Fibroblast Programmed Cell Death Ligand 1 Promotes Osteoclastogenesis in Odontogenic Keratocysts.

Local aggressive growth of odontogenic keratocysts (OKCs) can cause serious bone destruction, even resulting in pathologic fractures of the mandible. The mechanism of osteoclastogenesis in OKCs was explored by investigating the role of programmed cell death ligand 1 (PD-L1), a key immune checkpoint, in OKCs and its relationship with the M2 isoform of pyruvate kinase (PKM2), a key enzyme of glycolysis. The data from immunohistochemistry, real-time quantitative PCR, Western blot, and flow cytometry indicated that the expression level of PD-L1 was significantly increased in the stroma and fibroblasts of OKCs (OKC-Fs) when compared with oral mucosa. Double-labeling staining demonstrated that osteoclasts in OKCs spatially interacted with PD-L1-positive OKC-Fs. Exogenous expression of PD-L1 in OKC-Fs promoted osteoclastogenesis when OKC-Fs were co-cultured with osteoclast precursors (RAW264.7 cells). Because OKC-Fs exhibit energy dependency and acquire energy from PKM2-mediated glycolysis, this study generated stable PKM2 knockdown OKC-Fs using shRNAs against PKM2, and found that PD-L1 expression level was decreased by PKM2 knockdown. Furthermore, Spearman rank correlation analysis showed that there was a positive correlation between the immunostaining of PKM2 and PD-L1 in OKC samples. In addition, double-labeling immunofluorescence showed colocalizations between PKM2 and PD-L1 in the fibrous tissue walls of OKCs. In conclusion, PD-L1 in fibroblasts promotes osteoclastogenesis in OKCs, which is regulated by PKM2.

The IL-1ß-p65 axis stimulates quiescent odontogenic epithelial cell rests via TGF-ß signalling to promote cell proliferation of the lining epithelia in radicular cysts: A laboratory investigation.

AIM: Cyst formation of the jaws is frequently accompanied by the proliferation of odontogenic epithelial cells located in the periodontal ligament (PDL), which consists of heterozygous cells and includes the most fibroblasts. The lining epithelium of radicular cyst, an odontogenic cyst of inflammatory origin, is derived from the proliferation of the remnants of the Hertwig epithelial root sheath (odontogenic epithelial cell rests of Malassez; ERMs) in the PDL. ERMs are maintained at a lower proliferative state under physiological conditions, but the regulatory mechanisms underlying the inflammation-dependent enhanced-proliferative capabilities of ERMs are not fully understood. The aim of this study was to evaluate the effects of cytokine pathway association between TGF-ß signalling and IL-1ß signalling on the regulation of odontogenic epithelial cell proliferation using radicular cyst pathological specimens and odontogenic epithelial cell lines. METHODOLOGY: Immunofluorescence analyses were performed to clarify the expression levels of Smad2/3 and Ki-67 in ERMs of 8-week-old mouse molar specimens. In radicular cyst (n = 52) and dentigerous cysts (n = 6) specimens from human patients, the expression of p65 (a main subunit of NF-κB), Smad2/3 and Ki-67 were investigated using immunohistochemical analyses. Odontogenic epithelial cells and PDL fibroblastic cells were co-cultured with or without an inhibitor or siRNAs. Odontogenic epithelial cells were cultured with or without TGF-ß1 and IL-1ß. The proliferative capabilities and Smad2 phosphorylation levels of odontogenic epithelial cells were examined. RESULTS: Immunohistochemically, Smad2/3-positivity was increased, and p65-positivity and Ki-67-positivity were decreased both in ERMs and in the epithelial cells in dentigerous cysts, a non-inflammatory developmental cyst. In contrast, p65-positive cells, along with the expression of Ki-67, were increased and Smad2/3-positive cells were decreased in the lining epithelia of radicular cysts. Co-culture experiments with odontogenic epithelial cells and PDL fibroblastic cells revealed that PDL cells-derived TGF-ß1/2 and their downstream signalling suppressed odontogenic epithelial cell proliferation. Moreover, TGF-ß1 stimulation induced Smad2 phosphorylation and suppressed odontogenic epithelial cell proliferation, while IL-1ß stimulation reversed these phenotypes through p65 transactivation. CONCLUSIONS: These results suggest that IL-1ß-p65 signalling promotes odontogenic epithelial cell proliferation through suppressing TGF-ß-Smad2 signalling, which would be involved in the pathogenesis of radicular cysts.

