present study showed the statistically significant relationship with site of occurrence (maxilla/mandible) and age (p < 0.005). Further, depending on whether it occurs in anterior/mid/posterior site also showed a significant relationship with age (p ≤ 0.001). However, side of occurrence, left or right or site of occurrence, showed no statistically significance with age (p > 0.05). CONCLUSION: Adenomatoid odontogenic tumor occurs more frequently in the second decade of life with a significant female predominance and the commonest site is anterior maxilla. This study revealed few differences on demographic and clinical presentations of adenomatoid odontogenic tumor from some regions of the world.

Impact of changing classification systems on prevalence and frequency distribution of odontogenic tumors in tertiary care center of Nagpur.

INTRODUCTION: The classification of odontogenic tumors has been revised from time to time in order to provide unified terminology. This reclassification had considerable impact on their prevalence and frequency distribution. OBJECTIVES: This study was aimed to emphasize impact of changing classification systems on prevalence and relative frequency of odontogenic tumors. The secondary objective was to analyze demographics of various histological types of odontogenic tumors in comparison to published literature. Review of Indian studies (1992-2020) elaborating frequency of odontogenic tumors is summarized in the end. METHODS: This was a hospital-based retrospective study wherein case files of odontogenic tumors diagnosed from 1990 to 2019 period were retrieved. The classification system used originally at the time of diagnosis was retained and prevalence of odontogenic tumors in three different periods (1990-2004, 2005-2016 and 2017-2019) was compared. Further, prevalence, frequency distribution and demographics of all these tumors (1990-2019) were analyzed using latest World Health Organization 2017 classification. RESULTS: A total of 345 odontogenic tumors was diagnosed as per World Health Organization 2017 system of classification from 1990 to 2019. 96.81% tumors were benign and 3.81% constituted malignant odontogenic tumors. However, there was marked increase in prevalence of odontogenic tumors in 2005-2016 (6.2%) period as compared to 1990-2004 (3.87%) and 2017-2019 (3.47%). Ameloblastoma remained the most common tumor in three different periods, whereas keratocystic odontogenic tumor became second commonest tumor in 2005-2016 as compared to odontoma in 1990-2004 and adenomatoid odontogenic tumor in 2017-2019. CONCLUSIONS: The continuous evolving systems of classification may partly be responsible for inconsistency in odontogenic tumors, with inclusion of keratocystic odontogenic tumor,and has marked impact on prevalence and frequency distribution of odontogenic tumors. The geographical variations in demographics of odontogenic tumors might reflect genetic and environment influence; however it requires elucidation by further studies.

Prevalence of odontogenic cysts and tumors on turkish sample according to latest classification of world health organization: A 10-year retrospective study.

AIM: The aims of this study are to investigate the prevalence of odontogenic cysts and tumors occurred in a sample of Turkish population in the last 10 years and to compare the data with latest reports. METHODS AND MATERIAL: The present retrospective study was carried out at Gazi University, School of Dentistry (GUSD) in Ankara, Turkey. All the data was retrieved from the GUSD archive on patients treated for various oral and maxillofacial lesions between 2008 and 2018. Patients' demographical data, main clinical features of the lesions along with histopathological findings were retrieved from the dental files of the patients. The type of lesions was evaluated according to the latest Head and Neck Tumor (HNT) classification published by the World Health Organization (WHO) in 2017. Data was analyzed by descriptive statistics and Chi-square test using SPSS version 21.0 software. RESULTS: Among a total of 739 biopsy-conducted lesions, 467 (63.19%) were odontogenic cysts, 43 (5.82%) were benign odontogenic tumors, and 7 (0.95%) were malignant tumors. The rest of 222 cases were defined as others. CONCLUSIONS: The present study assessed the demographic and clinico-pathological characteristics of odontogenic cysts/tumors in a group of Turkish people, who visited GUSD for therapeutic purpose in the past 10 years. Results showed that male patients in their 5th-6th decades have the highest risk of odontogenic cyst/tumor, especially in the mandibular posterior region.

Clinico-pathological study of malignant odontogenic tumours from a national referral centre.

