Distribution of Epstein-Barr virus in the oral cavity of Thais with various oral mucosal conditions.

Objectives: We aimed to examine the presence of EBV, EBV strains, and variants among 3 oral conditions including normal oral mucosa (NOM), oral potentially malignant disorders/oral cancer (OPMDs/OC) and non-OPMDs/OC in a group of Thais. Material and methods: Oral exfoliated cells were obtained from 315 participants living in the northeastern and central regions of Thailand. The participants were divided into 3 groups encompassing the NOM, the OPMDs/OC and the non-OPMDs/OC groups. The presence of EBV was first determined by PCR using primers for LMP1 gene. Subsequently, EBV strains of EBNA3c and variants based on LMP1 sequences were determined by real-time PCR. Results: The prevalence of EBV in OPMDs/OC, non-OPMDs/OC and NOM were 72.0 %, 56.2 %, and 27.2 % respectively. EBV type A, B and AB were found in 52.1 %, 32.1 % and 15.8 % of all positive samples, respectively. The percentage of participants with EBV type A was more prominent in the NOM group (72.0 %) compared to the non-OPMDs/OC (54.8 %) and the OPMDs/OC group (41.8 %) whereas EBV type B was higher in the OPMDs/OC group (35.8 %) compared to the non-OPMDs/OC (31.5 %) and the NOM (24.0 %) groups. Regarding EBV variants, 30-bp deletion LMP1 variant (del-LMP1) which is more associated with malignant transformation was predominately found in the OPMDs/OC (32.8 %) and the non-OPMDs/OC (38.4 %) groups compared to the NOM group (20.0 %). Conclusions: High frequency of EBV was demonstrated in the OPMDs/OC group. EBV type A was more predominant in the NOM group whereas EBV type B was more prevalent in the OPMDs/OC group. The del-LMP1 variant was more common in the OPMDs/OC and the non-OPMDs/OC groups.

A Rare Case Report of Extraosseous Ameloblastic Carcinoma and Review Article on Diagnosis and Treatment Dilemma.

Peripheral ameloblastic carcinoma is an extremely rare odontogenic carcinoma. Its histopathological feature is identical to the intraosseous type. This case report details a case of peripheral ameloblastic carcinoma at the right posterior maxilla region in a 60-year-old Thai male. The patient underwent a definitive treatment by partial maxillectomy and reconstruction with buccal fat pad. After 1-year follow-up, no recurrence of the lesion was found.

Analysis of Epstein-Barr Virus Infection in Oral Potentially Malignant Disorders and Oral Cancer: A Cross-Sectional Study.

Aims and Objectives: The primary objective of this study is to determine the prevalence of Epstein-Barr virus (EBV) in oral potentially malignant disorders (OPMDs) and oral cancer (OC) in a group of Thais using polymerase chain reaction (PCR) and Epstein-Barr encoding regions (EBERs) in situ hybridization (ISH). The secondary objective is to investigate the risk factors of OC and the association between the presence of EBV and risk factors of OC/site of oral lesions. Materials and Methods: Sixty-one participants attending the screening project for OC and OPMDs at the Northeastern district hospitals of Thailand were recruited. Information related to risk factors and biopsy tissues for histopathological diagnosis was collected. Sixty-seven paraffin tissue blocks, including 52 OPMDs and 15 OC specimens, were investigated for EBV infection, using PCR analysis with latent membrane protein-1 (LMP-1) primer and EBERs ISH. Pearson's Chi-square or Fisher's exact test was used to analyze the differences in variables between participants with OPMDs and OC, as appropriate. The association between EBV infection and related risk factors was analyzed using logistic regression with a significant level at 0.05. Results: Using PCR analysis, 8 of 67 specimens (11.94%) were positive for LMP-1. Three cases of OPMDs were positive for both LMP-1 PCR and EBERs ISH. Regarding risk factors of OC, the two most common risk factors were betel nut chewing (52.46%) and working in sunlight (42.62%). The habit of taking alcohol was significantly different between the OC and the OPMDs groups (p = 0.009). The association between LMP-1 and the lesion at the tongue was statistically significant, with odds ratio = 4.900 (95% confidence interval = 1.046-22.943; p = 0.044). Conclusions: The prevalence of EBV infection in this group of participants was low. However, OPMDs at the tongue exhibited a significant association with EBV infection.

