Gene network analysis of the transcriptome impact of methylated microRNAs on oral squamous cell carcinoma.

BACKGROUND: Oral squamous cell carcinoma (OSCC) is one of the most common head and neck squamous cell tumors. MicroRNAs and DNA methylation, as epigenetic mechanisms, regulate the expression of oncogenes and tumor suppressor genes, contributing to the carcinogenic development. However, the current knowledge on the genetic and epigenetic landscape of OSCC is still limited. OBJECTIVES: To assess the transcriptomic impact of microRNAs found to be methylated through Infinium genome-wide methylation profiling of archived OSCC tissues, and to analyze their biological role using gene network analysis. MATERIAL AND METHODS: We used the Infinium array-based methylation assay to assess the genome-wide methylation status at the single-CpG-site level of DNA purified from archived OSCC tissue samples. After quality control, filtering out poorly performing probes and normalization of data, we identified the differentially methylated microRNA loci. We performed a literature-based analysis of OSCC transcriptomic data to identify the predicted target genes for each microRNA, followed by individual network and pathway enrichment analyses. RESULTS: The analysis of Infinium methylation array data revealed 1469 differentially hypomethylated loci, 4 of which were of interest, namely hsa-microRNA-124-3, hsa-microRNA-24-1, hsa-microRNA-769, and hsa-microRNA-4500. Network and pathway enrichment analyses revealed multiple pathways modulated through DNA methylation-microRNA expression axes. CONCLUSIONS: We describe the transcriptomic impact of 4 differentially methylated microRNAs in OSCC tissues samples and discuss their role in the pathology of OSCC. These results may contribute to a better understanding of how epigenetic mechanisms such as DNA methylation and microRNAs cooperate to impact the development of OSCC.

Changes in global DNA methylation and hydroxymethylation in oral mucosa according to tobacco smoke exposure.

OBJECTIVE: This prospective clinical study comparatively investigated the effects of tobacco smoking on global methylation and hydroxymethylation in oral epithelial cells. METHODS: Buccal cells from the inside of the cheeks were collected from 47 individuals, including smokers, former smokers, and never smokers. DNA was extracted using dedicated kits. Methylated and hydroxymethylated DNA fractions were measured using assays similar to enzyme-linked immunosorbent assays. The levels of methylation and hydroxymethylation were compared among groups using unpaired two-tailed t-tests or the Mann-Whitney U test; P < 0.05 was considered statistically significant. RESULTS: There was no statistically significant difference in the average number of cigarettes between smoker and former smoker groups. Although methylation levels were lower for smokers (3.1%) and former smokers (2.16%), compared with never smokers (4.16%), these differences were not statistically significant. There was a two-fold increase in hydroxymethylation level in never smokers, compared with smokers. CONCLUSIONS: Our findings suggest that smoking leads to global reductions in both methylation and hydroxymethylation levels in oral epithelial cells in a manner influenced by the intensity and length of exposure to tobacco smoke.

Trueness and Precision of Two Intraoral Scanners: A Comparative In Vitro Study.

The aim of this study was to evaluate the accuracy of two intraoral scanners used in the dental office. A molar fixed in a typodont was prepared for a ceramic onlay. The preparation was scanned using a high-resolution scanner (reference scanner) and saved as stereolithography (STL) format. The prepared resin molar was scanned again using the intraoral scanners, and all the scans were saved as well in STL format. All STL files were compared using metrology software (Geomagic Control X). Overlapping the meshes allowed the assessment of the scans in terms of trueness and precision. Based on the results of this study, the differences of trueness and precision between the intraoral scanners were minimal.

Oral Health Knowledge, Perceptions, and Habits of Adolescents from Portugal, Romania, and Sweden: A Comparative Study.

AIMS: The study aimed to assess and compare the self-reported oral health knowledge, habits, and perceptions of adolescents in Portugal, Romania, and Sweden and the factors that may affect them. MATERIALS AND METHODS: An oral health questionnaire with 25 questions was put together in English language and translated into Portuguese, Romanian, and Swedish language to investigate and compare oral health-related knowledge, habits, and perceptions of adolescents from the different countries. A voluntary sample of 879 teenagers completed it, mean aged 14.9 (±1.83) years, from Romania (n = 455), Portugal (n = 200), and Sweden (n = 224) as part of the EuHyDens project. The survey took place between November 2015 and June 2016. RESULTS: It showed some differences between the countries studied but more similarities between Portuguese and Romanian adolescents as related to perceptions of oral health and the use of oral services. Sweden and Portugal are more similar regarding oral health habits (toothbrushing and diet) as compared to Romanian adolescents. Portuguese adolescents have a higher oral health-related knowledge. CONCLUSION: Assessment of knowledge, perceptions, and habits of a population is essential for the adequate understanding of the oral health-care needs of the society. From the data collected, several differences were found. These differences can be used for tailor interventions to minimize inequalities between countries.

Self-reported oral health-related habits, attitudes and knowledge in adults from Portugal, Romania and Sweden-A comparative study.

