Objective　To study the effect of shortening the time of etching on the bonding strength of primary teeth and immature permanent teeth to provide some theoretical guidance for more proper control of acid etching time clinically. Methods　20 fresh and not crack primary molars, 20 not crack immature permanent teeth were selected and the enamel of tooth surface was grinded to form the dentin plane. Primary teeth were randomly divided into A, B, C, D group and immature permanent teeth were divided into E, F, G, H group. Group A and E should be etched for15 seconds by SB2, 7 seconds for group B and F. Group C and G should be etched by OV for 20 seconds, and 10 seconds for group D and H. Then layered resin was solidified and the crowns were restore. Finally, the teeth were cut piece into a cuboid shape sample with a cross-sectional area about 1.0 mm×1.0 mm and then micro tensile strength test was carried out. Results　Micro tensile strengths respectively were group A（14.95?3.79）MPa, group B（16.74?2.77）MPa, group C（20.80?3.97）MPa, group D (20.50?3.98)MPa, group E（20.95?2.68）MPa，group F（17.26?3.32）MPa，group G (25.70?2.95)MPa, group H (20.98?3.13)MPa. There was no significant difference between group A and group B ,group C and group D. Group F ＜ group E and group H ＜group G, the difference was statistically significant(P ＜0.05); Group C ＞ group A; group D ＞ group B; group G ＞group E; group H ＞ F group, the difference was statistically significant(P ＜0.05). Conclusions　Shortening the acid etching time, the bonding strength of the primary teeth did not change significantly, but the bonding strength of the immature permanent teeth significantly reduced; the bonding strength of applying OV is higher than that of the application of SB2 .

Objective To quantify and compare the volume of tooth preparation(the volume percentage of the tooth tissue prepared to the hard tissue of crown) and bonding area of mandibular first molar. Methods Ten extracted mandibular first molars were collected. The teeth were scanned by Micro CT, then reconstructed into 3D model and copied by 3D printing method into four groups（A、B、C、D）each with ten teeth，and the teeth were prepared with the following designs: ceramic crown（A1-A10），medial-occlusal cavity ceramic inlay（B1-B10）, and MOD ceramic inlay（C1-C10），D（D1-D10）was blank control group. Finally，the reverse engineering software Mimics and Geomagic Studio were applied to analyze the volume of tooth preparation and bonding area. Results Different designs of mandibular first molar were statistically significant in the volume of tooth preparation and the adhesive area. The volume of tooth preparation: ceramic crown (36.21%), medial-occlusal cavity ceramic inlay(5.75%), MOD ceramic inlay(11.93%); the bonding area: ceramic crown (169.96 mm2), medial-occlusal cavity ceramic inlay(40.27 mm2), MOD ceramic inlay(81.94 mm2); the enamel bonding area: medial-occlusal cavity ceramic inlay(26.55 mm2), MOD ceramic inlay(55.13 mm2), the dentin bonding area: medial-occlusal cavity ceramic inlay(12.92 mm2), MOD ceramic inlay(23.97 mm2), the enamel bonding area was more than dentin. Conclusions The volume of tooth preparation and bonding area are related to the type of dentures. The exposure of enamel identified at the margins of the ceramic inlays preparation suggests that enamel adhesions should be used.

