Cleft lip nasal deformity reconstruction is one of the difficult points of cleft palate sequence treatment. Treatment principle and method of cleft nasal deformity is mainly from the western scholars’point of view and technology. In this paper, according to the differences of typical form of east and west, we proposed the reconstructive theory and method corresponding to the Chinese. We hope that can deepen our understanding to the nasal deformity and the characteristics of cleft lip in order to improve reconstructive method.

Objective To construct strains containing green fluorescent protein（GFP） to study gene regulation in Saccharomyces albicans cells during the infection process. Methods pACT1-GFP was constructed, and Saccharomyces albicans CAI4 was transformed. The expression of GFP in yeast and hyphal compartments was observed with microscopy. Results 99% of Saccharomyces albicans cells containing pACT1-GFP fusion displayed significant fluorescence levels both in the yeast and hyphal compartments. The fluorescence intensity in two compartments had no obvious difference. Conclusion pACT1-GFP can be expressed stably in the yeast cells.

Objective To investigate the effect of gradually induced disordered occlusion（GIDO） on the expression of osteoprotegerin（OPG） and receptor activator of nuclear factor-кB ligand（RANKL） in mandibular condylar cartilage of rats. Methods Totally 48 rats, aged 8 weeks were included, and were divided into experimental and control groups randomly at 4 time points, with same gender distribution（n=3）. By inserting elastic rubber band the right side mandibular first molar and the left side maxillary first molar were moved mesially. Four weeks later, the right side mandibular third molar and the left side maxillary third molar were moved distally with same method. In this way, the GIDO was established in rats. The rats were sacrificed at the end of 2th, 4th, 6th and 8th week respectively after the application of the GIDO. The expression of OPG and RANKL in condylar cartilage was examined with immunohistochemical method and calculated by the area of positive cell percentage. Results OPG and RANKL expressed predominantly in condylar cartilage hypertrophic layer. The rats in experimental group expressed a higher OPG level in all of the 4 time points than their age-matched controls（P<0.05）, while RANKL were higher in 2, 6, 8 weeks subgroups（P<0.05）, but not in 4 weeks subgroup. No differences were found between male and female subgroups. Conclusion The present results suggest that both OPG and RANKL take part in the condylar cartilage remodeling procedure in the present at model.

Objective To study a reliable CT measuring method for quantitative diagnosis of unilateral zygomatic complex fracture and operation guiding. Methods 20 zygomatic complex fracture patients needed operation were collected, three dimensional CT images of all patients were measured and analyzed by Mimics software before operation. Standard anatomy points of bilateral zygomatic complex and adjacent bone were selected, then the distance of two same selected points and the angles of three same selected points were measured by Mimics software. Compared to uninjured side, the different value of the distance and the angle of injured side zygomatic complex were acquired, zygomatic complex fractures were operated based on the different value. All patients were examined by three dimensional CT postoperatively, and the different value of the distance and the angle of both side were measured using same method to pre-operation. Therapy effects were analyzed based on the data of different value of the distance and the angle. Results 1）The displacement of zygoma of most patients was backward and inward. The different value of the distance between uninjured and injured side was less than 2 mm, and the different value of the angle was less than 1°. All patients reached the three-dimensional symmetric, surgical results were satisfactory in recovery of occlusion and mouth opening. 2）The zygomatic arch protrusion angle was about 138.50°±1.15°, zygomatic prominent angle was about 132.72°±0.89°. The two data were normal distribution. Conclusion Three dimensional CT measurements of zygomatic complex can be achieved for the quantitative measurement of spatial displacement, and have directive significance for the reduction of the zygomatic complex fractures.

