IntroductionΤo describe the clinicopathological features of 26 oral lymphoepithelial cysts (LECs) and review the literature.Material and MethodsTwenty-six cases of oral LECs diagnosed during a 37-year period were retrospectively collected. The patients’ gender and age, as well as the main clinical features of the cysts were retrieved from the requisition forms. The main microscopic features were recorded after reevaluation of all cases. Pubmed and Google Scholar electronic databases were searched with the key word “oral LEC”. Inclusion criteria were the microscopic confirmation of LEC diagnosis and the report at least two of three main clinical features (gender, age and cyst’s location).ResultsThe 26 oral LECs represented 0.08% of 31,564 biopsies accessioned during the study period. They affected 25 patients, 14 females and 11 males with a mean age of 33.04±9.81 years. They appeared as smooth (92%) nodules, with soft (24%) or firm (76%) consistency and normal (28%), yellow to normal (20%), yellow (32%) or white (20%) hue, in the tongue (69.23%) or the floor of mouth (30.77%). They were covered by parakeratinized squamous (92.31%) or non-keratinized (7.69%) epithelium and contained desquamated epithelial cells, amorphous eosinophilic material and/or inflammatory cells (100%). The lymphoid tissue surrounded the cystic cavity partially (34.62%) or completely (65.38%), often in a follicular pattern with prominent germinal centers (53.85%). Literature review yielded 316 cases of oral LECs derived from 25 case reports, 3 case studies/retrospective studies with detailed information for each case and 7 studies with summarized data.ConclusionsOral LEC is a pathologic entity with discrete clinical presentation that is, however, commonly misdiagnosed in clinical practice as other, mostly benign, entities. Its pathogenesis remains obscure, as its clinicopathologic features are consistent with both theories suggested up to date. Key words:Oral lymphoepithelial cyst; developmental cyst; non odontogenic cyst; lymphoid tissue; oral tonsil.

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Introduction The social media attitude of health science students might affect patients' opinion about the health profession and have negative impact on e‐professionalism. The aim of this study is to investigate the behaviour of Greek dental students on Facebook, focusing on potentially unprofessional posts and the online student‐patient relationship. Materials and methods Five hundred and twelve dental students in Greece answered an anonymous, 23‐item questionnaire including multiple‐choice questions about various topics, including Facebook profile settings and content shared by dental students, student‐patient relationship via Facebook; and students' perception about the impact of their online behaviour. Results 93.2% of responders had a Facebook profile and 80.5% admitted that their online attitude might affect patients' opinion about dental profession. However, 71.7% posted pictures from holidays, 41.5% from nightclubs, and 26.2% photographs wearing swimwear/underwear, while 12.8% expressed online political party predilection. One quarter of students in clinical years were Facebook friends with patients and 58% and 30% of them had online discussion about topics related or not to dentistry, respectively, while 6.8% of dental students had posted defamatory comments about the dental school, faculty members or academic staff on Facebook. Discussion In accordance with studies in other countries, most Greek dental students had a Facebook profile and, although the majority realised the impact of Facebook behaviour on e‐professionalism, a considerable percentage posted unprofessional content. Conclusion Dental students might fall into pitfalls when it comes to e‐professionalism. As social media are becoming an integral part of life, there is need to include e‐professionalism in dental education curriculum.

Localized juvenile spongiotic gingival hyperplasia (LJSGH) is a gingival lesion with unique clinicopathologic features that may involve synchronously multiple sites. We present a case with lesions clinically consistent with LJSGH in four jaw quadrants, confirmed by biopsy and review the English literature on multifocal LJSGH cases. A 19 year-old woman presented with circumscribed, erythematous overgrowths on the right and left maxillary and mandibular gingiva. With the provisional diagnosis of multifocal LJSGH, total excision of four maxillary lesions was performed. Clinical, microscopic and immunohistochemical examination with cytokeratin 19 confirmed the diagnosis of LJSGH in multiple sites. The excised lesions showed partial to complete recurrence after 4 months, while spontaneous regression of all but one lesion was observed after 15 months. Twenty cases with synchronous involvement of the gingiva of at least two teeth were previously reported. Their clinical features were comparable to that of solitary LJSGH. Only one case involved all four jaw quadrants. Spontaneous remission has not been documented before. The recognition of multiple lesions with clinicopathologic features diagnostic of LJSGH in the same adult patient argue against the designations "localized" and "juvenile". Recurrences are common, while remission might occur.

Background This study aims at determining the biological effect of 75/25 w/w nano-hydroxyapatite/chitosan (nHAp/CS) scaffolds on bone regeneration, in terms of fraction of bone regeneration (FBR), total number of osteocytes (Ost), and osteocyte cell density (CD), as well as its biodegradability. Methods Two critical-size defects (CSDs) were bilaterally trephined in the parietal bone of 36 adult Sprague-Dawley rats (18 males and 18 females); the left remained empty (group A), while the right CSD was filled with nHAp/CS scaffold (group B). Two female rats died postoperatively. Twelve, 11, and 11 rats were euthanized at 2, 4, and 8 weeks post-surgery, respectively. Subsequently, 34 specimens were resected containing both CSDs. Histological and histomorphometric analyses were performed to determine the FBR, calculated as [the sum of areas of newly formed bone in lateral and central regions of interest (ROIs)]/area of the original defect, as well as the Ost and the CD (Ost/mm2) in each ROI of both groups (A and B). Moreover, biodegradability of the nHAp/CS scaffolds was estimated via the surface area of the biomaterial (BmA) in the 2nd, 4th, and 8th week post-surgery. Results The FBR of group B increased significantly from 2nd to 8th week compared to group A (P = 0.009). Both the mean CD and the mean Ost values of group B increased compared to group A (P = 0.004 and P < 0.05 respectively). Moreover, the mean value of BmA decreased from 2nd to 8th week (P = 0.001). Conclusions Based on histological and histomorphometric results, we support that 75/25 w/w nHAp/CS scaffolds provide an effective space for new bone formation.

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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 Marios Agelopoulos and Konstantinos I. Tosios have contributed equally to this work.