Severe dry eye is a refractory ophthalmologic disease. Our multidisciplinary research group treated severe dry eye by microvascular autologous transplantation of submandibular gland (SMG) during the past 20 years. The SMG, with its blood vessels and Wharton’s duct, was harvested from the submandibular triangle and transferred to the temporal area. The blood vessels in the SMG were anastomosed with the temporal blood vessels using a microsurgical technique. Then, the distal end of Wharton’s duct was sutured to form an opening in the upper lateral conjunctival fold. The tear was replaced by the secretion of the transplanted SMG to lubricate the ocular surface. In our study, the surgical techniques of blood vessel management were continuously modified to increase the survival rate of the transplanted SMG. A novel surgical modality of partial transplantation of SMG was established to prevent postoperative epiphora. A clinical study with the largest case number in the world was conducted and the effectiveness of transplantation of SMG for severe dry eye was fully confirmed. In order to resolve two main clinical problems including ductal obstruction resulted from low secretion rate during the latent period, and epiphora due to over secretion of the transplanted SMG in the later term of transplantation, the regulation of the secretion mechanism of the normal and transplanted SMG were investigated. New opinions on mechanisms of saliva secretion were provided. Based on the priniciple of translational medicine, the results of related basic research were applied in the clinic. The clinical guidelines for secretion regulation of transplanted SMG were established. A concept of chronic obstructive sialadenitis of transplanted SMG was provided and its diagnostic criteria, diagnostic technique of sialography, and therapeutic regimen were established. As a result, the surgical success rate was obviously elevated, the surgical complications were decreased, and life quality of the patients was greatly improved.

Objective： To investigate the characterization of the salivary microbiome in people with obesity and the differences in microbial composition, gene function and metabolic pathways of salivary microbiome between people with obesity and normal weight controls. Methods: The study was carried out in people with obesity and age- and sex-matched normal weight controls. None of these selected participants had the systemic disease, oral mucosal disease or periodontal disease. Unstimulated saliva samples were collected and oral examination was conducted. DNAs from saliva samples were extracted and sequenced in an Illumina NextSeq 500 platform. Community composition, linear discriminant analysis of taxonomic differences，gene prediction, gene set construction and annotation of gene function were performed. Results: The classified bacterial reads of the samples were 2，630，428 for each sample. A total of 11 phyla, 19 classes, 26 orders, 41 families, 62 genera and 164 species were detected ultimately. All samples had the same predominant phyla (Proteobacteria, Firmicutes, Bacteroidetes, Actinobacteria and Fusobacteria). There were statistical differences between the groups at the class, order, family, genus and species levels. At the class level, Negativicutes and Erysipelotrichia were more abundant in the obesity group, while Flavobacteriia and Bateroidetes dominated in normal weight group （P<0.05）. At the species level, 16 showed significant differences in relative abundance among the groups, in which Prevotella melaninogenica，Prevotella salivae，Solobacterium moorei and Atopobium parvulum ware more abundant in the obesity group, whereas Streptococcus sanguinis dominated in normal weight group (P<0.05). The people with obesity had a higher number of salivary microbial genes (P<0.05). We produced statistics on gene prediction and found salivary microbiome of obesity group had a higher number of genes (P < 0.05). Genes associated with the pathways of metabolism and environmental information processing and human diseases were significantly enriched in the saliva samples of people with obesity (P < 0.01). Conclusion: Significant differences were seen in composition, gene function and metabolic pathways of salivary microbiome between people with obesity and normal weight people. We hope to go on further study with larger sample size in the near future.

Objective：There is asingle nucleotide polymorphism (SNP) in the exon 2 of the vitamin D receptor (VDR) gene that can be distinguished using the restriction endonuclease FokⅠ, and accordingly divided into three genotypes: FF, Ff and ff. VDR-FokⅠ polymorphism was the only known SNP that could alter the protein structure of VDR. CYP24A1 is the gene encoding vitamin D 24 hydroxylase and is a vitamin D responsive gene. The influence of rs2228570 on transcriptional activation by VDR in human gingival fibroblasts (hGF) and periodontal ligament cells (hPDLC) was investigated in this study. Methods: hGF and hPDLC of 12 donors’ were primarily cultured and genomic DNA was extracted. A part of genomic DNA with the length of 267 bp was obtained using PCR, which contained the SNP. VDRFok Ⅰ genotypes were determined according to the results of restriction fragment length polymorphism. hGF and hPDLC were stimulated with 10 nmol/L 1α,25 dihydroxy vitamin D3 (1,25OH2D3) or 1 000 nmol/L 25 hydroxy vitamin D3 (25OHD3) for 48 h before RNA was extracted. Then VDR antagonist ZK159222 was used or not used during 1,25OH2D3 or 25OHD3 stimulation with hGF and hPDLC. After 1,25OH2D3 stimulation for 48 h, the proteins in hGF and hPDLC were also collected. The protein expressions of CYP24A1 and VDR were detected using Western blot. Results: Among the 12 donors’ cell cultures, the number of FF, ff and Ff genotypes was 4, 3 and 5, respectively.After stimulation with 1,25OH2D3or 25OHD3 for 48 h,CYP24A1 mRNA levels in FF-hGF were significantly higher than those in other hGF genotypes(1,25OH2D3: F=31.147, P<0.01; 25OHD3: F = 32.061，P <0.01), as was in FFhPDLC (1,25OH2D3: F=23.347, P<0.01; 25OHD3: F = 32.569，P < 0.01). When ZK159222 was used before 1,25OH2D3 stimulation, this statistically significant difference disappeared (hGF: F=0.246, P=0.787; hPDLC: F=0.574, P=0.583). When ZK159222 was used before 25OHD3 stimulation, the trend was similar (hGF: F = 1.636, P = 0.248; hPDLC: F =0.582, P=0.578).After stimulation with 1,25OH2D3 for 48 h, CYP24A1 protein levels in FF-hGF were significantly higher than those in the other hGF genotypes (F=12.368, P <0.01), as was in FFhPDLC (F=15.749, P <0.01). In hGF and hPDLC, the mRNA or protein expression of VDR of different genotypes was not significantly different under different stimulation conditions.The paired comparison showed that there was no statistically significant difference between the expression of CYP24A1 in hGF and that in hPDLC under all the stimulation conditions, as was the expression of VDR. Conclusion: In hGF and hPDLC, the FF-VDR genotype is associated with the more remarkable up-regulation of CYP24A1than the other genotypes, indicating that transcriptional activation of FF-VDR might be higher than those of other vitamin D receptors.

Objective： Growth-arrest-specific protein 6 （Gas6）is a vitamin K-dependent protein and involved in cell proliferation, survival, adhesion and migration . Also it has been shown to play an important role in the inflammatory response .The aim of present study was to investigate the role of Gas6 in the process of the expression of adhesion molecules and chemokines of human umbilical vein endothelial cells（HUVECs）induced by Porphyromonas gingivalis lipopolysaccharide（P.g-LPS）. Methods： After up-regulation and down-regulation of the expression of Gas6，the vascular endothelial cells were stimulated with 1 mg/L P.gLPS for 3 h and 24 h. Realtime quantitative polymerase chain reaction（realtime PCR）was taken to detect the expression of the cell adhesion molecules：intercellular adhesion molecule-1（ICAM-1） and E-selectin, as well as chemokines：interleukin-8（IL-8）and monocyte chemoattractant protein 1（MCP-1）. Wound healing assay was taken to observe the migration ability of endothelium cells in different groups. Results： After 3 h of P.g- LPS stimulation, the expression of adhesion molecules and chemokine in the down-regulation group was not significantly different from that in the control group，while in the up-regulation group the decrease of E-selectin, ICAM-1, IL-8 and MCP-1 was 81%±0%, 47%±3%, 76% ± 3%, 26% ± 6% respectively. After 24 h of P.g- LPS stimulation, the expression of adhesion molecules and chemokine in down-regulation group was significantly higher than that in control group (2.06±0.07, 1.99±0.11, 3.14±0.15, 1.84±0.03 flod), while these molecules in the down-regulation group was significantly lower than in the control group (29%±1%, 62%±3%, 69%±1%, 41%±2%）. Differences were statistically significant （P<0.01）. Wounding healing assay showed that down-regulation of Gas6 enhanced migration ability of endothelial cells while up-regulation of Gas6 weakened this ability，which was consistent with the trend of real-time PCR result. Conclusion： Down-regulation of the Gas6 gene enhanced the expression of ICAM-1, E-selectin, IL-8 and MCP-1 in HUVECs after P.g-LPS stimulating， while up-regulaiton of the Gas6 gene weakened the expression of ICAM-1, E-selectin, IL-8 and MCP-1 in HUVECs after P.g- LPS stimulating，suggesting that Gas6 may play a role in the process of endothelial cell adhesion.

