Epulis, a kind of inflammatory tumor-like hyperplasia, is the most common non-malignant gingival tumor which tends to occur at the gingival tissue in clinical work. As we all know, there are several different types of epulis, and we also have various classification methods simultaneously. This article discussed about the perfection of the classification methods for this kind of disease, summarized its epidemiology and clinical features based on the methods of classification, and concluded the research about pathogenesis mechanism by orientation, hoping the comprehensive discussion about this disease will provide the new standard and new ideas for clinical treatment and basic researches.

Objective　To investigate the photosensitization of photodynamic therapy (PDT) mediated by zinc phthalocyanines tetrasubstituted with carboxyl moieties on oral squamous cell carcinoma (OSCC) cells in vitro. Methods The human OSCC cell line HN4 was studied. The experiments were divided into dark reaction group and light reaction group and the cells in the light reaction group received vertical irradiation with gradient light dose. The effect of different light doses on cell proliferation was detected by Cell Counting kit-8 (CCK-8). The effects on cell cycle changes and apoptosis were determined with flow cytometry. The changes of Caspase-3, Bcl-2 expression were examined before and after the interference by Western-blot. Results Both drug concentration and light dose affected cell proliferation (P<0.05). The 50% inhibition concentration (IC50) in the dark reaction group was significantly higher than that in the light reaction groups (P<0.05). Within the certain concentration range, with the improvement of drug concentration, the S phase of the cell cycle relatively decreased, the G2/M phase relatively increased, the number of cell apoptosis increased, the Caspase-3 expression increased while the Bcl-2 expression decreased (P<0.05). Conclusion Zinc phthalocyanines tetrasubstituted with carboxyl moieties is an effective anti-cancer drug, which can effectively induce the apoptosis of OSCC.

Abstract：　Objective　 To establish an in vitro mechanical stimulation model of cranial base synchondrosis chondrocytes. To explore the effects of cyclic tensile strain (CTS) with different frequencies and elongation rates on cranial base synchondrosis chondrocytes. Methods　 Cyclic tensil stress was imposed to the second passage of cranial base synchondrosis chondrocytes by Flexcell Strain Unit-5000T. The elongation rates were 5% or 10%. The frequencies applied were 0.3Hz, 0.5Hz or 1Hz. After mechanical loading, total RNA of the cells harvested from six-well BioFlex was extracted. Real-time quantitative RT-PCR was performed to quantify the mRNA levels of type Ⅱ collagen and Sox9. Results　 Compared with the control group, the mRNA expression of Col-Ⅱ and Sox9 increased significantly(P＜0.05) when elongation rate was 10% and frequency was 0.5Hz or 1Hz. Conclusions　 Cyclic tensil stress with appropriate frequency and elongation rate can promote the synthesis of extracellular matrix of cranial base synchondrosis in vitro.

Object: To evaluate the effects of calcined tooth powder on mineralization of human periodontal ligament stem cells (hPDLSCs) in vitro and related mechanism. Method: The hPDLSCs were isolated and cultured with or without calcined tooth powder severally．The apoptosis of hPDLSCs was detected by flow cytometry. Western blot, immunofluorescence staining, alizarin red staining and alkaline phosphatase staining were performed to verify the effect of calcined tooth powder on autophagy and mineralization of hPDLSCs in vitro. Result: There are no significant differences of apoptosis between two groups of hPDLSCs. The protein level of Beclin1, ATG5 and the ratio of LC3II/LC3I of hPDLSCs cultured in calcined tooth powder conditioned medium were significantly higher than the control group hPDLSCs, while the expression of P62 was significantly lower than the control group. The calcium mineralization was significantly higher after osteogenic induction in the group of hPDLSCs calcined tooth powder treated than control group. Alkaline phosphatase expression levels were inhibited by inhibition of autophagy in the process of mineralization in vitro. Conclusions：The calcined tooth powder could up-regulate mineralization of hPDLSCs via inducing autophagy in vitro．

Abstract： Objective The caseinolytic protease (clp) gene deletion strains and complemented strains of Porphyromonas gingivalis (P.g) W83 were constructed and identified in order to make a foundation for exploring the role and mechanism of clpP gene in the pathogenesis of P.g W83. Methods The primer pair of clpP gene were designed and its upstream and downstream homologous fragments were amplified by PCR, which were cloned into plasmid pUC18. And the erythromycin resistance gene ermB from plasmid pMG36e was inserted as a screening marker to construct a recombinant plasmid，which was electrotransfered into P.g W83 to get the corresponding clpP deficient recombinant strain. The clpP gene fragment was amplified by PCR and ligated with the recombinant plasmid pUC18-△clpP-ermB and electrotransfered into the recombinant strain of P.g so as to construct the corresponding complemented recombinant strain. PCR and electrophoresis were used to identify the correctness of the sequence, and the high-expression strain was screened and selected using a resistant medium. Results The cloned clpP gene fragment was successfully cloned and introduced into the plasmid vector pUC18. The clpP gene deletion strain and the complemented strain of P.g W83 were successfully constructed and could be stably passaged in vitro. Conclusion In this study, the clpP gene deletion strain of P.g W83 was constructed using homologous recombination technology, and the method of using pUC18 plasmid as a vector to construct the complemented strains was established. What we did would help to study the role of clpP gene in the pathogenesis of P.g in future.

