High-risk human papillomavirus in patients with oral leukoplakia and oral squamous cell carcinoma-A multi-centre study in Sweden, Brazil and Romania.

OBJECTIVES: Although causal associations between oral leukoplakia (OL), oral squamous cell carcinoma (OSCC) and high-risk human papillomavirus (HR-HPV) have been speculated upon in several reports, conclusive evidence has not been presented. This study investigates whether the number of cases of HR-HPV in OL has increased over time and whether the prevalence of HR-HPV-positive OL differs in various parts of the world. PATIENTS AND METHODS: A total of 432 patients with OL from Sweden, Brazil and Romania were analysed. Patients were divided into historical (1992-2002) and contemporary (2011-2017) cohorts from the respective countries. Seventeen patients with OL developed oral squamous cell carcinoma (OSCC). A real-time PCR assay, targeting HPV sub-types 6,11,16,18,31,33,35,39,45,52,56,58 and 59, was performed to detect HR-HPV in patients with OL. RESULTS: In the Swedish and Romanian cohorts, none of the investigated HPV sub-types were detected. In the Brazilian cohorts, five patients with OL (3%) were positive for HR-HPV, including four patients from the contemporary cohort (HPV 16, 31, 33) and one from the historical cohort (HPV 11). All the cases of OL that transformed into OSCC were HR-HPV-negative, as were the corresponding tumours. CONCLUSIONS: In summary, the prevalence of HR-HPV in OL is low in all the tested countries, and the incidence has not changed over time. HR-HPV in OL does not seem to be a driver of oncogenesis.

Patient-reported pain after surgical removal of leukoplakia - an observational 1-year follow-up study.

OBJECTIVE: Oral leukoplakia (OL) presents as a white lesion of the oral mucosa and is not typically associated with the sensation of pain. OL should be surgically removed when possible because it is considered a potentially malignant oral disorder (PMOD). This study assessed the pain sensations experienced by patients in association with the occurrence and surgical treatment of OL. METHODS: Inclusion criteria were: a clinical diagnosis of OL; biopsy excision; and observation for at least 12 months in the ORA-LEU-CAN study. At the first visit, all the patients were asked about the occurrence of symptoms within the lesion. Ninety-four subjects were assessed over a period of 1 year. All patients underwent complete removal of OL. The patient cohort was divided into three sub-groups: (i) no pain before excision and at the 1-year follow-up; (ii) pain before excision; and (iii) pain at the 1-year follow-up. RESULTS: Overall, pain was reported by 21.3% of the patients at the study start whereas 13.8% of the patients reported pain 1 year after surgical treatment. Patient-reported pain from the lesion at study inclusion was significantly associated with lesions found on the lateral side of the tongue (p=.002). Pain reported by patients one year after surgery was significantly related to female gender (p=.038) and the presence of epithelial cell dysplasia (p=.022). CONCLUSION: We conclude that surgical removal of OL results in a low risk of long-term post-surgical pain. However, OL located on the lateral side of the tongue and in OL with dysplasia are more likely to be associated with pain.

Circadian rhythms and gene expression during mouse molar tooth development.

OBJECTIVES: Incremental markings in dental enamel suggest that the circadian clock may influence the molecular underpinnings orchestrating enamel formation. The aim of this study was to investigate whether the genes and microRNAs (miRNAs) oscillate in a circadian pattern during tooth and enamel development. MATERIAL AND METHODS: Comparative gene and miRNA expression profiling of the first mandibular molar tooth germ isolated at different time-points during the light and night period was performed using microarrays and validated using real-time RT-PCR. Bioinformatic analysis was carried out using Ingenuity Pathway Analysis (IPA), and TargetScan software was used in order to identify computationally predicted miRNA-mRNA target relationships. RESULTS: In total, 439 genes and 32 miRNAs exhibited significantly different (p < 0.05) levels of expression in the light phase compared with the night phase tooth germs. Genes involved in enamel formation, i.e. Amelx, Ambn, Amtn, and Odam, oscillated in a circadian pattern. Furthermore, the circadian clock genes, in particular Clock and Bmal1, oscillated in mouse molar tooth germ during 24-h intervals. The expression of Clock and Bmal1 was inversely correlated with the expression of miR-182 and miR-141, respectively. CONCLUSIONS: MiRNAs, including miR-182 and miR-141, are involved in the control of peripheral circadian rhythms in the developing tooth by regulating the expression of genes coding for circadian transcription factors such as CLOCK and BMAL1. Regulation of circadian rhythms may be important for enamel phenotype, and the morphology of dental enamel may vary between individuals due to differences in circadian profiles.