Objective： To explore the association between hypoxia-inducible factor 1α (HIF-1α) expression and lymph node metastasis in oral squamous cell carcinoma (OSCC). Methods: Tumor specimens from 125 patients with histologically-proven, surgically-treated OSCC were examined by immunohistochemical staining for expression of HIF-1α. The patients were divided into two groups by the expression of HIF-1α, high expression of HIF-1α group (H-group) and low expression of HIF-1α group (L-group). The main assessment parameters were lymph node metastasis rate and disease-specific survival (DSS). The lymph node metastasis rate and clinicopathologic features were compared using Mann-Whitney test. The Kaplan-Meier curve was generated for each group and compared using the log-rank test. Cox proportional hazard models were utilized for multivariate analyses of HIF-1α expression and other baseline factors with DSS. All calculations and analyses were performed using the SPSS 17.0 software package. Results: The protein expression levels of HIF-1α were up-regulated in OSCC and two patients were unable to evaluate. There were 48 patients in L-group and 75 patients in H-group. Lymph node metastasis rate was 37.5% (18/48) for L-group and 58.7% (44/75) for H-group (P=0.027). Expression of HIF-1α was significantly correlated with lymph node metastasis. The patients of L-group had a significantly better DSS than the patients of Hgroup (70.8% vs. 46.7%, P=0.005), while the patients of L-group had a significantly better disease-free survival (DFS ) than the patients of H-group (60.4% vs. 36.0%, P=0.009) by Kaplan-Meier method. A multivariate survival analysis also showed that HIF-1α expression (HR=2.164, 95%CI: 1.150-4.074, P=0.017) and Tstage (HR=1.387, 95%CI: 1.066-1.804, P=0.015) both were the independent factors associated with prognosis. Conclusion: HIF-1α expression is significantly correlated with lymph node metastasis in OSCC. HIF-1α expression is an independent predictive factor for prognosis of OSCC patients, and may serve as a potential biomarker for molecular diagnosis and targeted therapy in future.

Objective： To investigate the effects of Toll like receptors on the osteogenesis of human pe-riodontal ligament stem cells (hPDLSCs) and probable molecular mechanism. Methods: Real-time PCR and flow cytometry were applied to test the expression of TLRs in hPDLSCs and the positive cell percentage of TLR. hPDLSCs were cultured in osteogenic medium for 7 to 14 days with different TLR agonists at various concentrations . The effect of different TLR on osteogenic differentiation of hPDLSCs was evaluated by alizarin red S staining, alkaline phosphatase (ALP) staining and ALP activity assay. Western blotting was used to analyze the phosphorylation levels of extracellular regulated protein kinases (ERK), c-Jun N-terminal protein kinase (JNK), P38, AKT and expression of Runx2 an osteogenic related gene after treatment with TLR agonists, compared with the effect of inhibitors of mitogen activated protein kinase (MAPK) or protein kinase B (PKB or AKT) on Runx2 expression of hPDLSCs cultured in osteogenic medium. Results: Higher expressions of TLR1,3,4,6 were found in hPDLSCs through real-time PCR. Positive cell percentage of TLR was determined by flow cytometry and described as TLR1: 2.82%±0.68%; TLR2: 1.26%±0.09%; TLR3: 13.23%±2.05%; TLR4: 3.64%±0.79%; TLR6: 3.21%±1.64%, whose tendency was comparable to their mRNA expression in hPDLSCs. Most TLR ligands had no effect on the ALP staining, activity and mineralization of hPDLSCs at lower concentration except for 0.1 mg/L PolyI:C could induce the osteogenic ability of hPDLSCs. On the contrary, Higher concentration of TLR ligands (PolyI:C: 10 mg/L, LPS: 10 mg/L , Pam3CSK4: 1 mg/L, FSL-1: 50 μg/L) had obviously inhibitory effect on osteogenic differentiation of hPDLSCs. Activation of TLR using higher concentration of TLR ligands could downregulate the phosphorylation levels of ERK, P38, JNK and AKT, and also reduced the expression of Runx2, compared with the untreated control. The inhibitors of MAPK (U0126, SP600125，SB203580) and inhibitor of AKT (perifosine) could also inhibit Runx2 expression. Conclusion: Higher concentration of TLR ligands could inhibit osteogenic differentiation of hPDLSCs. This inhibitory effect seemed to be related to decreased phosphorylation of MAPK and AKT.

Objective： To compare the osteogenic effects of a nano-sized 58S bioactive glass (nano-58S BG) and a traditional 45S5 bioactive glass(45S5 BG) in penetrating parietal critical bone defects. Methods: Critical bone defect with 9 mm diameter was created in the parietal bone of New Zealand rabbits. The bone defects were then filled with either nano-58S BG, or 45S5 BG, or nothing but the newly-formed blood clot as the blank control at random. For histological observation, specimens were gained 4 and 8 weeks after the surgery, sectioned and stained by HE. The amount of collagen type Ⅰ was observed with PicricSirius Red staining through polarimetry. To observe the new bone formation with fluorescence under the laser confocal microscope, we injected fluorescent markers 14, 28, and 42 days after the surgery. The markers were tetracycline hydrochloride, alizarin red and calcin individually in chronological order. Image J software was used to quantify the bone regeneration. Results: HE staining showed that BG particulates were integrated with the surrounding tissue without any inflammatory cells infiltration 4 weeks after surgery. New bone regeneration was observed both from the border and in the center of the defects in both BG groups. No bone regeneration in defect center was observed in control group. At the end of 8 weeks, there was more bone regeneration in nano-58S group compared with 45S5 group and control group. The structure of the new bone in BG groups was hollow, which was similar to the natural normal parietal bone. No hollow structure was observed in the new bone of control group. Picric-sirius Red polarimetry showed that more amount of collagen type Ⅰ was found in nano58S group than in either 45S5 or control group. The fluorescent observation of the hard tissue slices at the end of 8 weeks showed statistically larger scope and faster new bone formation in nano-58S group with (29.4±4.48) μm thickness from 4－6 weeks and (35.3±3.74) μm from 6－8 weeks compared with 45S5 group ［(13.43±3.44) μm and (17.64±4.13) μm］ and control group ［(5.88±2.92) μm and (6.07±3.02) μm, P<0.01］. Conclusion: Compared with the traditional 45S5 bioactive glass, 58S nanosized bioactive glass showed better osteogenic effect in bone regeneration in parietal bones of rabbits.

Objective：To investigate the effects of 3 surface different treatments on the crystal structure, shear bond strength，roughness value and flexural strength of zirconia. Methods: The zirconia spe-cimens were prepared and randomly divided into 4 groups and received the following treatments: (1)blank control group，the specimens without treatments; (2)sandblasting with alumina group, sandblasting the specimens with 110 μm alumina particles for 21 s as working pressure 0.25 MPa and working distance 10 mm; (3)laser etching group, coating the surface of the specimens with graphite powder and using Er:Yttrium Aluminum Garnet (Er:YAG) laser to irradiate the surface 30 s; (4) hot-etching group, putting the specimens in a closed reactor within a 1 ∶1 mixture of 40%(mass traction) nitric acid and 68%(mass traction) hydrofluoric acid liquid, the reaction of 30 min in a water bath at 100 degrees centigrade. The changes of crystal structure, shear bond strength(SBS) and flexural strength of zirconia after different surface treatments were tested. Results： The X-ray diffractometer(XRD) patterns showed that the volume percentage of monoclinic phase of the 4 groups was 0.91%, 12.50%, 6.64% and 17.81% respectively. The roughness value for the four groups  were as follows: blank control group,(0.29±0.01) μm; sandblasting with alumina group, (1.05±0.11) μm; laser etching group, (0.73±0.04) μm; hot-etching group, (1.31±0.06) μm, respectively(P<0.05). Mean SBS was (7.09±0.46) MPa in blank control group, (12.14±1.51) MPa in sandblasting with alumina group, (8.82±0.74) MPa in laser etching group and (11.97±0.99) MPa in hot-etching group. There was no statistically significant difference between sandblasting with alumina group and hot-etching group (P>0.05), but the difference between the other groups were statistically significant(P<0.05). Mean three-point bending was (933.70±44.13) MPa in blank control group, (850.95±60.66) MPa in sandblasting with alumina group, (771.53±68.08) MPa in laser etching group and (766.27±57.49) MPa in hot-etching group. There was no statistically significant difference between sandblasting with alumina group and hot-etching group (P>0.05), but the difference between the other groups were statistically significant(P<0.05). Conclusion: After different surface treatments, the surface of zirconia has changed from tetrago-nal to monoclinic phases in varying degrees. In addition, surface treatments could improve the bond strength of zirconia to resin cement, and also lead to a decrease in the flexural strength of zirconia.