Objective To investigate the stress distribution in dentin of the maxillary central incisor restored with post-core which is related to different shapes and materials. Methods CT scan, digital-image processing and Unigraphics（UG） software were applied to construct the three-dimensional finite element models of maxillary central incisor restored with cone or column post-core. Based on this model, stress distribution of Von Mises in dentin with three different materials（polyethylene fiber resin, carbon fiber and zirconia） were analyzed respectively. Static loading（100 N） was used on the lingual boundary line between upper-one-third and middle-one-third of maxillary central incisor, the direction of the loading was 45° to the tooth long axis. Results In posts made of zirconia and restored with column post, the stress distribution in dentin was higher than with cone post（P＜0.05）. In posts made of polyethylene fiber resin or carbon fiber, there was no significant difference between the two post shapes （P＞0.05）. The elastic modulus of post-core materials affected the stress distribution, and the higher the elastic modulus was, the higher the stress concentrated. Conclusion Cone post excels column post in higher elastic modulus materials. Using the lower elastic modulus materials possibly can avail to the stress distribution and prevent the root breakage. During the root canal preparation, the dentin around the root neck should be conserved as more as possible, especially the dentin in the labial side.

Objective To assess the effect of platelet rich plasma（PRP） on proliferation and differentiation of human MG63 osteoblast-like cells and the biological function of PRP in vitro. Methods PRP was obtained from venous blood of a health volunteer by two step centrifugation. CaCl2 and thrombin were used to activate PRP. The differentiation of MG63 cells, which were exposed to various concentrations of PRP（0, 1%, 2%, 3%） was detected by alkaline phosphatase（ALP） activity. Propidium iodide（PI） fluorescent coloration staining was used to observe the morphology of cells. Immunocytochemistry was used to evaluate the expression level of transforming growth factor-β（TGF-β） in MG63 cells in different concentration of PRP. The cells adhered to calcium phosphate material was observed by scanning electron microscopy（SEM）. The proliferation was evaluated by cell counting kit-8（CCK-8） proliferation assay. The cell cycle assay was performed by flow cytometry（FCM） to detect the effect of PRP on MG63 cells in different time points. The mRNA level of Col-Ⅰ in MG63 cells cultured under different concentration PRP was checked by reverse transcription polymerase chain reaction（RT-PCR）.Results ALP activity experiment demonstrated that the maximum effect was got in 3% PRP group. PRP had a positive effect on the proliferation of MG63 cells but cells also presented disengage phenomena from the glass slides. The PI staining showed that PRP improved fluorescent intensity of cell nucleus. Immunocytochemistry showed that TGF-β expression level was significantly enhanced on 3% PRP group（P＜0.05）. SEM showed that cells grew well on material in PRP group. The results of CCK-8 showed that the mean absorbency number A450 nm of 4.8% PRP was significantly higher than that of control group（P＜0.05）. FCM showed that S period cells percentage of PRP group was higher than that of control group in the 2nd day（P＜0.05）; G0/G1 period cells percentage of PRP group was significant increased than that of control group in the 10th day（P＜0.05）; G2/M period cells percentage of PRP group was higher than that of control group except the 6th day. PRP promoted the expression of Col-Ⅰ in MG63 cells by RT-PCR. Conclusion These data suggest that PRP has a positive influence on MG63 proliferation, transference and the expression of relative protein and gene in an appropriated concentration. The findings of this study also demonstrated that PRP may play a beneficial role of unifying and modulating the biological behavior of MG63 cells.

Objective To synthesize and evaluate a novel injectable and water-swelling gingival displacement materials. Methods A kind of water-swelling polymer, kaolin and aluminum chloride were mechanically mixed at certain ratio in water solution, resulting to a novel paste materials for gingival displacement. Then, its stability in aqueous solution and water swelling properties were evaluated in vitro. The effect on gingival displacement was evaluated by animal experiments in dogs. A commercial gingival displacement materials paste of Expasyl R was used as control. Results While contacting with water, the novel gingival displacement paste did not collapse, maintained its integrity structure, and could expand for adsorbing water. Animal experiments in dogs showed that the materials could lead to displace the gingival margins from the dental root surfaces. Conclusion The novel injectable and expanded gingival displacement material is efficient to retract free gingival margin with potential clinical application.

