Associations between clinical and histopathological characteristics in oral leukoplakia.

OBJECTIVES: To identify possible associations between patients' demographics and habits and the clinical aspects and histopathological characteristics of oral leukoplakia (OL) at patients' first visit. METHOD: A total of 140 consecutive patients with OL at a single institute between 1997 and 2019. All biopsies were microscopically examined for classic dysplasia (CD) (WHO definition oral epithelial dysplasia) and differentiated dysplasia (DD) known from differentiated vulvar intraepithelial neoplasia. Clinical characteristics were correlated to histopathological diagnosis and odds ratios (OR) were calculated. RESULTS: A total of 96 females and 44 males, mean age 58 years, were presented. OLs were found mainly on the tongue (41%) and floor of mouth (FOM) (18%). Homogeneous OLs (58%) were associated with smoking, FOM and size <2cm and non-homogeneous OLs (42%) with non-smokers. No dysplasia was present in 40% and any dysplasia (AD) in 60%. Tongue OLs were correlated with AD (OR:6.0) and CD (OR:5.7). FOM OLs were correlated with CD (OR:4.5). DD was correlated with non-homogeneous OLs (OR:2.6). CONCLUSIONS: CD was most frequently observed in tongue and FOM OLs, while DD was associated with non-homogeneous OLs. In this series of patients, there was no consistent reliable association between the clinical and histopathological features and clinical characteristics can therefore not substitute microscopic examination of biopsies.

The value of regular follow-up of oral leukoplakia for early detection of malignant transformation.

OBJECTIVES: Evaluate whether regular follow-up of oral leukoplakia (OL) resulted in early detection of malignant transformation (MT). METHOD: Two hundred and twenty-two consecutive patients with OL (147 females, 75 males); median follow-up period of 64 months (range: 12-300). Three groups were distinguished: group A (n = 92) follow-up at the hospital; group B (n = 84) follow-up by their dentist; group C (n = 46) lost to follow-up. RESULTS: OLs in group B compared to group A, were smaller in size (<2 cm; p < 0.001), showed more hyperkeratosis (p < 0.001) and less moderate/severe dysplasia (p < 0.001). MT occurred in 45 (20%) patients: 32 (35%) in group A, five (6%) in group B and eight (17%) in group C. There was no significant difference in clinical tumour size between group A (median: 15 mm, range: 1-40) and group B (median: 10 mm, range: 3-25; p = 0.496). Tumour size was smaller for patients in groups A and B (median: 10 mm, range 1-40) compared to group C (median: 33 mm, range: 3-100; p = 0.003). There was a positive correlation between tumour size and interval between the last visit in all patients (p = 0.022). CONCLUSION: Regular follow-up of OL resulted in early detection of MT. If properly selected, follow-up of OL performed by the dentist seems feasible.

Resorption of the mandibular residual ridge: A micro-CT and histomorphometrical analysis.

OBJECTIVES: The aim of this study was to investigate whether the extent of mandibular resorption and gender is related to the bone turnover and microarchitecture of the edentulous mandible. PARTICIPANTS AND METHODS: A mandibular bone sample was obtained at canine position from 36 edentulous participants (50% women; mean age: 65 years) during dental implant surgery. All female participants were postmenopausal. Mandibular height, duration of edentulous state and resorption pattern (Cawood classification) were recorded. Microcomputed tomography was used to determine bone mineral density, bone volume fraction, trabecular connectivity density, trabecular number, trabecular thickness and trabecular separation. Histomorphometric analysis was used to assess bone turnover: osteoid area and surface were measured as a parameter for bone formation and osteoclast numbers were determined as a parameter for bone resorption. Correlations between micro-CT, histomorphometrical parameters and clinical data were analysed with correlation coefficients and parametric and non-parametric tests. RESULTS: Lower mandibular height was strongly associated with higher bone mineral density in trabecular bone. Women showed higher osteoclast numbers in trabecular bone than men. In trabecular bone of women, bone volume was significantly related to osteoclast numbers, osteoid surface and osteoid area. CONCLUSIONS: The higher trabecular bone mineral density found in the edentulous mandible could either indicate a restructuring process of the resorbed mandible or suggests that the inferior region of the mandible is more highly mineralised. In women, higher bone turnover is associated with lower bone volume, suggesting an effect of postmenopausal oestrogen deficiency on bone turnover in the edentulous mandible.

