Association of the XPD and XRCC3 gene polymorphisms with oral squamous cell carcinoma in a Northeastern Brazilian population: A pilot study

Objectiveto evaluate the association between XPD and XRCC3 polymorphisms and oral squamous cell carcinoma (OSCC).Designthe sample consisted of 54 cases of OSCC and 40 cases of inflammatory fibrous hyperplasia (IFH). Genotypes were determined by the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method.ResultsXPD-Lys/Gln was more common in IFH (n = 28; 70%) than in OSCC (n = 24; 44.4%) (OR: 0.3; p < 0.05). XPD-Gln was more frequent in high-grade lesions (0.48) than in low-grade lesions (0.21) (OR: 3.4; p < 0.05). The Gln/Gln genotype was associated with III and IV clinical stages (OR: 0.07; p < 0.05). XRCC3-Met was more frequent in OSCC (0.49) than in IFH (0.35) (OR: 2.6; p < 0.05). The Met/Met genotype was associated with the presence of metastases (OR: 8.1; p < 0.05) and with III and IV clinical stages (OR: 0.07; p < 0.05).Conclusionsin this sample, the frequency of XPD-Gln in IFH suggests that this variant may protect against OSCC. The presence of the XRCC3-Met allele seems to contribute to the development of OSCC, metastases and more advanced stages in these lesions.     

Potential chemotherapeutic effects of diosgenin,zoledronic acid and epigallocatechin-3-gallate on PE/CA-PJ15 oral squamous cancer cell line

ObjectiveTo study the potential chemotherapeutic effects of Diosgenin, zoledronic acid and Epigallocatechin-3-gallate on oral squamous cell cancer (OSCC).Materials and methodsCell viability, migration, apoptosis and cell cycle evaluation assays were performed in order to assess the effects of different doses of Diosgenin, zoledronic acid and Epigallocatechin-3-gallate on the PE/CA-PJ15 cell line.ResultsDoses of 100 μM of diosgenin or zoledronic acid reduced cell viability significantly after 72 h (p < 0.001), as well as increasing apoptosis (p < 0.05 and p < 0.01 respectively). All three agents reduced cell migration and altered the cell cycle, each at a different phase of the cycle.Conclusionwhile DG and ZA reduced cell viability, increased apoptosis, inhibited cell migration and modified the cell cycle in different ways, EGCG only modified the cell cycle and reduced cell migration. These agents present a potential chemotherapeutic effect on PE/CA-PJ15 OSSC cell line, which have to be further studied.     

Effects of risedronate on osteoblastic cell cultures

ObjectiveBisphosphonates (BPs) have been widely used in the treatment of bone disorders due to their ability to modulate bone turnover. The biological mechanisms through BFs exert their effects on osteoclasts are well established. However, the role of BFs on the osteoblasts is controversial. The present study aimed to evaluate the effects of risedronate on osteoblastic cells.DesignMC3TE-E1 cells were exposed to risedronate at 0, 10⁻⁸, 10⁻⁶, 10⁻⁴, and 10⁻³ M. The following parameters were assayed: (1) cell proliferation by hemocytometer counting after 24, 48 and 72 h, (2) cell viability by MTT assay after 24, 48 and 72 h, (3) Type I Collagen quantification by ELISA after 24, 48 and 72 h, (3) alkaline phosphatase activity after 7 and 10 days and (4) matrix mineralization after 14 days.ResultsAfter 24 h, risedronate did not affect both cell proliferation and viability (p > 0.05). However, after 48 and 72 h, a decrease in cell proliferation and viability was detected in osteoblastic cultures exposed to risedronate at 10⁻⁴ and 10⁻³ M (p < 0.05). After 48 and 72 h, Type I Collagen synthesis was stimulated by risedronate at 10⁻⁴ M (p < 0.05). High levels of ALP activity were detected in cultures exposed to risedronate at 10⁻⁴ M after 7 and 10 days (p < 0.05). After 14 day, high calcium content was observed in cultures exposed to risedronate at 10⁻⁴ M (p > 0.05).ConclusionThese results indicated that risedronate can promote osteoblast differentiation.     