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.

Association between Clinical/Radiographic Characteristics and Histopathological Diagnoses of Periapical Granuloma and Cyst.

OBJECTIVE: The aim of this study was to determine the association between clinical/radiographic characteristics and histopathological diagnoses of periapical granuloma and cyst obtained from the teeth treated with endodontic microsurgery. MATERIALS AND METHODS: The clinical, radiographic (periapical and cone-beam computed tomography), and histopathological data were collected from patients' dental records of endodontic microsurgery on the teeth with periapical lesions. These lesions were histopathologically diagnosed as either granuloma or cyst, at the Endodontic Clinic, Faculty of Dentistry, Mahidol University, Bangkok, Thailand, from 2016 to 2021 according to inclusion and exclusion criteria. The data were analyzed using bivariate analysis and a multinomial logistic regression at a significance level of p-value less than 0.05. RESULTS: A total of 83 patients (58 females and 25 males) with an average age of 45 to 49.5 years old met the criteria including 68 periapical granulomas (81.9%) and 15 periapical cysts (18.1%). A periapical lesion involving multiple teeth in a periapical radiograph was significantly associated with the histopathological diagnosis of periapical cyst (p < 0.05). Such periapical lesion was six times more likely to be periapical cyst than periapical granuloma. CONCLUSIONS: A significant factor for predicting periapical cyst from periapical granuloma was the presence of a periapical lesion with multiple-teeth involvement in a dental radiograph.

Epstein-Barr Virus Detection and LMP-1 Expression in Thai Patients with Oral Squamous Cell Carcinoma.

BACKGROUND: To date, high-risk human papillomavirus (HPV) is primarily linked to oropharyngeal carcinoma, but only a small subset of oral squamous cell carcinoma (OSCC) is truly driven by high-risk HPV. In addition, Epstein-Barr virus (EBV) is another potential oncogenic virus for OSCC development. This study aims to investigate the role of EBV infection in Thai patients with OSCC. METHODS: Forty-seven formalin-fixed paraffin-embedded specimens of OSCC were obtained. EBV DNA was detected by polymerase chain reaction analysis using primers for LMP-1 region of EBV. EBV-positive OSCC cases were subjected to LMP-1 immunohistochemical analysis and EBV-encoded small RNA (EBER) in situ hybridization to determine EBV cellular localization in OSCC. LMP-1 immunohistochemical analysis was also performed in all EBV-negative OSCC cases. RESULTS: Of the 47 OSCC specimens, ten (21%) exhibited EBV DNA by PCR analysis. Seven of ten (70%) EBV-positive specimens showed high-grade LMP-1 expression by immunohistochemistry. However, no EBER expression was detected in all EBV-positive OSCC specimens. In EBV-negative specimens, LMP-1 was also negative except in 3 specimens which showed low grade expression of LMP-1. CONCLUSION: The prevalence of EBV infection in OSCC in this group of Thai patients was 21%. Most of EBV-positive OSCC cases showed LMP-1 expression but a lack of EBER expression. From our findings, we presume that EBV may take some roles in OSCC development in this group of participants.

Detection of Human Papillomavirus and p16INK4a Expression in Thai Patients with Oral Squamous Cell Carcinoma.