Radiation-induced changes in the microstructure of epithelial cells of the oral mucosa: A comparative light and electron microscopic study.

OBJECTIVES: The microplicae is a typical structure of the epithelial cell surface of the oral mucosa. The cell surface is potentially of great significance, as it provides the underlying basis for the protective function of the salivary pellicle. The aim of this study was to investigate whether radiation therapy affects the surface morphology of the superficial cells of the human oral mucosa in patients who have received radiotherapy for oral cancer. MATERIAL AND METHODS: Oral mucosal tissue samples from 91 patients were collected during dental implant surgery or ablative surgery. Study group 1 consisted of 28 patients who underwent dental implant surgery after radiotherapy. Group 2 consisted of five patients who developed osteoradionecrosis. Group 3 consisted of eight oral cancer patients without radiotherapy. Group 4 consisted of 50 clinically healthy subjects as controls. The samples were studied with scanning electron microscopy and compared with both light and transmission electron micrographs. RESULTS: Radiation therapy (RT) induces breakage and destruction in the microplicae morphology and declines the density of the microplicae surface structures. In some of the irradiated cells, the microplicae were completely vanished, especially in patients who developed osteoradionecrosis. In non-irradiated tissue, the microplicae of the superficial epithelial cells were intact in all cases. CONCLUSION: Scanning electron microscopy, in contrast to light microscopy, appears to be a useful tool to reveal the condition of superficial oral mucosal cells. In respect of the possible pathogenesis of osteoradionecrosis, the radiation-induced damage of the microplicae and its influence on the mucosal salivary pellicle is discussed.

Design and evaluation of an immunology and pathology course that is tailored to today's dentistry students.

Curricular reform provides new opportunities to renovate important pillars of the dentistry curriculum, such as immunology and pathology, with novel approaches that appeal to new generations of students. When redesigning a course that integrates both immunology and pathology at the level that provides dentistry students with sustainable knowledge that is useful for their entire career, several challenges must be met. The objective of the present study was to describe the considerations involved in the design phase of such a new course. First, the course should be compatible with the new view on the incorporation of more active learning and teaching methods. Practically, this means that the course design should contain fewer lectures and more seminars and tutorials, where the students have fewer contact hours and actively engage in using recently acquired knowledge within a contextual background. A mandatory session of team-based learning provides opportunities to apply knowledge in combination with academic reasoning skills, teamwork, and communication. Second, for a 4-week course, choices must be made: students will not become immunologists nor pathologists in such a short period. A governing principle for this course's design is that it should be based on understanding the basic principles of immunology and pathology. The ultimate goal for the students is to make the course immuno-logical and patho-logical, challenging them to reach a next level but clearly without oversimplification. Part of the course design should allow room for students to further study an immunological topic of their own choice, thereby contributing to their immunological curiosity and to their academic development. Third, to make it tailored to a new generation of dentists, examples from the field of dentistry are actively integrated in all aspects of the course. Finally, the era of ChatGPT provides novel opportunities to use generative artificial intelligence (AI) tools in the learning process, but it demands critical thinking of how to use it in a newly designed course. A mid-course evaluation revealed that students acknowledged that immunology and pathology were presented as an integrated course. The final course evaluation endorsed the use of these various educational methods. These methods proved to be appropriate and logical choices for reaching the learning goals of the course.

The relevance of uniform reporting in oral leukoplakia: definition, certainty factor and staging based on experience with 275 patients.