BACKGROUND: Malignant odontogenic tumours are extremely rare tumours occurring within the jaws. Our study was performed to determine the demographic and clinico-pathological features of malignant odontogenic tumours amongst a multi-ethnic Asian population. METHODS: This was a retrospective cross-sectional study of malignant odontogenic tumours diagnosed at the Institute for Medical Research, Malaysia, from 2009 to 2019. All cases were independently reviewed and reclassified following the criteria set out in the latest edition of the World Health Organization 2017 reference text. Demographic and clinico-pathological data were recorded for each case. RESULTS: Twenty-four cases of malignant odontogenic tumours were identified. The patients' age ranged from 16 to 79 years with the mean age at diagnosis being 50.8 years (SD = 16.18). There was a male predominance (66.7%) in this cohort of patients. The ethnic distribution appeared to reflect the Malaysian population with most cases seen amongst the Malay ethnic group (66.7%). Ameloblastic carcinoma was the most frequently diagnosed malignant odontogenic tumour (45.8%) and was also predominantly seen in males (90.9%). All patients with clear cell odontogenic carcinoma were females. There was no obvious sex predilection in primary odontogenic carcinoma not otherwise specified (NOS). The mandible (79.2%) was more frequently involved compared to the maxilla. CONCLUSIONS: Diagnosis and management of malignant odontogenic tumours are challenging due to the rarity of these tumours. Our study has elucidated the clinico-pathological features of malignant odontogenic tumours seen in a multi-ethnic Asian population.

An international collaborative study of 105 new cases of adenomatoid odontogenic tumors.

OBJECTIVE: The aim of this study was to report the clinicopathologic features of 105 new cases of adenomatoid odontogenic tumor (AOT) from Brazil, Guatemala, Mexico, and South Africa. STUDY DESIGN: Clinical and radiographic data were collected from records of 5 oral pathology laboratories, and all cases were microscopically reviewed. RESULTS: This series of cases included 36 (34.2%) from South Africa; 33 (31.4%) from Brazil; 23 (21.9%) from Mexico; and 13 (12.3%) from Guatemala. Seventy-two patients (68.5%) were females and 33 patients (31.4%) were males, with an average age of 19.2 years. The tumors predominantly affected the anterior maxilla (48.5%), followed by the anterior mandible (29.5%); posterior mandible (15.2%); and posterior maxilla (6.6%). Sixty-three tumors (63.6%) were follicular, 34 (34.3%) were extrafollicular, and 2 (2%) were peripheral. In most cases, the tumors caused considerable cortical expansion (average size 3.4 cm). Microscopically, most cases showed rosette-like and duct-like structures. CONCLUSIONS: This is one of the largest case series of AOTs reported in the literature and the first multicenter study involving populations from Latin America and South Africa. In a fifth of the present cases, the posterior regions of the gnathic bones were affected and the tumors demonstrated larger sizes compared with cases occurring in other populations.

Descriptive Epidemiology of Odontogenic Tumors in Nigeria: An African Oral Pathology Research Consortium Multicenter Study.

BACKGROUND: Many studies have investigated the burden of odontogenic tumor (OT) in Nigeria; however, the true burden and prevalence of these lesions are not known because these studies are based on a center/region. AIMS: Hence, the aim of this study is to evaluate the true burden of OTs in Nigeria, using a multicenter approach. MATERIALS AND METHODS: This is a 10-year retrospective cross-sectional study of OT seen in eight tertiary health institutions in different geographic locations in Nigeria. RESULTS: A total of 990 cases were included in this study. The highest prevalence of OT was in the third decade of life (n = 274, 27.7%). Most lesions were benign (n = 961, 97.1%), with a slight male preponderance; and the mandible was the commonest site (n = 814, 82.2%). There were a significant association between the diagnosed OTs and the age group and site (P = 0.002 and 0.031, respectively). CONCLUSION: OTs showed a slightly higher preponderance in males, occurring mostly in the third decade. Benign lesions were frequent and ameloblastoma was the commonest OT. Variations exist in the occurrence of OTs from the different geographic locations in Nigeria. This study essentially sheds a broader light on the clinicopathological distribution of OTs across Nigeria, using a large multicenter approach.

New World Health Organization classification of odontogenic tumours: impact on the prevalence of odontogenic tumours and analysis of 1231 cases from Turkey.

The aims of this study were to describe the frequency of odontogenic tumours (OT) based on the World Health Organization (WHO) 4th edition of Head and Neck Tumours in Turkey, to compare the results with other regions and to assess the frequency changes of OT worldwide after the new WHO classification. OT were selected from the pathology department's files between 1971-2018. In a total of 1231 OT, 1215 (98.7%) were benign, whereas malignant OT were only 16 cases (1.3%). The three most common tumours were ameloblastoma (n=366, 29.7%), odontoma (n=335, 27.2% both complex and compound types), and odontogenic myxoma (n=190, 15.4%), respectively. After the 2017 classification, the decrease of OT frequency was found among 20%-42% in the selected epidemiological series because of re-classification of some lesions. The pattern of incidence in the Turkish population is similar to that in other populations. However, there are some differences in the frequency of the tumour types. It is obvious that the relative frequency of odontogenic tumours worldwide will change based on the new classification. It should be kept in mind that this is not a real decrease of OT cases. These marked changes in the frequency and prevalence of OT is just related to reclassification of some entities.