Nested PCR for detection of HSV-1 in oral mucosa.

BACKGROUND: It has been estimated that 15%-20% of human tumours are driven by infection and inflammation, and viral infections play an important role in malignant transformation. The evidence that herpes simplex virus type 1 (HSV-1) could be involved in the aetiology of oral cancer varies from weak to persuasive. This study aimed to investigate by nested PCR (NPCR) the prevalence of HSV-1 in samples from normal oral mucosa, oral leukoplakia, and oral squamous cell carcinoma (OSCC). MATERIAL AND METHODS: We investigated the prevalence of HSV-1 in biopsies obtained from 26 fresh, normal oral mucosa from healthy volunteers as well as 53 oral leukoplakia and 27 OSCC paraffin-embedded samples. DNA was extracted from the specimens and investigated for the presence of HSV-1 by nested polymerase chain reaction (NPCR) and DNA sequencing. RESULTS: HSV-1 was detected in 14 (54%) of the healthy samples, in 19 (36%) of the oral leukoplakia samples, and in 14 (52%) of the OSCC samples. The differences were not statistically significant. CONCLUSIONS: We observed a high incidence of HSV-1 in healthy oral mucosa, oral leukoplakia, and OSCC tissues. Thus, no connection between OSCC development and presence of HSV-1 was detected.

Telemedicine--a complement to traditional referrals in oral medicine.

INTRODUCTION: Introducing telemedicine into clinical practice has not been without difficulties. Within the framework of the European Union project "Health Optimum," telemedicine consultations with specialists at the Department of Oral & Maxillofacial Surgery at Uppsala University Hospital (Uppsala, Sweden) have been offered to dentists in the public dental health service. The aim is to streamline the consultation process, improve/develop the skills of the participating dentists and dental hygienists, and save time and money for patients, healthcare authorities, and society. SUBJECTS AND METHODS: Patient records are collected in a database for demonstration and discussion, and the system is also available for referrals. Both medical and dental photographs and x-rays are digitized in the same system. These can be viewed during telemedicine rounds and by the consultants at the hospital prior to a consultation. Secure, interactive conferencing software is used, which provides a quick, easy, and effective way to share video and data over the Internet. Both parties can demonstrate different parts of an image using a pointer or a drawing system. Conference phones are presently used for verbal communication. RESULTS: Ten patients were discussed during telemedicine rounds (3 males and 7 females), all of whom would normally have been referred to a specialist. As a result of the telemedicine round, 2 were referred to a specialist, whereas diagnoses were made for the other 8, and treatment was suggested. The dental health clinic could thus provide treatment without the need for referral to a consultant. CONCLUSIONS: The telemedicine system described here allows patient care to be provided rapidly and more economically. Future plans include "live" rounds using a videocamera, providing the possibility to relay real-time information about the intraoral situation. A camera is being developed and should preferably be permanently installed chair side.

Combined loss of expression of involucrin and cytokeratin 13 is associated with poor prognosis in squamous cell carcinoma of mobile tongue.