Objective To investigate the effect of silver loaded titanium dioxide (TiO2) nanotube implant and its effect on the inflammatory response of surrounding tissues. Methods The planting nails were divided into pure titanium polishing group (PT group), TiO2 nanotube group (NT group), low concentration of Ag loaded TiO2 nanotube group (NAg-L group) and high concentration of Ag loaded TiO2 nanotube group (NAg-H group), which were implanted into the bilateral mandible of adult dogs. The gingival crevicular fluids of every group were collected and their volume changes were analyzed. The Infiltration condition of inflammatory corpuscle in soft tissue was observed by HE staining, and the expression of TNF-? mRNA around soft tissue was detected by real time quantitative PCR. The morphological changes of adherent cells at different times were observed by electron microscope. Results When tested for 7d,the gingival crevicular fluid volume of NAg-L group was significantly lower than that of other groups(P＜0.05);when tested for 14d,the gingival crevicular fluid volume of NAg-H group was significantly lower than that of PT group(P＜0.05);when tested for 28d,there was no significant difference in gingival crevicular fluid volume in each group(P>0.05).The histological observation of each group at different times showed that PT group, compared with NT group, NAg-H group and NAg-L group, had more inflammatory cell infiltration. When tested for 7 d, the expression level of TNF-? mRNA in the NAg-L group was significantly lower than that of other groups (P <0.05), while the expression level of TNF-? mRNA in the NAg-H group was significantly higher than that of other groups (P <0.05). When tested for 14d,the expression level of TNF-? mRNA in the NAg-H group was significantly lower than that of other groups (P <0.05);the expression level of TNF-? mRNA in the NAg-L group was significantly lower than that of PT group and NT group(P <0.05).When tested for 28d,the expression level of TNF-? mRNA was not statistically significant among the groups (P >0.05).The surface adhesion cells in different groups at different times by electron microscope observation showed that when tested for 7d, there was no significant difference in the surface adherent cell of each group, and all presented star shaped protrusions; when tested for 14d, the cells of NT, NAg-H and NAg-L groups showed typical long spindle stretch of fibroblasts, while the cell of PT group had no typical morphology and small extension area; when tested for 28d,the surface cells of each group had good extension. Conclusion TiO2 nanotubes have better biocompatibility, which can make the soft tissue around the implant produce a smaller inflammatory response, and the low dose of Nano silver particles can significantly inhibit the inflammatory response.

Objective To metrically assess the vertical changes of the occlusal landmarks for biogenerically reconstructed inlays in CEREC CAD/CAM system. Methods Stone replicas of 20 untreated maxillary first molars were scanned and measured with Infinite Focus system. Relative heights of the tip of mesiopalatal cusp (MPC) and the central pit (CP) to the tip of mesiobuccal cusp were calculated and the inclination of the line passing through MPC and CP was measured as a representation of the mesiopalatal cuspal inclination (MPCINC). The casts were prepared for mesiopalatal inlay restoration and restored with CEREC chair-side system using biogeneric tooth model. Inlays seated on the corresponding casts were scanned again. The same items were measured and calculated. Differences between the restorations and natural teeth (△MPC, △CP and △MPCINC) were tested by paired Student’s t test (P=0.05). Bland-Altman plots were used to assess agreements between the two occlusal surfaces. Relationships between the differences and MPCINC of natural tooth were evaluated using Pearson’s correlation coefficient. Results The vertical differences of occlusal landmarks between natural teeth and biogeneric reconstructions were (101.87±33.21) μm for MPC, (-201.72±55.28) μm for CP and (4.66°±0.31°) for MPCINC. All three differences were statistically significant (P<0.05). There was a significant correlation between △MPCINC and MPCINC of natural tooth (P<0.01) while △MPC and △CP were independent from MPCINC. Conclusions Significant differences associated with three occlusal landmarks exist between the automatic occlusal reproduction by biogeneric tooth model and the natural occlusal morphology.

