Objective: To discuss the association between single nucleotide polymorphisms in let-7 and genetic susceptibility to head and neck cancer (HNC) in Han Chinese. Methods: In this case-control study, 503 newly and histologically confirmed HNC patients were consecutively recruited as cases and 900 cancer-free controls were randomly selected as controls. Designed questionnaires were used to acquire patients’ information on demographic data and age, sex, smoking, and alcohol consumption. Approximate 5 ml of venous blood sample was collected from each subject for DNA extraction and genotyping. We used TaqMan allelic discrimination assay to genotype two polymorphisms of rs10877887 and rs13293512 in let-7. The associations of SNPs with HNC risks were estimated by computing the crude and adjusted odds ratios (ORs) and their 95% confidence intervals (CIs) using logistic regression analyses. Results: The frequencies of genotype TT, CT and CC of rs10877887 were 45.7% (227/503), 42.9% (213/503) and 11.4% (57/503) in case group; while separately 40.8% (361/900), 47.7% (422/900) and 11.5% (101/900) in control group. The frequencies of genotype TT, CT and CC of rs13293512 were 31.9% (157/503), 52.3% (257/503) and 15.8% (78/503); while separately 30.2% (270/900), 49.2% (439/900) and 20.6% (194/900) in control group. Logistic regression analyses showed that there was no statistic significe in the relationship between rs10877887 and susceptibility to HNC (CC+CT/TT：adjusted OR=0.82, 95% CI: 0.90-1.23, P=0.087), while rs13293512 CC genotype significantly decreased susceptibility to HNC (CC/TT+CT：adjusted OR=0.73, 95% CI：0.55-0.98, P=0.039). Conclusions: The polymorphism of rs13293512 in let-7 may be a biomarker of susceptibility to HNC in Han Chinese.

Objective：By studying the expression of stromal interaction molecule 1 (STIM1) in lesions of oral lichen planus (OLP) to explore the pathogenesis of OLP. Methods：The mRNA expression level of STIM1 in 37 OLP and 17 healthy adults’ peripheral blood lymphocytes was determined by real-time fluorescence quantitative PCR．The protein expression level of STIM1 from the same populations was determined by Western blot. Results：Increased STIM1 mRNA expression was found in OLP to be higher than that in healthy populations (P<0.01); Expression of STIM1 protein was significantly higher in OLP than in healthy controls (P<0.01). Differences between two groups of OLP patients were not statistically significant (P＞0.05). Conclusions：Increased expressions of STIM1 in OLP peripheral blood lymphocytes, which can regulate lymphocyte immune response，may be involved in the pathogenesis of OLP and play an important role in the process of repeated episodes of OLP.

Objective: The main reason for restoration failure is secondary caries at the tooth-restoration margins, caused by acid production by biofilms. The objectives of this study were to incorporate quaternary ammonium dimethylaminododecyl methacrylate (DMAHDM) into dental adhesive resin and to investigate their effects on antibacterial and dentin bonding properties. Methods: DMADDM was synthesized and incorporated into a commercial dentin bonding agent at mass fraction of 10%. The dental plaque microcosm biofilm model was used to evaluate biofilm viability. The dentin bond strength was measured in 4-point flexure test before and after water-aging or biofilm incubation for 14 days. Results: Incorporating DMADDM significantly reduced the biofilm viability. 14-day biofilm degradation had much less influence on the bond strength of dental adhesive resin containing DMADDM. Conclusions: Bonding agent containing DMADDM had strong antibacterial potency and could resist the oral environment degradation. The novel dentin bonding agent may have wide applicability in clinic.