BACKGROUND: This study aimed to evaluate the prognostic significance of expression levels of involucrin (IVL), cytokeratin (CK)-10 and -13 at different intratumor sites (tumor center and invading area) of oral tongue squamous cell carcinoma (OTSCC). METHODS: IVL, CK13 and CK10 expression levels were examined in a multicenter cohort of 146 OTSCCs using immunohistochemistry. External mRNA datasets were used for expression analysis and/or to validate survival associations. RESULTS: External transcriptomic datasets showed downregulation of IVL and KRT13 in oral malignancies including OTSCC as compared to normal controls. The combined loss of IVL and CK13 expression at the invading core but not at the center core was significantly associated with poor differentiation and reduced 5-year overall survival. Multivariate Cox analysis confirmed the loss of CK13 and IVL expression to be an independent prognostic factor. Transcriptomic dataset corroborated immunohistochemistry results. CONCLUSIONS: Combined expression levlels of IVL and CK13 might be useful as prognostic biomarkers in OTSCC.

Expression of p53, p63, podoplanin and Ki-67 in recurring versus non-recurring oral leukoplakia.

Oral leukoplakia (OL), a potentially malignant disorder, recurs in 40% of cases after surgical removal. Recurrence is a risk factor for malignant transformation. We aimed to examine the prognostic significance of four biomarkers related to cell proliferation: p53, p63, podoplanin (PDPN) and Ki-67 in predicting recurrence. Formalin-fixed-paraffin-embedded specimens from excised OL (n = 73, 33 recurrent; 40 non-recurrent) were collected in a prospective study. Immunohistochemistry was used to visualise expression of p53, p63, PDPN and Ki-67. Image analysis software was used for quantification of p53-, p63- and Ki-67-expressing cells, while PDPN was analysed visually. The expression of all four proteins were higher in recurrent compared with non-recurrent OL, only expression of p53 was statistically significant. In uni- and multivariable Cox regression analyses of individual markers, expression of p63 was significantly associated with higher recurrence risk (p = 0.047). OL with a combined high expression of both p53 and p63 had a significantly higher risk to recur [Log Rank, p = 0.036; multivariate Cox, HR: 2.48 (1.13-5.44; p = 0.024)]. Combination of p53 and p63 expression may be used as a prognostic biomarker for recurrence of OL.

COVID-19 salivary signature: diagnostic and research opportunities.

The COVID-19 (caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)) epidemic started in Wuhan (Hubei Province, China) in mid-December 2019 and quickly spread across the world as a pandemic. As a key to tracing the disease and to implement strategies aimed at breaking the chain of disease transmission, extensive testing for SARS-CoV-2 was suggested. Although nasopharyngeal/oropharyngeal swabs are the most commonly used biological samples for SARS-CoV-2 diagnosis, they have a number of limitations related to sample collection and healthcare personnel safety. In this context, saliva is emerging as a promising alternative to nasopharyngeal/oropharyngeal swabs for COVID-19 diagnosis and monitoring. Saliva collection, being a non-invasive approach with possibility for self-collection, circumvents to a great extent the limitations associated with the use of nasopharyngeal/oropharyngeal swabs. In addition, various salivary biomarkers including the salivary metabolomics offer a high promise to be useful for better understanding of COVID-19 and possibly in the identification of patients with various degrees of severity, including asymptomatic carriers. This review summarises the clinical and scientific basis for the potential use of saliva for COVID-19 diagnosis and disease monitoring. Additionally, we discuss saliva-based biomarkers and their potential clinical and research applications related to COVID-19.

Transcriptomic analysis of MicroRNA expression in enamel-producing cells.