Objective：To evaluate the effects of different surface treatments on the shear bond strength between zirconia and resin cement. Methods: Forty zirconia discs were randomly divided into four groups (10 discs in each group) for different surface treatments: control, no surface treatment; sandblast, applied air abrasion with aluminum oxide particles; ultraviolet (UV), the zirconia sample was placed in the UV sterilizer at the bottom of the UV lamp at 10 mm, and irradiated for 48 h; cold plasma, the discs were put in the cold plasma cabinet with the cold plasma generated from the gas of He for 30 s. Specimens of all the groups were surface treated prior to cementation with Panavia F 2.0 cement. The surface morphology and contact angle of water were measured. The shear bond strengths were tested and the fai-lure modes were examined with a stereomicroscope. Results: Surface morphology showed no difference between the UV/cold plasma group and the control group. Sandblasted zirconia displayed an overall he-terogeneous distribution of micropores. The contact angle of the control group was 64.1°±2.0°. After sandblasting, UV irradiation and cold plasma exposure, the values significantly decreased to 48.8°±2.6°, 27.1°±3.6° and 32.0°±3.3°. The values of shear bond strength of the specimens with sandblasted (14.82±2.01) MPa were higher than those with no treatment (9.41±1.07) MPa with statistically significant difference (P<0.05). The values of shear bond strength of the specimens with UV irradiation (10.02±0.64) MPa were higher than those with no treatment (9.41±1.07) MPa, but without statistically significant difference (P>0.05). The values of cold plasma group (18.34±3.05) MPa were significantly higher than those of control group (9.41±1.07) MPa, even more than those with sandblast(14.82±2.01) MPa (P<0.05). X-ray photoelectron spectroscopy (XPS) showed increase in oxygen (O) and decrease in carbon (C) elements after UV and cold plasma treatment. The surface C/O ratio also decreased after UV and cold plasma treatment. Conclusion: Zirconia specimens treated with UV and cold plasma could significantly improve the hydrophilicity. The surface morphology was unaffec-ted by the UV irradiation and cold plasma treatments. The improvements of ziconia shear bond strength were slight in UV group without statistically significant difference. Cold plasma treatment significantly improved the shear bond strength between zirconia and resin cement.

Objective： To investigate influence of setting time on bond strength of different bioactive pulp capping materials with self-etch or etch-and-rinse adhesive. Methods: Sixty specimens were prepared for each of the three tested capping materials, namely mineral trioxide aggregate (MTA), iRoot BP Plus (BP) and iRoot FS (FS). Specimens of each material were divided into three groups and bonded at three setting time points of the materials respectively: initial setting time (4 h for MTA, 2 h for BP and 20 min for FS), 24 h after application and 7 d after application. The specimen surfaces of each group were treated with self-etch mode or etch-and-rinse mode of one universal adhesive (Single Bond Universal, SBU) (n=10). The bonding area was restricted to a round area with 3 mm diameter, on which composite cylinders were build up with flowable composite and light cured completely. The shear bond strength was tested immediately with a shear strength tester and fracture mode was observed under stereo microscope and recorded. The mean shear bond strength for each group was analyzed with SPSS 19.0 software ANOVA method. The surface morphology of each material was observed after setting and acid treatment under scanning electron microscope. Results: There was no significant difference among the three tested materials at either initial setting point or 7 d after application (P<0.05). The bond strength of MTA was significantly higher than those of BP and FS 24 h after application in both bonding modes (P<0.05). For all the three tested materials, shear bond strength was significantly higher for complete setting group than for initial setting group of the same material (P<0.05). Under scanning electron microscope, the characteristic crystal patterns could be observed on the three bioactive materials surfaces after complete setting, the size of which was bigger for MTA than for BP and FS. These features were lost to some extent after self-etch primer application or phosphoric acid etching. Conclusion: Based on the present results, adequate bond strength can be obtained for FS at initial setting time, which is comparable with BP and MTA. This implies that clinically composite restoration can be placed over bioactive direct capping materials after shortened initial setting process in one visit.

Objective： To evaluate the influence of an epoxy resin-based sealer on the bond strength of adhesive resins to dentin and the cleaning efficacy of different solvents in removing sealer residues. Methods: The occlusal enamel of 25 freshly extracted human third molars without caries were removed to expose flat surfaces of dentin. The teeth were randomly divided into five groups according to the treatment received: For negative control group, the dentin surfaces were not contaminated with AH-Plus; For the other 4 experimental groups, the samples were contaminated with AH-Plus for 5 min and different mea-sures were taken:For positive control group, the sealer were wiped with dry cotton pellets; For solvents experimental groups: cotton pellets saturated with 95% (volume fraction) ethanol, 99.5% (volume fraction) acetone or 99% (volume fraction) amyl acetate were used to wipe the sealer until the surface appeared clean when viewed through a stereomicroscope under ×10 magnification, then rinsed with de-ionized water for 3 s. After sealer removal, a self-etching adhesive system was applied on the surfaces with resin composite. The samples were sectioned into 1.0 mm×1.0 mm stick specimens (n=45) for microtensile test. Failure modes at the dentin-resin interface were observed using a stereomicroscope. The samples were sectioned into 1.0 mm piece specimens (n=4) for scanning electron microscope observation. The microtensile bond strength data were analyzed by one-way ANOVA. Chi-square test were used to analyse the failure modes between the groups. Results: There was significant difference among the five groups (P<0.001). For dry cotton pellet group (38.69±8.60) MPa and the ethanol group (37.14±12.01) MPa, the microtensile bond strength significantly declined when compared with negative control group (43.86±7.99) MPa (P<0.05). No significant difference of bond strength was found between the dry cotton pellet group and the ethanol group (P=0.426). There was no statistical significant difference among acetone group, amyl acetate group and negative control group (P>0.05). The bond strength of acetone group and amyl acetate group were (45.94±10.37) MPa and (43.99±7.01) MPa, respectively. The ethanol group exhibited lower bond strength than that of acetone group and amyl acetate group (P<0.05). Scanning electronic microscope observation revealed that in dry cotton pellet group and ethanol group, the resin tags were short and loose. Moreover, sealer residues were identified in the interface in the ethanol group samples, while the resin tags in the acetone and amyl acetate group were as dense and uniform as in negative control group. The distribution of failure modes showed no significant difference in the five groups (P=0.086). Conclusion: The microtensile bond strength of dentin to composite resin was lower after exposure to sealer. Compared with ethanol and dry cotton pellets, the clea-ning effect of acetone and amyl acetate on sealer-contaminated dentin surface were better.

Objective： To evaluate the effect of acid etching of retropreps on seal of different retrofill materials. Methods: In the study, 80 freshly extracted lower molar teeth were used. They were examined under 3.5× magnifying glass to rull out fractures. They were cleaned and stored in distilled water before use. The distal roots were sectioned off and underwent root canal treatment. Rotary nickel-titanium instruments were used during instrumentation and the roots were obturated using lateral condensation technique. The apical portion (3 mm in length) was removed with a fine grit diamond bur, the root tip was retroprepared with a ultrasonic tip (3 mm in depth). The retroprepared roots were randomly assigned to 4 groups and retrofilled with amalgam, intermediate restorative material (IRM), iRoot BP Plus and mineral trioxide aggregate (MTA). The groups were further divided into subgroups according to treatment of the root end cavity (etch and non-etch). The root tips were covered with alginate impression material and were left to set in PBS solution for a week and stained with methylene blue for a week. The roots were removed from the dye solution, thoroughly rinsed and dried, split in halves along the long axis with a diamond disk and observed under a stereoscope. The linear dye leakage was measured and analyzed. One way ANOVA and Tamhane’s T2 method were used to analyze the data. The significance level was set at 0.05. Results: The dye leakage results (mean±standard deviation) according to the treatment groups were: amalgam etch (2.80±0.72) mm, amalgam non-etch (2.07±0.86) mm, IRM etch (1.54±0.19) mm, IRM non-etch (1.12±0.28) mm , iRoot BP Plus etch (0.20±0.20) mm, iRoot BP Plus non-etch (0.11±0.08) mm, MTA etch (0.19±0.19) mm, and MTA nonetch (0.17±0.14) mm. One way ANOVA showed significant differences between the groups. Comparison between the groups using Tamhane’s T2 method showed roots retrofilled with iRoot BP Plus and MTA had significant less leakage than those retrofilled with amalgam and IRM (P<0.05); There was no significant difference in terms of leakage between iRoot BP Plus and MTA; Acid etching increased leakage of IRM but did not affect MTA, iRoot BP Plus or amalgam retrofillings. Conclusion: Acid etching is not shown to benefit apical sealing of retrofill materials.

Objective：To evaluate the wear intensity and surface roughness of occlusal veneers on premolars made of microhybrid composite resin or two kinds of ceramics in vitro after the thermocycling and cyclic mechanical loading tests. Methods: In the study,24 fresh extracted human premolars without root canal treatment were prepared （cusps reduction of 1.5 mm in thickness to simulate middle to severe tooth wear, the inclinations of cusps were 20°）. The prepared teeth were restored with occlusal veneers made of three different materials: microhybrid composite, heatpressed lithium disilicate ceramic and computeraided design/computer-aided manufacturing (CAD/CAM) lithium disilicate ceramic in the thickness of 1.5 mm. The occlusal veneers were cemented with resin cement. The specimens were fatigued using the thermocycling and cyclic mechanical loading tests after being stored in water for 72 h. The wear of specimens was measured using gypsum replicas and 3D laser scanner before and after the thermocycling and cyclic mechanical loading tests and the mean lost distance (mm) was used to indicate the level of wear. The surfaces of occlusal contact area were observed and the surface roughness was recorded using 3D laser scanning confocal microscope before and after the fatigue test. Differences between the groups were compared using ONE-way ANOVA（P<0.05）. Results: All the specimens successfully survived after the thermocycling and cyclic mechanical loading tests. The mean wear of microhybrid composite group, heatpressed lithium disilicate ceramic group, and CAD/CAM lithium disilicate ceramic group was （-0.13±0.03） mm, （-0.05±0.01） mm and （-0.05±0.01） mm, the wear of microhybrid composite was significantly higher than the two ceramic groups（P<0.001）.The mean surface roughness（Ra）before the fatigue test was(1.24±0.20) μm, （0.75±0.09） μm, （0.73±0.14） μm and it became （1.81±0.24） μm, （1.53±0.26） μm and （1.77±0.23） μm after the test . Before the fatigue test, the surface roughness of microhybrid composite was significantly higher than the two ceramic groups（P<0.001） and after the test, the surface roughness of heat-pressed lithium disilicate ceramic was significantly lower than microhybrid composite（P=0.005） and CAD/CAM lithium disilicate ceramic(P=0.010). Conclusion: From the view of wear speed, microhybrid composite was significantly higher than the two kinds of ceramics, but it was similar to enamel when the opposing tooth was natural. The surface roughness before the themocycling and cyclic mechanical loading test of microhybrid composite was significantly higher than that of the two ceramic groups. After the test, the surface roughness of heat-pressed ceramic was significantly lower than that of the other two groups. From the view of surface roughness, heat-pressed ceramic has more advantage.