Objective：To explore the effect of vitamin C on the development of the induced rat periapical periodontitis. Methods：Periapical disease was induced by pulp exposure of the mandibular first molar on 100 male Wistar rats (8-week-old). Rats were divided into vitamin C groups (0，0.1, 0.5 and 1 mg/mL, respectively) and a normal group, then were sacrificed on day1, 3, 7, 14 and 21. We measured the area of the periapical lesions by radiographs and obtain histological results by HE staining. Results：Periapical lesions were significantly expanded from day 3 onwards, in a time-dependent manner, and peaked on day 21. There was no difference between day 1 and 3. On day 7,14 and 21，the periapical lesion areas of practiced groups were remarkably lower than that of the control group. The periapical lesions of the 0.1 mg/mL group was the lowest among all practiced groups. Vitamin C groups also had less bone resorption lacunae and smaller alveolar bone destruction. Conclusions：To some extent，vitamin C effectively inhibited the progress of the rat periapical periodontitis.

Objective：To evaluate the effects of Prevotella intermedia supernatant on the expression of receptor activator of NF-κB ligand (RANKL) and osteoprotegerin (OPG) in human gingival fibroblasts (HGFs). Methods：The HGFs were treated with gradient Prevotella intermedia supernatant. HGFs were observed under the microscope. The real-time RT-PCR and Western blot analysis were used for testing the expression of RANKL and OPG, and the RANKL/OPG ratio was calculated. Results：The number of cells decreased with increase of the supernatant concentration. At 50 μg/mL, no cell survival could be observed under the microscope. The ratio of RANKL/OPG was increased in the cells treated with 12.5 μg/mL of Prevotella intermedia supernatant（P < 0.01）. Conclusions：Prevotella intermedia supernatant could disrupt the homeostasis of RANKL/OPG, destroy the microenvironment of osteoclast differentiation. Prevotella intermedia supernatant may play a regulatory role in osteoclast differentiation and bone resorption in periodontitis.

Objective： To analyze the correlation between synuclein gamma (SNCG) and matrix metalloproteinase-9 (MMP-9) and the clinicopathological features of tumor,we investigated the expression of SNCG and MMP-9 in oral and maxillofacial carcinoma and its adjacent tissues. Methods：Immunohistochemistry method was used to detect the expression of SNCG and MMP-9 in oral and maxillofacial carcinoma and its adjacent tissues. Results：The incidence rate of SNCG and MMP-9 in oral and maxillofacial carcinoma was 78.0% (117/150) and 68.68%(103/150), respectively. While that of SNCG and MMP-9 in its adjacent tissues was 8.0%(11/150) and 14.0%(21/150), respectively. There were significantly differences in SNCG and MMP-9 between them(P<0.001). The incidence rates of SNCG and MMP-9 were higher in poorly or medium differentiated (P<0.001). However, the expression of SNCG and MMP-9 between poorly differentiated and well differentiated carcinoma had no significant difference. According to stages, the incidence rates of SNCG and MMP-9 in Ⅲ-Ⅳ period were significantly higher than those inⅠ-Ⅱ period, and there were significant difference (SNCG: χ2＝4.20, P＝0.041; MMP-9: χ2＝26.66, P＝0.000). The expression of SNCG and MMP-9 in metastatic tumor were higher (SNCG: 90.77%；MMP-9:93.85% ) than that in non-metastatic tumor (SNCG: 68.24%; MMP-9: 49.41%), and there were significant difference(SNCG: χ2＝10.09, P＝0.0014; MMP-9: χ2＝33.80, P＝0.000). Conclusions：The excessive expression of SNCG and MMP-9 in oral and maxillofacial carcinoma,which was positively associated with the pathologic process, differentiation degree of carcinoma, and TNM stages of tumor.The expression of SNCG and MMP-9 are expected to be the marker in the tumor of oral and maxillofacial carcinoma for the judgment of advancement and prognosis.