There is little evidence for the involvement of microRNAs (miRNAs) in the regulation of circadian rhythms during enamel development. Few studies have used ameloblast-like cell line LS8 to study the circadian rhythm of gene activities related to enamel formation. However, the transcriptomic analysis of miRNA expression in LS8 cells has not been established yet. In this study, we analyze the oscillations of miRNAs in LS8 cells during one-day cycle of 24 h by next generation deep sequencing. After removal of low quality reads, contaminants, and ligation products, we obtained a high number of clean reads in all 12 samples from four different time points. The length distribution analysis indicated that 77.5% of clean reads were between 21 and 24 nucleotides (nt), of which 35.81% reads exhibited a length of 22 nt. In total, we identified 1471 miRNAs in LS8 cells throughout all four time-points. 1330 (90.41%) miRNAs were identified as known miRNA sequences, whereas 139 (9.59%) were unannotated and classified as novel miRNA sequences. The differential expression analysis showed that 191 known miRNAs exhibited significantly (P-value < 0.01) different levels of expression across three time-points investigated (T6, T12, and T18) compared to T0. Verification of sequencing data using qRT-PCR on six selected miRNAs suggested good correlation between the two methods. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed significant enrichment of predicted target genes of differentially expressed miRNAs. The present study shows that miRNAs are highly expressed in LS8 cells and that a significant number of them oscillate during one-day cycle of 24 h. This is the first transcriptomic analysis of miRNAs in ameloblast-like cell line LS8 that can be potentially used to further characterize the epigenetic regulation of miRNAs during enamel formation.

Recurrence rates after surgical removal of oral leukoplakia-A prospective longitudinal multi-centre study.

Oral leukoplakia (OL) is a potentially malignant oral disorder. The Gold Standard treatment is to remove surgically the OL. Despite optimal surgery, the recurrence rates are estimated to be 30%. The reason for this is unknown. The aim of this study was to investigate the clinical factors that correlate with recurrence after surgical removal of OL. In a prospective study data were collected from 226 patients with OL. Forty-six patients were excluded due to incomplete records or concomitant presence of other oral mucosal diseases. Overall, 180 patients proceeded to analysis (94 women and 86 men; mean age, 62 years; age range, 28-92 years). Clinical data, such as gender, diagnosis (homogeneous/non-homogeneous leukoplakia), location, size, tobacco and alcohol use, verified histopathological diagnosis, and clinical photograph, were obtained. In patients who were eligible for surgery, the OL was surgically removed with a margin. To establish recurrence, a healthy mucosa between the surgery and recurrence had to be confirmed in the records or clinical photographs. Statistical analysis was performed with the level of significance set at P<0.05. Of the 180 patients diagnosed with OL, 57% (N = 103) underwent surgical removal in toto. Recurrence was observed in 43 OL. The cumulative incidence of recurrence of OL was 45% after 4 years and 49% after 5 years. Fifty-six percent (N = 23) of the non-homogeneous type recurred. Among snuff-users 73% (N = 8) cases of OL recurred. A non-homogeneous type of OL and the use of snuff were significantly associated with recurrence after surgical excision (P = 0.021 and P = 0.003, respectively). Recurrence was also significantly associated with cancer transformation (P<0.001). No significant differences were found between recurrence and any of the following: dysplasia, site of lesion, size, multiple vs. solitary OL, gender, age, use of alcohol or smoking. In conclusion, clinical factors that predict recurrence of OL are non-homogeneous type and use of snuff.

Combined Testing of p16 Tumour-suppressor Protein and Human Papillomavirus in Patients With Oral Leukoplakia and Oral Squamous Cell Carcinoma.

BACKGROUND: Oral leukoplakia (OL) is a potentially malignant oral mucosal disorder. A casual association between OL, oral squamous cell carcinoma (OSCC) and human papillomavirus (HPV) infection has been suggested, but no conclusive evidence has been presented. p16, a tumour-suppressor protein, is used as a surrogate marker for HPV infection. The aim of this study was to investigate how overexpression of p16 correlates with HPV infection in OL and in OSCC. PATIENTS AND METHODS: Seventy-four patients with OL and 13 with OSCC with p16 overexpressed, were analyzed by immunohistochemistry visualizing p16 and a real-time polymerase chain reaction (PCR) assay targeting HPV types 6, 11, 16, 18, 31, 33, 35, 39, 45, 52, 56, 58 and 59. RESULTS: Overexpression of p16 was observed in 18% of patients with OL. None of the HPV subtypes were detected by PCR analysis in patients with OL. In the p16-positive OSCC specimens, 38% were also HPV16-positive. CONCLUSION: Overexpression of p16 was not found to be a reliable biomarker for HPV infection in patients with OL and OSCC.

