Objective　Osteoporosis was characterized by reduced bone density and bone mass, which affected the stability of implants. The purpose of this study was to investigate the effects of magnesium-containing hydroxyapatite (MgHA) coating on implant fixation in ovariectomized (OVX) rats. Methods　Control group possessed hydroxyapatite (HA) coating prepared by sol-gel method, while the experimental group used coating of MgHA with 10 % Ca2+ replaced by Mg2+ prepared in the same way. 18 OVX rats were randomly divided into two groups; one group received a HA implant separately in the bilateral femoral telecentric end and the other group got MgHA implants. 12 weeks later, implants together with surrounding bone tissue were harvested for histomorphometry, Micro-CT evaluation, and biomechanical testing. Results　In MgHA group, bone-to-implant contact rate and bone area ratio were （52.57±4.73）%,（36.76±3.31）%, while those in HA group were （34.06±5.20）%,（27.26±2.92）%. The maximum push-out force and interfacial shear strength were (63.98±4.08)N, and (2.63±0.25)N/mm2 in MgHA group, while those in HA group were (41.44±7.07)N, (2.22±0.33)N/mm2. In addition, bone volume fraction, trabecular thickness, trabecular number, trabecular separation, connectivity density, and osseointegration rate in MgHA group were （24.5±6.1）%,（80.6±11.9）μm, （5.8±0.5）mm?1,（194.7±38.2）μm, （51.9±5.6）mm?3, （58.6±6.2）%, while those in HA group were （16.6±4.3）%,（68.4±10.3）μm、（5.2±0.6）mm?1、（220.8±30.6）μm、（44.1±4.5）mm?3、（45.1±3.8）%. All the differences were statistically significant (P<0.05) except trabecular separation. Conclusions　Magnesium element can improve biological performance of implants in osteoporosis bone.

Objective:　To investigate the expression of cell adhesion molecules CD44v5 and CD44v7 and their significance in oral squamous cell carcinoma(OSCC). Methods　Specimens from 43 cases of OSCC and their 13 metastatic lymph nodes were used to detect the expression of CD44v5 and CD44v7 by immunohistochemical SP method. Results　As to 13 cases which had lymph nodes involvement, the expression level of CD44v5 was much higher in the primary tumor than that in the metastasis(lymph nodes), and there was statistial significance (P<0.05); the expression level of CD44v7 was much higher in the primary tumor without metastatic lymph node than that with metastatic lymph node, and there was statistial significance (P<0.05). In the 43 cases of primary tumor, no significant difference was observed in the expression of CD44v5 between OSCC with and without metastatic lymph node; there was no statistically significant difference in the expression of CD44v7 in the metastasis and primary tumor (P>0.05). Conclusions　CD44v5 and CD44v7 may be related to metastasis in OSCC.

Objective　To explore the effect whether biomembrane was applied or not in maxillary sinus augmentation together with mucosa perforation. Methods　6 sites for implants were chosen in 3 health adult mongrel dogs and were randomly divided into 2 groups. In the control group, models with mucosa perforation at the maxillary sinus floor were established, and the diameter of the mucosa perforation was 5mm. Implants were implanted synchronously. Autogenous bone and artificial bone particles (hydroxyapatite) were also implanted. In the experimental group, models were extablished in the same way. Biological collagen membrane was used to cover the area between sinus floor perforation site and implants. CT photos were taken 1 month and 3 months after the operation. 3 months later, the animals were sacrificed. Observe the osseointegration of implants, mucosa healing at sinus floor, and changes in lengths of implants that protruded into maxillary sinus cavity. Results　1 implant fell off in control group, and a lot of sanies overflowed from maxillary sinus cavity. The rest 4 implants were good in osseointegration. 3 months later, the lengths of the implant exposed increased both in the experimental group and control group, but there was no significant difference between the two groups (P > 0.05). Mucosa at maxillary sinus floor healed well under macroscopic observation. HE staining showed that submucosa at sinus floor in both groups was thickened, and mucosal epithelium ciliated cells disappeared. Conclusions　In this experiment, when mucosa perforation occurred at maxillary sinus floor in maxillary sinus augmentation, biological membrane had no obvious positive effect on the preservation and osteogenesis of artificial bone.