In Silico Analysis of Genes Associated with the Pathogenesis of Odontogenic Keratocyst.

Odontogenic keratocyst (OK) is a benign intraosseous cystic lesion characterized by a parakeratinized stratified squamous epithelial lining with palisade basal cells. It represents 10-12% of odontogenic cysts. The changes in its classification as a tumor or cyst have increased interest in its pathogenesis. OBJECTIVE: Identify key genes in the pathogenesis of sporadic OK through in silico analysis. MATERIALS AND METHODS: The GSE38494 technical sheet on OK was analyzed using GEOR2. Their functional and canonical signaling pathways were enriched in the NIH-DAVID bioinformatic platform. The protein-protein interaction network was constructed by STRING and analyzed with Cytoscape-MCODE software v 3.8.2 (score > 4). Post-enrichment analysis was performed by Cytoscape-ClueGO. RESULTS: A total of 768 differentially expressed genes (DEG) with a fold change (FC) greater than 2 and 469 DEG with an FC less than 2 were identified. In the post-enrichment analysis of upregulated genes, significance was observed in criteria related to the organization of the extracellular matrix, collagen fibers, and endodermal differentiation, while the downregulated genes were related to defensive response mechanisms against viruses and interferon-gamma activation. CONCLUSIONS: Our in silico analysis showed a significant relationship with mechanisms of extracellular matrix organization, interferon-gamma activation, and response to viral infections, which must be validated through molecular assays.

Immunohistochemical expression of SPARC in odontogenic keratocysts: a comparative study with other odontogenic cysts.

BACKGROUND: Secreted protein acidic and rich in cysteine (SPARC) has been shown to modulate aggressive behavior in several benign and malignant tumors. Little is known about SPARC expression in odontogenic keratocyst (OKC), an odontogenic cyst with an aggressive nature. To the best of our knowledge, only one study has been investigated the expression of this protein in OKCs. This study aimed to characterize SPARC expression in OKCs. Additionally, to determine whether SPARC is associated with aggressive behavior in OKCs, SPARC expression in OKCs was compared with radicular cysts (RCs), dentigerous cysts (DCs) and calcifying odontogenic cysts (COCs). These odontogenic cysts showed no or less aggressive behavior. METHODS: SPARC expression was evaluated in 38 OKCs, 39 RCs, 35 DCs and 14 COCs using immunohistochemistry. The percentages of positive cells and the intensities of immunostaining in the epithelial lining and the cystic wall were evaluated and scored. RESULTS: Generally, OKCs showed similar staining patterns to RCs, DCs and COCs. In the epithelial lining, SPARC was not detected, except for ghost cells in all COCs. In the cystic wall, the majority of positive cells were fibroblasts. Compared between 4 groups of odontogenic cysts, SPARC expression in OKCs was significantly higher than those of RCs (P < 0.001), DCs (P < 0.001) and COCs (P = 0.001). CONCLUSIONS: A significant increase of SPARC expression in OKCs compared with RCs, DCs and COCs suggests that SPARC may play a role in the aggressive behavior of OKCs.

[Three-dimensional radiographic features of calcifying odontogenic cyst and calcifying epithelial odontogenic tumor].