The aim of the present study was to evaluate the definition of oral leukoplakia, proposed by the WHO in 2005 and taking into account a previously reported classification and staging system, including the use of a Certainty factor of four levels with which the diagnosis of leukoplakia can be established. In the period 1997-2012 a hospital-based population of 275 consecutive patients with a provisional diagnosis of oral leukoplakia has been examined. In only 176 patients of these 275 patients a firm diagnosis of leukoplakia has been established based on strict clinicopathological criteria. The 176 patients have subsequently been staged using a classification and staging system based on size and histopathologic features. For use in epidemiological studies it seems acceptable to accept a diagnosis of leukoplakia based on a single oral examination (Certainty level 1). For studies on management and malignant transformation rate the recommendation is made to include the requirement of histopathologic examination of an incisional or excisional biopsy, representing Certainty level 3 and 4, respectively. This recommendation results in the following definition of oral leukoplakia: "A predominantly white lesion or plaque of questionable behaviour having excluded, clinically and histopathologically, any other definable white disease or disorder". Furthermore, we recommend the use of strict diagnostic criteria for predominantly white lesions for which a causative factor has been identified, e.g. smokers' lesion, frictional lesion and dental restoration associated lesion.

Irradiation Alters the Expression of MUC1, CD44 and Hyaluronan in Oral Mucosal Epithelium.

Purpose: It is well established that cancer cells exploit aberrant synthesis of mucin 1 (MUC1) and hyaluronan (HA) synthesis along with HA's physiological cell surface receptor CD44. However, their role in irradiated oral tissue has not been reported previously. We, therefore, aimed to study MUC1, CD44 and HA immunohistochemically in irradiated oral mucosa and their role in the long-term effects after radiotherapy. Materials and Methods: Oral mucosal biopsies were obtained from healthy subjects as controls and from patients after radiotherapy for head and neck cancer (irradiated group) during dental implant surgery.The presence of MUC1, CD44, and HA in oral mucosa was studied by immunohistochemical methods. The differences in the localization and intensity in the oral epithelium between control and irradiated tissue were analyzed. Results: The staining intensity of MUC1 was confined to the superficial epithelial layer, whereas HA and CD44 were found in the cell membranes in the epithelial basal and intermediate layers of control specimens. In irradiated epithelium, MUC1 staining was distributed throughout all the layers of the oral epithelium, with significant staining in the basal and intermediate layers. Accordingly, HA and CD44 staining extended to involve the superficial cells of the irradiated epithelium. The staining pattern of MUC1 and CD44 showed significant changes in irradiated samples. Conclusions: Our results showed that the staining intensities of MUC1, CD44, and HA were significantly elevated in irradiated tissue compared to controls. MUC1, CD44, and HA are important markers and take part in long-term changes in the oral mucosa after radiotherapy.

Regional differences in microarchitecture and mineralization of the atrophic edentulous mandible: A microcomputed tomography study.

OBJECTIVE: The aim of the present study was to assess mineralization and trabecular microarchitecture in atrophic edentulous mandibles and to identify regional differences and relations with the extent of resorption. METHODS: Cortical and trabecular bone volumes in anterior, premolar and molar regions of 10 edentulous cadaveric mandibles (5 males and 5 females; mean age ± SD: 85.4 ± 8.3 years) were assessed by microcomputed tomography. Mandibular height and Cawood & Howell classes were recorded. Concerning trabecular volumes, bone mineral density (BMD), bone volume fraction, trabecular tissue volume fraction, connectivity density, trabecular number, trabecular thickness, trabecular separation, degree of anisotropy, and structural model index were measured; concerning cortical volumes porosity, BMD and cortical thickness were measured. RESULTS: In molar regions, the bone volume fraction and trabecular number were lower, whereas trabecular separation, degree of anisotropy and cortical BMD were higher compared to anterior regions. In premolar regions, mandibular height correlated negatively with trabecular number (Spearman's correlation r = 0.73, p = 0.017) and connectivity density (Spearman's correlation r = 0.82, p = 0.004), and correlated positively with trabecular separation (Spearman's correlation r = - 0.65, p = 0.04). Cortical BMD was higher at bucco-inferior cortex of molar and inferior border of premolar region and lower at anterior cranial buccal and lingual surface. CONCLUSIONS: In the premolar region, increased resorption coincides with local impairment of trabecular bone quality. Cortical bone BMD is higher in areas with highest strains and lower in areas with most mandibular resorption. Trabecular bone volume and quality is superior in the anterior region of the edentulous mandible, which might explain improved primary stability of dental implants in this region.