Objective To evaluate the effect of extraction and non-extraction decompensation to bimaxillary orthognathic surgery in skeletal class Ⅲ malocclusion and the effect on postoperative. Methods Records of 36 completed surgical-orthodontic treatment skeletal class Ⅲ malocclusion patients were obtained from School of Stomatology, China Medical University, 18 underwent maxillary premolar extraction, the other 18 underwent non-extraction. Their postdecompensation and postsurgery cephalometric radiographs were analyzed objectively, and their profile scissors-shadows in different groups were evaluated subjectively. Results The cephalometric index of post -presurgical orthodontics showed that there were significant deviations between the extraction and non-extraction groups including U1-SN, Overjet and Cm-Sn-UL values（P<0.05）. During surgery, mandible was retruded（8.66±1.42）mm in extraction group compared with（6.21±3.06）mm in non-extraction group（P<0.05）. After surgery, the extraction group achieved more normal ANB, U1-SN, NA-PA values（P>0.05）. Conclusion Maxillary premolar extraction can make incisor decompensation more complete so that mandible can be retruded to more ideal position and concave face can be successfully corrected.

Objective To study the clinic presentation, radiology, pathology of recurrent ameloblastoma（RAB）. Methods All RAB cases accepted treatment in School of Stomatology of Nanjing University during 1996.1-2008.3 were retrospected. The clinic presentation, the radiological classification and pathological classification were summarized and analyzed. Results There were 23 RAB patients during 1996.1-2008.3. 3 patients recurred twice, 20 patients recurred once, and 26 cases were found together. 19 patients were performed conservative surgery while 4 patients were performed radical surgery in the primary treatment; 4 patients were performed conservative surgery and 19 patients were performed radical surgery in the recurrence. The radiological classification included 12 cases multicystic, 6 cases unicystic, and 8 cases extraosseous. The pathological classification included 21 cases follicular ameloblastoma, and 5 cases plexiform ameloblastoma. The multicystic after conservative surgery（11 cases） and extraosseous ameloblastoma after radical treatment（8 cases） were more than others according the radiological classification and treatment. Conclusion Conservative surgery has apparent higher recurrences rate than radical surgery. The follicular ameloblastoma has more aggressive biological behave and is more liable to recurred.

Objective To study morphology feature of mandibular anatomical characteristics and mandibular nerve
canal of hemimandibular elongation（HE） using CT, and provide reference for the clinical treatment. Methods 19
patients with HE were scanned using multidetector CT. Mimics 10.0 software was used for three-dimensional reconstruction,
and CT images were reconstructed on different sections. The position of mandibular nerve canal, mandibular
foramen and thickness of mandibular cortical bone were measured, and compared with control group（without mandibular
lesion）. Results Compared with the control group, the distance between mandibular nerve canal and mandibular surface were statistically different at the section of long axis of mandibular first molar centre（LAMFM）-lingual, long axis of mandibular second molar centre（LAMSM）-buccal, LAMSM -superior, retromolar area centre to the mandibular angle（RAC-MA）-buccal, RAC-MA-superior, RAC-MA-inferior and horizontal level of mandibular foramen under 5 mm （HLMFU5）-lingual, HLMFU5-anterior, HLMFU5-posterior（P<0.05）; the thickness of mandibular cortical bone were statistically different at the LAMFM-buccal, LAMFM-inferior（P<0.05）; lowest point of mandibular foramen（LPMF）- superior border of mandibular ramus（SBMR） and LPMF-inferior border of mandibular ramus（IBMR） were statistically different（P<0.05）. Conclusion In the patients with hemimandibular elongation, the thickness of mandibular cortical bone gradually decreases in all directions from the mandibular first molar to the mandibular ramus. Compared with the control group, mandibular nerve canal located buccally and superiorly at mandibular second molar and retromolar area, mandibular foramen located more anterior and lower inside mandibular ramus.