This study investigated the prevalence of human papillomavirus (HPV) infection in oral squamous cell carcinoma (OSCC) cases, as well as the association between HPV presence and p16INK4a expression, in Thai patients with OSCC. Eighty-one formalin-fixed paraffin-embedded specimens of OSCC were obtained. DNA extraction was performed; this was followed by nested polymerase chain reaction analysis to determine HPV DNA status, using consensus primers for the L1 region of HPV. HPV subtypes were determined by DNA sequencing. HPV-positive specimens and HPV-negative specimens from age- and sex-matched patients were subjected to immunohistochemical analysis to determine p16INK4a expression status. Of the 81 OSCC specimens, eight (9.9%) exhibited HPV DNA; DNA sequencing confirmed that the viral subtype was HPV-18 in all eight specimens. These eight HPV-positive specimens, as well as eight HPV-negative specimens from age- and sex-matched patients, were subjected to immunohistochemical analysis to determine p16INK4a expression status. Three of eight (37.8%) HPV-positive specimens and three of eight (37.8%) HPV-negative specimens showed positive p16INK4a expression findings. However, we did not find a significant association between HPV status and p16INK4a expression status in our OSCC samples. In conclusion, the prevalence of high-risk HPV was low in this group of OSCC patients; no association between HPV status and p16INK4a expression status was identified.

Association of HPV and EBV in Oral Verrucous Squamous Cell Carcinoma and Oral Verrucous Hyperplasia.

OBJECTIVE: Oral verrucous squamous cell carcinoma or oral verrucous carcinoma (OVC) is a rare verrucous variant of oral squamous cell carcinoma (OSCC), which accounts for 2 to 12% of all oral carcinomas. Oral verrucous hyperplasia (OVH) is clinically similar to OVC and has been proposed to be a precursor lesion of OVC. Etiopathogenesis of both lesions is still inconspicuous. Oncogenic viruses such as human papillomavirus (HPV) and Epstein-Barr virus (EBV) have been reported to be associated with some cases of OSCC, and we hypothesized that it may act as a causative agent of these verrucous lesions. This study aimed to investigate frequency of HPV and EBV infections in OVC and OVH. MATERIAL AND METHODS: Using polymerase chain reaction (PCR), a total of 35 formalin-fixed paraffin-embedded (FFPE) tissue samples, including 27 OVC samples and 8 OVH samples, were investigated for HPV and EBV infection. HeLa and B95-8 cell lines were used as positive controls of HPV and EBV PCR, respectively. RESULTS: All OVC and OVH samples show a positivity to GAPDH, whereas neither HPV nor EBV PCR products was detected in both OVC and OVH samples. CONCLUSIONS: In summary, our study demonstrated that HPV and EBV are not involved in pathogenesis of OVC and OVH. Other etiologic factors contributing to OVC and OVH need to be further clarified.

Frequency of BRAF V600E mutation in a group of Thai patients with ameloblastomas.

OBJECTIVE: BRAF V600E mutation has recently been reported in a high proportion of ameloblastomas. This study was conducted to investigate the frequency of this mutation in ameloblastoma and unicystic ameloblastoma. The correlation between clinicopathologic data and BRAF V600E mutation was also analyzed. STUDY DESIGN: A total of 51 archival samples of ameloblastomas and 22 cases of unicystic ameloblastomas were examined for BRAF V600E mutation by using anti-BRAF V600E (clone VE1) immunohistochemistry. RESULTS: Positivity for anti-BRAF V600E antibody was detected in 72.5% (37 of 51) of ameloblastomas, but the mutation showed no significant correlation with the clinicopathologic parameters. With regard to unicystic ameloblastoma, 95.5% (21) of the 22 cases exhibited positive immunostaining for BRAF V600E, whereas only 1 case showed the mural subtype of wild-type BRAF. CONCLUSIONS: A high frequency of BRAF V600E mutation was detected in a group of Thai patients with ameloblastomas, suggesting the future use of BRAF-targeted therapy in patients with BRAF-mutated ameloblastoma. However, no significant association between BRAF V600E mutation and the clinicopathologic characteristics of ameloblastomas was found in our study.

Differential Expression of EZH2 and H3K27me3 in Oral Verrucous Carcinoma and Oral Verrucous Hyperplasia.