Overexpression of immunosuppressive cytokines is associated with poorer clinical stage of oral squamous cell carcinoma

ObjectiveThe aim of this study was to evaluate the expression of IL-10 and TGF-β2 in oral squamous cell carcinoma (OSCC) and its relationship with prognostic clinical and microscopic parameters.DesignImmunohistochemistry was used to assess the expression of IL-10 and TGF-β2 in OSCC samples from 43 patients who had undergone surgical excision and neck dissection. Metastatic lymph nodes were included in the study (n = 23). Samples of healthy oral mucosa (n = 20) were used as controls. The sections were evaluated using a semi-quantitative method in conjunction with staining intensity.ResultsOur findings showed that the expression of IL-10 and TGF-β2 by neoplastic and stromal cells was high in most of the OSCC samples (>70% of samples), especially when compared to the controls (≅10% of samples) (P < 0.05). OSCC neoplastic cells in cervical lymph nodes were also positive for IL-10 and TGF-β2. An association between high expression of IL-10 by neoplastic cells and advanced clinical stage (T3-T4) was verified (P = 0.02). Although not statistically significant, the expression of TGF-β2 was also augmented in advanced stage tumours.ConclusionsThese data suggest that the ability of OSCC neoplastic cells to secrete immunosuppressive cytokines could contribute to clinical progression by maintaining a microenvironment conducive to evasion and tumour proliferation.     

Probiotic intervention influences the salivary levels of Matrix Metalloproteinase (MMP)-9 and Tissue Inhibitor of metalloproteinases (TIMP)-1 in healthy adults

ObjectiveTo study the effect of orally administered Bifidobacterium animalis subsp. lactis BB-12 and Lactobacillus rhamnosus GG on the salivary levels of Matrix Metalloproteinases (MMP)-8, MMP-9 and of Tissue Inhibitor of Metalloproteinases (TIMP)-1 in healthy adults. Furthermore, the correlations between MMP-8, MMP-9 and TIMP-1 and plaque and gingival indices, salivary mutans streptococci and lactobacilli counts, and stimulated saliva secretion rate were analysed.DesignThe salivary samples originated from a randomized controlled trial where healthy student volunteers consumed probiotic or placebo lozenges twice a day for four weeks. The saliva samples were collected and clinical parameters measured at the baseline and at the end of the original study. For this study, the salivary levels of MMP-8, MMP-9 and TIMP-1 were analysed with immunofluorometric assay (IFMA) and enzyme-linked immunosorbent assay (ELISA).ResultsIn the probiotic group (n = 29), salivary MMP-9 levels increased (p < 0.01) and TIMP-1 levels decreased (p < 0.01) significantly during the intervention. Furthermore, MMP-9/TIMP-1 ratio differed significantly from the baseline level (p < 0.01). These changes were not observed in the control group (n = 31). In the whole data, salivary MMP-9 and gingival index correlated (r = 0.260, p < 0.05 at baseline and r = 0.354, p < 0.01 at the end of the study). Intergroup differences or correlations with other clinical parameters were not found. Probiotic consumption did not affect the saliva flow rate.ConclusionsIncreased MMP-9 and decreased TIMP-1 levels in saliva may indicate that probiotics have immunomodulatory effects in the oral cavity. Furthermore, increased salivary MMP-9 levels may be an indication of the defensive potential of matrix metalloproteinases.     