Objective： To develop a digital workflow of orthodontic-prosthodontic multidisciplinary treatment plan which can be applied in complicated anterior teeth esthetic rehabilitation, in order to enhance the efficiency of communication between dentists and patients, and improve the predictability of treatment outcome. Methods: Twenty patients with the potential needs of orthodontic-prosthodontic multidisciplinary treatment to solve their complicated esthetic problems in anterior teeth were recruited in this study. Digital models of patients’ both dental arches and soft tissues were captured using intra oral scanner. Direct prosthodontic (DP) treatment plan and orthodontic-prosthodontic (OP) treatment plan were carried out for each patient. For DP treatment plans, digital wax-up models were directly designed on original digital models using prosthodontic design system. For OP treatment plans, virtual-setups were performed using orthodontic analyze system according to orthodontic and esthetic criteria and imported to prosthodontic design system to finalize the digital wax-up models. These two treatment plans were shown to the patients and demonstrated elaborately. Each patient rated two treatment plans using visual analogue scales and the medians of scores of two treatment plans were analyzed using signed Wilcoxon test. Having taken into consideration various related factors, including time, costs of treatment, each patient chose a specific treatment plan. For the patients chose DP treatment plans, digital wax-up models were exported and printed into resin diagnostic models which would be utilized in the prosthodontic treatment process. For the patients chose OP treatment plans, virtual-setups were used to fabricate aligners or indirect bon-ding templates and digital wax-up models were also exported and printed into resin diagnostic models for prosthodontic treatment after orthodontic treatment completed. Results: The medians of scores of DP treatment plan and OP treatment plan were calculated and analyzed by IBM SPSS 20. The median of scores of DP treatment plan was 8.4, the minimum value was 6.9 and the maximum value was 9.3. The median of scores of OP treatment plan was 9.0, the minimum value was 7.9 and the maximum value was 9.6. The median of scores of OP was significantly higher than that of DP (Z=-3.23, P<0.01). Finally, 12 patients chose OP treatment plans and 8 patients chose DP treatment plans. Conclusion: For cases with complex esthetic problems in anterior teeth, a digital workflow can demonstrate final treatment outcome and help patients make suitable treatment decisions. In our study, the orthodonticprosthodontic multidisciplinary treatment plan is feasible which can provide predictions of treatment outcome and improve esthetic outcome with patients’ satisfaction.

Objective： Three kinds of zirconia specimens were made respectively by milling of the pri-sintered blocks and by three dimensional (3D) gel deposition for in vitro evaluation of their optical translucency under three different thicknesses and their color masking effect on discolored teeth. The study aims for establishing the principle for guiding the materials selection in clinical practice. Methods: Ninety A2-colored zirconia disc specimens with diameter of 14 mm were prepared and were divided into three groups (n=30). (1) Group CZ, by milling of the pre-sintered blanks; (2) Group NZW, by 3D gel deposition, without a color masking opaque inner layer; (3) Group NZY, by 3D gel deposition, with a color masking opaque inner layer. Furthermore, each group was divided into three sub-groups (n=10) according to the sample thickness, i.e., 0.6, 1.0 and 1.5 mm, respectively. The maxillary anterior teeth with severe discoloration, extracted owing to periodontal disease, were collected and embedded. By gentle gridding and polishing a plane, larger than 6 mm2×6 mm2, was generated on the labial surface of each tooth. Chromatic values(CIE1976-L*a*b*) of the zirconia samples in the nine subgroups were measured by the spectrophotometer Crystaleye in front of the black or white background in a cassette, and the translucency parameter (TP) values were calculated for each sample. Thereafter the zirconia specimens were bonded onto the labial surface of the polished teeth for measuring the chromatic values, using the chromatic value of the medium 1/3 of the standardized Vita A2 as a control. The color aberration ΔE between each zirconia specimen and the control value was calculated, respectively. The results were statistically analyzed by One-way ANOVA and Bonferroni. Results: (1) The optical transparency of the three kinds of zirconia disc specimens with the thickness of 0.6, 1.0 and 1.5 mm was 14.09, 12.31 and 10.45 for group CZ；19.84, 16.54 and 12.44 for group NZW；14.81, 13.16 and 11.92 for group NZY. In each group, the degree of optical transparency of the specimens showed a clear tendency as in the sub-group 0.6 mm >1.0 mm >1.5 mm. The TP value of the specimens in the three groups with the same thickness showed a tendency of the group NZW >group NZY >group CZ. (2) After bonding onto the polished labial surface of the teeth, the color aberration ΔE of the specimens with the thickness of 0.6, 1.0 and 1.5 mm was calculated to be 10.77, 9.94 and 8.50 for group CZ; 6.84, 5.89 and 5.29 for group NZW; 4.16, 3.92 and 3.67 for group NZY. In each group, the color aberration of the specimens showed a clear tendency as in the sub-group 0.6 mm >1.0 mm >1.5 mm; the color aberration of the three groups with the same thickness was in the order of the group CZ >group NZW >group NZY. Conclusion: In all the specimen groups with a fixed specimen thickness, the optical translucency of the specimen was the highest in group NZW made by 3D gel deposition, and the best color masking effect was obtained in specimens with a color masking opaque inner layer in group NZY, where a thickness of 0.6 mm was sufficient enough for obtaining the ideal color masking effect.

Objective： To explore the accuracy of periapical film in evaluating the infrabone root surface area of singleroot teeth with different types of resorption of the alveolar bone. Methods: In this study, the medical records and imaging data of patients in Department of Periodontology of Peking University Hospital of Stomatology from January 2014 to December 2016 were retrospectively analysed. The involved teeth were divided into two groups: horizontal bone loss group and vertical bone loss group. Digital threedimensional models of teeth were segmented from cone beam computed tomography (CBCT) data, and the percentage of the infrabone root surface area was measured. While the percentage of the residual alveolar bone was measured on the periapical films. The correlation of the two percentages were analyzed, and the differences between the two percentages of each group were compared. Results: Thirty-two patients and 79 single-root teeth were involved totally, in whom there were 25 men and 7 women, aged 26－60 years, and of which there were 41 teeth in the horizontal bone loss group and 38 teeth in the vertical bone loss group. The remaining alveolar bone height percentages were 45.13%－90.39% on the periapical films, and at the same time, the infrabone root surface area percentages were 36.27%－93.03% on CBCT. The residual alveolar bone height percentage of the horizontal bone loss group was not subject to normal distribution, so the residual alveolar bone height percentage and the infrabone root surface area percentage were analyzed by Wilcoxon matched pair rank test (P = 0.382), and the result showed no statistically significant difference. The mean value of difference value of the two measurements was 0, and the consistency limit of 95 % was －9.7%－9.8%, between the clinical consistency limit (-15%-15%).The residual alveolar bone height percentage and the infrabone root surface area percentage of the vertical bone loss group were analyzed by paired T test (P ＜ 0.001), and the result showed statistically significant difference. The mean value of difference value of the two measurements was 7.2 %, and the consistency limit of 95% was －13.1%－27.5%, beyond clinical consistency limit (－15%－15%). Conclusion: For the teeth with horizontal bone loss, the proximal residual alveolar bone height reflected on the periapical films could show the infrabone root surface area relatively accurately. For the teeth with vertical bone loss, the periapical films could not show the degree of periodontal tissue loss accurately, and it would underestimate the extent of bone destruction usually, so CBCT might be taken to show the bone destruction condition of this type of teeth if necessary.

Objective： To evaluate the difference of features of alveolar bone support under lower anterior teeth between high-angle adults with skeletal class Ⅱ malocclusions and high-angle adults presenting skeletal class Ⅲ malocclusions by using cone-beam computed tomography (CBCT). Methods: Patients who had taken the images of CBCT were selected from the Peking University School and Hospital of Stomatology between October 2015 and August 2017. The CBCT archives from 62 high-angle adult cases without orthodontic treatment were divided into two groups based on their sagittal jaw relationships: skeletal class Ⅱ and skeletal class Ⅲ. vertical bone level (VBL), alveolar bone area (ABA), and the width of alveolar bone were measured respectively at the 2 mm, 4 mm, 6 mm below the cemento-enamel junction (CEJ) level and at the apical level. After that, independent samples t-tests were conducted for statistical comparisons. Results: The ABA of the mandibular alveolar bone in the area of lower anterior teeth was significantly thinner in the patients of skeletal class Ⅲ than those of skeletal class Ⅱ, especially in terms of the apical ABA, total ABA on the labial and lingual sides and the ABA at 6 mm below CEJ level on the lingual side (P<0.05). The thickness of the alveolar bone of mandibular anterior teeth was significantly thinner in the subjects of skeletal class Ⅲ than those of skeletal class Ⅱ, especially regar-ding the apical level on the labial and lingual side and at the level of 4 mm, 6 mm below CEJ level on the lingual side (P<0.05). Conclusion: The ABA and the thickness of the alveolar bone of mandibular anterior teeth were significantly thinner in the group of skeletal class Ⅲ adult patients with highangle when compared with the sample of high-angle skeletal class Ⅱ adult cases. We recommend orthodontists to be more cautious in treatment of highangle skeletal class Ⅲ patients, especially pay attention to control the torque of lower anterior teeth during forward and backward movement, in case that the apical root might be absorbed or fenestration happen in the area of lower anterior teeth.