Objective　To observe the histological changes in periodontal tissue and the serum levels of TNF-α, IL-6 and PAI-1 in type 2 diabetic rats with periodontitis, and to investigate the influence of expression of TNF-α, IL-6 and PAI-1 on the histological changes of periodontal tissue remodeling in periodontitis rats with type 2 diabetes mellitus. Methods: Sixty SD Wistar rats aged 8-9 weeks were divided into four groups according to different modeling methods: ○1diabetic rats with periodontitis group(n=15);○2diabetic rats without periodontitis group(n=15); ○3non-diabetic rats with periodontitis group(n=15); ○4non-diabetic rats without periodontitis group(n=15). Diabetic model was established by intraperitoneal injection of streptozotocin(STZ). Diabetes was determined by measuring blood glucose in rat tail vein once a week after giving the drug and for four successive weeks . The rat experimental periodontitis was induced by wrapping 3/0 silk ligature inoculated with Porphyromonasgingivalis around the left maxillary second molar of the rats and then the model was copied. The rats were sacrificed at 20th week after ligature by intraperitoneal injection of chloral hydrate . The blood was collected from aorta abdominalis. Then serum levels of TNF-α, IL-6 and PAI-1 were measured with ELISA method. The attachment loss(AL) was measured before sacrifice. The histological changes of periodontal tissues were observed under microscope with HE staining. Results: The diabetic rats showed a significant increase in blood glucose and weight(P<0.05).The serum insulin level and insulin resistance values of the diabetic rats significantly increased(P<0.05). The rat experimental periodontitis showed typical clinical characteristics of periodontitis after ligature inoculated with Porphyromonasgingivalis. The levels of serum TNF-α, IL-6 and PAI-1 were significantly higher in diabetic rats with periodontitis than those in diabetic rats without periodontitis group(P<0.05). Conclusion: Diabetes can decrease the periodontal tissue resistance to local pathogenic factors by promoting the expression of serum inflammatory factors, thereby further aggravating and accelerating the progress of periodontitis.

Objective To determine the relationship between the occlusal support and the condyle position by cone beam CT(CBCT). Methods A total number of 84 patients who were treated at our institution from 2013 to 2016 were retrospectively included. The space of the bilateral joints and the condyle position were measured with NNT on CBCT multiplanar images. The association between the condyle position and occlusal support was statistically analyzed. Results The mean distances of the anterior, superior and posterior joint space were (2.23±0.79)mm, (1.98±1.18)mm, (3.53±0.99)mm respectively. The occlusal support was classified into type A(22), type B(31) and type C(31). The superior and posterior joint spaces were significantly associated with occlusal support. However, no significant relationship was found between occlusal support and anterior joint space. The condyle position was defined as anterior(39 sides), concentric(48 sides) and posterior(81 sides).The distribution of condyle position was associated with occlusal support. Conclusions There is a significant correlation between occlusal support change and the condyle position.

Abstract Objective：To observe the clinical effects of percutaneous puncturing of foramen rotundum(FR) and foramen oval(FO) for radiofrequency thermocoagulation to treat primary maxillary nerve neuralgia under X-ray. Methods：69 cases of simple maxillary neuralgia patients were divided into two groups, which were hospitalized in our hospital from 2008 to 2015. Group A: 33 cases were punctured into FO by Hartel, measure the cranial - the vertical distance line between the needlepoint and ear-clinoidal line, then radiofrequency thermocoagulation. Group B: 36 cases were punctured into FR , at first puncture into pterygopalatine fossa (PPF)with curved needle, inject 2% lidocaine 1ml, under X-ray locate the direction, then piercing into FR, under X-ray into the FR was determined before radiofrequency thermocoagulation.Results：All patients were successfully completed surgery, the needles are accurate in the FR and FO, pain was relief after treatment immediatly, and no serious complications were occurred, infraorbital region and palate are insensitive. All patients were followed up for 6 months to 2 years, Two groups of 3 days of efficiency, postoperative recurrence rate difference is not significant (P > 0.05).Two groups in the risk of a significant difference was found in the incidence of no trouble nerve injury (P < 0.05). Group A:Operation average time are 48.79 minutes; group B: Operation average time are 50.32 minutes.Intraoperative pain score: group A: the average are 7.48 points;Group B: the average are 2.92 points.Conclusion：It is worth promoting for the treatment of maxillary nerve neuralgia with piercing FR pass by PPF because of certain advantages.