Circadian clock and oral cancer.

The circadian clock is comprised of a master component situated in the hypothalamic suprachiasmatic nucleus and subordinate clock genes in almost every cell of the body. The circadian clock genes and their encoded proteins govern the organism to follow the natural signals of time, and adapt to external changes in the environment. The majority of physiological processes in mammals exhibit variable circadian rhythms, which are generated and coordinated by an oscillation in the expression of the clock genes. A number of studies have reported that alteration in the expression level of clock genes is correlated with several pathological conditions, including cancer. However, little is known about the role of clock genes in homeostasis of the oral epithelium and their disturbances in oral carcinogenesis. The present review summarizes the current state of knowledge of the implications of clock genes in oral cancer. It has been demonstrated that the development of oral squamous cell carcinoma undergoes circadian oscillation in relation to tumor volume and proliferation rate. The circadian clock gene period (PER)1 has been associated with oral cancer pathogenesis and it is suggested that changes in the expression of PER1 may exhibit an important role in the development, invasion, and metastasis of oral squamous cell carcinoma. However, its role remains elusive and there is a need for further research in order to understand the underlying mechanisms of the clock genes in oral cancer pathogenesis.

Regulatory roles of microRNAs in human dental tissues.

MicroRNAs (miRNAs) are a class of small, non-coding RNAs that provide an efficient pathway for regulation of gene expression at a post-transcriptional level. Tooth development is regulated by a complex network of cell-cell signaling during all steps of organogenesis. Most of the congenital dental defects in humans are caused by mutations in genes involved in developmental regulatory networks. Whereas the developmental morphological stages of the tooth development already are thoroughly documented, the implicated genetic network is still under investigation. The involvement of miRNAs in the regulation of tooth genetic network was suggested for the first time in 2008. MiRNAs regulate tooth morphogenesis by fine-tuning the signaling networks. Unique groups of miRNAs are expressed in dental epithelium compared with mesenchyme, as well as in molars compared with incisors. The present review focuses on the current state of knowledge on the expression and function of miRNAs in human dental tissues, including teeth and the surrounding structures. Herein, we show that miRNAs exhibit specific roles in human dental tissues and are involved in gingival and periodontal disease, tooth movement and eruption, dental pulp physiology including repair and regeneration, differentiation of dental cells, and enamel mineralization. In light of similarities between the tooth development and other organs originating from the epithelium, further understanding of miRNAs` function in dental tissues may have wide biological relevance.

Prevalence of human papillomavirus in oral lichen planus in an Iranian cohort.

CONTEXT: Oral lichen planus (OLP) is a chronic inflammatory mucocutaneous disease with female predominance with the potential for malignant transformation. Human papillomavirus (HPV) is associated with both malignant and benign disease in the head and neck region. AIMS: The present study assesses the prevalence of high-risk HPV-16 and HPV-18 in tissue and saliva samples from an Iranian population diagnosed with OLP. SUBJECTS AND METHODS: Deoxyribonucleic acid was extracted and investigated using polymerase chain reaction from tissue and saliva samples of the same individuals from 40 OLP cases and saliva samples of 40 healthy controls. STATISTICAL ANALYSIS: The prevalence of data was compared using the Chi-square test and inter-group differences were analyzed using Fisher's exact test. RESULTS: OLP specimens were HPV-positive in 11 of 40 (27.5%) cases compared with three of 40 (7.5%) saliva specimens, representing a statistically significant difference (P = 0.0367). HPV-16 and HPV-18 were positive in eight of 40 (20%) OLP tissues and three of 40 (7.5%) saliva samples. Five of the 40 healthy saliva samples were positive for HPV-16. In the OLP patients with dysplasia, four of seven tissue samples were HPV-positive; threeof these four were HPV-16- positive in comparision with seven of 33 HPV-positive samples from OLP patients without dysplasia. CONCLUSIONS: Biopsies were more accurate than saliva analysis for evaluating HPV prevalence in OLP patients. HPV prevalence was higher in dysplastic than nondysplastic OLP lesions in this Iranian cohort.