Objective To study the efficiency of connected miniscrews as anchorage to lower molar intrusion . Methods 3 patients with overerrupted lower molars were selected. Two miniscrews, 1.6 mm in diameter, 9 mm in length, were placed buccully in the interradicular areas between second premolar and first premolar. Two buccally placed miniscrews were connected by 2 straight 0.48 mm×0.64 mm orthodontic stainless steel archwires were welded. The distal ends of the wires were bent to form a hook stretching to the buccal lingual side of the molars.. A elastic generating 1N force was connected to the lingual and buccal hooks to intrude the overerrupted molar. Results All the implatation was successful and there was no loosening in the treatment. After 5 months' treatment, the overerupted lower posterior molars were lowered . Conclusion Connected miniscrews can be effective anchorage to lower overerupted molars．

Abstract: Objective To evaluate the remineralization effect of incipient enamel caries after treated with fluoride iontophresis in vitro. Methods All specimens of artificial incipient enamel caries were subjected to a pH-cycling process for 7 d and a remineralizing process for 2 d. Different groups were examined with scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM).Result Micrographs of SEM showed a rough etching enamel surface in the control group, while those in 1.23% APF gel group and FI group showed relatively homogeneous surfaces. Fluorescence lesion area and lesion depth were significantly less (pH,A<0.001) in APF gel group （38230.87±2704.43）μm2,（40.51±4.26）μm and FI group （43407.27±4666.09）μm2,（41.90±6.83） μm than those in control group, although no statistical differences could be detected between the two treatment groups（PH=0.912，PA=0.679）. Conclusion Fluoride iontophoresis was effective in promoting incipient enamel remineralization, although no differences could be observed between 1.23% acidulated phosphate ?uoride gel.

Abstract： Objective To evaluate the influence of three kinds of hot acid solution on short-term shear bond strength of zirconia to resin. Methods 40 zirconia ceramic slices were obtained. After sandblasting, they were divided into 5 groups based on the surface treatment to be applied: group A: H2SO4 / (NH4)2SO4 hot mixed solution etching + application of 10-MDP contained primer Clearfil; group B: HF / HNO3 hot mixed solution etching + application of Clearfil; group C: H2SO4 / HF / HNO3 hot mixed solution etching + application of Clearfil; group D: application of Clearfil; E: no further treatment. Shear bond strength of the specimens was tested and statistically analyzed. The morphology of zirconia surfaces treated by sandblasting with or without hot mixed solution etching was observed with a scanning electron microscope (SEM). Results The shear bond strength of group E was the lowest （3.03±0.94） MPa. The shear bond strength of group B was the second lowest（7.53±1.37） Mpa. The shear bond strength of group A, B, and C was higher than that of the other two groups, which was respectively （9.16±1.12） MPa，（8.89±1.06） MPa，（8.95±1.36） MPa (P<0.05), while no statistical difference was found between the three acid etched groups. SEM images showed obvious morphological difference between groups treated by sandblasting with hot mixed solution etching and groups treated only by sandblasting. Morphology of surfaces treated with three kinds of mixed etching solution was also obviously different. Conclusion Hot acid solution etching combined with application of 10-MDP contained primer provided better bonding for zirconia.

Objective The objective of this study was To investigate the function of luxS gene in iron metabolism of Streptococcus mutans. Methods The absorbance of standard strains and deficient strains of Streptococcus mutans cultured in the iron-limited defined medium for 24 hours was measured and analyzed. exogenous iron or the supernatant fluid of standard strains was added into iron-limited defined medium of deficient strains of luxS gene mutant, and the A value was further measured and analyzed. Results After incubation for 24 hours, the growth of both standard and luxS gene mutant strains in medium containing 0.1 mmol/L of 2,2′-bipyridyl was not significantly inhibited. However, the growth of luxS gene mutant strains in medium containing 0.3 mmol/L and 0.5 mmol/L of 2,2′-bipyridyl was significantly inhibited. The growth inhibition of luxS gene mutant strains in medium containing 0.3 mmol/L of 2,2′-bipyridyl was relieved by adding exogenous iron and culture supernatant of standard strain into the medium, so was it when the luxS gene mutant strains were tranferred into fresh medium, and the growth of luxS gene mutant strains could get relatively high cell concentrations. Conclusions luxS gene plays a role in iron metabolism, and it may regulate the growth of Streptococcus mutans to a certain degree in iron-limited medium via AI-2.