Objective To measure the mesiodistal and buccolingual alveolar bone mass of back teeth in posterior alveolar crest at different height by cone beam computed tomography（CBCT）, and analyze the safe area of microscrew implanted at back teeth in posterior alveolar crest. Methods 30 cases of adult scan image data were selected for the study of jaw bones scan reconstruction. From the distal of first premolar backward, buccolingual（plate）width and the mesiodistal size between each interfurcal region（including tuber maxillae） were measured from alveolar crest at top of 2, 4, 6, 8, 10 mm. ANOVA and LSD methods were made by SPSS 16.0 software for comparison. Results 1）The mesiodistal bone mass of back teeth in maxilla at the same height with different position had statistically significant difference（P<0.05）. The biggest mesiodistal bone mass was located at the palatal roots between the second premolar and the first molar. The statistically significant difference of buccolingual bone mass also existed at different position and height（P<0.05）. The biggest buccolingual bone mass was located at the middle of the first molar and the second molar. 2）The mesiodistal bone mass of back teeth in maxilla at different height and position had statistically significant difference（P<0.05）. The statistically significant difference of buccolingual bone mass also existed in the same position with different height（P<0.05）. The biggest mesiodistal and buccolingual bone mass was located at the middle of the first molar and the second molar. Conclusion The safe area of microscrew implanted at back teeth in posterior alveolar crest is tested by CBCT, which provides valuable reference for the follow-up clinical application

Objective To evaluate the adjunctive effect of diode laser irradiation for the treatment of periodontalendodontic combined lesions. Methods 30 cases with periodontal -endodontic combined lesions were selected. All cases were randomly divided into experimental group and control group（n=15）. In the control group, patients were treated with root canal therapy and conservative periodontal treatment（scaling and root planning）, and patients in the experimental group were treated with root canal therapy and conservative periodontal treatment followed by diode laser irradiation. Clinical measurements including pocket probing depth（PPD）, clinical attachment level（CAL）, modified bleeding index（mBI）, periapical index（PAI） were taken before treatment（baseline）. Three and six months after the treatment, the adjunctive effects of diode laser in the treatment of periodontal -endodontic combined lesions were evaluated. Results Three months after the treatment, the average PPD, CAL and mBI levels were reduced significantly in both groups. But the average PPD reduction in the experimental group was significantly greater（P<0.05） than in control group. However the average CAL and mBI reduction were not significantly different between two groups. Six months after the treatment, the average PPD, CAL and mBI levels were further reduced in the experiment group, but not in the control group. The average PAI levels were reduced significantly in both groups, but the PAI reduction was not significantly different between two groups. Conclusion The use of diode laser as an adjunct procedure in the treatment of periodontal-endodontic combined lesions can aid in achieving success.

Objective To explore whether the dental restoration of nickel-chromium（Ni-Cr） based alloys will lead to extra excretions of urinary Ni and Cr. Methods Urinary Ni and Cr were repeatedly measured in 33 patients before and 2 months after the dental restoration of Ni-Cr alloys. The associations between alloy restoration and urinary Ni or Cr were analyzed by paired t test and general linear model of repeated measures. Results A slightly higher urinary Ni was found in patients after 2 month of the alloy restoration, but the difference was not statistically significant （before: 46.4 μg·mol-1 crea; after: 67.6 μg·mol-1 crea; P=0.063）. This difference was only in female subjects（before: 44.8 μg·mol-1 crea; after: 73.7 μg·mol-1 crea; P=0.068）. A significant higher urinary Cr was found in patients after 2 month of the alloy restoration（before: 57.0 μg·mol-1 crea; after: 99.4 μg·mol-1 crea; P=0.024）. This significant difference was only in female subjects（before: 59.8 μg·mol-1 crea; after: 124.4 μg·mol-1 crea; P=0.023）. General linear models of repeated measurements showed that urinary excretions of Ni and Cr were associated with the number of restoration and the area of metal basis uncovered with porcelain. Conclusion Dental restoration of Ni-Cr alloy might lead to the enhanced excretions of urinary Ni and Cr.