OBJECTIVE: To analyze the three-dimensional radiographic characteristics of calcifying odontogenic cyst and calcifying epithelial odontogenic tumor using spiral computed tomography (CT) and cone-beam computed tomography (CBCT). METHODS: Clinical records, histopathological reports, and CBCT or non-enhanced spiral CT images of 19 consecutive patients with calcifying odontogenic cyst (COC) and 16 consecutive patients with calcifying epithelial odontogenic tumor (CEOT) were retrospectively acquired, and radiographic features, including location, size, expansion, internal structure and calcification, were analyzed. RESULTS: Among the 19 COC cases (12 males and 7 females, with an average age of 27 years), 89.5% (17/19) of the lesions originated from the anterior and premolar areas, 100.0% of them exhibited cortex expansion, and 78.9% had discontinued cortex. Among the 16 CEOT cases (3 males and 13 females, with an average age of 36 years), 81.3% (13/16) of the lesions were in the premolar and molar areas, 56.3% of them exhibited cortex expansion, and 96.8% had discontinued cortex. According to the distribution of internal calcifications, these lesions were divided into: Ⅰ (non-calcification type): absence of calcification; Ⅱ (eccentric marginal type): multiple calcifications scattered along one side of the lesion; Ⅲ (diffused type): numerous calcifications diffusely distributed into the lesion; Ⅳ (plaque type): with a ≥ 5 mm calcified patch; Ⅴ (peri-coronal type): multiple calcifications clustered around impacted teeth. Calcifications were present in 73.7% of COC lesions, including 9 type Ⅱ, 3 type Ⅲ and 2 type Ⅳ lesions, and 42.8% of CEOT lesions had calcification images, including 2 type Ⅲ and 5 type Ⅴ lesions. Six COC lesions had odontoma-like images. Moreover, 8 of 9 type Ⅰ CEOTs were histologically Langerhans cell-rich subtype, which had a smaller size (with an average mesiodistal diameter of 17.8 mm) and were not associated with impacted teeth. CONCLUSION: COC lesions tended to originate from the anterior part of the jaw and exhibit cortex expansion, and were sometimes associated with odontoma. CEOT commonly occurred in the posterior jaw and had discontinued cortex. Two lesions had significantly different calcification map. Over 70% of COC lesions had calcification images, which were mostly scattered along one side of the cysts, far from the impacted teeth. Approximately 60% of CEOT lesions exhibited smaller size and non-calcification, and the remaining CEOT cases often had calcification images clustered around the impacted teeth.

Orofacial Cysts: A Single Institution Experience of 85 Cases in Enugu, Nigeria.

BACKGROUND: Orofacial cysts are pathologic cavities that could be symptomatic and may cause facial disfigurement. The only epidemiologic report of such lesions in Southeast Nigeria studied jaw cysts from 1987 to 1996. New studies reflecting recent research findings and classifications on the subject in Southeast Nigeria are lacking. AIM: To determine the prevalence and distribution of orofacial cysts in a tertiary hospital in Enugu, Southeast Nigeria. METHODS: A 10-year retrospective study of patients with orofacial cysts diagnosed by histology was carried out. RESULTS: Orofacial cysts constitute 9.5% (85) of 897 orofacial lesions identified. The male-to-female gender ratio was 1.2:1. The mean age (± standard deviation) at the onset of the cystic lesion was 28.58 (±16.98) years. Developmental odontogenic cysts 52.9% (45) and salivary cysts 18.8% (16) were the most common group of orofacial cysts. The most prevalent orofacial cysts were odontogenic keratocysts at 25.9% (22), mucoceles 16.5% (14), and dentigerous cysts 14.1% (12). Straw-colored aspirates 34.8% (16) and dark brown aspirates 28.3% (13) were the predominant cystic contents. The mandible 45.9% (39) and maxilla 27.1% (23) were the commonest sites for orofacial cysts, while the lip 9.4% (8) was the most frequent soft tissue site. A significant association exists between anatomical site and cyst type at a 95% confidence interval with P = 0.000, X2 = 247.17. Unilocular radiolucency 62.5% (20) and multilocular radiolucency 34.4% (11) were the most common radiographic features. CONCLUSION: Developmental odontogenic cysts particularly odontogenic keratocysts were most prevalent while mucocele was the most common soft tissue cyst.

Significance of EGFR investigation in odontogenic keratocyst: a narrative review.

BACKGROUND: The recent classification of odontogenic keratocysts (OKSs) recognized them as benign neoplasms, although previous findings have revealed their aggressive nature. Immunohistochemical and molecular analyses have investigated OKSs, but the role of epidermal growth factor receptor (EGFR) has not been fully investigated, despite the importance of this oncogene in the process of carcinogenesis in tumors of epithelial origin. The EGFR protein is usually overexpressed, and the EGFR gene is mutated or amplified. AIMS OF STUDY: This brief review aims to emphasize the importance of EGFR detection in these types of cysts. METHODS AND RESULTS: It was revealed that the majority of the studies examined EGFR protein expression using immunohistochemical methods; however, considering EGFR gene variants, mutations were less explored in the previous period from 1992 to 2023. Although EGFR gene polymorphisms are clinically important, they were not identified in the present study. CONCLUSIONS: In light of the current significance of EGFR variants, it would be beneficial to examine them in odontogenic lesions. This would enable resolving of discrepancies about their nature, and potentially enhance classifications OKCs in the future.