Comparison between single PCR and nested PCR in detection of human papilloma viruses in paraffin-embedded OSCC and fresh oral mucosa.

BACKGROUND: Infection with human papilloma virus (HPV) has been implicated as one of the risk factors for the development of oropharyngeal cancer. Many different HPV tests exist, and information regarding their specific technical, analytical, and clinical properties is increasing. AIM: This study aimed to compare the level of detection of HPV using two reliable polymerase chain reaction (PCR) methods, nested PCR (NPCR) and single PCR (SPCR), in archival paraffin-embedded oral squamous cell carcinoma (OSCC) samples and fresh oral mucosa specimens. MATERIALS AND METHODS: The presence of HPV genome in two groups of tissue samples was analyzed: (i) 57 paraffin-embedded OSCC samples from Sudan and (ii) eight healthy fresh oral mucosal samples from Swedish volunteers. The specimens were tested by SPCR with primer pair MY9/MY11 and NPCR using GP5+/GP6+ primer sets. RESULTS: Eighteen (32%) out of the 57 paraffin-embedded OSCC samples, and five (62%) out of the eight fresh clinically healthy samples were found to be HPV-positive with NPCR. With SPCR, four (7%) out of the paraffin-embedded OSCC samples were HPV-positive. A statistically significant difference between HPV-positive and -negative samples was found when comparing NPCR and SPCR in OSCC and fresh oral mucosa (p<0.0001). The comparative test between SPCR and NPCR showed 100% sensitivity and 69% specificity for OSCC. CONCLUSION: The use of the GP5+/GP6+ nested PCR increased the positivity rate, efficiency rate and sensitivity of HPV detection in oral samples significantly and should be considered as the method of choice.

Prevalence of Epstein-Barr virus in oral squamous cell carcinoma, oral lichen planus, and normal oral mucosa.

OBJECTIVE: The Epstein-Barr virus (EBV) is associated with both malignant and benign diseases in the head and neck region. In several studies it has also been associated with oral squamous cell carcinoma (OSCC). Oral lichen planus (OLP) is a disease with unknown origin, and viral antigens have been proposed as etiologic agents. Smoking and alcohol habits are known risk factors for oral cancer development. In this study, the prevalence of EBV in OSCC and OLP was investigated, along with the effect of smoking, alcohol use, and age on EBV prevalence. STUDY DESIGN: We examined 29 patients with OSCC, 23 with OLP, and 67 with clinically healthy oral mucosa. For EBV DNA analysis, a nested polymerase chain reaction method was used. RESULTS: The overall EBV prevalence in patients with oral disease was 32.1%. Of the OSCC patients, 37.9% were EBV positive; and of the OLP patients, 26.1% were EBV positive. Both percentages were statistically significant compared with that of control patients (7.3%). The difference in EBV prevalence between the smoking control group and the nonsmoking control group was insignificant. Increased age did not enhance EBV prevalence. CONCLUSIONS: This investigation shows that EBV is present in oral diseases such as OSCC and OLP. Smoking, alcohol use, or age does not seem to be a risk factor for EBV infection. The etiologic role of EBV in OSCC and OLP needs to be examined in a prospective follow-up study.

Viruses and oral cancer. Is there a link?

Oral squamous cell carcinoma (OSCC) is the most common malignant tumour of the oral cavity. The aetiology of epithelial cancer of the head and neck is considered to be a multifactorial, sequential process. DNA viruses are found in many different cancers and are also capable of transforming cells to a malignant phenotype. Human Papilloma Virus (HPV) has been proposed as risk factors in OSCC development and HPV type 16 is the most important subtype. Other oncogenic virus species i.e., Epstein-Barr Virus and Herpes Simplex Virus Type 1 have been proposed to be involved in oral carcinogenesis. However, no convincing evidence exist that they are an established risk factor in OSCC. Therefore more studies are needed in order to clarify the different aspects of virus involvement. Here, we review the existing literature on viral involvement in oral cancer.