Osteocyte Apoptosis, Bone Marrow Adiposity, and Fibrosis in the Irradiated Human Mandible.

Purpose: To assess the effect of radiation therapy on osteocyte apoptosis, osteocyte death, and bone marrow adipocytes in the human mandible and its contribution to the pathophysiology of radiation damage to the mandibular bone. Methods and Materials: Mandibular cancellous bone biopsies were taken from irradiated patients and nonirradiated controls. Immunohistochemical detection of cleaved caspase-3 was performed to visualize apoptotic osteocytes. The number of apoptotic osteocytes per bone area and per total amount of osteocytes, osteocytes per bone area, and empty lacunae per bone area were counted manually. The percentage fibrotic tissue and adipose tissue per bone marrow area, the percentage bone marrow of total area, and the mean adipocyte diameter (µm) was determined digitally from adjacent Goldner stained sections. Results: Biopsies of 15 irradiated patients (12 men and 3 women) and 7 nonirradiated controls (5 men and 2 women) were assessed. In the study group a significant increase was seen in the number of empty lacunae, the percentage of adipose tissue of bone marrow area, and the adipocyte diameter. There was no significant difference in bone marrow fibrosis nor apoptotic osteocytes between the irradiated group and the controls. Conclusions: Irradiation alone does not seem to induce excessive bone marrow fibrosis. The damage to bone mesenchymal stem cells leads to increased marrow adipogenesis and decreased osteoblastogenic potential. Early osteocyte death resulting in avital persisting bone matrix with severely impaired regenerative potential may contribute to the vulnerability of irradiated bone to infection and necrosis.

Annual malignant transformation rate of oral leukoplakia remains consistent: A long-term follow-up study.

OBJECTIVES: Numerous clinical and histopathological characteristics have been associated with malignant transformation (MT) of oral leukoplakia (OL), including classic and differentiated epithelial dysplasia, but MT predictions remain suboptimal. The objective of this study was to determine the annual MT rate of OL and to identify clinicopathological risk factors associated with MT. PATIENTS AND METHODS: 170 patients with OL were included in this retrospective cohort study, 117 females and 53 males. Follow-up ranged from 12 to 219 months (median 54). The analyzed variables included age, gender, smoking habits, clinical presentation, subsite, size and treatment. In a subgroup of 140 patients, histopathological diagnoses were reviewed with regard to the presence of dysplasia, discerning both classic dysplasia and differentiated dysplasia. RESULTS: MT occurred in 23% of the patients, resulting in an annual MT rate of 4.9% (95% CI: 3.5 - 6.6) which remained consistent. High-risk subsite (tongue and floor of mouth) was the only clinical predictor for MT (Hazard Ratio = 2.7, 95% CI: 1.3 - 5.5, p = 0.007). In 140 patients, classic dysplasia (Hazard Ratio = 7.2, 95% CI: 1.6 - 33.1, p = 0.012) and differentiated dysplasia (Hazard Ratio = 6.6, 95% CI: 1.2 - 25.4, p = 0.026) were predictors for MT. Binary grading between dysplasia and no dysplasia was significant for predicting MT (Hazard Ratio = 6.4, 95% CI: 1.5 - 27.5, p = 0.013). CONCLUSION: Since annual MT rate of OL remains stable during follow-up, regular long-term or even life-long follow-up is advocated. Specific oral subsites and epithelial dysplasia are predictors for MT of OL.

