Objective To investigate the relationship between matrix metalloproteinase-2（MMP-2）activity and cell proliferation, growth and invasion of ameloblastoma. Methods The cells and xenograft of ameloblastoma were treated with MMP-2 inhibitor Ro31-9790 and the effects of Ro31-9790 on the cell proliferation and growth of ameloblastoma were observed. Primary culture in vitro, subcapsular kidney xenograft in vivo, MTT assay, flow cytometry, neoplasitc volume measurement and histochemistry were employed to study the effects of cell proliferation and growth produced by Ro31-9790. Results There was no significant different in cell proliferation at same interval among several groups(P＞0.05). The ratio of G0/G1 stage, G2/M stage and apoptotic cells didn't increase following increased Ro31-9790, and the ratio of S stage cells also didn't reduce following increased Ro31-9790. The tumor volume and its increase in treatment group were significant less than those in control group. Conclusion Ro31-9790 does not influence proliferation of ameloblastoma cells in vitro, but it can effectively inhibit the ameloblastoma growth in vivo. MMP-2 activity has no relationship to proliferation of ameloblastoma cells, but it can contribute to the ameloblastoma growth and may be a reason of invasion in ameloblastoma. .

Objective To investigate the expression of epidermal growth factor receptor（EGFR） during the mineralization of human periodontal ligament cells（hPDLC）in vitro. Methods Studies using specific antibodies to immunolocalize EGFR in the mineral differentiating hPDLC were undertaken to investigate the different expression during the inducing process. In situ hybridization and RT-PCR technique were used to investigate the transcripts encoding the protein of EGFR. Results The results showed that immunocytochemical labeling gradually decreased following the elong of the induce time, downing to nearly negative at the 4th week and the signal of EGFR transcripts was weaker in the induced hPDLC than that in uninduced. Conclusion EGFR has a negative regulation function during the mineralization of hPDLC.

Objective To investigate the development of novel cell delivery carriers and evaluate the effects of platelet-rich plasma（PRP） and platelet-poor plasma（PPP） on cellular attachment and proliferation. Methods Rat gingival fibroblasts, periodontal ligament fibroblasts and osteoblasts were cultured in vitro. The biodegradable membranes were treated with PRP and PPP that were obtained from rat whole blood by gradient density centrifugation. The cellular attachment, proliferation and morphology on the untreated membranes and membranes treated with PRP and PPP were tested in vitro for 48 hours. Results There were significant differences between the untreated membranes and the membranes treated with PRP and PPP for three kinds of rat cells used in the experiment. There were no significant differences between those membranes treated with PRP and those treated with PPP. Three kinds of cells on the membranes treated with PRP were slight higher than those on the membranes treated with PPP. There were no significant differences in the same group for cells attachment. The rate of different cells proliferation on the untreated membranes was significant lower than those on the membranes treated with PRP and PPP at 1 hour and 48 hours after seeding. At the same time, the rate of different cells proliferation on the treated membranes at 48 hours was significant higher than those on the treated membranes at 1 hour. There was no significant differences in the same group for the rate of cells proliferation. Most of the cells attached on the membranes treated with PRP and PPP exhibited robust and elongated forms with numerous filopodial extensions. Conclusion The results showed that the biodegradable membranes treated with PRP and PPP could promote rat cell attachment and proliferation. It suggests that this novel technique will provide the experimental basis for the development of cell delivery carriers and periodontal regeneration.

Objective  To study the spatial distribution of free Ca2+ in osteoclast-like cells cultured on glass. Methods  To detect the free Ca2+ in osteoclast-like cells, the images were analyzed with image software, using the laser scanning confocal microscope and fluorescent probe. Results  At 37 ℃ the free Ca2+ in osteoclast-like cells could be labelled effectively with 10 μmol/L Fluo-3/AM, the intensity of Ca2+ fluorescent signal in the central part was greater than that in the peripheral part and in the same section the signal was not distributed evenly. Conclusion  The intensity of Ca2+ fluorescent signal is different among various organellae in osteoclast-like cell, which suggests the osteoclast-like cell modulate its own function through the spatial difference of free Ca2+ concentration.