Objective：To evaluate the accuracy and reliability of detecting alveolar bone dehiscence and fenestration of maxillary anterior teeth of Angle class Ⅲ by cone-beam computed tomography (CBCT). Methods: Eighteen Angle class Ⅲ patients with 108 maxillary anterior teeth were included (3 males and 15 females) who accepted modified corticotomy in orthodontic therapy. The mean age was 23.6 years (18-30 years). The clinical detection of dehiscence and fenestration was done when modified corticotomy was performed by the same periodontist. The CBCT examination was conducted pre-ope-ration and the detection of dehiscence and fenestration by CBCT was done by two periodontists. The data in modified corticotomy were used as the golden standard to calculate the parameters, such as sensitivity, specificity, positive and negative predictive values, Youden index (YI), positive and negative likelihood ratio. Kappa statistic was used to analyze the agreement between the clinical detection and the CBCT detection. Results: The incidence of dehiscence and fenestration was about 10.19% and 13.89% respectively, which mainly occurred on lateral incisors and canines. The median values of length and width of dehiscence were about 5 mm and 4 mm, and the median values of length and width of fenestration were 3 mm and 2 mm, respectively. Most fenestrations were detected on the middle third to the apical third of the root. For dehiscence, the agreement between clinical detection and CBCT detection was statistically significant (P<0.05). For fenestration, the agreement between clinical detection and CBCT detection was statistically significant (P<0.05). The values of sensitivity and specificity for detecting dehiscence were more than 0.7. The values of positive and negative predictive values for detecting dehiscence were 0.44 and 0.97. The values of sensitivity and specificity for detecting fenestration were 0.93 and 0.52. The values of positive and negative predictive values for detecting fenestration were 0.24 and 0.98. Conclusion: For dehiscence, the agreement between clinical detection and CBCT detection was good. For fenestration, the agreement between clinical detection and CBCT detection was general. Detection of dehiscence and fenestration of maxillary anterior teeth of Angle class Ⅲ by CBCT had limited diagnostic value in clinical practice with overestimation of dehiscence and fenestration incidence.

Objective：To test the accuracy and credibility of cone-beam computed tomography (CBCT) on measuring the height and volume of alveolar bone defects before periodontal regeneration surgery. By comparing the bone density measured by CBCT before and after the operation, the time to evaluate the efficacy of the periodontal regenerative surgery would be determined. Methods: Periodontal regenerative surgeries were performed on three-wall bone defects of ten teeth in nine patients. The height of bone defects was measured using both periapical film of distant parallel technique and CBCT before periodontal regenerative surgery. Before the surgery, CBCT data were used to measure the volume of the bone defects and the bone density around the defective areas. The height of the bone defects was measured during pe-riodontal regeneration surgery, and the volume of the defective areas was obtained with bone wax in opera-tion. CBCT was taken 6, 12 and 24 weeks after surgery to measure the bone density in the regenerated region. Results: The Wilcoxon test showed that the height of the bone defects measured preoperatively using periapical film was (0.822±0.222) mm deeper than the intraoperative measurement results, and the difference was statistically significant (P<0.05). Whereas CBCT measurement results was (0.150±0.171) mm less than the intraoperative measurement results, without statistical significant (P＞0.05). The regression analysis and the Bland-Altman method also showed that the results of CBCT measurement were more accurate. The Wilcoxon test showed that the bone defect volume measured by CBCT preoperatively was accurate, and the difference between the preoperative and the intraoperative measurements was not statistically significant, ranging from 0.38 to 2.83 mm3 (P＞0.05). The bone density of the regenerated areas measured by CBCT was (0.49±0.03) times in the sixth week, (0.74±0.09) times in the twelfth week and (1.16±0.11) times in the twentieth week as that of the areas around the bone defects after the surgery. Conclusion: The present data suggest that using CBCT before periodontal regenerative surgery could result in accurate measurement of height and volume of al-veolar bone defects. For the purpose of evaluating the effectiveness of regenerative surgery, CBCT could be taken 24 weeks after surgery.

Objective： To evaluate the influence of the rough surface of dental implants prepared by selective laser melting (SLM) on early bone healing around titanium implants. Methods: A total of sixteen titanium implants were involved in our research, of which eight implants were prepared by SLM (TIXOS-Cylindrical, Leader-Novaxa, Milan, Italy; 3.3 mm×10 mm, internal hex) and the other eight were sandblasted, large-grit and acid-etched (SLA) implants (IMPLUS-Cylindrical, Leader-Novaxa, Milan, Italy; 3.3 mm×10 mm, internal hex). All of the dental implants were inserted into the healed extraction sockets of the mandible of two adult male Beagle dogs. Half of the dental implants were designed to be healed beneath the mucosa and the other half were intended to be healed transgingivally and were immediately loaded by acrylic resin bridge restoration. Three types of tetracycline fluorescent labels, namely calcein blue, alizarin complexone and calcein, were administered into the veins of the Beagle dogs 2, 4, and 8 weeks after implant placement respectively for fluorescent evaluation of newly formed bone peri-implant. Both Beagle dogs were euthanized 12 weeks after implant insertion and the mandible block specimens containing the titanium implants and surrounding bone and soft tissue of each dog were carefully sectioned and dissected. A total of 16 hard tissue slices were obtained and stained with toluidine blue for microscopic examination and histomorphometric measurements. Histological observation was made for each slice under light microscope and laser scanning confocal microscope (LSCM). Comparison on new bone formation around titanium implants of each group was made and mineral apposition rate (MAR) was calculated for each group. Results: Dental implants prepared by selective laser melting had achieved satisfying osseointegration to surrounding bone tissue after the healing period of 12 weeks. Newly formed bone tissue was observed creeping on the highly porous surface of the SLM implant and growing into the pores of surface structure. Higher MAR values were shown for SLM implants compared with SLA implants (P<0.01). Conclusion: Dental implants prepared by selective laser melting could promote early bone healing and improve mineral apposition rate.

Objective： To present a prognostic model for evaluating the outcome of root canal treatment in teeth with pulpitis or apical periodontitis 2 years after treatment. Methods: The implementation of this study was based on a retrospective study on the 2-year outcome of root canal treatment. A cohort of 360 teeth, which received treatment and review, were chosen to build up the total sample size. In the study, 143 teeth with vital pulp and 217 teeth with apical periodontitis were included. About 67% of the samples were selected randomly to derive a training date set for modeling, and the others were used as validating date set for testing. Logistic regression models were used to produce the prognostic models. The dependent variable was defined as absence of periapical lesion or reduction of periapical lesion. The predictability of the models was evaluated by the area under the receiver-operating characteristic (ROC) curve (AUC). Results: Four predictors were included in model one (absence of apical lesion): pre-operative periapical radiolucency, canal curvature, density and apical extent of root fillings. The AUC was 0.802 (95%CI: 0.744-0.859). And the AUC of the testing date was 0.688. Only the density and apical extent of root fillings were included to present model two (reduction of apical lesion). The AUC of training dates and testing dates were 0.734 (95%CI: 0.612-0.856) and 0.681, respectively. As predicted by model one, the probability of absence of periapical lesion 2 years after endodontic treatment was 90% in pulpitis teeth with sever root-canal curvature and adequate root canal fillings, but 51% in teeth with apical periodontitis. When using prognostic model two for prediction, in teeth with apical periodontitis, the probability of detecting lesion reduction with adequate or inadequate root fillings was 95% and 39% 2 years after treatment. Conclusion: The preoperative periapical status, canal curvature and quality of root canal treatment could be used to predict the 2year outcome of root canal treatment.