Objective To investigate the effects of different polishing and glazing procedures on the surface roughness and wear behavior of dental zirconia ceramic .Methods 18 zirconia ceramic specimens were made and randomly divided into three groups （n ＝6）:two groups were respectively treated with polishing and glazing ,the surface of the third group was treated with nothing. Surface roughness values were measured. The volume loss of opposite talcum ceramic and tested specimens as well as natural enamel were also measured by the wear test. Results The surface roughness values of each group were 0.358±0.020、0.384±0.011、1.597±0.068μm. The surface roughness values of polished and glazed specimens were significantly lower than the specimens that were not treated（P<0.01）.There was no significantly difference between the surface roughness values of polished and glazed specimens ( P>0.05）.The volume loss of tested specimens was significantly less than the nature enamel（P<0.01）.The volume loss of polished specimens was significantly less than the glazed ones（P<0.01）.The volume loss of opposite talcum ceramic among groups was significantly more than the nature enamel（P<0.01）.The volume loss of opposite talcum ceramic by polished ceramics was significantly less than that of glazed ones（P<0.01）.Conclusions 　The polishing procedures of zirconia ceramic surface are clinically acceptable compared with glazing. Polished zirconia ceramic uses less material and antagonist wear than the glazed one.

Objective The purpose of this investigation to evaluate the clinical efficacy of mineral trioxide aggregate (MTA) as an apical barrier materital when used in teeh with incomplete root formation. Methods Twenty eight teeth with open apices in 28 patients were treated by standard endodontic procedures. An absorbable collagen sponge and MTA apical barrier were placed in the apical portion of the root canal under dental operating microscope (DOM) after a calcium hydroxide intracanal dressing had been applied for 1 week. The remainder of canal was back-filled with AH plus sealer thermoplastisized Gutta-Percha 1d following MTA placement and access cavity was restored with composite resin followed by all crown. Follow-up evaluations were carried out clinically and radiographically at 6-month and 1-year intervals. Results Sixty-five percent of these teeth were successful at 6-month appointment. Ninety-one percent of these teeth were successful at 1-year appointment. Periapical index scores at 6-month and 1-year recall appointments were improved. Chi-square test indicated that successful cases in recall times did significantly influence clinical outcome. Conclusions These results indicated that the mineral trioxide aggregate apical barrier technique is a successful method for treating teeth with immature apices.

Abstract: Objective To analyze the anesthesia effect of compound articaine on children's dental pain, and provide reference for clinical anesthesia. Methods 160 children who were treated with gums painless dental anesthesia in hospital from May 2015 to October 2015 were selected, then patients were divided into observation group (80 cases)and control group(80 cases). Observation group patients were taken clinical anesthesia of compound articaine anesthesia, while control group patients were taken clinical anesthesia of Procaine hydrochloride anesthesia, and anesthetic effects of patients were compared. Results Total effective rate of anesthesia of observation group (97.6%) was significantly higher than control group(83.7%), P <0.05, painless rate of the observation group (80.0%) was significantly higher than control group(57.5%), P <0.05, both before and after anesthesia heart rates of two groups had no significant changes, P> 0.05. Conclusion In children's dental gums painless anesthesia, the anesthetic effect of compound articaine is significant and can be improved, with a promotional value.

Objective To evaluate the effect of fluoride varnish Duraphat in preventing caries of primary teeth on 3-year-old children population in Shanghai by using fluoride varnish Duraphat and implementing oral health methods in the kindergarten. Methods 1905 children whose ages were 3 year-old were randomly chosen from kindergartens in 3 districts of Shanghai, and were randomly divided into 3 groups followed up for 2 years. The first group was varnished by 2.26% fluoride two times a year. The second group was varnished by 2.26% fluoride once a year, and the third group was blank group. Protective measures were applied for all the children. All the data were collected and the clinical effects of 3 groups were compared by using Software Package of SPSS 17.0. Results The caries incidence and average caries index of 2.26% fluoride varnish groups were lower than those of control group with the difference was statistically significant (P<0.05). Conclusion 2.26% fluoride varnish Duraphat is effective in preventing caries of primary teeth in children.

Dentin hypersensitivity is a common oral disease, seriously affecting the patient’s oral health and quality of life. As a commonly used treatment, laser alone or in combination with other agents have obtained good therapeutic benefits and attracted extensive attentions among the oral medicine community. In this paper, the progress of laser treatment of dentin hypersensitivity is reviewed.