Objective  To compare the different restorations of endodontically treated premolars, and to choose the best method. Methods  10 pairs of symmetry maxillary first premolars were collected from 10 patients，and randomly divided into 2 groups. Every pair received different treatment accordingly. The test group was set up the medial－occlusal cavities model under the same standard. The 10 pairs teeth were test by instron 4302 universal test machine in speed of 1.00 mm/min until broken up and the top load was recorded. The load angle was 45 degree to the long axis of the teeth, as the load was pointed to the middle of the lingual surface on the buccal cusp. The records were analyzed by paired samples t test. Results  Based on the medial-occlusal cavities, the fracture strength of the full crowned teeth was lower than the full natural teeth，and the fracture strength of the post-crowned teeth was higher than the full natural teeth. Conclusion  From the point of biomechanics, the different trauma of the endodontically treated teeth fits to different restorations. The medial-occlusion cavities fit the post-crown restoration mostly.

Objective  To adopt a criterion summarized in long-term practice to judge the immune status of recurrent aphthous ulceration（RAU）patients, and to analyze its rationality and feasibility. Methods  60 cases were included, whose clinical information, such as age, sex, constitution status, history of system diseases and severity of ulceration were collected. The subjective judgement results of the immune status were obtained according to the criterion summarized in clinical practice. At the same time, peripheral blood parameters about immune function were examined in order to obtain the objective examination results of the immune status. With the examination result as the gold standard, the rationality of the criterion was estimated through its sensitivity and specificity. Results  According to subjective judgment, there were 86.67% cases with abnormal immune status（28.33% cases with elevated immune status, and 58.33% cases with reduced immune status）. According to objective examination, there were 93.33% cases with abnormal immune status(23.33% cases with elevated immune status, and 70.00% cases with reduced immune status. Sensitivity and specificity were 89.29% and 50.00% when the criterion was used to judge immune abnormality, 42.86% and 76.09% when the criterion was used to judge immune elevation, and 64.29% and 55.56% when the criterion was used to judge immune reduction. Conclusion  It is of some rationality and feasibility to judge the immune status according to the criterion based on clinical information，and the criterion can be used in small clinics.

Objective  To evaluate the efficacy of minocycline as an adjunct to scaling and root planning(SRP)in treating chronic periodontitis. Methods  64 male smokers with moderate to advanced periodontitis were randomly divided into two groups: SRP alone（SRP） and SRP plus minocycline（SRP+M）. All clinical parameters including plaque index（PlI）, gingival index（GI）, bleeding on probing（BOP）, probing depth（PD）and attachment gain were recorded at baseline, 3 and 6 months after treatment. Results  According to PlI, GI and BOP, there was no significant difference between the two groups at 3 and 6 months after periodontal therapy（P＞0.05）. However, PD reduction and attachment gain were significantly greater for SRP+M than that for SRP（P＜0.05）. For SRP+M and SRP groups, PD reduction were 1.98 mm and 1.32 mm, and attachment gain were 1.87 mm and 1.14 mm respectively. Deep pockets in SRP+M group showed more obvious PD reduction（3.48 mm versus 2.21 mm, P＜0.01） and attachment gain（2.62 mm versus 1.23 zmm, P＜0.01） than that in SRP group. Conclusion  Treatment with SRP plus locally delivered minocycline is more effective than SRP alone in male smokers with chronic periodontitis. Mechanical debridement plus locally delivered antibiotics are recommended especially for smokers with deep pocket periodontitis.