Elective Neck Dissection or Sentinel Lymph Node Biopsy in Early Stage Oral Cavity Cancer Patients: The Dutch Experience.

BACKGROUND: Sentinel lymph node biopsy (SLNB) has been introduced as a diagnostic staging modality for detection of occult metastases in patients with early stage oral cancer. Comparisons regarding accuracy to the routinely used elective neck dissection (END) are lacking in literature. METHODS: A retrospective, multicenter cohort study included 390 patients staged by END and 488 by SLNB. RESULTS: The overall sensitivity (84% vs. 81%, p = 0.612) and negative predictive value (NPV) (93%, p = 1.000) were comparable between END and SLNB patients. The END cohort contained more pT2 tumours (51%) compared to the SLNB cohort (23%) (p < 0.001). No differences were found for sensitivity and NPV between SLNB and END divided by pT stage. In floor-of-mouth (FOM) tumours, SLNB had a lower sensitivity (63% vs. 92%, p = 0.006) and NPV (90% vs. 97%, p = 0.057) compared to END. Higher disease-specific survival (DSS) rates were found for pT1 SLNB patients compared to pT1 END patients (96% vs. 90%, p = 0.048). CONCLUSION: In the absence of randomized clinical trials, this study provides the highest available evidence that, in oral cancer, SLNB is as accurate as END in detecting occult lymph node metastases, except for floor-of-mouth tumours.

Odontogenic keratocysts located in the buccal mucosa: A description of two cases and review of the literature.

Odontogenic keratocysts make up 4%-12% of all odontogenic cysts. Most cysts are sporadic but sometimes they arise in the context of basal cell nevus syndrome (Gorlin syndrome). Most odontogenic keratocysts arise in the posterior region of the mandible, but they can occur anywhere in the jaw. In rare instances, they are located peripherally in the gingiva. Even more rare, they are found in the soft tissues of the mouth. There have been a few case reports and small case series of such peripheral odontogenic keratocysts. Some controversy exists as to whether these truly represent a peripheral counterpart of the intraosseous odontogenic keratocysts and if their origin is at all odontogenic. We hereby present two cases of peripheral odontogenic keratocysts, both being located in the soft tissue of the buccal mucosa, and review the literature on peripheral odontogenic keratocysts.

Clear Cell Odontogenic Carcinoma: Occurrence of EWSR1-CREB1 as Alternative Fusion Gene to EWSR1-ATF1.

Clear cell odontogenic carcinoma (CCOC) is a rare, low-grade malignant epithelial neoplasm, occurring in the jawbones, mainly affecting the mandible of elderly patients. In addition to hyalinizing clear cell carcinoma of the salivary gland, it is one of the epithelial neoplasms known to harbor an EWSR1-ATF1 fusion. Therefore, a link between these tumors seems plausible. We describe six cases of CCOC showing EWSR1 rearrangements, with two cases being positive for the ATF1 partner gene using FISH analysis. In one case, an EWSR1-CREB1 fusion was identified using RT-PCR, which we report for the first time in this tumor type. The other three cases investigated by FISH were negative for ATF1, CREB1 and CREB3L2. In conclusion, our data show that EWSR1-CREB1 is an alternative fusion gene to EWSR1-ATF1 in CCOC.

Human Salivary Micro-RNA in Patients with Parotid Salivary Gland Neoplasms.