Enhancer of zeste homolog 2 (EZH2), a component of the polycomb repressive complex 2 that catalyzes trimethylation of H3K27 (H3K27me3), has been shown to promote tumor development and progression. Expression of EZH2 is associated with cell cycle regulation and cell proliferation in various neoplasms. Oral verrucous hyperplasia (OVH) and Oral verrucous carcinoma (OVC) are rare entities and share several clinical and histopathologic features. Problems distinguishing these lesions are added by a lack of adjacent normal tissue of the biopsy samples and poorly oriented tissue sections. The aim of this study was to investigate the expression of EZH2 and H3K27me3 in OVH and OVC and comparing the expression with normal oral mucosa and oral squamous cell carcinoma (OSCC). Seventy-eight samples, including 25 cases of OVC, 8 cases of OVH, 35 cases of OSCC and 10 cases of normal oral mucosa, were retrieved and submitted for immunohistochemical staining. The results demonstrated that the mean labeling indices (LIs) of EZH2 and H3K27me3 expression were highest in OSCC, followed by the OVC, OVH, and normal mucosa. Statistical differences in EZH2 LI were observed among these lesions whereas H3K27me3 LI was significantly different among OSCC, OVH and normal mucosa. EZH2 LI was found to have a sensitivity of 72.00% and specificity of 87.50% in distinguishing OVH from OVC, and a sensitivity of 57.14% and specificity of 84.00% in distinguishing OVC from OSCC. A positive correlation between EZH2 and H3K27me3 expression was significantly found in OVC but not in OVH and OSCC. These findings highlight the involvement of epigenetic regulation by EZH2-mediated H3K27me3 in the pathogenesis of OVH and OVC, and EZH2 expression indicates disease progression of these verrucous lesions. Diagnostic test analysis further suggests that EZH2 may be used as an additional test for differentiating OVH from OVC in questionable cases.

Oral Potentially Malignant Disorders and Squamous Cell Carcinoma at the Tongue: Clinicopathological Analysis in a Thai Population.

OBJECTIVE: Tongue is regarded as one of the common sites of oral squamous cell carcinoma (OSCC). This study aimed to determine the prevalence and clinicopathological profile of OSCC and oral potentially malignant disorders (OPMDs) at the tongue. MATERIALS AND METHODS: We retrospectively analyzed clinicopathological characteristics of 208 Thai patients diagnosed with SCC and OPMDs at the tongue in the period from 1996 to 2015. Chi-squared test was used to compare differences between patient's clinical and histopathological features. RESULTS: Seventy-eight tongue SCC and 130 tongue OPMD cases were present over the study period. Slight male predominance was found for tongue SCC, while a slight female predominance was present for tongue OPMDs. Both tongue SCC and tongue OPMDs were mostly diagnosed in the old age patients (>40 years old). The majority of tongue SCC and OPMDs occurred at the tip and lateral of the tongue. The most common histologic grading of tongue SCC was well differentiated and no poor differentiation was found in this study. More than a half of tongue OPMDs showed epithelial dysplasia. Both tongue SCC and OPMDs demonstrated no significant correlation between clinical feature and histopathologic diagnosis. CONCLUSIONS: Tongue SCC and OPMDs were particularly found in the elderly population and frequently developed at the tip and lateral of the tongue. Most of tongue OPMDs, particularly all of tongue erythroplakia, exhibited epithelial dysplasia. For dental practitioners, awareness in the early detection and diagnosis of these tongue lesions should be raised.

Expression profile of polycomb group proteins in odontogenic keratocyst and ameloblastoma.