Comprehensive cornified envelope protein profile of odontogenic keratocysts clarifies the characteristics of non-keratinized oral epithelium.

BACKGROUND: Odontogenic keratocysts constitute 10%-20% of odontogenic cysts and exhibit a distinctive corrugated parakeratinized lining epithelium. Considering that cornified envelope formation is an important phenomenon during keratinocyte differentiation, this study aimed to clarify the characteristics of cornified envelope formation in odontogenic keratocysts. METHODS: We investigated the cellular distribution of cornified envelope-related proteins (transglutaminases and their substrates), as well as the upstream regulatory protein c-Fos, by immunohistochemical analysis of the lining epithelium of 20 odontogenic keratocysts. We examined the corresponding mRNA levels by quantitative polymerase chain reaction. Ten dentigerous cysts served as control non-keratinized cysts. RESULTS: The distributions of transglutaminase and their substrates except loricrin and small protein-rich protein 1a significantly differed between odontogenic keratocysts and dentigerous cysts. There was no significant difference in c-Fos expression between odontogenic keratocysts and dentigerous cysts. The mRNA levels of transglutaminases and their substrates were significantly higher in odontogenic keratocysts than in dentigerous cysts. However, c-Fos mRNA levels did not significantly differ between groups. CONCLUSION: Surprisingly, the overall appearance of cornified envelope-related proteins of odontogenic keratocysts was consistent with the characteristics of non-keratinized oral mucosa identified in previous studies. These findings indicate that the contribution of cornified envelope-related molecules in odontogenic keratocysts is similar to that in non-keratinized oral epithelium, rather than keratinized oral epithelium, suggesting that odontogenic keratocysts are not genuine keratinized cysts. The upregulation of cornified envelope-related genes in odontogenic epithelium could be an important pathognomonic event during odontogenic keratocyst development.

Differential expression of PEA3 in odontogenic cysts and tumors.

BACKGROUND: PEA3 transcription factor has been identified as a downstream target of the MAPK and PI3K pathways, and PEA3 overexpression has been observed in a variety of tumor types. We aimed to evaluate PEA3 expression in odontogenic cysts and tumors and compare the expression among odontogenic lesions. In addition, the correlations between PEA3 expression and clinicopathological characteristics of conventional ameloblastoma and unicystic ameloblastoma were investigated. METHODS: This study was performed on 165 samples of odontogenic cysts and tumors including 20 dentigerous cysts, 20 odontogenic keratocysts, 16 adenomatoid odontogenic tumors, 5 ameloblastic fibromas, 45 unicystic ameloblastomas, and 59 conventional ameloblastomas. The sections were immunohistochemically stained with mouse monoclonal anti-PEA3 antibody and PEA3 expression was evaluated as the immunoreactive score. RESULTS: PEA3 expression was absent in all dentigerous cysts (DCs) and odontogenic keratocysts, while all adenomatoid odontogenic tumors showed either no (75%) or low (25%) expression of PEA3. Most of the ameloblastic fibromas (60%) displayed no PEA3 expression. A high expression of PEA3 was observed in a substantial number of unicystic ameloblastomas (48.9%) and conventional ameloblastomas (49.2%) in our study. PEA3 expression in DCs, odontogenic keratocysts and adenomatoid odontogenic tumors were significantly different from that in conventional ameloblastomas and that in unicystic ameloblastomas (p < 0.05). The expression of PEA3 was significantly different in the age groups of unicystic ameloblastomas and histological subtypes of conventional ameloblastomas (p < 0.05). CONCLUSION: PEA3 overexpression is predominant in unicystic ameloblastomas and conventional ameloblastomas compared to other odontogenic lesions, indicating a pivotal role of PEA3 as a downstream effector of MAPK pathway in these two odontogenic lesions.

The molecular basis of odontogenic cysts and tumours.