Abstract: Objective To assess the color stability of different resin cements after accelerated ageing. Methods Four different resin cements were included in the study (1mm thickness). The resin cements were bonded to ceramic disks (0.5mm thickness) built with the VITABLOCS MARK-Ⅱ ceramic(n=10). All of the samples were stored in 37 ?C distilled water at dark. Then color measurement were determined using spectrophotometric before and after accelerated ageing in a weathering machine. Changes in color (ΔE) were obtained using the CIE Lab system coordinates where a ΔE data above 3 was accepted as visible discoloration. Results The ΔE of Superbond C?B, Variolink Ⅱ, RelyX Veneer and Filtek Z350 Flow were 2.32±0.21, 2.50±0.29, 0.68±0.24 and 0.79±0.20 respectively. The Superbond C?B and Variolink Ⅱachieved significant higher ΔE than the other groups (P<0.05). There was no significant difference between Superbond C?B and Variolink Ⅱ as well as RelyX Veneer and Filtek Z350 Flow (P>0.05). Conclusion All of the resin cements assessed in this study show varying degrees of discoloration after accelerated ageing. However, the color change are not beyond the clinical aesthetic demand. And the RelyX Veneer and Filtek Z350 Flow demonstrate a higher color stability.

Abstract: Objective To study the clinical effects and operation designs of aesthetic implantation surgery in cases of maxillary central incisor lost with insufficient vertical alveolar bone height. Methods 25 patients with maxillary central incisors loss were placed with 34 ITI implants. The cases of insufficient bone were implanted with Bio-Oss artificial bone and covered with Bio-Gide absorbable biological film in maxillary edentulous ridges. Superior restorations were completed 3-6 months subsequently. All cases were followed up for 6-12 months. Results All the 34 implants in 25 patients were all firm, without obvious discomfort. Short-term implantation success rate was 100%. In the follow-up, gingival loss occurred to 1 patient. Patients’ satisfaction rate of clinical effects was 96%. Conclusion In case of maxillary central incisor loss with insufficient alveolar bone height, different surgical methods should be chosen according to the widths of alveolar ridges. Also the GBR technique should be adopted to rebuild adequate alveolar bone, make sure of the implantation success rate, and satisfy patients’ aesthetic requirements.

Objective To evaluate the clinical effects of the crown lengthening surgery on the restoration of posterior residual roots and crowns with subgingivally involved defects. Methods From December 2009 to December 2011, according to the subgingival depths of the defects, 50 teeth from 48 patients with subgingivally involved defects were divided into three groups: group A(depth<3.0 mm),group B (3.0 mm ≤depth≤4.0 mm), group C(depth>4.0 mm). All teeth were treated by the crown lengthening first and then underwent post-crown prosthesis 6 weeks after operation. PD, SDI, and lengths from gingival margin to the frature ends of teeth before operation and 6 weeks after operation were recored and compared. Results The teeth sections of AB groups were exposed preferably and the periodontal health was good. The effective rate was 100%. 60% of C group were exposed well and were repaired well. There was significant difference between A and C groups, as well as B and C groups (P<0.05) . Postoperative PD,and SBI were better than those preoperative values(P<0.05). There was no differences between A and B groups (P>0.05), while there was significant differences between group C and groups A and B (P <0.05). Conclusion Crown lengthening surgery is a good method for the protection and restoration of posterior residual roots and crowns, but dentists should pay attention to the selection of the indications.

Objective To evaluate the effects of IPS e．max CAD LT ceramic crowns in posterior teeth restoration．Methods 86 teeth of 54 patienls were restored with IPS e．max CAD LT ceramic crowns．3,6 and 12 months later,the restorations were checked and evaluated according to the standards of APHA(Alnerican Public Health Association), and patient satisfaction surveys were conducted．Result 12 months later, there was only one crown lossening, while 96％ of the 86 restorations were scored A in color，shape，margin coloring and margin sealing. More than 94％ of the patients were satisfied with the treatment effects．Conclusion IPS e．max CAD LT ceramic crown is a clinically effective method for posterior tooth restoration．It is of great value in clinical application．

Objective To induce the periodontal ligament stem cells in vitro into adipocytes．Methods Periodontal ligament tissue was obtained from extracted orthodontal teeth, then cultivated in nutrient solution. hPDLSC was selected with immunomagnetic beads method. hPDLSC was induced into adipocytes in the adipogenic nutrient solution. Results hPDLSC was selected successfully with immunomagnetic beads method. hPDLSC was induced into adipocytes successfully.Conclusion Immunomagnetic beads method is an effective way to isolate and purify the hPDLSC and hPDLSC was able to transfer into adipocyte.