Objective To test the diagnostic accuracy of qualitative and semi-quantitative evaluations on root resorption associated with orthodontic force（RRAOF） using orthopantomogram（OPG） and periapical film, through comparing with assessments with cone beam computed tomography（CBCT）, which is considered as the gold standard. Methods Before and after treatment, OPG, periapical film, CBCT images of 121 upper anterior teeth in 32 orthodontic patients were obtained. Blind evaluation of RRAOF was performed according to Levander and Malmgren’s method by three trained radiographers through examining three kinds of images of these teeth. The diagnostic accuracy of qualitative and semi-quantitative evaluations on RRAOF using OPG and periapical films were test through comparing with assessments with CBCT, which was considered as the gold standard. Results To the same sample, the RRAOF qualitative and semi-quantitative diagnostic classification  Rults of OPG and periapical films compared with CBCT were significant differences（P<0.05）. The sensitivity of periapical films and OPG was 71.6% and 78.4%. The specificity of periapical films and OPG was 25.5% and 51.1%. The accuracy of periapical films and OPG was 53.7% and 67.8%, respectively.

Objective To study the effect of risk management in nursing management of head and neck oncology. Methods In 2010, risk management was applied to the nursing management of head and neck oncology through risk identification, increasing awareness of risk management, defining risk management responsibilities, strengthening the capacity of specialist nurses and emergency response, and strengthening risk control measures. Patients’satisfaction, care complaints, nursing risk occurrence, nurse praised visits between 2009 and 2010 were compared. Results There were significant differences comparing 2009 with 2010 in patient satisfaction, care complaints, nursing risk occurs, nurse praised visits in head and neck oncology（P<0.05）. Conclusion Application of risk management in nursing management will relieve care complaints and nursing risk occurrences, improve patients’satisfaction. It is worth to further promote in the clinical nursing management.

Objective To investigate the effect of different premolar extraction models on postextraction Bolton overall ratio among different classes of malocclusion. Methods 180 patients with equivalent skeletal and dental classifications were chosen（Group Ⅰ, Ⅱ and Ⅲ, with 60 per group）. According to dental casts, the Bolton overall ratios of each group were measured and compared before and after hypothetical premolar extraction（the four premolar extraction models were all first premolars, all second premolars, upper first and lower second premolars, and upper second and lower first premolars）. Chi-square Test analysis was taken within each group in order to compare the abnormal rates of postextraction Bolton overall ratios. Results The differences of pretreatment Bolton overall ratios among three types of malocclusions were found statistically significant（P=0.000）. For Class Ⅰ and Class Ⅱ group, the four extraction models made no statistically significant differences in the abnormal rates of postextraction Bolton overall ratio（P>0.05）. For Class Ⅲ group, the four extraction models made statistically different results that was the upper second and lower first premolar extraction model creating lower abnormal rates than the upper first and lower second premolar extraction model（P=0.002）. Conclusion As far as the postextraction Bolton overall ratios are concerned, Class Ⅰ and Ⅱ malocclusions can choose any of four premolar extraction models, while to Class Ⅲ malocclusions, the upper second and lower first premolar extraction model fits better than the upper first and lower second premolar extraction model.

Objective To measure the root anatomic topography of mandibular first molar using cone beam CT （CBCT）, calculate the proper space for dowel preparation. Methods The roots of 121 mandibular first molars from 71 patients were scanned by CBCT, the images from cross section, sagittal plane, and coronal plane were got respectively. The dowel preparation spaces according to established three dimensional images and dowel preparation requirements were analyzed. Results Three dowels could be prepared. The dowel length for distal-root was （7.19±0.91）mm, dowel diameter was（0.80±0.12）mm on the level of 4 mm above root apex. The dowel length for mesio-root was（6.92±1.02）mm, and dowel diameter was （0.71±0.08）mm on the lever of 4 mm above root apex for buccal side and （0.71± 0.07）mm for lingual side. Dowel should be prepared cone-shaped. Conclusion Many factors affect dowel preparation, individualized design is needed. CBCT can provide reliable radiographic evidence.