Objective： To present a theoretical analysis of how the presence of bone in interstitial brachytherapy affects dose rate distributions with MCNP4C Monte Carlo code and to prepare for the next clinical study on the dose distribution of interstitial brachytherapy in head and neck neoplasm. Methods: Type 6711,125I brachytherapy source was simulated with MCNP4C Monte Carlo code whose cross section library was DLC-200. The dose distribution along the transverse axis in water and dose constant were compared with the American Association of Physicists in Medicine (AAPM) TG43UI update dosimetry formalism and current literature. The validated computer code was then applied to simple homogeneous bone tissue model to determine the affected different bone tissue had on dose distribution from 125I interstitial implant. Results: 125I brachytherapy source simulated with MCNP4C Monte Carlo code met the requirements of TG43UI report. Dose rate constant, 0.977 78 cGy/(h·U), was in agreement within 1.32% compared with the recommended value of TG43UI. There was a good agreement between TG43UI about the dosimetric parameters at distances of 1 to 10 cm along the transverse axis of the 125I source established by MCNP4C and current published data. And the dose distribution of 125I photon emitting source in different bone tissue was calculated. Dose-deposition capacity of photons was in decreasing order: cortical bone, spongy bone, cartilage, yellow bone marrow, red bone marrow in the same medium depth. Photons deposited significantly in traversal axis among the phantom material of cortical bone and sponge bone relevant to the dose to water. In the medium depth of 0.01 cm, 0.1 cm, and 1 cm, the dose in the cortical bone was 12.90 times, 9.72 times, and 0.30 times of water respectively. Conclusion: This study build a 125I source model with MCNP4C Monte Carlo code, which is validated, and could be used in subsequent study. Dose distribution of photons in different bone medium is not the same as water, and its main energy deposits in bone medium surface, so we should consider the effect of bone medium when we design the target area adjacent to the bone tissue in 125I sources implantation plan.

Objective： To make more accurate occlusal quantitative analysis of  three-dimensional (3D) virtual dental models and to compare the occlusal contact obtained by intraoral and dental cast scan. Methods: In this study, 5 subjects were intraoral scanned using laser scanner (3 shapes, Germany) to obtain the 3D virtual models of one tooth (the first molar), two teeth (the second premolar and the first molar), three teeth (the premolars and the first molar) and their opposite teeth, respectively. The silicone impressions were made and dental stone models were poured for each of them. The dental casts were scanned and then they were fixed to the maximum intercuspal position with a special locating jig for a rescanning of occlusal position. The virtual models taken intraorally and obtained with dental cast scan were introduced to a 3D quantitative analysis system, and some criteria regarding to occlusal contact were calculated and analyzed. The occlusal criteria were mean values of occlusal clearance space between the upper and lower occlusal surface (clearance), occlusal contact area (area), and cusp inclination (angle) of the mandibular first molar. Paired t tests were used to evaluate differences of occlusal criteria between the virtual models obtained with the intraoral scan and dental cast scan (α=0.05). Results: The mean values of occlusal clearance of one to three teeth obtained by way of intraoral scan were smaller than those obtained by way of cast scan by 0.134 mm, 0.177 mm, and 0.207 mm, respectively. While the occlusal contact areas were greater than the cast scan by 8.65 mm2, 10.28 mm2, and 11.46 mm2. No statistically significant differences were found between the cusps inclinations obtained with the two scanning methods, and the interclass correlations were high. Conclusion: Occlusal clearance obtained by intraoral scan was less than that by cast scan while the occlusal contact area was greater than the latter, indicating that intraoral occlusal contact was closer. The difference of the standard deviations of occlusal clearance measured by the two methods were small and that of occlusal contact area was influenced by the number of teeth scanned intraorally. There was no statistical difference in cusp inclination between the two methods.

Objective：To analyze the stress distribution in the periodontal ligament (PDL) under different loading conditions at the stage of space closure by 3D finite element model of customized lingual appliances. Methods: The 3D finite element model was used in ANSYS 11.0 to analyze the stress distribution in the PDL under the following loading conditions: (1) buccal sliding mechanics (0.75 N,1.00 N,1.50 N), (2) palatal sliding mechanics (0.75 N,1.00 N,1.50 N), (3) palatalbuccal combined sliding mechanics (buccal 1.00 N + palatal 0.50 N, buccal 0.75 N + palatal 0.75 N, buccal 0.50 N+ palatal 1.00 N). The maximum principal stress, minimum principal stress and von Mises stress were evaluated. Results: (1) buccal sliding mechanics（0.75 N,1.00 N,1.50 N）: maximum principal stress: at the initial of loading, maximum principal stress, which was the compressed stress, distributed in labial PDL of cervix of lateral incisor, and palatal distal PDL of cervix of canine. With increasing loa-ding, the magnitude and range of the stress was increased. Minimum principal stress: at the initial of loading, minimum principal stress which was tonsil stress, distributed in palatal PDL of cervix of lateral incisor and mesial PDL of cervix of canine. With increasing loading, the magnitude and range of minimum principal stress was increased. The area of minimum principal stress appeared in distal and mesial PDL of cervix of central incisor. von Mises stress：it distributed in labial and palatal PDL of cervix of la-teral incisor and distal PDL of cervix of canine initially. With increasing loading, the magnitude and range of stress was increased towards the direction of root. Finally, there was stress concentration area at mesial PDL of cervix of canine. (2) palatal sliding mechanics（0.75 N,1.00 N,1.50 N）: maximum principal stress: at the initial of loading, maximum principal stress which was the compressed stress, distributed in palatal and distal PDL of cervix of canine, and distalbuccal and palatal PDL of cervix of late-ral incisor. With increasing loading, the magnitude and range of the stress was increased. Minimum principal stress: at the initial of loading, minimum principal stress which was tonsil stress, distributed in distalinterproximal PDL of cervix of lateral incisor and mesial-interproximal PDL of cervix of canine. With increasing loading, the magnitude and range of the stress was increased.von Mises stress: von Mises stress distributed in palatal and interproximal PDL of cervix of canine. With increasing loading, the magnitude and range of stress was increased. Finally, von Mises stress distributing area appeared at distalpalatal PDL of cervix of canine. (3) palatalbuccal combined sliding mechanics: maximum principal stress: maximum principal stress still distributed in distal-palatal PDL of cervix of canine. Minimum principal stress: minimum principal stress distributed in palatal PDL of cervix of lateral incisor when buccal force was more than palatal force. As palatal force increased, the stress concentrating area transferred to mesial PDL of cervix of canine.von Mises stress: it was lower and more well-distributed in palatal-buccal combined sliding mechanics than palatal or buccal sliding mechanics. Conclusion: Using buccal sliding mechanics，stress majorly distributed in PDL of lateral incisor and canine, and magnitude and range of stress increased with the increase of loading; Using palatal sliding mechanics，stress majorly distributed in PDL of canine, and magnitude and range of stress increased with the increase of loading; With palatal-buccal combined sliding mechanics, the maximum principal stress distributed in the distal PDL of canine. Minimum principal stress distributed in palatal PDL of cervix of lateral incisor when buccal force was more than palatal force. As palatal force was increasing, the minimum principal stress distributing area shifted to mesial PDL of cervix of canine. When using 1.00 N buccal force and 0.50 N palatal force, the von Mises stress distributed uniformly in PDL and minimal stress appeared.

Objective： To compare the shaping ability of ProGlider, HyFlex EDM Glidepath File and RaCe ISO 10 with that of PathFile and stainless steel K-file hand instruments in simulated root canals. Methods: A total of 60 simulated resin blocks were divided randomly into five groups (n=12), each group prepared with each instrument, respectively. Preparation time was recorded. Pre- and post-operative images were obtained using a scanner and superimposed using Photoshop. The material removal from the inner and outer canal walls beginning from 0 mm at the end point of the canal were measured using ImageJ. Centering ability was determined, accordingly. The data were analyzed using the One-Way ANOVA at a significance level of P < 0.05. Results: Preparation time for ProGlider was (61.018±5.020) s, significantly the fastest (P < 0.05), that for SS K-file (111.100±6.987) s, the slowest (P < 0.05), and the differences among the other 3 groups were not significant (P>0.05). The removal of resin from the outer wall at the apical portion was significantly lower for HyFlex EDM Glidepath File than for ProGlider (P<0.05), both of them were significantly lower than the other 3 groups (P<0.05). For the removal from the inner wall at the curvature portion, ProGlider was the least whilst SS K-file the most (P<0.05). At the straight portion, RaCe ISO 10 removed the most not only from the inner but also the outer wall (P<0.05), HyFlex EDM Glidepath File the second most, and the other 3 groups among the same levels. As far as the centering ability was concerned, at the apical portion, HyFlex EDM Glidepath File was the best, ProGlider the second best, no significant difference identified among the other 3 groups. At the curvature portion, ProGlider and HyFlex EDM Glidepath File were the best, PathFile the second, RaCe ISO 10 the third, the worst was the SS K-file. At the straight portion, the difference amongt the 5 groups was not significant. Conclusion: The shaping abilities of ProGlider, HyFlex EDM Glidepath File and RaCe ISO 10 were better or comparable to that of PathFile, while the preparation time for ProGlider reduced significantly, and HyFlex EDM Glidepath File and RaCe ISO 10 removed significantly more resin at the straight portion of the canal.