PURPOSE：Prepare zinc-containing coatings with different concentrations on pure titanium by micro-arc oxidation, and compare the surface morphology, element distribution and antibacterial properties. METHODS: The experiment was divided into 5 groups. Pure titanium after polishing was used as the control group (group A), Without added zinc was used as zinc-free group(group B), according to the introduction of different concentrations of zinc was divided into low-zinc group (group C)、medium-zinc group(Group D) and high-zinc group (Group E); SEM and EDS were used to observe the surface morphologyand element distribution of each group; Film coating method was used to test the inhibitory effect of Escherichia coli and Staphylococcus aureus.RESULTS: ①SEM observation: There was no pore structure on the surface of Group A, and troughs were formed. The voids on the surface of the four experimental groups showed a crater-like structure. The diameter of the nanopore on the surface of group B and C is 200-300nm, the diameter of the nanopore on the surface of group D is 100-200nm, and the diameter of nanopore on the surface of group E is 50-100nm. ② EDS showed that compared with group A and group B, zinc was successfully introduced on the surface of the coating in groups C, D, and E, and the atomic ratio increased in turn, there was a significant statistical difference(P<0.01)；③Film coating test results: There was a statistically significant difference in the number of colonies between the groups (P<0.01).Conclusion: The zinc-containing coating prepared by micro-arc oxidation has antibacterial properties, and the antibacterial property increases with the increase of zinc ion concentration.

Objective To investigate whether the acid etching has an influence on the surface morphology and internal microstructure of the machinable ceramic. Methods 32 resin infiltration ceramics and lithium disilicate glass ceramic specimens each having a size of 4 mm × 4 mm × 2 mm were prepared. After grinding and cleaning, they were randomly divided into 4 groups (n=8): (1) 4% hydrofluoric acid 20 s, (2) 9.5% hydrofluoric acid, 20 s, (3) MBEP all-ceramic treatment solution, 20 s, (4) control group. The surface roughness and three-dimensional shape of the test piece were measured by AFM, and the Si/C ratio of the resin-infiltrated ceramic and the Si/K ratio of the lithium disilicate glass ceramic were detected by EDS. Results The surface roughness parameters of the 4% and 9.5% hydrofluoric acid treated specimens of the two materials were higher than those of the control group. The Si/C ratio of the 4% and 9.5% hydrofluoric acid treated groups of the resin-infiltrated ceramics was lower than that of the control group. Scanning electron microscopy showed that the 9.5% hydrofluoric acid treatment group of both materials had a more aggressive surface etching pattern, and the all-ceramic treatment group produced a similar surface etching pattern to the control group. Conclusions Acid etching affects the surface topography and internal micro-structure of the two machinable ceramics. MBEP all-ceramic treatment liquid has a mild acid etching ability.

Objective To explore the influence of periodontitis on platform-switched implant marginal bone level alterations compared with the periodontal health group. Methods From January 2013 to January 2016，20 periodontitis patients（PP） and 20 health-periodontal patients（HP） with a total of 56 Ankylos implants in the posterior region were?incorporated into the retrospective study. Peri-implant conditions were examined and X-ray during the follow-up periods was recorded in both groups.Radiographic marginal bone loss of implants and adjacent teeth was calculated and analyzed with SPSS13.0 software package. Results No implant loss occurred in both groups with the mean prosthesis function time of 39.2±6.1months. The annual crestal bone loss was significantly greater at teeth than that around implants in the PP group （P<001）, while no statistically significant difference was found in the HP group（P=0.849）. No statistically significant difference was found between groups when comparing the peri-implant marginal bone loss（P=0.612）.Conclusions The platform-switched implant marginal bone level seemed more stable in comparison to that around the natural teeth in periodontitis patients，which can obtain the same successful implant restoration as patients with health periodontium.