The advances in molecular technologies have allowed a better understanding of the molecular basis of odontogenic cysts and tumours. PTCH1 mutations have been reported in a high proportion of odontogenic keratocyst. BRAF p.V600E are recurrent in ameloblastoma and KRAS p.G12V/R in adenomatoid odontogenic tumour, dysregulating the MAPK/ERK pathway. Notably, BRAF p.V600E is also detected in ameloblastic carcinoma, but at a lower frequency than in its benign counterpart ameloblastoma. Recently, adenoid ameloblastoma has been shown to be BRAF wild-type and to harbour CTNNB1 (ß-catenin gene) mutations, further suggesting that it is not an ameloblastoma subtype. CTNNB1 mutations also occur in other ghost-cell-containing tumours, including calcifying odontogenic cysts, dentinogenic ghost cell tumours and odontogenic carcinoma with dentinoid, but the link between CTNNB1 mutations and ghost cell formation in these lesions remains unclear. Regarding mixed tumours, BRAF p.V600E has been reported in a subset of ameloblastic fibromas, ameloblastic-fibrodentinomas and fibro-odontomas, in addition to ameloblastic fibrosarcoma. Such mutation-positivity in a subset of samples can be helpful in differentiating some of these lesions from odontoma, which is BRAF-wild-type. Recently, FOS rearrangements have been reported in cementoblastoma, supporting its relationship with osteoblastoma. Collectively, the identification of recurrent mutations in these aforementioned lesions has helped to clarify their molecular basis and to better understand the interrelationships between some tumours, but none of these genetic abnormalities is diagnostic. Since the functional effect of pathogenic mutations is context and tissue-dependent, a clear role for the reported mutations in odontogenic cysts and tumours in their pathogenesis remains to be elucidated.

Pediatric Oral Pathology: Odontogenic Cysts.

Cysts encountered in the head and neck typically arise from epithelium that would normally be programmed to form teeth or tooth-supporting structures (odontogenic epithelium). These cysts come with a confusing array of similar-sounding names and histopathologic features that are sometimes shared between conditions. Here we describe and contrast the relatively-common lesions: hyperplastic dental follicle, dentigerous cyst, radicular cyst, buccal bifurcation cyst, odontogenic keratocyst, glandular odontogenic cyst, and the less-common gingival cyst of the new-born and thyroglossal duct cyst. The goal of this review is to help clarify and simplify these lesions for the general pathologist, pediatric pathologist, and surgeon.

Histopathological and histomorphometric analysis of glandular odontogenic cyst-A diagnostic aid.

OBJECTIVES: Compare recognized microscopic parameters, including variations in width, plaque-like thickenings, intra-epithelial microcysts, clefts, mucous, hob-nail, ciliated and clear cells, between glandular odontogenic cyst (GOC) and GOC-like cysts, investigate the extent of cyst circumference exhibiting these features, and inflammation. MATERIALS AND METHODS: Archival records of cysts with histological features of GOC evaluated between 2000 and2020 were retrieved. Slides were revised, and the expression of features throughout the cyst wall was analyzed. Cysts with at least 5 features were classified as GOC, cysts with 3-4 features as GOC-like. RESULTS: The study included 74 cysts, 47 males M, 25 females (2 unknown gender), aged 19-81 years, 62 (83.8%) GOC, 12 (16.2%) GOC-like. Mandible was involved in 44 (59.5%), maxilla in 30 (40.5%), 18 (25%) were associated with unerupted teeth. Cyst classified as GOC had significantly higher rates of all parameters investigated, (except ciliated and clear cells), than GOC-like cysts (p ≤ 0.05). 26 (40.6%) cases showed GOC features in >50% of cyst circumference, 21 (32.8%) involved 25-50%, 17 (26.6%) <25%. More than 50% circumference involvement was highly and independently predictive for a diagnosis of GOC, <25% was highly and independently predictive for GOC-like (p = 0.003). Hobnail cells (p = 0.008) and plaque-like thickenings (p = 0.038) were significantly more frequent in inflamed cysts. CONCLUSION: Besides the number and type of histological features, GOC can be characterized by their distribution within the cyst circumference (focal Vs diffuse), and it may serve as a new diagnostic aid. It is suggested that GOC and GOC-like may represent a single spectrum.

Refined Topical 5-Fluorouracil Technique for the Targeted Treatment of Odontogenic Keratocysts.