Objective To study the gene expression profiles of traumatic occlusion in early stage with the animal model of rats. Methods The occlusal surface of the upper left first molar of rat was raised by placing a stainless steel wire to induce occlusal trauma in the lower left first molar. After 24 hours, the alveolar bone tissue of the first molars at the both sides of rats’lower jaws were taken out under anesthesia. The different expressive genes were shown by genome-wide microarray, which comprises about 27 000 genes and analyzed the different expressive genes with Pathway and GO analysis, finally the results of the microarray were examined by real time-polymerase chain reaction（RTPCR）. Results In the results of the study, 586 different expressions were found, of which the expressions of 166 genes increased and 420 genes decreased. 106 different pathways were involved with Pathway analysis and 270 different functional classification related to GO analysis. Conclusion The balance of the lower alveolar bone is destroyed after 24 hours of traumatic occlusion. At early phase of the occlusal trauma, osteogenesis and bone formation in alveolar bone are inhibited, yet osteoblast genesis and bone resorption are not significant.

Objective To investigate the correlation between the combination of smoking and the polymorphisms of cytochrome P450（CYP） 1A1-MspⅠ and glutathione S-transferase（GST） T1 genes and oral cancer. Methods The genetic polymorphisms of CYP1A1-MspⅠ and GSTT1 were detected by polymerase chain reaction（PCR） technique in peripheral blood leukocytes of 300 oral cancer cases and 300 non-cancer controls, and the correlation between smoking, the two metabolic enzymes genetic polymorphisms and oral cancer were analyzed. Results The frequencies of CYP1A1-MspⅠ（m2/m2） and GSTT1（-） were 38.33% and 69.33% in oral cancer cases and 21.00% and 44.33% in healthy controls respectively. Statistical tests showed significant difference in the frequencies between the two groups （P<0.01）. The risk of oral cancer with CYP1A1-MspⅠ（m2/m2） was significantly higher than that of controls（OR= 2.34, 95%CI 1.76-4.07）. The individuals who carried with GSTT1（-） had a high risk of oral cancer（OR=2.84, 95% CI 1.98-4.54）. Combined analysis of the polymorphisms showed that percentage of CYP1A1-MspⅠ（m2/m2)/GSTT1（-）in oral cancer and control groups was 30.67% and 6.67% respectively（P<0.01）. The people who carried with CYP1A1-MspⅠ（m2/m2）/GSTT1（-） had a high risk of oral cancer（OR=8.27, 95%CI 3.63-11.29）. The smoking rate of the case group was significantly higher than that in the control group（OR=2.71, 95%CI 1.31-4.52, P<0.01）, and statistic analysis suggested an interaction between smoking and CYP1A1-MspⅠ（m2/m2）/GSTT1（-） genotypes polymorphisms which increased risk of oral cancer（OR=25.00, 95%CI 11.87- 35.64）. Conclusion CYP1A1-MspⅠ（m2/m2） and GSTT1（-）are the risk factors in oral cancer． Smoking is also related to the susceptibility to oral cancer. There may be a synergetic interaction among CYP1A1-MspⅠ（m2/m2）, GSTT1（-） and smoking on the elevated susceptibility of oral cancer.

Objective In order to determine the function of PG0839 gene from Porphyromonas gingivalis（P.gingivalis） W83 strains, we intended to create a mutant in the PG0839 gene by homologous recombination. Methods 1 584 bp PG0839 gene fragment was amplified, digested by BamH Ⅰ and EcoR Ⅰ, purified and ligated to pUC19. The recombinant plasmid was designated as pPG0839-1. The erm cassette（2 101 bp） was inserted into the EcoR Ⅴ restriction site of the PG0839 gene. The resultant recombinant plasmid, pPG0839-2, was used as a donor in the electroporation of P.gingivalis W83. After electroporated and selected on erythromycin brain heart infusion plates, a single colony was collected and designated as PG0839 gene-defective mutant. Results A mutant in PG0839 gene was created by insertional inactivation, and inactivation of PG0839 gene was confirmed by restriction endonuclease digestive, sequencing, polymerase chain reaction（PCR） and reverse transcription PCR. Conclusion A PG0839 gene-defective mutant was created successfully.