BACKGROUND: Currently, clinical examination, ultrasound scanning (with or without fine needle aspiration cytology), preoperative CT-scan and MRI are available for the differential diagnosis of parotid gland swelling. A preliminary non-invasive salivary diagnostic tool may be helpful in the clinical decision making process. Altered salivary micro-RNA (miRNA) expression levels have been observed in saliva from patients with various cancers. Therefore, we investigated miRNA expression levels in saliva samples from patients with a parotid gland neoplasm using Human miRNA cards in comparison to controls. RESULTS: In the discovery phase, eight miRNAs were identified having different expression levels in patients compared to controls. In the validation phase, the differences in miRNA expression levels between patients and controls were confirmed for seven out of eight discovered miRNAs (p < 0.001). A combination of two miRNAs yielded a receiver-operator-characteristics curve with an AUC of 0.94 (95% CI: 0.87-1.00; sensitivity 91%; specificity 86%). Validation of discovered miRNAs in segregated collected parotid saliva revealed that expression of these miRNAs differ between whole saliva and parotid saliva. CONCLUSIONS: A two miRNA combination can predict the presence of a parotid gland neoplasm. Furthermore, this study suggested that the identified, patient-specific, salivary miRNAs were not derived from the parotid gland itself.

Discovery and prevalidation of salivary extracellular microRNA biomarkers panel for the noninvasive detection of benign and malignant parotid gland tumors.

PURPOSE: This study was conducted to explore the differences in salivary microRNA (miRNA) profiles between patients with malignant or benign parotid gland tumors as a potential preoperative diagnostic tool of tumors in the salivary glands. EXPERIMENTAL DESIGN: Whole saliva samples from patients with malignant (n = 38) or benign (n = 29) parotid gland tumors were obtained from the Salivary Gland Tumor Biorepository (SGTB). After total RNA isolation, human miRNA cards were used for miRNA profiling. The differential miRNA expression was analyzed using two-sided Wilcoxon test. Quantitative real-time PCR (qRT-PCR) was used to validate selected miRNAs in an independent sample set. Receiver-operating characteristics curve and probability of malignancy was exploited to evaluate the diagnostic power of the validated miRNAs. RESULTS: With miRNA profiling, 57 of 750 investigated miRNAs were differently expressed, of which 54 showed higher miRNA expression in samples from patients with malignant tumors than those from patients with benign tumors. Validating the expression in an independent sample set of 9 miRNAs revealed indeed higher expression of miRNAs in malignant samples compared with benign samples. The expression of 6 validated miRNAs was statistically significantly different between the two groups (P < 0.05). A four miRNA combination was able to discriminate between saliva samples from patients with malignant tumors from those of patients with benign parotid gland tumors (sensitivity 69%, specificity 95%). CONCLUSIONS: Salivary miRNA profiles differ in saliva from patients with malignant from saliva from patients with a benign parotid gland tumor. These preliminary results are promising to develop a noninvasive diagnostic tool for diagnosing tumors in the salivary glands.

Visualization of the sentinel node in early-stage oral cancer: limited value of late static lymphoscintigraphy.

OBJECTIVE: Various lymphoscintigraphic imaging protocols exist for sentinel node (SN) identification in early-stage oral cancer. This study aimed to evaluate the clinical value of performing additional late lymphoscintigraphic imaging. METHODS: We retrospectively analysed early (directly following injection of 99mTc-Nanocoll) and late (2-4 h after injection) imaging results of 60 early-stage (T1-T2, cN0) oral cancer patients scheduled for SN procedure. Lymphoscintigraphic results of late imaging were categorized into: (a) no visualization of additional hotspots considered to be SNs; (b) additional hotspots visualized that are considered to be SNs and (c) hotspots visualized only during late imaging. Histopathological results of the harvested SNs were related to the corresponding hotspot. RESULTS: In all patients (n=60) lymphoscintigraphy was able to visualize a hotspot that was identified as an SN. In 51/60 (85%) patients, early imaging was able to visualize at least one hotspot, whereas in 9/60 (15%) patients, mostly with oral cavity tumours other than mobile tongue and floor-of-mouth tumours, only late imaging was able to visualize hotspots. In 14/51 (27%) patients, late imaging resulted in additionally visualized hotspots marked as SNs, resulting in a more extensive surgical procedure. These additionally removed SNs appeared to be of no clinical relevance, as all SNs identified during early imaging correctly predicted whether the neck was positive or negative for cancer. CONCLUSION: Results of this study indicate that additional late lymphoscintigraphic imaging should be performed only in selected cases.