Objective　To observe the repeated non-surgical therapeutic effects on mild, moderate and severe peri-implantitis. Methods 29 patients with 31 peri-implantitis implants that were repaired for over 2 years were chosen. According to the severity, there were 12 peri-implantitis implants in mild group, 10 in moderate group and 9 in severe group. The 31 peri-implantitis implants were treated twice with non-surgical combination scheme, ultrasonic mechanical debridement + air-polishing with amino acid glycine powder + minocycline ointment injection + chlorhexidine rinse. One month later, the treatment was repeated again. The PD, BOP positive site numbers, suppuration positive site numbers at the three time points were recorded respectively (the time before therapy denoted as T0, 1month after 1st therapy as T1, 1month after 2st therapy as T2). The changes of clinical parameters were compared at different time points. Results After two treatments, in mild peri-implantitis group, although the mean PD had no statistical difference (P >0.05) between T0 and T1, the difference between T0 and T2 became more obvious (P <0.05), and BOP positive site numbers decreased (T0 vs.T1, P <0.05; T0 vs.T2， P <0.01), ,at T0 none suppuration site was detected. In moderate group, PD, BOP positive site numbers, suppuration positive site numbers decreased continuously through repeated non-surgical therapy (T0 vs.T1, P <0.05; T0 vs.T2， P <0.01). In sever group, there were obvious differences in PD, suppuration positive site numbers (T0 vs.T1, P <0.05; T0 vs.T2 ，P <0.01), while there were no statistical differences in BOP among the three time points. At the time of T2, there were still deep PD sites, BOP sites, suppuration sites in both moderate and sever groups. Conclusions The non-surgical therapy can improve the clinical parameters but cannot cure the peri-implantitis thoroughly. Repeated therapy procedure is needed. Mild peri-implantitis can be basically controlled after two repeated non-surgical therapies while moderate and severe peri-implantitis cannot be controlled thoroughly.

Objective To assess function and facial appearance after instant rehabilitation of BrownⅡmaxilla defect with digital prosthesis. Methods Due to tumor resection, 10 patients with BrownⅡmaxilla defect were treated with prosthesis from August, 2016 to August, 2017 in operation. The speech intelligibility, swallowing function, masticatory function and facial symmetry were evaluated 1 month, 3 months and 6 months after operation. Results Speech intelligibility was improved significantly via prosthesis rehabilitation 1 month, 3 months and 6 months after operation (P=0.004, 0.015, 0.001, P<0.05). The effective rate and apparent rate of swallowing were respectively 25% (2/8) and 75% (6/8). The skewed degree of mouth corner, the difference of bilateral lip height, the maximum deviation distance and the change area volume decreased significantly (P=0.007, 0.044, 0.039, 0.042, P<0.05). The ratios of biting force were (20.45±2.55)% and (79.55±2.55)% in affected and normal sides. Asymmetric index of biting force was (59.10±5.09)%. Biting force in affected side was recovered to (25.82±4.04)%. Conclusion Digital prosthesis can repair Brown maxillaⅡdefect in surgery with excellent rehabilitation of facial appearance and function.

Objective：The aim of this study was to investigate the three-dimensional anatomy characteristics of parotid duct system. Methods：The CBCT sialography data from 34 healthy people were reconstructed by Mimics software to test and analysis duct length, the types of branch duct and so on. Results：The mean length of the parotid main ducts in 34 cases was 52.67±10.68 mm. The rate of occurrence of the accessory parotid gland was 41.3% (14/34), and the mean angle was 47.73 ° between the accessory parotid ducts and the main ducts. The 25 cases exhibited Bifurcation ducts at the end of the main ducts, the mean angle was 73.30°±20.70° between two bifurcation ducts; 74 lateral parotid ducts with a mean angle of 58.22 ° attached to the main ducts. Conclusions：The main parotid ducts are thick and smooth. The terminal of the main ducts usually separate two bifurcation ducts. And the main parotid ducts can separate some lateral parotid ducts.

Abstract: Objective To evaluate the efficacy of chlorhexidine gel (CHX), calcium hydroxide (CH) and calcium hydroxide combined with chlorhexidine (CHX+CH) as a root canal disinfection drug in root canal therapy, in order to find the ideal root canal disinfection drug and provide scientific evidence. Methods Sixty teeth with chronic apical periodontitis were randomly divided into CHX, CH and CHX+CH groups, respectively, 20 in each group. Rinse with conventional mechanical preparation was conducted respectively. CHX, CH and CHX+CH were selected, and the samples of the bacterial specimens in the root canal were sampled and cultured before and after the preparation of the root canal, and the changes in the number of bacteria in the aerobic and anaerobic bacteria were determined. The clinical efficacy of the dental seals before and after 7 days was observed and scored, and the average sealing time of the teeth was recorded. Results After the teeth of three groups were sealed, the number of aerobic and anaerobic bacteria in the root canal (the logarithmic value) was significantly lower than that before the seal (p<0.05). The bacteriological examination of aerobic and anaerobic bacteria after 7 days of root canal sealing in the three groups showed that there was no significant difference in the number of bacteria in the root canal between the CHX group and the CH group (p>0.05). However, there was a statistically significant difference in the number of the aerobic and anaerobic bacteria in the root canal between the CHX+CH group and the other two groups (p<0.05). After 7 days of root canal sealing in the three groups, the clinical scores of each group were statistically significant (p<0.05), indicating that all three root canal disinfectants had certain curative effect. In CHX group and CH group, there was no significant difference in the difference of clinical scores before and after 7 days of sealing (p>0.05), but the difference of clinical scores before and after 7 days of sealing between CHX+CH group and the other two groups was statistically significant (p<0.5). ). The three groups of teeth reached the clinical fillable requirements through different treatment time. There was no significant difference between the CHX group and the CH group (p>0.05), but the difference between the CHX+CH group and the other two groups was statistically significant (p < 0.5). Conclusion CHX, CH and CHX+CH as root canal disinfection drugs all have good curative effects on chronic apical periodontitis, and the comprehensive evaluation of antibacterial effect and clinical efficacy of CHX gel combined with CH paste are the best, which is expected to be a disinfectant with good clinical treatment effect.