Polycomb group (PcG) proteins are repressive chromatin modifiers required for proliferation and development. PcG proteins form two large repressive complexes, namely, Polycomb Repressive Complex 1 and 2. These proteins have been shown to drive tumorigenesis by repressing cell-type specific sets of target genes. Using immunohistochemistry, we investigated the expression patterns of five human PcG proteins, including Bmi-1, Ring1b, Mel-18, Ezh2, and Suz12, in various cellular components of odontogenic keratocysts (OKCs), ameloblastomas and, pericoronal follicles (PFs). In OKCs, expression of PcG proteins were found in the majority of cases while the expression pattern was relatively different for each PcG proteins. All PcG proteins were strongly expressed in the basal cells while some proteins showed variable expression in the parabasal and luminal cell layer of OKCs. In ameloblastomas, almost all PcG proteins showed a similar expression pattern of moderate to strong staining in the peripheral ameloblast-like cells and metaplastic squamous cells. Some of the central stellate reticulum-like cells also showed positive reaction to most PcG proteins. In PFs, most PcG proteins were intensely expressed in odontogenic epithelium lining the follicles, except Mel-18 and Suz12. The present study provides the initial evidence regarding epigenetic involvement by PcG proteins in these odontogenic lesions. Although these proteins are known to be in the same repressive group proteins, differential expression patterns of these proteins in OKCs and ameloblastomas indicates that these proteins may play different roles in pathogenesis of these odontogenic lesions.

Oral and maxillofacial lesions in a Thai pediatric population: a retrospective review from two dental schools.

OBJECTIVE: To determine the prevalence of oral and maxillofacial lesions in a Thai pediatric population. MATERIAL AND METHOD: Oral biopsy records from pediatric patients between the ages of 0 and 15 years in the files ofFaculty of Dentistry, Mahidol University, and the files of Faculty of Dentistry, Khon Kaen University were reviewed. The patients were divided into three age groups, including 0 to 5, 6 to 10, and 11 to 15 years. Excluding the diagnosis of normal tissues, the oral and maxillofacial lesions were classified into nine categories. RESULTS: Of 13,050 biopsied oral and maxillofacial lesions, 1,389 cases (10.6%) came from pediatric patients. The largest number of lesions was odontogenic cysts and tumors, followed by inflammatory and reactive lesions, and salivary gland pathology The top ten most prevalent lesions contributed 73% of all oral biopsies. The most common lesion was dentigerous cyst, followed by mucocele and pyogenic granuloma. CONCLUSION: The vast majority of oral diseases in children were benign and related to either developmental or tissue reaction, while malignant lesions were found in a very small proportion of all oral biopsies.

A clinicopathologic study of 1,047 cases of salivary gland tumors in Thailand.

OBJECTIVE: The objective of this study was to analyze the clinicopathologic data of salivary gland tumors in Bangkok, Thailand. METHOD AND MATERIALS: Cases diagnosed with salivary gland tumors were retrieved from a dental school and a medical school in Bangkok, Thailand. Clinicopathologic data were recorded and analyzed with respect to gender, age, site, and histologic type. RESULTS: Of the 411,851 cases, 1,047 salivary gland tumors (0.2%) were found. The male to female ratio was 1:1.2. The age of patients ranged from 1 to 88 years with an average age of 47.1 years. 721 cases were benign tumors (68.8%) while 326 cases (31.2%) were malignant tumors. The parotid gland was the most common site (62.7%), followed by the submandibular gland (18.8%), and the intraoral minor salivary glands (18.0%). Among the intraoral minor salivary glands, palate was the most common site (49.2%). The most common benign and malignant tumors were pleomorphic adenoma and mucoepidermoid carcinoma. CONCLUSIONS: Salivary gland tumors are rare. Compared with Western countries, the prevalence of polymorphous low-grade adenocarcinoma (PLGA) in Southeast Asia is low. Data from this study may be helpful for dentists in making differential diagnoses.

Ring1a/b polycomb proteins regulate the mesenchymal stem cell niche in continuously growing incisors.