PURPOSE: An innovation in the treatment of odontogenic keratocysts (OKCs) is the adjunctive application of 5-fluorouracil (5-FU). Although the original approach remains effective, it may often be a challenge for the patient to return postoperatively and/or tolerate non-resorbable packing removal. The purpose of the present study is to determine whether our refined approach, where we directly apply 5-FU-coated absorbable gelatin sponge to the surgical cavity, would be an effective treatment for OKCs with similar efficacy as with our original approach. MATERIALS AND METHODS: A retrospective case series studying the treatment efficacy of our refined topical 5-FU approach on OKCs was reviewed. The study population was composed of all patients presenting for evaluation and management of OKCs with our refined technique between September 1, 2017 and July 1, 2022 at Stony Brook University Hospital. The primary outcomes included 1) time to OKC recurrence, and 2) incidence of trigeminal nerve injury following OKC treatment with the refined topical 5% 5-FU technique. Other study variables included age, gender, tumor location, and tumor size. Data analyses included descriptive statistics reported as median [interquartile range], and Kaplan-Meier survival analysis for time to OKC recurrence. RESULTS: Thirteen patients with 15 OKCs were reviewed (6 women and 7 men). There were no OKC recurrences with a median follow-up time of 28.5 (24) months. Normal bony healing was observed in all cases and there were no adverse local or systemic events, no alterations in sinus function, and no incidences of infraorbital or inferior alveolar nerve paresthesia. CONCLUSIONS: Our case series demonstrates that this refinement further increases technical ease, decreases operating time, and precludes the need for packing removal, with similar efficacy as the original approach.

Sociodemographic and clinical characterization of cases of 1,103 non-syndromic and 66 syndromic odontogenic keratocyst: a Brazilian multicenter study.

OBJECTIVES: This multicenter study aimed to evaluate cases of non-syndrome and syndromic odontogenic keratocyst, as well as cases of recurrence within these two groups. METHODS: This descriptive, analytical, retrospective cross-sectional study evaluated the sex, age and presence of multiple lesions in 1,169 individuals seen at 10 Brazilian oral and maxillofacial pathology centers. Of these, 1,341 odontogenic keratocysts were analyzed regarding clinical diagnosis, size, site, imaging appearance, signs and symptoms, type of biopsy, treatment, and recurrence. RESULTS: There was a similar distribution by sex. The median age of non-syndromic and syndromic patients was 32 and 17.5 years, respectively. The posterior mandible was the site most affected by small and large lesions in both groups and in recurrent cases. Unilocular lesions were more frequent, also in recurrent cases. Mainly small lesions showed this imaging appearance. Signs and symptoms were absent in most cases. Conservative treatment was the most frequent modality in all age groups, regardless of the patient's condition and recurrence. Recurrences were uncommon. CONCLUSION: This study showed a higher frequency of non-syndromic keratocysts in the population. Clinicopathological features related to the involvement of multiple sites, age, and recurrence may differ between syndromic and non-syndromic cases. Furthermore, we found an association between lesion size and some clinical features and between the time interval to recurrence and the syndromic spectrum. CLINICAL RELEVANCE: To contribute to a better understanding of the distribution and association between clinical, imaging, and sociodemographic characteristics in each spectrum of the lesion.

Detection and Segmentation of Radiolucent Lesions in the Lower Jaw on Panoramic Radiographs Using Deep Neural Networks.

Background and Objectives: The purpose of this study was to develop and evaluate a deep learning model capable of autonomously detecting and segmenting radiolucent lesions in the lower jaw by utilizing You Only Look Once (YOLO) v8. Materials and Methods: This study involved the analysis of 226 lesions present in panoramic radiographs captured between 2013 and 2023 at the Clinical Hospital Dubrava and the School of Dental Medicine, University of Zagreb. Panoramic radiographs included radiolucent lesions such as radicular cysts, ameloblastomas, odontogenic keratocysts (OKC), dentigerous cysts and residual cysts. To enhance the database, we applied techniques such as translation, scaling, rotation, horizontal flipping and mosaic effects. We have employed the deep neural network to tackle our detection and segmentation objectives. Also, to improve our model's generalization capabilities, we conducted five-fold cross-validation. The assessment of the model's performance was carried out through metrics like Intersection over Union (IoU), precision, recall and mean average precision (mAP)@50 and mAP@50-95. Results: In the detection task, the precision, recall, mAP@50 and mAP@50-95 scores without augmentation were recorded at 91.8%, 57.1%, 75.8% and 47.3%, while, with augmentation, were 95.2%, 94.4%, 97.5% and 68.7%, respectively. Similarly, in the segmentation task, the precision, recall, mAP@50 and mAP@50-95 values achieved without augmentation were 76%, 75.5%, 75.1% and 48.3%, respectively. Augmentation techniques led to an improvement of these scores to 100%, 94.5%, 96.6% and 72.2%. Conclusions: Our study confirmed that the model developed using the advanced YOLOv8 has the remarkable capability to automatically detect and segment radiolucent lesions in the mandible. With its continual evolution and integration into various medical fields, the deep learning model holds the potential to revolutionize patient care.