Objective  To evaluate the distribution of DIAGNOdent value according to varying clinical caries severity. Methods  A total of 541 deciduous molar teeth in children aged from 5 to 6 were examined using DIAGNOdent by one trained dentist. The most severity site in every tooth was recorded. The same sites were examined visually by another dentist. The distribution regular of DIAGNOdent value was analyzed according to the clinical severity score by Ekstrand index. Results  The higher the visual score, the higher the mean DIAGNOdent value. The variation of values in each visual category was larger than that of values recommended by manufacturers. When clinical severity score was 0, 1, 2, 3 and 4, the median of DIAGNOdent value was 0, 5, 19, 49 and 99 respectively. The mean value for sound surfaces was lower in primary teeth than the cut-off points recommended by manufacturers, but the value of DIAGNOdent was increased obviously when the transparency change of enamel was detected visually. Conclusion  DIAGNOdent is useful in detecting occlusal caries in deciduous teeth, but the cut-off levels is not coinciding perfectly with manufacturer suggesting.

Objective  To investigate the frequency and intensity of Candida spp. incidence from the oral cavities of the healthy elderly in Chengdu, and to study the role of the dentures in the distribution of oral Candida spp. Methods  A total of 212 individuals（age >60 years） were divided into four groups: A1（48 man with dentures）, B1（61 man without dentures）, A2（53 women with dentures） and B2（50 women without dentures）. Samples of their oral flora were obtained by rinsing with 10 mL PBS solution. The samples were centrifuged and resuspended in PBS（500 μL）, and plated onto Sabouraud's dextrose agar. CHROMagar CandidaTM, sugar assimilation patterns（API 20C AUX tests） were used to determine Candida spp. The total number of yeast colonies on the plates was considered as the relative intensity of oral Candida. Results  Candida spp. was isolated from 116 healthy elderly individuals（54.72%）, such as C.albicans, C.parapsilosis, C. krusei, C.guilliermondii, C.tropicalis, etc. The frequency of Candida spp. in A1, B1, A2 and B2 was 66.67%, 36.07%, 64.15%, and 56.00%, respectively. The frequency of C. albicans in A1, B1, A2 and B2 was 56.25%, 21.31%, 56.60% and 38.00%, respectively. The frequency of Candida spp. and the intensity of Candida spp. were greater for individuals in the denture-wearing group than that in the control. Conclusion  The frequency and intensity of Candida spp. incidence from the healthy elderly are closely correlated with denture-wearing, and the differences of the frequency and intensity of Candida spp. incidence in the elderly are due to the differences of frequency and intensity of C.albicans incidence.

 Objective  To study the clinical characteristics, diagnosis and treatment strategy of oral and maxillofacial malignancies in multiple primary malignant neoplasms（MPMNs）. Methods  21 cases of oral and maxillofacial malignancies associated with MPMNs admitted to our hospital between 1985 and 2000 were studied respectively. Results  There were 44 malignant cases in the 21 MPMNs patients. Among the 44 cases, there were 24 cases in alimentary and respiratory tract such as oral, pharynx, esophagus, stomach and lung, and 10 cases in salivary gland, breast and female reproductive system. There were 25 cases malignant neoplasms in oral and maxillofacial region where squamous cell carcinoma was the most common pathologic type, secondly adenoid cystic carcinoma. In oral and maxillofacial region, MPMNs were often found in tongue, parotid and submandibular gland, buccal mucosa and gingival. Conclusion  Tongue and salivary gland were the common locations with MPMNs, and they were closely associated with alimentary and respiratory tract. Patients with malignancies of oral and maxillofacial region associated with MPMNs must be submitted to a long-term and careful follow-up. For female patients, breast and female reproductive system should be examined specially. Regular follow-up, early detection, early diagnosis, active and effective treatment can help to improve the survival quality of MPMNs patients.