Objective： To evaluate the accuracy of virtual occlusal definition in non-Angle class Ⅰ molar relationship, and to evaluate the clinical feasibility. Methods: Twenty pairs of models of orthognathic patients were included in this study. The inclusion criteria were: (1) finished with pre-surgical orthodontic treatment and (2) stable final occlusion. The exclusion criteria were: (1) existence of distorted teeth, (2) needs for segmentation, (3) defect of dentition except for orthodontic extraction ones, and (4) existence of tooth space. The tooth-extracted test group included 10 models with two premolars extracted during preoperative orthodontic treatment. Their molar relationships were not Angle class Ⅰ relationship. The non-tooth-extracted test group included another 10 models without teeth extracted, therefore their molar relationships were Angle class Ⅰ. To define the final occlusion in virtual environment, two steps were included: (1) The morphology data of upper and lower dentition were digitalized by surface scanner (Smart Optics/Activity 102; Model-Tray GmbH, Hamburg, Germany); (2) the virtual relationships were defined using 3Shape software. The control standard of final occlusion was manually defined using gypsum models and then digitalized by surface scanner. The final occlusion of test group and control standard were overlapped according to lower dentition morphology. Errors were evaluated by calculating the distance between the corresponding reference points of testing group and control standard locations. Results: The overall errors for upper dentition between test group and control standard location were (0.51±0.18) mm in non-tooth-extracted test group and (0.60±0.36) mm in tooth-extracted test group. The errors were significantly different between these two test groups (P<0.05). However, in both test groups, the errors of each tooth in a single dentition does not differ from one another. There was no significant difference between errors in tooth-extracted test group and 1 mm (P>0.05); and the accuracy of non-tooth-extracted group was significantly smaller than 1 mm (P<0.05). Conclusion: The error of virtual occlusal definition of none class I molar relationship is higher than that of class I relationship, with an accuracy of 1 mm. However, its accuracy is still feasible for clinical application.

Objective：To evaluate the effects of endoscopy-assisted sialodochoplasty for the treatment of severe sialoduct stenosis with concurrent megaducts. Methods: From Jul.2010 to Dec. 2016, 8 patients presenting with severe parotid duct stenosis and 3 patients with occlusion of the Wharton’s duct underwent endoscopyassisted sialodochoplasty.All these patients had concurrent severe ductal ectasiaand mani-fested a painful swelling of the involved salivary glands.The diameter of ectasia and length of stenosis of the sialoducts were measured preoperatively by sialography, computed tomography, or ultrasonography. The megaducts were opened transorally and sutured to the buccal or oral floor mucosa, therefore creating a neo-ostium. All the patients were followed up periodically after operation. The treatment effects were evaluated by clinical signs, sialogram and sialometry. Results: The length of the Stensen’s duct stenosis was 5-12 mm, and the diameter of the concurrent ectasia was 8-16 mm. The length of the Wharton’s duct stenosis was 10-20 mm, and the diameter of the concurrent ectasia was 6-8 mm.The neo-ostiums healed uneventfully 2 weeks after operation. The duration of the follow-up varied from 6 to 78 months (median: 24 months). Among the 8 patients with Stensen’s duct stenosis, two experienced re-obliteration of the neo-ostium, but the buccal bulge and clinical symptoms disappeared; one reported recurrent clinical symptoms after initial alleviation, which could be controlled with self-massaging; the remaining 5 patients had satisfactory clinical results, i.e., disappearance of the obstruction symptoms and buccal bulge, patent ostium,clean saliva and improvement of the ductal ectasia on sialogram. Three patients with Wharton’s duct occlusion were asymptomatic with clear saliva and patent ostium;two exhibited approximately normal appearance and one showed improvement of the sialogram.Sialometry was performed in 9 patients with patent neo-ostium of the involved glands,the resting saliva flow rate of the affected glands showed no differences compared with the normal side, and stimulated flow rate showed a significant increase, though less than the control side.The clinical results included good in 5 patients, fair in 4 patients, and poor in 2 patients, with a total effective rate of 82% (9/11). Conclusion: Endoscopyassisted sialodochoplasty appears to be effective and can be a viable option for patients presenting with severe sialoducts tenosis and concurrent ectasia.

Objective：To investigate the effectiveness of preemptive analgesia with loxoprofen sodium orally, which was a kind of non-steroid anti-inflammatory drugs, in extractions of mandibular impacted third teeth. Methods: There were questionnaires about postoperative pain for patients whose mandibular impacted third teeth were extracted from July 2017 to August 2017 in First Clinical Division of Peking University School and Hospital of Stomatology. All the patients did their routine clinical examinations and imaging examinations. After their mandibular impacted third teeth were extracted, the questionnaires were sent to them. The questionnaires were filled in by the patients on their own and returned one week later. There were 120 questionnaires that were sent and 105 questionnaires returned, of which 98 questionnaires were filled in completely. According to the inclusive criteria and exclusion criteria, 66 questionnaires were totally selected in this study. According to the time when the patients took their loxoprofen sodium orally firstly, the patients were divided into 3 groups. The first group was for patients who didn’t take loxoprofen sodium during their extractions (non-medicine group). The second group was for patients who took 60 mg loxoprofen sodium 30 min before their extractions (preoperative group). The third group was for patients who took 60 mg loxoprofen sodium 30 min after their extractions (postoperative group). The operation time among the 3 groups was analyzed by Kruskal-Wallis method. The postoperative time points were 2, 4, 12,24 and 48 h after operation. The scores of visual analogue scales (VAS) for postoperative pain in each group at different postoperative time points were analyzed by Friedman method. At each postoperative time point, VAS scores in the different groups were analyzed by Kruskal-Wallis me-thod. The numbers of the patients taking loxoprofen sodium home and drug adverse reactions were also analyzed. Results: The operation time of the 3 groups was 15.0 (5.0,30.0) min and had no significant differences (P=0.848).VAS scores of non-medicine group 2,4, 12,24 and 48 h after operation were 1.75 (0.1,10.0), 6.25 (1.5,10.0), 2.00 (0.1,8.0), 2.00 (0.1,6.0) and 0.5 (0.1,5.5) separately and had significant differences (P<0.001).The VAS score at 4 h after operation was higher than the VAS scores at other time points after operation (P<0.005). Four hours after the operations, the VAS scores of preoperative group ［2.0 (0.1,10.0)］ and postoperative group ［2.0 (0.1,5.0)］ were lower significantly than those of non-medicine group ［6.25 (1.5,10.0)］ (P<0.001).The numbers of the patients taking loxoprofen sodium home were 9(40.9%) in non-medicine group,5(21.8%) in preoperative group and 7(33.3%) in postoperative group. The number of the patients who had drug adverse reactions in preoperative group (n=3,13.0%) and in postoperative group (n=4,19.0%) was less than the number of the patients who had drug adverse reactions in non-medicine group (n=8,36.4%). Conclusion: There were two protocols of preemptive analgesia with loxoprofen sodium orally in extractions of mandibular impacted third teeth, which were taking 60 mg loxoprofen sodium orally 30 min before the extractions and taking 60 mg loxoprofen sodium orally 30 min after the extractions. Both of the two preemptive analgesia protocols could decrease the postoperative pain significantly.

Objective： To evaluate the two-year outcomes of primary molars pulpotomy using mineral trioxided aggregate (MTA) and to find out the potential influence factor, with the help of electronic medical record database. Methods: Children who received primary molars pulpotomy in the Department of Pediatric Dentistry in Peking University School and Hospital of Stomatology from May, 2014 to November, 2015 were searched in the Electronic Medical Record Database of Peking University School and Hospital of Stomatology, via the database for scientific research provided by the corporation of Kaientai. The children who were healthy, no more than 8 years old and followed up over 1.5 years were selected as the subjects of this study. At the same time, those children who didn’t have complete medical records and X-rays before and after treatment were removed. Basic information, the relevant medical records and radiographic records of those children were collected. All molars were examined clinically and radiographically, and classified into 1 of 5 outcomes: N, H, P0, PX, PY. Molars classified into P0, PX and PY were regarded as failed. Survival analysis was applied. The survival rate and survival time of the deciduous teeth were calculated．Multivariate analysis was performed by using Cox proportional hazard model. Results: One hundred and fifteen children were finally included，aged from 2.6 to 8.2 years, with the mean age of (4.5±1.1) years. 211 primary molars were included, and the average follow up time was (880±154)  days. A good level of agreement between the raters was found for molars with five outcomes(κ=0.913). Intrarater reliability was good for molars with five outcomes (κ=0.916). Forty-nine molars failed by September, 2017. Fortythree molars had abnormal radiographic manifestation. Six molars suffered premature loss. Only fourteen molars had an associated gingival swelling or parulis, or pa-thologic mobility upon clinical examination. The cumulative survival probability of half a year, one year, one year and a half, two years, two year and a half for the pulpotomy was 100%, 98.5%, 92.9%, 90.5%,73.8% through the Kaplan-Meier method, respectively. Through the analysis of Cox proportional hazard model, the survival probability was significantly higher when the age was younger. When sodium hypochlorite and the saline were used as the irrigation at the same time, the survival probability was not improved for those teeth with more bleeding in the operation compared with that used saline only. The teeth with preformed metal crown (PMC) gained longer median survival time than those restored with resin composite and others, but the difference was not significant, either. What’s more, gender, the restoration time of PMC, the restoration of the opposite teeth were not found to be associated with the success of the treatment. Conclusion: The cumulative survival probability of two years after the primary pulpotomy was 90.5%, complying the current instructions in our department. The survival probability of the molars after the treatment was significantly affected by the age.