Objective To investigate the clinical efficiency of cone-beam computed tomography (CBCT) in the diagnosis and treatment of C-shaped canals of mandibular second molars. Methods Sixty-two mandibular second molars that failed in the root canal therapy were included in this study. The periapical films could not indicate the anatomic forms of root canals and the suspicious missed canals. Results Fixty-two canals (83.87%) were diagnosed as C-shaped canals, among which the numbers of C1 type, C2 type and C3 type were 28 (53.84%), 18 (34.62%) and 6 (11.54%), respectively. Among the 62 teeth with C-shaped canals, 2 teeth failed to receive the root canal therapy due to root canal perforation, and 60 teeth received gutta-percha filling through warm gutta-percha obturation and vertical condensation. After endodontic retreatment, 60 teeth (96.77%) showed satisfactory outcome with no complications identified. CBCT functioned in positioning the lesioned root canals with a high accuracy. Conclusions CBCT can analyze the configuration of root canals in a three-dimensional view, which is of prime importance in the diagnosis and treatment of C-shaped canals of mandibular second molars.

Objective　 To investigate the accuracy and repeatability of Quantitative Cervical Vertebral Maturation (QCVM) for adolescents with normal occlusion. Methods　According to the Fishman Skeletal Maturity Indicators (SMI), which was believed to be the golden standard for skeletal maturation evaluation, 120 adolescents aged from 8.0 to 16.5 years old were selected and divided into four groups. Each group consists of 30 people. The lateral cephalograms were grouped in double-blind trials and the maturation of cervical vertebrae was estimated by senior experts (SE) and postgraduate students (PS). The accuracy between QCVM and SMI was analyzed by Spearman rank correlation test and the repeatability of SE and PS was compared by ANOVA. Results　As for the accuracy, skeletal maturation evaluation by QCVM was consistent with that by Fishman Skeletal Maturity Indicators (SMI). As for the repeatability, there were no significant differences in both SE and PS (P>0.05). SE was relatively better than PS, but the differences did not achieve statistical significance. Conclusions　As for the application of QCVM，both SE and PS are good in accuracy and repeatability. QCVM could provide more objective and reliable basis for diagnosis and treatment in Orthodontics. Meanwhile it avoids an extra radiation exposure for the patients.

Objective The investigate the correlation between deciduous caries of preschool children and knowledge of oral health of their parents in Jinan, so as to provide basis for targeted oral health care service on children. Method The representative samples were selected by multi-stage, stratified and random sampling from 4 regions in Jinan City (2 rural areas and 2 urban areas). Dental caries of 538 children were recorded (urban: 268; rural: 244) according to Oral Health Surveys: Basic Methods from World Health Organization. The questionnaires on oral health behaviors were finished by the parents of the 538 children. chi-squre test. Results 1. The prevalence and dmft of deciduous caries of preschool children in Jinan City were 71.95% and 3.84 respectivel．The prevalence of deciduous caries in preschool children was 62.18％in urban areas and 81.72％in rural areas. The difference was statistically significant. 2. The frequency of eating sugary foods of preschool children was high. The frequency of taking in sweets, sodas and carbonated beverage was higher in rural children than in urban children. Urban children began to brush teeth earlier than rural children; their frequency of brushing teeth and proportion of using fluoridated toothpaste were also higher compared with rural children. 3. The parents of preschool children showed relatively poor in knowledge of oral health (59.48%), and parents in urban areas (66.07%) were better than those in rural areas (52.88%). There was significant difference in comparison between rural and urban areas. Conclusion Decidous caries status of preschool children was positively correlated with oral health knowledge of parents; publicity and education on oral health knowledge of parents, especially parents in rural areas, should be strengthened in Jinan City.