OBJECTIVE: The aim of the present study was to compare the self-reported oral health knowledge, habits and attitudes of adults in Portugal, Romania and Sweden, each benefitting from a different oral health system. METHODS: A cross-sectional study was conducted on 1081 adults in the three countries, using an adapted version of the WHO oral health questionnaire. This survey took place between November 2015 and June 2016. RESULTS: The mean age of the respondents was 46.85 with 95% CI (45.84, 47.86). Over 85% of the Portuguese and the Swedish, but only 55% of the Romanians, reported having 20 or more teeth left (P < 0.001). Most Swedes visit the dental office regularly, but only 50.5% of the Portuguese and 20.6% of the Romanians do so (P < 0.001). Interdental cleaning aids and fluoridated toothpaste were used the most in Sweden and the least in Romania. Daily consumption of sweets was lowest for Portugal and highest for Romania (P < 0.001), and daily intake of fresh fruits and vegetables was lowest for Sweden (P < 0.001). CONCLUSIONS: There is a difference between the three countries regarding oral health, diet, dental attendance and oral health-related quality of life, with Romania being in most need of improvement in these areas. The differences could be explained by the distinct healthcare systems adopted by the countries.

The cytotoxicity of dental alloys studied on cell culture.

The metal alloys used in dental practice are the subject of numerous discussions referring to the effect they have on oral cavity tissues. Numerous scientists established that the organic molecules did not exert a significant influence on the degradation of metallic implants. The aim of this study was to test the cytotoxic potential of the most used dental alloys, the Ni-Cr alloy and the Co-Cr alloy. The tests were made on cell culture of pure cell line dermal fibroblasts and of those obtained from skin biopsies, for both, dental alloys and their eluates. The results were compared with control samples. At seven days after inoculation, we observed the relative similarity between the Ni-Cr alloy and the Co-Cr alloy, where the cells did not detach from the plate and they grow to the edge of the material. In case of the eluates, there were no fragments detached, the cells having a relatively high confluence. Therefore, the cytotoxic effects of the two alloys are similar, even if there are speculations in the literature according to which Ni-Cr alloys would have a more pronounced effect. In conclusion, our study revealed non-cytotoxicity of these two dental alloys, and we believe so they can be used successfully in dental practice.

In vitro evaluation of laser fluorescence devices for caries detection through stereomicroscopic imaging.

The aims of this study were to determine the diagnostic accuracy and reproducibility of the laser fluorescence device (LF), and the relationship between laser fluorescence readings taken at the entrance of the fissure, ICDAS visual examination caries detection system and the histological depth of the lesion. Two hundred and forty teeth (122 human third molars and 118 bicuspids) were selected from 62 patients enrolled in the study. Visual and LF examinations (Diagnodent, Kavo, Biberach, Germany) of the occlusal surfaces were performed in vivo. After tooth extraction, histological sections were evaluated by stereomicroscopy in vitro. Statistical analysis was performed using multiple statistical methods (SPSS ver. 17). Intra-examiner reproducibility for the LF measurements was excellent: intra-class-correlation coefficient (ICC) for LF was 0.957. Kappa values for each examiner's reproducibility were 0.74-0.82. The diagnostic performance of the LF device gave a good overall diagnostic accuracy according to ICDAS II codes and histological values as indicated by the area under the ROC curve of 0.707 and 0.709 respectively. The results of the study showed acceptable diagnostic accuracy for the laser fluorescence device. This supports the view that dentists can be site specific in applying fluorescence-based devices to multiple discrete sites within the same surface. In conclusion, these diagnostic methods have different characteristics, indications and limitations for use. In order to detect caries on occlusal surfaces thoroughly, a combination of methods would be the best practice moderated by clinical knowledge and experience.

The heterogeneity of craniofacial morphology in Prader-Willi patients.

Prader-Willi syndrome is a complex genetic disorder with narrow spectrum of facial phenotypic signs, which make the clinical diagnosis difficult in some cases. There are several reports describing the craniofacial appearance of Prader-Willi patients, but there are only a few cephalometric studies for these patients. In this study were included 18 patients with Prader-Willi syndrome and a control group of 18 subjects of both sexes selected based on specific criteria. The cephalometric radiographs of the patients were taken using the standardized technique with centric teeth in occlusion and lips in relaxed position. Angular, horizontal and linear measurements were analyzed for the study group and for the control group. We established that in Prader-Willi patients, there is a decrease of the majority of parameters but the degree of this reduction varies widely between patients and clinically typical facies not always have smaller measurements which can be found in an unusual facies. Facial dysmorphism in Prader-Willi patients varies a group ranging from miss proportions that do not alter the facial architecture as regard of facial typology, skeletal class and pattern of development to a severe disturbance of those. There is a degree of clinical heterogeneity between subjects with Prader-Willi syndrome on clinical evaluation and cephalometric study confirms the heterogeneity for this patients. Because the identification of smaller dimensions for majority of parameters in children and adults, the possibility of developmental delay or growth retardation delay can be excluded. These findings are important for the orthodontist for optimum timing of orthodontic management of patients with Prader-Willi syndrome.