Promoter methylation of MGMT in oral carcinoma: A population-based study and meta-analysis

IntroductionThe relevance of DNA methylation of O⁶-methylguanine-DNA methyltransferase (MGMT) in relation to several cancers and other disorders has been extensively explored in several cancer types.AimsTo ascertain the significance of DNA methylation of MGMT promoter in oral squamous cell carcinoma (OSCC), we undertook a study to a) analyse the methylation patterns of MGMT gene promoter in afflicted and normal population of coastal Karnataka, b) determine the expression status of MGMT in oral cancer cell lines (CAL-27 and SCC-4) and its relationship to DNA methylation and c) performed a meta-analysis of the published data.MethodsBisulfite sequencing of MGMT promoter region was performed on non-malignant/malignant oral samples, and oral cancer cell lines, followed by gene expression studies. Further, using a systematic search, 1024 publications were retrieved from PubMed, Scopus, Google Scholar and Web of Science and 23 relevant articles were reviewed.ResultsSignificant association of MGMT promoter methylation with OSCC (p < 0.0001) was observed in the case-control study. The studies chosen for meta-analysis showed predictive significance of MGMT gene promoter. Overall, we obtained a statistically significant (p < 0.0001) association for both sensitivity and specificity of MGMT DNA promoter methylation in oral cancer cases without publication bias. Gene expression was significantly elevated in both oral cancer cell lines (p < 0.03) after treatment with a demethylating agent (5-Aza-2′-deoxycytidine).ConclusionDNA promoter hypermethylation and gene expression of MGMT may associate with recursive mutagenesis and is a promising biomarker for OSCC prediction. Studies suggest further validation in large distinct cohorts to facilitate translation to clinics.     

Cytotoxicity and potential anti-inflammatory activity of velutin on RAW 264.7 cell line differentiation: Implications in periodontal bone loss

ObjectivesHypoxia-inducible factor-1α (HIF-1α) has been implicated in periodontal tissue inflammation and possibly in osteoclast differentiation, while polyphenols are known to be anti-inflammatory natural compounds that are capable of regulating the NF-κB protein complex pathway. The objective of this study was to investigate cytotoxicity and HIF-1α expression through the NF-κB pathway by polyphenol velutin (Euterpe oleracea Mart.), found in the pulp of acai fruit, during inflammatory RAW 264.7 differentiation.DesignRAW 264.7 mouse monocyte macrophage cells were stimulated with RANKL (30 ng/mL) and Porphyromonas gingivalis lipopolysaccharide (1 μg/mL). Cells were treated with various concentrations of velutin (0.5–2 μM) to check for viability, morphology, osteoclast differentiation, and HIF-1α expression (Western blot).ResultsAlamar blue cell viability assay showed no toxicity to RAW cells with the use of velutin in all concentrations tested (p > 0.05). Velutin did not induce cell apoptosis based on caspase 3/7 assay (p > 0.05). Fluorescence images stained by DAPI showed no alteration in the morphology of RAW cell nuclei (p > 0.05) treated with velutin. TRAP assays demonstrated a dose-dependent reduction in osteoclast formation by velutin when compared with control (p < 0.05). Velutin showed a reduction in HIF-1α expression related to IκB phosphorylation when compared with control (p < 0.001).ConclusionsAt the tested concentrations, velutin was not cytotoxic to RAW 264.7 and differentiated cells. Velutin reduced osteoclast differentiation and downregulated HIF-1α through the NF-κB pathway.     

Genetic polymorphism of interleukin-10 (-A592C) among oral cancer with squamous cell carcinoma

ObjectiveInterleukin-10 (IL-10) is a pleiotropic cytokine with either immunosuppressive or immunostimulative activities. It has been reported that in cancer, the promoter region polymorphism of IL-10 (-A592C) alters both the expression and serum levels of this cytokine. In the present study, we have addressed the question as to whether the single nucleotide polymorphisms (SNPs) at positions −592 A/C in the IL-10 gene promoter, could predispose an individual to oral squamous cell carcinoma (OSCC).DesignWe analyzed the genotype of the IL-10 (-A592C) gene, in 250 histopathologically confirmed OSCC patients and similar number of healthy volunteers taken as controls, in an Indian population by using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. Allele and genotype frequencies were analyzed by the Student's t-test and the chi-squared test, and strength of associations by the odds ratio (OR) with 95% confidence intervals.ResultsThe genotype and allele distribution of IL-10 (-A592C) gene polymorphism was significantly different between OSCC cases and controls (genotype AA vs AC: OR 2.87; 95 % CI 1.50–5.48; p = 0.0016 and AA vs CC: OR 4.08; 95 % CI 1.98–8.41; p = 0.0002). The −592 C alleles were found to be significantly different among OSCC cases and controls (OR: 1.44, 95% CI: 1.12–1.85, p < 0.0051).ConclusionsThe IL-10 gene promoter region (-592) A/C polymorphism is significantly associated with reduced risk of OSCC. The OSCC group had a significantly greater frequency of genotype AA as compared to control group.     