Objective：To evaluate the inhibitory activity of farnesol to the Candida albicans biofilms in vitro. Methods：Candida albicans biofilms were formed on flat-bottom 96-well microtiter plates and two study groups (12 h and 24 h Group) were noted, then respectively incubated in the RPMI 1640 with different concentration of farnesol (100-900 μmol/L) for 24 h. The XTT reduction assay was employed to evaluate the inhibitory effect of farnesol to the biofilms. Biofilm morphology was observed by inverted microscope. Results：Farnesol （100 -900 μmol/L） has inhibitory effect on Candida albicans biofilms. With the increase of concentration of farnesol, the inhibition rate tends to increas.The sessile minimal inhibitory concentration 50%（SMIC50）of 12 h biofilm is 200 μmol/L；the SMIC50 of 24 h biofilm is 200 μmol/L. Conclusions：The inhibitory effect of Farnesol on C. albicans biofilms was obvious.The inhibitory potency of farnesol was associated with its concentration and the phase of biofilms,and the farnesol of higher concentration are more effective than that of lower concentration.

[Abstract] Objective: To evaluate the effect of skimmed milk and Hank’s Balanced Salt Solution(HBSS) as preservation medium on the root healing and root resorption of the avulsed tooth. Methods: 60 bilateral maxillary first molars was extracted from 30 6-week-old SPF Wistar male rats which were divided randomly into 5 groups (6 each group), and replanted back into the sockets after being placed in HBSS or skimmed milk or in the air ( as negative control) for 30 min right after extraction. The rats were sacrificed on day1,day 3,day7,day14 and day21 after the operation. Then the maxillae were scanned with X-ray and the shadow areas around the mesial roots of maxillary first molars were measured with IPP software. After decalcification, the specimens were made into slices and stained with HE for histological observation. Results: There was no statistically significant difference between milk group and HBSS group regarding the shadow area around mesial roots；the inflammation of root tissue in milk group came to a lighter degree with less resorption, and both the two groups had periodontal healing. Conclusions: Skimmed milk can be recommended as suitable substitute for HBSS and promoted in large-scale.

Objective: To evaluate the effects of Er:YAG laser irradiation on shear strength between glass ionomer cement and root surface dentine in the elderly.Methods: 20 elderly people(≥ 60) and 20 young people(≤20) teeth without caries and subfissure were selected from February to May in 2013 for this study and made into specimens with exposed root dentine by cutting the enamel and dentine around the mesial enamel-dentinal junction with a diamond bur.The teeth from the elderly people were randomly divided into group G1 and group G2 and teeth from the young people were randomly divided into group M1 and M2,each group contain ten teeth.Using defferent technique to prepare the root dentine:Group G1 and group M1 using Er:YAG laser irradiation,group G2 and group M2 using diamond bur preparation. Embedding each tooth in self-curing plastic,filling with GC Fuji Ⅸ GP CAPSULE glass ionomer cement after preparing the root dentine.All specimens were tested shear strength in universal testing machine after thermocycling.Results: The comprison of shear strength showes: group G1 >group G2, group M1 >M2, group G1> M1, group G2 > M2 (P < 0.05).Conclusions: Er: YAG laser irradiation can improve the shear strength between the dentin and ionomer cement; root dentin of elderly ones obtain higher shear bond strength to ionomer cement than the ones of the young.

Runt-related transcription factor 2(Runx2) is a transcription factor that plays an important role in osteoblast differentiation and tooth development, which regulates the expression of specific matrix proteins of teeth and bone at transcriptional level. Considering the characteristics of Runx2 and its expression during tooth development, it is speculated that Runx2 play important role in tooth development and mineralization.

T lymphocytes is an important immune cells and is in the central part of the entire immune response.The activation and proliferation of T cells is the basis for its implementation immune function. But under normal culture conditions, T lymphocyte is in a quiescent state, survival time in vitro is short, transfection and subculture is very difficult. Therefore, the proliferation and activation of T lymphocyte becomes a hotspot.The study found that there are many ways for activation of T lymphocytes and after activation T cell will express different cell surface activation molecules in different period , marking the success of activation. The article makes review on the progress of the activation methods in vitro in recent years of T lymphocyte