Abstract: The implant cases in the aesthetic area of anterior teeth were often accompanied by insufficient bone mass and soft tissue, while the aesthetic effect of implant restoration was seriously affected by the low fullness of the labial side of implant denture, and the increment of soft tissue could effectively increase the keratinized gingiva around the implant. Effective reduction of soft tissue around implant depression, increase implant denture repair predictability.

After decades of development, the overall success rate of implant restoration has reached a relatively satisfactory level, but there are still many cases of failure in the aesthetic area, especially the failure caused by poor aesthetic effect. If poor lip fullness occurs after implant restoration in the aesthetic area, it will greatly affect the aesthetic effect, causing great trouble to patients, and its post-treatment is relatively cumbersome. There is no uniform solution in clinical practice. The purpose of this paper is to review the relevant literature and discuss the strategies to solve the problem of poor lip fullness after implant restoration in aesthetic area, so that clinicians can have a more comprehensive consideration when facing such problems.

Chitin is the second most abundant natural resource after cellulose. Chitosan is the product of of the deacylation reaction of chitin. It is the unique cationic polysaccharide in the nature which excellent properties of biocompatibility and biodegradability. The drug delivery systems based on chitosan are proved to be in favor of improving the drug bioavailability , changing its delivery mode and controlling drug release. This review summarizes the research progress of chitosan-based drug delivery systems and its applications in bone tissue engineering.

Plaque is a complex biofilm that participates in the development of caries. The accumulation of biofilm on dental tissues and materials is one of the most important factors in the development of secondary caries. The composite resin material with antibacterial effect mainly utilizes antibacterial monomer, antibacterial filler, antibacterial and remineralization combination, bioactive resin, surfactant, etc.. Reduce plaque accumulation on the surface of dental tissues and dental materials by bactericidal, bacteriostatic, inhibiting protein adsorption, and regulating biofilm to prevent secondary caries. This article describes the progress and limitations of the materials studied so far in terms of the composition of antibacterial and bioactive dental resins, and at the same time describes its antibacterial mechanism.

With the improvement of people's living standards and the rapid development of the oral implant industry,the method of implant is gradually being taken into consideration for patients with dentition defects and missing dentition. In recent years, advances in the design and development of implants,especially platform switching (PLS),have promoted the development of clinical techniques. The biological benefits and clinical effects have been confirmed by many research reports. This technology was first proposed in 2005 and there are a large number of clinical studies confirming that PLS technology can reduce the absorption of marginal bone tissue around the implant. This article reviews the biological width of PLS technology,the micro-gap of implant abutment, and the distribution of stress. However, the problems found in the study of immediate weight-bearing and animal studies still need to be studied through long-term, randomized, prospective and multicenter trials on a large number of implants.

In recent years, the direction and research hotspot of the treatment of pulpal and periapical diseases has been focused from traditional root canal therapy to pulp tissue regeneration. Pulp tissue regeneration includes nerve regeneration, revascularization, dentin regeneration and so on. This paper reviews the research progress of the related factors, cells and microenvironment of pulp revascularization.

　Bleeding after tooth extraction is one of the most common complications during and after operation. With the “three high” (high blood pressure, high blood fat, high blood sugar) and other chronic systemic disease incidence and the incidence of a younger age, the incidence of bleeding after tooth extraction is increasing year by year, and often results in various physiological and psychological consequences, especially with the "dental phobia" is attracting attention, to reduce or avoid the extraction method of bleeding has great research value. In this paper, the relevant literature of CNKI during 1990-2017 was researched, and the keywords "tooth extraction", "hemostasis", "complications" and so on were used. After screening, 62 articles were included in the collation and induction. In this paper, the mechanism, advantages and disadvantages and clinical efficacy of various methods of tooth extraction and hemostasis in traditional Chinese and Western medicine in recent 30 years are reviewed. The purpose is to provide a scientific basis for the new method of tooth extraction and hemostasis in the future.