[Basal cell nevus syndrome: the interface between dentistry and dermatology]. / Het basaalcelnaevussyndroom: raakvlak tussen tandheelkunde en dermatologie.

Basal cell nevus syndrome is a rare, autosomal dominant disorder, predominantly caused by a mutation in the PTCH1 gene. As basal cell carcinomas and keratocysts are the most common abnormalities, dermatologists, orofacial maxillary surgeons, and dentists play a key role in patient care. From the age of 8, screening for odontogenic keratocysts with an orthopantomogram or MRI is recommended every other year. The intensity increases to annual screening after the development of the first odontogenic keratocyst. If BCNS is caused by an underlying SUFU mutation, screening is not indicated since there are no reports of odontogenic keratocyst in these patients to date. Radiation exposure by, for example, computed tomography, should be minimized as it induces new BCCs. Regular follow-up by a dermatologist for early diagnosis and treatment of (multiple) BCC's is recommended for life.

Increased M2 Isoform of Pyruvate Kinase in Fibroblasts Contributes to the Growth, Aggressiveness, and Osteoclastogenesis of Odontogenic Keratocysts.

To investigate the role of glycolysis and the M2 isoform of pyruvate kinase (PKM2) in odontogenic keratocysts (OKCs), the glycolytic flux of primary odontogenic keratocyst fibroblasts (OKC-Fs) and normal oral mucosa fibroblasts (OM-Fs) was determined by glucose uptake, lactate production, and cell proliferation assays. Wound healing assay and Matrigel-coated chamber system were used to investigate the effects of PKM2 on migration and invasion capacities of OKC-Fs. Co-culture of OKC-Fs with osteoclast precursors (RAW264.7 cells) was used to clarify the role of glycolysis in the osteoclastogenic effects of OKC-Fs. In addition, hypoxia-inducible factor 1α and some key enzymes related to glycolysis, including PKM2, 6-phosphofructo-2-kinase/fructose-2, 6-biphosphatase 3, hexokinase 2, and lactate dehydrogenase A, were detected to assess the activation of glycolysis in OKC stroma by immunohistochemistry. Results showed that the glucose uptake and lactate production were significantly higher in OKC-Fs than OM-Fs. PKM2 was elevated in OKC-Fs compared with that in OM-Fs. PKM2 significantly regulated glycolysis, proliferation, migration, invasion, and osteoclastogenic effects of OKC-Fs. Additionally hypoxia-inducible factor 1α, 6-phosphofructo-2-kinase/fructose-2, 6-biphosphatase 3, hexokinase 2, and lactate dehydrogenase A were markedly overexpressed in OKC stroma, and correlated with PKM2. Moreover, the expression of PKM2 was regulated by oxygen concentration in vitro. In sum, PKM2-mediated glycolysis regulated the growth, aggressiveness, and osteoclastogenesis of OKC.

Glandular odontogenic cysts: A collaborative investigation of 22 cases and proteins related to invasiveness.

BACKGROUND: A glandular odontogenic cyst (GOC) has an intriguing, aggressive behaviour whose mechanisms have not yet been clarified. OBJECTIVE: To conduct a collaborative cross-sectional study on the clinical, demographic, microscopic and immunohistochemical characteristics of GOCs, emphasizing the histopathological characteristics and expression of proteins related to invasiveness. METHODS: Twenty-two cases of GOC from three oral and maxillofacial pathology services in Brazil were selected from 1988 to 2018. Clinical and demographic data were collected. Histopathological features were evaluated in detail. Sixteen cases of GOC were also submitted to immunohistochemistry to detect MT1-MMP, TKS4, TKS5 and cortactin, the key regulators of invadopodia formation. RESULTS: Glandular odontogenic cysts were primarily seen in men over 40 years of age, in the posterior mandible and the anterior maxilla as a unilocular, radiolucent lesion. All cases presented hobnail cells, clear cells and variable thickness of the lining epithelium, 3 of the 10 key histopathological parameters to be evaluated in GOCs. Immunohistochemistry revealed a greater expression of the studied proteins in the GOCs than in the controls (p < 0.0001). CONCLUSION: Overexpression of proteins that regulate cell invasiveness was identified, and the present study's findings suggest that invadopodia activity is a possible mechanism used by GOCs to promote local invasion, which could partly explain its intriguing biological behaviour.