Study of the participation of MMP-7, EMMPRIN and cyclophilin A in the pathogenesis of periodontal disease

Background and objectivePeriodontal disease is an infectious disease resulting from the immunoinflammatory response of the host to microorganisms present in the dental biofilm which causes tissue destruction. The objective of this study was to evaluate the immunohistochemical expression of matrix metalloproteinase 7 (MMP-7), extracellular matrix metalloproteinase inducer (EMMPRIN) and cyclophilin A (CypA) in periodontal disease.DesignGingival tissue samples were divided as follows: clinically healthy gingiva (n = 32), biofilm-induced gingivitis (n = 28), and chronic periodontitis (n = 30). Histological sections of 3 μm were submitted to immunoperoxidase method and undergone quantitative analysis. The results were analyzed statistically by the Mann-Whitney and Spearman correlation tests, with the level of significance set at 0.05 (α = 0.05).ResultsImmunopositivity for MMP-7, EMMPRIN and CypA differed significantly between the three groups, with higher percentages of staining in chronic periodontitis specimens, followed by chronic gingivitis and healthy gingiva specimens (p < 0.05). Immunoexpression of CypA and MMP-7 was higher in the intense inflammatory infiltrate observed mainly in cases of periodontitis (p < 0.05). CypA expression was positively correlated with MMP-7 (r = 0.831; p < 0.001) and EMMPRIN (r = 0.289; p = 0.006). In addition, there was a significant positive correlation between probing depth and expression of MMP-7 (r = 0.726; p < 0.001), EMMPRIN (r = 0.345; p = 0.001), and CypA (r = 0.803; p < 0.001).ConclusionThese results suggest that MMP-7, EMMPRIN and CypA are associated with the pathogenesis and progression of periodontal disease.     

Cytotoxicity and effect on protease activity of copolymer extracts containing catechin

ObjectiveTo evaluate cytotoxicity and effect on protease activity of epigallocatechin-gallate extracted from experimental restorative dental copolymers in comparison to the control compound chlorhexidine.MethodsCopolymer disks were prepared from bis-GMA/TEGDMA (70/30 mol%) containing no compound (control) or 1% w/w of either epigallocatechin-gallate or chlorhexidine. MDPC-23 odontoblast-like cells were seeded with the copolymer extracts leached out into deionized water. Cell metabolic activity was quantified by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay at 24, 48, 72 h. Inhibition of protease activity by resin extracts was measured by a collagenolytic/genatinolytic enzyme activity assay and gelatin zymography. Data for MTT and protease inhibition were analyzed using two-way ANOVA followed by Tukey or Bonferroni post hoc tests (α = 0.05).ResultsThe MTT revealed that at 72 h, extracts from control (16.7%) and chlorhexidine (22.3%) copolymers induced significant reduction in cell metabolism (p < 0.05). All copolymer extracts caused enzymatic inhibition in a dose dependent manner (p < 0.01). Even when highly diluted, epigallocatechin-gallate extract had a significant antiproteolytic activity (p < 0.05). Zymograms showed that all extracts reduced activity of MMP-2 and MMP-9 (pro- and active forms), with MMP-9 exhibiting the highest percentage inhibition revealed by densitometry.ConclusionsEpigallocatechin-gallate and chlorhexidine extracts did not exert cytotoxicity on evaluated cells when compared to control extracts. Both compounds retained antiproteolytic activity after extraction from a dental copolymer.Clinical significanceOnce extracted from a dental copolymer, epigallocatechin-gallate is not cytotoxic and retains antiproteolytic activity. These results may allow incorporation of epigallocatechin-gallate as a natural-safe alternative to chlorhexidine in functionalized restorative materials.     