Objective To investigate the application of the perceptual assessment in the diagnosis of the velopharyngeal
function, to provide a reference to the improvement of the velopharyngeal function diagnosis through comparing
the consistency between the diagnosis of the perceptual assessment and the objective assessment. Methods All subjects（
254） were selected from the Department of Cleft Lip and Palate Surgery, West China School of Stomatology,
Sichuan University, from 2000—2010. The results of the perceptual and the nasopharyngeal fiberscope（NPF） assessment were retrospectively analyzed, and the consistent rate between the two assessment methods was calculated. The Kappa test and the correlation analysis were performed to analyze the consistency and correlation, and the factors relating to the perceptual assessment were analyzed by the correlation coefficient. Results There were 254 patients met the inclusion criteria. The consistent number of the patients diagnosed by the perceptual and the objective assessment as velopharyngeal competence（VPC） and velopharyngeal insufficiency（VPI） were 58 and 167 respectively. The consistent rate was 88.58% for all patients, and 66.67% for the VPC patients. The Kappa value was 0.721, Spearman’s R=0.751, P＜0.05. There were correlation between the hypernasality, the nasal emission and the subjective assessment, and Spearman’s R=0.697, 0.590, P＜0.05. Conclusion The VPC patients and the VPI patients with moderate and severe hypernasality and nasal emission diagnosed by the perceptual assessment could be exempt from the objective examination. Patients diagnosed with mild hypernasality and nasal emission by the perceptual assessment should be further referred to NPF or other instruments.

Objective To study the antibacterial effect of polymethyl methyacrylate（PMMA） resin base containing Ag-TiO2 antibacterial agent against common conditioned pathogen and their bacterial plaque in vitro. Methods Different qualities of Ag-TiO2 antibacterial agent were added into PMMA resin base in order to prepare antibacterial PMMA resin base. Then, in vitro analysis of antibacterial effect of the resin base against Streptococcus mutans, Staphylococcus aureus, Saccharomyces albicans were assayed with the pellicle-sticking method. Furthermore, the growth of Streptococcus mutans and Saccharomyces albicans bacterial plaque on the antibacterial PMMA resin base were examined by scanning electron microscope. Results The inhibition percent for Staphylococcus aureus was 93.3% by antibacterial PMMA resin base with 0.7% Ag-TiO2; for Streptococcus mutans 90.2% with 1.5% Ag-TiO2; for Saccharomyces albicans 91.2% with 2.5% Ag-TiO2. Bacterial plaque of Streptococcus mutans and Saccharomyces albicans on antibacterial resin base were inhibited effectively. Conclusion The antibacterial property of the PMMA resin base is effectively enhanced with Ag-TiO2 antibacterial agent.

Objective To observe the changes of surface morphology and temperature of dental pulp cavity in vitro after irradiated by Er：YAG laser with different energy and irradiation time. Methods All of the 96 samples from 24 teeth in vitro were collected from dental clinical departments then divided into two groups（group A and group B） randomly. We chose the energy of 20 Hz, and 1, 2, 3, 4, 5, 6 W to treat the samples in group A and group B and the irradiation time was 10 s or 20 s. We recorded the temperature changes of dental pulp cavity by digital thermometer and observe the morphology of tooth enamel by scanning electron microscope（SEM）. Results With the extension of irradiation time and increasing of energy, the temperatures of dental pulp cavity were significantly increased after the treatment of Er：YAG laser. The two groups of tooth enamel surface morphology were changed after irradiated by Er： YAG laser with different energy and irradiation time. However, there was no melting and carbonation on the surface of tooth enamel after the treatment of Er：YAG laser in two groups. Conclusion The temperatures of dental pulp cavity were increased after irradiated by increasing laser energy density fom 1W to 6W. No melting or carbonized phenomenon was found in enamel within the energy of 1 W to 6 W. All the data would provide evidences for clinical treatment of cavity. 