Orthokeratinized odontogenic cysts: A clinicopathologic study of 159 cases and molecular evidence for the absence of PTCH1 mutations.

BACKGROUND: Orthokeratinized odontogenic cyst (OOC), a newly designated entity of odontogenic cysts, is an intraosseous jaw cyst that is entirely or predominantly lined by orthokeratinized squamous epithelium. The aim of this study was to report a large series of OOC to substantiate its clinicopathologic profiles and to investigate PTCH1 mutations in OOCs. METHOD: The clinicopathologic features of 167 OOCs from 159 patients were analyzed and the immunohistochemical expression of markers related to cell differentiation and proliferation was evaluated. Furthermore, PTCH1 mutations were analyzed in 14 fresh samples of OOC. RESULTS: OOCs occurred mostly in the third and fourth decades (60.4%) with a male predilection (66.7%). The lesions developed more often in the mandible than maxilla, primarily in the posterior mandible and ramus. Eight patients (5.0%) showed multiple locations of either bilateral posterior mandible (n = 6) or both the maxilla and mandible. Radiographically, the majority of OOCs (91.2%) showed a well-demarcated, unilocular radiolucency with 14 multilocular cases (8.8%). A follow-up of 131 patients (123 treated by enucleation with or without marsupialization and eight by peripheral ostectomy) revealed no recurrence during an average period of 4.56 years after surgery. Immunohistochemistry indicated lower proliferative activity and a varying epithelial differentiation pattern in OOC compared with odontogenic keratocysts (OKC). No PTCH1 mutation was detected, except for three known single nucleotide polymorphisms. CONCLUSION: The clinicopathological and molecular differences between OOC and OKC justified their separation, and unlike OKCs, OOCs did not harbor PTCH1 mutations, suggesting different pathogenesis underlying these two jaw cysts.

Decoding a gene expression program that accompanies the phenotype of sporadic and basal cell nevus syndrome-associated odontogenic keratocyst.

BACKGROUND: Odontogenic keratocyst is characterized by local aggressive behavior and a high recurrence rate, as well as its potential to develop in association with the basal cell nevus syndrome. The aim of this study was to decode the gene expression program accompanying odontogenic keratocyst phenotype. METHODS: 150-bp paired-end RNA-sequencing was applied on six sporadic and six basal cell nevus syndrome-associated whole-tissue odontogenic keratocyst samples in comparison to six dental follicles, coupled with bioinformatics and complemented by immunohistochemistry. RESULTS: 2654 and 2427 differentially expressed genes were captured to characterize the transcriptome of sporadic and basal cell nevus syndrome-associated odontogenic keratocysts, respectively. Gene ontologies related to "epidermis/skin development" and "keratinocyte/epidermal cell differentiation" were enriched among the upregulated genes (KRT10, NCCRP1, TP63, GRHL3, SOX21), while "extracellular matrix organization" (ITGA5, LOXL2) and "odontogenesis" (MSX1, LHX8) gene ontologies were overrepresented among the downregulated genes in odontogenic keratocyst. Interestingly, upregulation of various embryonic stem cells markers (EPHA1, SCNN1A) and genes committed in cellular reprogramming (SOX2, KLF4, OVOL1, IRF6, TACSTD2, CDH1) was found in odontogenic keratocyst. These findings were highly shared between sporadic and basal cell nevus syndrome-associated odontogenic keratocysts. Immunohistochemistry verified SOX2, KLF4, OVOL1, IRF6, TACSTD2/TROP2, CDH1/E-cadherin, and p63 expression predominantly in the odontogenic keratocyst suprabasal epithelial layers. CONCLUSION: The odontogenic keratocyst transcriptomic profile is characterized by a prominent epidermal and dental epithelial fate, a repressed dental mesenchyme fate combined with deregulated extracellular matrix organization, and enhanced stemness gene signatures. Thus, we propose a developed epidermis-like phenotype in the odontogenic keratocyst suprabasal epithelial cells, established in parallel to a significant upregulation of marker genes related to embryonic stem cells and cellular reprogramming.