Association of thalassemia major and gingival inflammation: A pilot study

ObjectivesThis cross-sectional study aimed to investigate the relationship between thalassemia major (TM) and gingival inflammation through the salivary, serum, and gingival crevicular fluid (GCF) levels of matrix metalloproteinase (MMP)-8, MMP-9 and tissue inhibitor of MMP (TIMP)-1.MethodsBiofluid samples and full-mouth clinical periodontal recordings were obtained from 29 otherwise healthy patients with TM and 25 systemically healthy (SH) individuals. Biofluid samples were evaluated by immunofluorometric assay (IFMA) and enzyme-linked immunoassays (ELISAs). Data were tested statistically by Kolmogorov Simirnov, Mann–Whitney U tests, Spearman correlation analysis.ResultsAge, smoking status, bleeding on probing, plaque index were similar in the study groups, but probing depth, gender data exhibited significant differences (p = 0.037 for both). Salivary MMP-8, MMP-9, TIMP-1 concentrations were significantly higher in the TM than SH group (p = 0.014; p < 0.001; p = 0.042, respectively). Serum TIMP-1 concentrations were significantly higher; MMP-8/TIMP-1, MMP-9/TIMP-1 molar ratios were significantly lower in the TM than SH group (p < 0.001; p = 0.005; p = 0.022, respectively). Very few GCF samples revealed biochemical data above the detection limits. Numerous correlations were found between clinical periodontal parameters and biochemical data.ConclusionsIt may be suggested that TM may exacerbate the local inflammatory response as manifested in salivary MMP-8, MMP-9, TIMP-1 levels.     

Hypermethylation of Death-Associated Protein Kinase (DAPK1) and its association with oral carcinogenesis - An experimental and meta-analysis study

ObjectivesThe value of abnormal DNA methylation of DAPK1 promoter and its association with various cancers have been suggested in the literature. To establish the significance of DNA methylation of DAPK1 promoter in oral squamous cell carcinoma (OSCC), we a) performed a case-control study, b) evaluated published data for its utility in the diagnosis and prognosis of OSCC and c) identified the association of DAPK1 gene expression with promoter DNA methylation status.DesignBisulfite gene sequencing of DAPK1 promoter region was performed on non-malignant and malignant oral samples. Further, using a systematic search, 330 publications were retrieved from PubMed, Scopus, and Google Scholar and 11 relevant articles were identified.ResultsSignificant association of DAPK1 promoter methylation with OSCC (p < 0.0001) was observed in the case-control study. The studies chosen for meta-analysis showed prognostic and predictive significance of DAPK1 gene promoter, despite defined inconsistencies in few studies. Overall, we obtained a statistically significant (p-value < 0.001) association for both sensitivity and specificity of DAPK1 DNA promoter methylation in oral cancer cases, without publication bias.ConclusionDNA hypermethylation of DAPK1 gene promoter is a promising biomarker for OSCC prediction/prognostics and suggests further validation in large distinct cohorts to facilitate translation to clinics.     