Objective To study the biocompatibility of porous calcium phosphate ceramics nanocomposite． Methods The biocompatibility was evaluated via experiments including the hemolysis test, hemopexis test, acute systemic toxicity test, pyrogen test, and intramuscular implant test, in which biphasic calcium phosphate nanocomposite（NanoBCP） presented as leaching solution, suspension or blocks of 5 mm×5 mm×1 mm. Animals including New Zealand Rabbits, Kunming mice, SD rats were selected as the host. Results The hemolysis of NanoBCP was 1.1%（＜5%）. Four coagulation index levels were within the normal range. In pyrogen test, the temperature of each experimental rat increased by 0.35, 0.40, 0.28 ℃（＜0.60 ℃, in accordance with the pyrogen-free criterion for biomedical materials）. No consequent death, dyspnoea, organ dysfunction, severe peritoneal irritation or ptosis was observed in acute systemic toxic test. Newly-formed fibrous tissue could be found after the implantation. Conclusion The material possesses outstanding biocompatibility and degradability with no toxicity or irritation, contains no pyrogen, as well as better degradation properties than biphasic calcium phosphate.

Objective To investigate caries status of primary and permanent teeth among 6-year-old children in Sichuan Province and correlation between caries of deciduous molars and first permanent molars. Methods Referenced to the sampling programme of the third national epidemiological survey of oral health status, a total of 714 children aged 6 were randomly sampled in clusters including 3 urban sampling spots and 3 rural sampling spots, the correlation between caries of deciduous molars and first permanent molars was explored. Results The prevalence rate of deciduous tooth caries of 6-year-old children in Sichuan province was 74.37%, the mean number of dmft of 6-year-old was 3.94± 3.93, the filling rate was only 4.96%. The prevalence rate and mean dmft of deciduous tooth caries showed no significant difference between different area and gender（P>0.05）, however, the children came from city showed significant higher filling rate than those from countryside（P<0.05）. The first permanent molars erupted have 2.98% in caries, the filling rate was 7.69%. Caries of deciduous molars was the first permanent molars caries risk factors among 6-year-old children in Sichuan province[P=0.001, r=0.175, OR=5.756, 95%CI（1.733, 19.121）]. There was weak correlation between caries of deciduous molars and first permanent molars（P<0.001, r=0.194）. Conclusion Caries status of primary among 6-year-old children in Sichuan Province are serious. Caries experience of deciduous molars may play an important role in predicting the first permanent molars caries in clinic and prevention.

Objective This study was to investigate the mechanical properties of thermodynamic nickel-titanium （NiTi） archwires of different brands under controlled temperature and in artificial saliva to provide some reference for its clinical application. Methods Using a modified partial dental arch bending system, four types of thermodynamic NiTi archwires were tested under controlled temperature（25, 33, 37, 60℃） and in artificial saliva. An Instron Universal Testing Machine was used to apply 3 mm deflections of archwires in the lateral incisor area. The load-deflection curves were determined from the passive position to deflections of 3 mm. The following variables from unloading curves were calculated：Stiffness between 2.5 mm UDP（unloading deflection point） to 0.5 mm UDP after unloading. Any statistically significant differences in these variables for the different brands, temperature and moments levels were analyzed using one-way analysis of variance. Results Unloading values of four types thermodynamic nickel-titanium archwires increased with controlled temperature rising. The unloading stiffness of the same brand archwires were approximate at 25, 33, 37 ℃, while their unloading stiffness increased obviously at 60 ℃. Conclusion Different brands thermodynamic NiTi archwires demonstrated different mechanical behaviours, but all of them exhibited super elasticity and practical shape memory effect. The four thermodynamic NiTi archwires displayed temperature sensitivity at the four test temperatures.

In recent years, though more and more ulcerations of oral mucosa caused by allergy to drug occurred clinically, allergy to sodium fluoride glycerin is extremely rare. A case of allergy to sodium fluoride glycerin occurred in Qianfoshan Campus Hospital of Shandong University. After treatment by sodium fluoride glycerin, there was mucosal edema, a large number of red miliary granules in buccal and palatal mucosa. After 3 hours, there were swallowing difficulties, but no breathing difficulties. Next day large ulcers of oral mucosa developed. The patient was cured 7 days after treatment. Fluoride-sensitive test result was positive.

It is to address torquing an individual tooth using a gate spring. The gate spring is made of a rectangular stainless steal wire, in the shape of a gate, which is incorporated to the archwire by spot welding. Torque is generated by the combined effects of the gate spring and the archwire. After 2 -3 months, the gate spring can obviously torque individual tooth.