Rodent incisors are capable of growing continuously and the renewal of dental epithelium giving rise to enamel-forming ameloblasts and dental mesenchyme giving rise to dentin-forming odontoblasts and pulp cells is achieved by stem cells residing at their proximal ends. Although the dental epithelial stem cell niche (cervical loop) is well characterized, little is known about the dental mesenchymal stem cell niche. Ring1a/b are the core Polycomb repressive complex1 (PRC1) components that have recently also been found in a protein complex with BcoR (Bcl-6 interacting corepressor) and Fbxl10. During mouse incisor development, we found that genes encoding members of the PRC1 complex are strongly expressed in the incisor apical mesenchyme in an area that contains the cells with the highest proliferation rate in the tooth pulp, consistent with a location for transit amplifying cells. Analysis of Ring1a(-/-);Ring1b(cko/cko) mice showed that loss of Ring1a/b postnatally results in defective cervical loops and disturbances of enamel and dentin formation in continuously growing incisors. To further characterize the defect found in Ring1a(-/-);Ring1b(cko/cko) mice, we demonstrated that cell proliferation is dramatically reduced in the apical mesenchyme and cervical loop epithelium of Ring1a(-/-);Ring1b(cko/cko) incisors in comparison to Ring1a(-/-);Ring1b(fl/fl)cre- incisors. Fgf signaling and downstream targets that have been previously shown to be important in the maintenance of the dental epithelial stem cell compartment in the cervical loop are downregulated in Ring1a(-/-);Ring1b(cko/cko) incisors. In addition, expression of other genes of the PRC1 complex is also altered. We also identified an essential postnatal requirement for Ring1 proteins in molar root formation. These results show that the PRC1 complex regulates the transit amplifying cell compartment of the dental mesenchymal stem cell niche and cell differentiation in developing mouse incisors and is required for molar root formation.

Investigation of basement membrane proteins in a case of granular cell ameloblastoma.

Granular cell ameloblastoma is a rare, benign neoplasm of the odontogenic epithelium. A case of massive granular cell ameloblastoma in a 44-year-old Thai female is reported. Histopathological features displayed a follicular type of ameloblastoma with an accumulation of granular cells residing within the tumor follicles. After treatment by partial mandibulectomy, the patient showed a good prognosis without recurrence in a 2-year follow-up. To characterize the granular cells in ameloblastoma, we examined the expression of basement membrane (BM) proteins, including collagen type IV, laminins 1 and 5 and fibronectin using immunohistochemistry. Except for the granular cells, the tumor cells demonstrated a similar expression of BM proteins compared to follicular and plexiform ameloblastomas in our previous study, whereas the granular cells showed strong positivity to laminins 1 and 5 and fibronectin. The increased fibronectin expression in granular cells suggests a possibility of age-related transformation of granular cells in ameloblastoma.

A clinicopathologic study of oral leukoplakia and erythroplakia in a Thai population.

OBJECTIVES: To determine the prevalence of oral leukoplakia and erythroplakia in a group of Thai patients and to study the clinical and pathologic features of these 2 lesions. METHOD AND MATERIALS: Cases having provisional diagnoses of leukoplakia and erythroplakia between 1973 and 2004 were retrieved from the files of the Department of Oral Pathology, Faculty of Dentistry, Mahidol University. Clinical and pathologic features were reviewed and analyzed. RESULTS: Of 7,177 biopsy specimens, 123 cases (1.7%) of leukoplakia and 9 cases (0.13%) of erythroplakia were found. There was no significant gender predilection in leukoplakia (male:female = 1.2:1). The peak of age-frequency distribution of leukoplakia was in the fourth decade among men and fifth decade among women. The most common site of leukoplakia was buccal mucosa (28.5%), followed by alveolar mucosa (18.7%) and tongue (16.3%). Microscopic study of leukoplakia revealed hyperkeratosis with or without acanthosis in 60.9% of cases, epithelial dysplasia in 10.6%, and squamous cell carcinoma in 4.9%. Erythroplakia was found in 6 men and 3 women. It was most frequently seen during the seventh decade of life. The palate was the most common site. Epithelial dysplasia and squamous cell carcinoma were found in 6 patients with erythroplakia (66.7%). CONCLUSIONS: Leukoplakia occurred 13 times more frequently than erythroplakia. However, squamous cell carcinoma was more frequently found in erythroplakia cases. Both lesions were found most frequently in elderly individuals and affected men more than women.