In vitro dentine remineralization with a potential salivary phosphoprotein homologue

ObjectiveAdvantages of introducing a salivary phosphoprotein homologue under standardized in vitro conditions to simulate the mineral-stabilizing properties of saliva have been proposed. This study longitudinally investigates the effects of casein, incorporated as a potential salivary phosphoprotein homologue in artificial saliva (AS) solutions with/without fluoride (F) on in vitro dentine lesion remineralization.DesignThin sections of bovine root dentine were demineralized and allocated randomly into 6 groups (n = 18) having equivalent mineral loss (ΔZ) after transverse microradiography (TMR). The specimens were remineralized using AS solutions containing casein 0 μg/ml, F 0 ppm (C₀–F₀); casein 0 μg/ml, F 1 ppm (C₀–F₁); casein 10 μg/ml, F 0 ppm (C₁₀–F₀); casein 10 μg/ml, F 1 ppm (C₁₀–F₁); casein 100 μg/ml, F 0 ppm (C₁₀₀–F₀) or casein 100 μg/ml, F 1 ppm (C₁₀₀–F₁) for 28 days with TMR taken every 7 days.ResultsSurface mineral precipitation, evident in group C₀–F_1, was apparently inhibited in groups with casein incorporation. Repeated measures ANOVA with Bonferroni correction revealed higher ΔZ for non-F and non-casein groups than for their counterparts (p < 0.001). Subsequent multiple comparisons showed that mineral gain was higher (p < 0.001) with 10 μg/ml casein than with 100 μg/ml when F was present in the earlier stages of remineralization, with both groups achieving almost complete remineralization after 28 days.ConclusionCasein is a potential salivary phosphoprotein homologue that could be employed for in vitro dentine remineralization studies. Concentration related effects may be clinically significant and thus must be further examined.     

Hypoxia inhibits mineralization ability of human dental pulp cells treated with TEGDMA but increases cell survival in accordance with the culture time

ObjectiveTo evaluate the cytotoxicity and mineralization effects of TEGDMA in human dental pulp cells (hDPCs) under hypoxic and normoxic culture conditions.DesignCell viability was evaluated using XTT assay after incubation periods of 24, 48, or 72 h. The expression of mineralization-related genes (osteonectin, osteopontin, dentin sialophosphoprotein, collagen type 1) and heme oxygenase 1 (HO-1) was assessed by quantitative real-time polymerase chain reaction at 24 and 72 h.ResultsIn XTT assay, viability was higher in 0.3, 1, 2, 4, and 5 mM groups in the presence of 21% O₂ after 24 h (p < 0.05). Additionally, while 0.3, 1, 2 mM groups had higher cell viability in the presence of 21% O₂ after 48 h (p < 0.05), in 3 mM groups cell viability was higher under 3% O₂ than 21% O₂ after both 24 and 48 h (p < 0.05). 1–3 mM groups had higher cell viability under 3% O₂ after 72 h (p < 0.05). There was no difference between 4 and 5 mM groups with regards to cell viability after 48 or 72 h (p > 0.05). In the gene expression study, TEGDMA-treated hDPCs showed lower mineralization potential in the presence of 3% than with 21% O₂ (p < 0.05). hDPCs revealed higher HO 1 expression in 0.3 and 1 mM groups under hypoxic than under normoxic conditions after a 72-h time period (p < 0.001).ConclusionsHypoxic conditions increased cell survival in accordance with the culture period but inhibited the odontoblastic differentiation of hDPCs treated with TEGDMA.     

VEGF expression from human dysplastic or malignant oral epithelium may be related to mast cell density and the subsequent angiogenetic phenomena

Vascular endothelial growth factor (VEGF) is an angiogenic cytokine and mast cells play a role in neoangiogenesis in various malignancies. The aim of the present study was to elucidate the role of VEGF and mast cells in the early stages of tumorigenesis in oral squamous cell carcinoma (OSCC). Immunohistochemistry was conducted to study VEGF expression and microvessel density (MVD) in 49 tissue samples, 31 OSCCs, 13 leukoplakias (8 with and 5 without dysplasia) and 5 samples from normal oral tissue. Counterstaining with tolouidine blue was conducted to reveal mast cells. The number of microvessels and mast cells were counted at the same optical field. A gradually increased VEGF expression was observed from normal oral epithelium to leukoplakia and OSCC. MVD was found to increase significantly between normal oral tissue and OSCC (p = 0.000). The number of mast cells was found to increase significantly between normal oral tissue, dysplasia (p = 0.012) and OSCC (p = 0.000). In the early stages of tumorigenesis in OSCC, VEGF, which is secreted by the epithelium, is gradually increased immediately affecting the population of mast cells, which are then related to the increase of microvessels.     