As a global epidemic, obesity is higly correlated with certain systemic diseases such as diabetes, hypertension, cardiovascular disease, etc., and particularly has a close correlation with periodontitis. Adipose tissue can secrete a series of adipocytokines, such as visfatin, leptin, resistin, adiponectin, etc., and it also exists in the cells of periodontal tissue. Adipokines can not only regulate the sensitivity of insulin but also participate in body's inflammatory response, therefore, these two diseases may be linked by adipokines. This review focuses on the effects of adipokines on periodontitis.

Abstract: Periodontitis is a chronic inflammatory disease induced by dental plaque. The disease implicates damage to the tooth-supporting tissues, causing the tooth mobility, even tooth loss. Forkhead box O1 is at the crossroads of many signal transduction pathways. As a critical signaling integrators, FOXO1 can regulate a number of important host cell progress including oxidative stress response, cell cycle, apoptosis and autophagy. Recently, studies have demonstrated the potential role of FOXO1 in the occurrence and progression of periodontitis. FOXO1 may involve in regulating innate immune responses, oxidative stress responses and alveolar bone remodeling directly and indirectly by interacting with protein kinase B, c-Jun N-terminal kinase and activating transcriptional factor 4. Thus, uncovering the role of FOXO1 in periodontitis development would be a big step towards treatment of the periodontitis.

[Abstract] Implant abutments not only guarantee the wound healing with soft tissue adhesion ,but also take part in the esthetic implantology.So it is important to explore the porperties of implant abutment and its effects.We make a comprehensive from several aspects,including abutment materials,surface roughness,surface wettability,surface topography and surface cleanliness.In brief,it is generally considered that titanium and zirconia are suitible materials,hydrophilic surface and clean surface are also benefit to soft tissue adhension,but the current literatures provide insufficient evidence about the other factors.

Comet assay is a method which can detect DNA damage and repair under level of single cell, being a kind of fast, cost-efficient technique to detect genotoxicity such as DNA single-strand breaks, DNA double-strand breaks, alkali-labile sites and so on, has been extensively employed in fields like toxicology genetic, eco-genotoxicity. In recent years, new dental materials develop constantly, in the meantime, dental materials contact with the oral enviroment directly and act on human body for a long time. The genetic toxicty evaluation system of it needs to be improved immediately. Comet assay has been employed in various of fields and becomes an indispensable part of genetic toxicity assessment. Therefore, it is necessary to apply the method to detect the biosafety of new dental materials.

A major issue in modern dentistry research is the prevention and treatment of oral infectious disease caused by pathogenic bacteria. To achieve this goal, nanodentistry has attracted lots of attention due to its distinct advantages. The main concern of nanodentistry is the promotion of oral health and enhancement of life quality by utilizing novel nanomaterials, biotechnology, tissue engineering, nanomedicine and so forth. Lately, nanodentistry shows unique advantages in antibacterial, osseointegration, bone regeneration, and physical performance improvement. Consequently, in this review, the various applications of nanodentistry in antibacterial filed were systematically summarized with the aim to inspire the researchers engaged in this field.

Graphene and its derivatives have been attracting considerable interest worldwide due to its remarkable physical and chemical properties as well as alluring biocompatibility. As a new kind of carbon material, graphene has a number of potential medical applications in many fields. In this review, efforts are made to expect in elucidating the synthesis and characterization of graphene derivatives, with emphasis on their latest developments in oral biology.

Polyetheretherketone (PEEK) and its composites have excellent chemical stability, good biological properties and its mechanical properties are very close to natural teeth and dense bone, which make it become the focus of the area of oral medicine. Excellent comprehensive properties of the PEEK make it an alternative to traditional materials used in the fixed restoration, removable restoration and implant of new biological materials. This paper reviewed the characteristics of PEEK as dental materials, and the application and research of PEEK in prosthodontics.researches of PEEK in prosthodontics.