Objective： To investigate the effects of the Arg-Gly-Asp polypeptedes (RGD) peptides-modified porous tantalum surface on osteoblasts morphology and expressions of osteogenesis factors, and to evaluate RGD peptides promotes junctura ossium of tantalumbone interface in vivo. Methods: RGD peptides of different concentrations (1 g/L, 5 g/L, and 10 g/L) were loaded to porous tantalum slices with a diameter of 10 mm and a thickness of 3 mm by physical absorption. The 3rd generation of MG63 cells were co-cultured with tantalum and divided into 4 groups: Ta-cells (control) group, 1 g/L cells/Ta/RGD group, 5 g/L cells/Ta/RGD group, and 10 g/L cells/Ta/RGD group. Porous tantalum compo-sites and osteoblasts-tantalum interface were observed by scanning electron microscopy. The adhesion rate of osteoblasts was detected and immunocytochemistry was used to detect the expressions of filamentous actin (F-actin), osteocalcin (OC) and fibronectin (FN). Results: The scanning electron microscope (SEM) revealed that osteoblasts distributed on the surface of porous tantalum and secreted extracellular matrix on outside and inner of micro-pores. The osteoblasts adhesion rate on porous tantalum modified with RGD was higher than that in the unmodified porous tantalum at the end of 24, 48, and 72 hours. The best adhesion effect was got in 5 g/L cells/Ta/RGD group at hour 48 ［(68.07±3.80) vs. (23.40±4.39), P<0.05］. The results of immunocytochemistry showed that the expressions intensity of F-actin, OC and FN in osteoblasts on porous tantalum modified groups with RGD were stronger than that in the unmodified groups, and the expressions of 5 g/L cells/Ta/RGD group were significantly higher than those in the 10 g/L group and 1 g/L group ［OC: (18.08±0.08) vs. (15.14±0.19), P<0.05; (18.08±0.08) vs. (14.04±0.61), P<0.05. FN: (24.60±0.98) vs. (15.90±0.53), P<0.05; (24.60±0.98) vs. (15.30±0.42), P<0.05. Factin: (29.20±1.31) vs. (24.50±1.51), P<0.05; (29.20±1.31) vs. (16.92±0.40), P<0.05］. Correspondingly F-actin in osteoblasts was showed in longitudinal arrangement, and the expressions intensity was stronger than those OC and FN. Conclusion: The RGD peptides is beneficial to enhance adhesion of osteoblast, spreading and reorganization of cytoskeleton on porous tantalum surface and improve the interface morphology, further promoting osteoblasts-tantalum conjunctive interface osseointegration.

Objective：To investigate the safety and perioperative experience of the segmental resection of the vena cava. Methods: From May 2015 to July 2017, 92 renal tumor patients with venous tumor thrombus were treated in Peking University Third Hospital, of whom 17 underwent nephrectomy with resection of the invaded vena cava for renal tumor with tumor thrombus invading vena cava. The preoperative features included that 15 patients were male and 2 female, the mean age was (59.2±12.9) years (31-84 years), 6 cases were left sided and 11 right sided, and the mean diameter of the renal tumor was (9.1±3.7) cm (3-14.5 cm). Results: In this group of 17 cases, 5 patients underwent resection of the vena cava via laparoscopy (including 2 open conversions), and 12 via open procedures (including 2 cardiopulmonary bypasses). The mean operation time was (430.4±120.7) min (284-694 min) and the mean intraoperative blood loss was (2 918.8±2 608.2) mL (300-10 000 mL). The vena cava from the bottom to the top was transected. The median length of the tumor thrombus in the vena cava was 10 cm (3-21 cm). Postoperative complications were found in 11 patients, including grade Ⅰ in 1 case, grade Ⅱ in 7 cases, grade Ⅳ in 2 cases and grade Ⅴ in 1 case according to the Clavien system. The median postoperative creatinine was 116 μmol/L (79-645 μmol/L) with 2 patients needing dialysis. The postoperative pathology revealed that renal clear cell carcinoma in 10 cases, papillary carcinoma in 5 cases, urothelial carcinoma in 1 case and fusiform cell sarcoma in 1 case. During the median followup of 8 (1-28) months, 1 patient died during perioperative period, 1 patient died from multiple metastasis in 9 months postoperatively, 3 patients found distant metastasis and 2 cases remained lower extremity edema after operation. Conclusion: The segmental resection of the vena cava may be a good choice for non-metastatic renal tumors with tumor thrombus invading vena cava. The short term follow-up results revealed a satisfactory safety and feasibility.

Objective：To compare the dosimetric differences between volumetric modulated arc therapy and intensity modulated radiotherapy for breast cancer patients after breastconserving surgery. Methods: Ten patients who received radiotherapy after breast-conserving surgery were selected. Eclipse planning system was used to design volumetric rotating intensity-modulated (2FRapidArc) and two field intensity-modulated radiation therapy (2F-IMRT) planning for each patient. 2F-RapidArc plans were made using two partial arcs with gantry rotation from 287°－293° to 152°－162°, and 0° to 90° was avoidance sector. The gantry angle of 2F-IMRT were 301°－311° and 125°－135°. The prescription dose was 46 Gy/23 fractions. All plans required 95% of the target volume receiving the prescription dose. The dose distribution of the target, organs at risk, machine unit (MU) and treatment time were compared. Results: 2F-RapidArc and 2FIMRT plans’ uniformity index was 1.12±0.02 and 1.11±0.03 (P=0.282), respectively; conformal index was 0.80±0.03 and 0.65±0.04 (P＜0.001), respectively. V110 of plan target volume was 20.98%±14.47% and 10.43%±10.49% (P=0.030), respectively. Compared with the 2F-IMRT, 2F-RapidArc plans had a higher dosimetric parameters for left lung: V5 (48.06%±17.32% vs. 24.23%±6.56%，P=0.001), V10 (28.89±9.28 vs.17.07±4.78 %，P=0.004), Dmean ［(9.70±2.14) Gy vs. (6.86±1.77) Gy，P=0.002］, increased the double lung: V5 (22.85%±7.55% vs. 11.01%±2.95%，P=0.001), V10 (13.16%±4.33% vs. 7.76%±2.16%，P=0.006), Dmean ［(4.66±0.95) Gy vs. (3.17±0.82) Gy，P=0.001］, reduced the left lung: V40 (3.58%±1.46% vs. 6.19%±3.04%，P=0.006), reduced the double lung: V40 (1.61%±0.64% vs. 2.81%±1.39%，P=0.005), increased cardiac: V5 (39.3%±17.19% vs. 8.79%±4.24%，P＜0.001), V10 (21.31%±13.8% vs. 5.73%±3.42%，P=0.002), V20 (7.80%±6.08% vs. 4.05%±2.85%，P=0.018), Dmean ［(0.64±0.25) Gy vs. (0.29±1.39) Gy，P＜0.001］，reduced the heart: V40(0.50%±0.40% vs. 1.86%±1.94%，P=0.037)，increased the contralateral breast Dmean ［(1.63±1.26) Gy vs. (0.09±0.05) Gy, P=0.004］. Compared with 2F-IMRTplan, 2F-RapidArc increased the treatment time ［(132.9±7.2) s vs. (140.3±11.6) s，P=0.030］. Both the machine units were almost the same ［(467.0±30.4) MU vs. (494.7±44.9) MU，P=0.094］. Conclusion: Both 2F-RapidArc and 2F-IMRT plans could reach the clinical requirements. 2F-RapidArc had a better conformal index, reduced the high dose area, but increased the low dose regions of the lung, heart, body area, and increased the average dose of the contralateral breast. The treatment time of 2F-RapidArc was longer than that of 2F-IMRT, and the MU of 2F-RapidArc and 2F-IMRT plans were almost the same.

Objective： To investigate the incidence of peri-anesthesia allergy in a tertiary teaching hospital. Methods： This was a retrospective cohort study. Patients who received anesthesia in operation rooms at Peking University First Hospital from January 2012 to April 2017 were enrolled. Researchers reviewed all the patients’ electronic records and screened suspect allergy cases. Allergy was diagnosed according to the definition in Consensus on Management of Perioperative Allergy (China) and Scandinavian Clinical Practice Guidelines on the Diagnosis, Management and Follow-up of Anaphylaxis during Anesthesia. After obtaining the electronic records, two researchers began to screen and supplement mis-sing data according medical records independently, then they checked out each other’s data. The final data were reviewed by another two researchers. We collected the patients’ basic characteristics, surgery type, anes-thesia type, perianesthesia use of drugs, prognosis and other data. Univariate logistic regression was employed to screen potential factors of allergy. Factors with statistical significance (P<0.05) in univariate Logistic regression were entered into multivariate Logistic regression to identify independent risk factors of allergy. Results: In the study, 106 074 patients entered final statistic analysis. The incidence of peri-anesthesia allergy was about 1.5/1 000 (156/106 074). The incidence of Grades Ⅰ, Ⅱ and Ⅲ allergy was 64.1% (100/156), 30.1% (47/156), and 5.8% (9/156) respectively. Multivariate logistic regression showed 5 independent risk factors of allergy including history of allergy (OR=6.836, 95%CI: 4.461-10.474, P<0.001), intraoperative use of sufentanil (OR=1.993, 95%CI: 1.228-3.232, P=0.005), intraoperative use of cisatracuronium (OR=2.495, 95%CI: 1.599-3.893, P<0.001), intraoperative infusion of antibiotics (OR=2.005, 95%CI: 1.375-2.924, P<0.001) and frozen fresh plasma (OR=3.055, 95%CI: 1.842-5.068, P<0.001). Conclusion: The incidence of perianesthesia allergy is high and further attempt is needed to establish standard operation process of diagnosis and treatment of allergy.