Extracapsular spread and FDG PET/CT correlations in oral squamous cell carcinoma

The purpose of this study was to evaluate the use of ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) to identify extracapsular spread (ECS) with histologic correlations in oral squamous cell carcinoma (OSCC). The medical records of 80 patients who underwent of FDG PET/CT for OSCC before surgery were reviewed. ECS was present in 60% (24/40) dissected necks and in 55% (39/71) of dissected cervical levels. A significant difference was found between the maximum standardized uptake (SUV_max) values of cervical lymph nodes with ECS and without ECS (3.33 ± 1.91 vs. 1.12 ± 1.24, p < 0.001). When receiver operating characteristic (ROC) curve analysis and SUV_max values were used to detect ECS, the area under the ROC curve was 0.864 ± 0.045 (p < 0.001). At an optimal SUV_max cut-off value of 2.25 the sensitivity and specificity were 85% and 88%, respectively. The presence of ECS and a SUV_max > 2.25 had a significant adverse effect on 5-year disease specific survival. A SUV_max > 2.25 was found to be associated with a greater risk of cervical lymph node metastasis in OSCC.     

Amplification and up-regulation of microRNA-30b in oral squamous cell cancers

ObjectivesMicroRNAs (miRNAs) are negative regulators of protein coding genes which are frequently deregulated in mammary cancers. Over-expression of microRNA-30b (hsa-miR-30b) is implicated in tumour invasion and immunosuppression during metastasis. The chromosome locus of MIR30B gene, 8q24, is frequently amplified in oral squamous cell cancers (OSCCs). In the present study, we aimed to investigate the copy number variations as well as expression levels of MIR30B gene in OSCCs and analyse their correlation with tumour stage.DesignQuantitative real-time PCR was performed to examine the copy number of MIR-30B gene as well as hsa-miR-30b expression in 107 OSCC samples with matched adjacent normal tissues. Proportional odds regression and two-way repeated measurement ANOVA were used to analyse the association between copy number variations (CNVs) and hsa-miR-30b expression.ResultsCopy number gains of MIR-30B gene were detected in a relatively large percentage of the OSCC samples (27.1%, 29 out of 107) and were correlated with tumour stages (p < 0.001). MIR30B gene amplification also showed a close correlation with hsa-miR-30b over-expression in OSCCs (p < 0.001). On the other hand, enhanced miR-30b expression was also detected in a group of OSCC samples with unaltered copy number of MIR30B gene.ConclusionsCopy number increase of MIR30B is frequent in advanced OSCC and is correlated with hsa-miR-30b over-expression. Sporadic OSCCs can exhibit different mechanisms of MIR30B regulation.     

Evaluation of physical properties of fiber-reinforced composite resin

ObjectivesThis study aimed to investigate physical properties of a fiber-reinforced CAD/CAM resin disc, which included woven layers of multi-directional glass fibers.MethodsFiber orientations of CAD/CAM specimens (TRINIA, SHOFU) were specified as longitudinal (L), longitudinal-rotated (LR), and anti-longitudinal (AL). A fiber-reinforced composite (everX posterior, GC (E)) and a conventional composite (Beauti core flow paste, SHOFU (B)) were also tested.A three-point bending test and a tensile test with notchless prism-shaped specimens were conducted using a universal testing machine (AUTOGRAPH AG-IS, Shimadzu). A water absorption test was also carried out after the specimens were stored in water for 24 h or 1 week. Flexural strength and fracture toughness were obtained by conducting a three-point bending test.ResultsTRINIA L and LR groups showed significantly high flexural strength (254.2 ± 22.3 and 248.8 ± 16.7 MPa, respectively). Those were approximately 2.5 times higher than those in AL, E, and B groups (96.8–98.0 MPa) (p < 0.05, ANOVA and Tukey HSD test). No significant difference was shown in flexural modulus among the experimental groups. The fracture toughness in L group (9.1 ± 0.4 MPa/m^1/2) was found to be significantly higher than those in other groups (1.9–3.0 MPa/m^1/2; p < 0.05). TRINIA group demonstrated significantly lower water absorption (4.7 ± 1.9 μg/mm³) than did E (16.1 ± 3.1 μg/mm³) and B (17.3 ± 3.7 μg/mm³) groups (p < 0.05).SignificanceTRINIA demonstrated distinct anisotropy. TRINIA can be used as a superior restorative material when specifying directions of its fiber mesh layers.     