Smokeless tobacco, viruses and oral cancer.

Oral Squamous Cell Carcinoma (OSCC) is the most common epithelial malignancy in the oral cavity. OSCCs and their variants constitute over 90% of oral malignancies, and the disease is associated with poor prognosis. OSCC is a complex malignancy where environmental factors, viral infections, and genetic alterations most likely interact, and thus give rise to the malignant condition. The International Agency for Research on Cancer (IARC) in 2007 concluded: "there is sufficient evidence in humans to establish smokeless tobacco as carcinogenic, i.e. smokeless tobacco causes cancer of the oral cavity and pancreas". ST products contain a large array of carcinogens, although the number found is actually smaller than in cigarette smoke. Worldwide, ST products have many different names depending on the region where it is produced. However, there are two main types of ST, chewing tobacco and snuff. It is estimated that approximately 150 million people in the world use ST. Herein, we review available literature regarding smokeless tobacco and oral Carcinogenesis. We also discuss the role of viral infections in combination with ST in OSCC development.

A retrospective study of patients with mandibular fractures treated at a Swedish University Hospital 1999-2008.

BACKGROUND: Fracture of the mandible is one of the most common fractures of the maxillofacial skeleton. However, the etiology, gender, and age distribution vary between different regions and countries, and the purpose of this study was to evaluate the current trend of patients with mandibular fractures at the Department of Oral and Maxillofacial Surgery, in Uppsala, Sweden. AIM: The aim of this retrospective study was to analyze patients with mandibular fractures treated in the University Hospital of Uppsala (the county capital of Uppland) Sweden during a 10-year period (1999-2008). MATERIALS AND METHODS: This study was designed as a retrospective study of patients admitted to the Department of Oral and Maxillofacial Surgery at Uppsala University Hospital, Sweden. The location of fractures was evaluated clinically by the surgeon and on the X-rays. We classified the data according to gender, age, etiology, day of the week, month of the year, fracture site, and method of treatment of the fractures. RESULTS: Records were collected from patient charts from 266 patients. One hundred eighty-seven patients (70%) with mandibular fractures were of male gender, and 132 patients (50%) were aged 16-30 years. Interpersonal violence constituted the most common etiological factor for mandibular fractures (24%), followed by falls (23%). Forty-nine percentages of the patients were treated surgically, and 51% were treated conservatively. There was an increase of the annual incidence of fractures toward the end of the period, even though not statistically significant. CONCLUSIONS: Mandibular fractures occurred primarily among younger men between 16- and 30-year-old. Condyle fractures were the most common fracture site and 50% of the patients required surgery. Summer months and weekends were the most common time of mandibular fractures.

Loss of 5-hydroxymethylcytosine and TET2 in oral squamous cell carcinoma.

AIM: Epigenetic modifications, such as DNA methylation, are considered important in the regulation of target genes in cancer development. 5-Hydroxymethylcytosine (5hmC) was recently discovered to be related to the process of malignant transformation. The influence of DNA methylation in oral squamous cell carcinomas (OSCC) is not fully-understood. Therefore, the aim of the present study was to investigate the DNA methylation pattern in OSCC compared to healthy oral epithelium. MATERIALS AND METHODS: Oral mucosal samples from patients with OSCC (n=15) and healthy mucosa (n=12) were analyzed using immunohistochemistry with antibodies against 5hmC, 5mC and ten-eleven-translocation-2 (TET2). RESULTS: A significant decrease in 5hmC and TET2 expression was found in OSCC compared to healthy oral epithelium. In contrast, there was a significant increase in 5mC expression in OSCC compared to healthy epithelium. CONCLUSION: Our results indicate that loss of 5hmC is an epigenetic event of OSCC.