Adhesion procedures for CAD/CAM indirect resin composite block: A new resin primer versus a conventional silanizing agent

PurposeThe purpose of this study was to evaluate the effectiveness of both a resin primer containing methyl methacrylate (MMA) and a silanizing agent on bonding to indirect resin composite blocks, using two types of build-up hybrid resin composites.MethodsSHOFU BLOCK HC (Shofu) specimens were blasted with alumina, after which one of two surface treatments was applied: CERA RESIN BOND (Shofu, the Silane group) or HC primer (Shofu, the MMA group). Resin composites made using either Solidex Hardura (SDH, Shofu) or Ceramage Duo (CMD, Shofu) were built up and micro-tensile bond strength (μTBS) values were measured after storage in water for either 24 h or 6 months (n = 24 per group). The fracture surfaces after μTBS measurements and the resin block/build-up resin interfaces were observed by scanning electron microscopy (SEM).ResultsThe bond strength of the Silane/SDH group significantly decreased after 6 months (p < 0.001), whereas in the MMA group there was no significant loss after 24 h or 6 months (p = 0.99). In the CMD group, the bond strength after 6 months was significantly lowered in both the Silane group (p < 0.001) and the MMA group (p < 0.001), but the latter still showed greater adhesion. SEM images demonstrated that the matrix resin was partially destroyed at the fracture surfaces of the MMA group and fracture surface unevenness was observed.ConclusionsA primer containing MMA produced stronger bonding to CAD/CAM resin even after long-term aging compared to a silane treatment.     

Influence of microcapsule parameters and initiator concentration on the self-healing capacity of resin-based dental composites

ObjectiveFracture is one of the main causes for failure of resin-based composite restorations. To overcome this drawback, self-healing resin-based composites have been designed by incorporation of microcapsules. However, the relationship between their self-healing capacity and microcapsule and resin parameters is still poorly understood. Therefore, the objective of this study was to systematically investigate the effect of initiator concentration (in the resin) and microcapsule size and concentration on the self-healing performance of commercially available flowable resin-based composites.MethodsPoly(urea-formaldehyde) (PUF) microcapsules containing acrylic healing liquid were synthesized in small (33 ± 8 μm), medium (68 ± 21 μm) and large sizes (198 ± 43 μm) and characterized. Subsequently, these microcapsules were incorporated into a conventional flowable resin-based composite (Majesty Flow ES2, Kuraray) at different contents (5–15 wt%) and benzoyl peroxide (BPO) initiator concentrations (0.5–2.0 wt%). Fracture toughness (K_IC) of test specimens was tested using a single edge V-notched beam method. Immediately after complete fracture (K_IC-initial), the two fractured parts were held together for 72 h to allow for healing. Subsequently, fracture toughness of the healed resin-based composites (K_IC-healed) was tested as well.ResultsThe fracture toughness of healed dental composites significantly increased with increasing microcapsule size and concentration (2 wt% BPO, p < 0.05). The highest self-healing efficiencies (up to 76%) were obtained with microcapsules sized 198 ± 43 um.Significancecommercially available resin-based composites can be rendered self-healing most efficiently by incorporation of large microcapsules (198 ± 43 μm). However, long-term tests on fatigue and wear behavior are needed to confirm the clinical efficacy.