Objective  To investigate the changes of upper airway of obstructive sleep apnea syndrome（OSAS） patients after the treatment of Silensor snoreguard. Methods  42 patients with OSAS were treated with dental appliance. Cephalometric analysis was carried out to compare the changes of upper airway before and after the treatment. Results  SPP-SPPW increased from（9.10±2.25） mm to（12.24±2.61） mm. PAS increased from（8.99±3.20） mm to（11.24±3.79） mm. CL decreased from（26.26±6.04） mm to（14.37±8.14） mm. H-MP decreased from（21.27±6.12） mm to（12.14±5.89） mm. V-RGn decreased from（55.15±5.61） mm to（51.63±5.87） mm. OPAA increased from（7.01±1.54） mm2 to（7.85±1.61） mm2. HPAA increased from（3.02±0.89） mm2 to（3.61±1.61）mm2. Conclusion  Dental appliance worked with the effect of enlarging upper airway.

Objective  To evaluate the treatment effect of mandible fractures. Methods  Clinical data of 275 mandibular fracture patients of Tongchuan people's hospital were analysed. Results  ①The systemic health of 27 non-surgery cases were influenced during the intermaxillary ligation and 3 cases of them had deformity of maxillofacial region. ② In the surgery group, 5 of 73 cases fixed by steel wire had disorder of occlusion, 6 of 169 cases fixed by titanium mini plate accepted secondary operation of removing the plates, and 6 cases fixed by bioabsorbable mini plate had better effect. Conclusion  The internal rigid fixation is an appropriate and effective method for the mandible fractures.

  Objective  To study the risk factors of alveolar bone loss（ABL）of primary teeth in Chinese children. Methods Caries, restoration, food impact, pulp pathosis, calculus, and periodontal status were examined in 106 children aged 3-10 years old. Bite-wing radiographs of posterior teeth were scanned into computer. The distance from the cemento-enamel junction to alveolar bone crest was measured from the mesial surface of the first primary molar to the distal surface of the second primary molar using Adobe Photoshop 5.0 image analyzing system. ABL was recorded if the distance was more than 2 mm and the lamina dura was absent. All patients were divided into ABL group and non-ABL group. All data were analyzed by SPSS 10.0. Results  Alveolar bone loss was found in 31 children（29%）. Most of the affected areas were located at the proximal surface of primary molars. The mean of dmft and proximal dmft in ABL group were higher than those in non-ABL group（P<0.01）. Logistic regression also confirmed that proximal caries was high related factor. Inadequate restoration, and pulp pathosis were also related to alveolar bone loss in primary tooth. Conclusion  In children, alveolar bone loss was mainly associated with local factors such as proximal caries, inadequate restoration, and pulp pathosis. Caries and pulp pathosis might be treated in time. Children with bone loss should be re-examined regularly.

Objective  To analyze the value and reliability of combined free flap and pedicled pectoralis major myocutaneous flap in the reconstruction of extensive composite head and neck defects. Methods  Nine consecutive cases of combined free flap and pedicled pectoralis major myocutaneous flap transfers for extensive head and neck defects from March 2002 to April 2005 were reviewed. Data concerning the operation included defect description, type of free flap, recipient vessel and complications. Results  There were 9 cases in this group, with 7 males and 2 females. Among the 9 free flaps, there were 6 radial forearm flaps, two fibula flaps, and one anterolateral thigh flap. The overall flap survival rate was 100%(all of 18 flaps), without partial or total flap necrosis. One radial forearm flap developed venous thrombosis 24 hours after operation, but salvaged by emergent exploration and re-anastomosis of veins. The overall complication rate was 44.4%. Conclusion  In selected cases, the combined free flap and pedicled pectoralis major myocutaneous flap method provided satisfactory reconstruction for extensive head and neck defect, and simplified the double free flap method.

Objective  To study the feasibility of close and three-dimensional reconstruction of maxillary  defects combination with pedicled buccal fat pad graft, temporalis myofascial flap and titanium mesh. Methods  Among 11 patients with maxillary tumors, 9 were malignant and 2 were benign. 8 cases underwent subtotal maxillectomy and 3 cases underwent total maxillectomy. Maxillary defects were closely reconstructed combination with pedicled buccal fat pad graft(BFP), temporalis myofascial flap（TMF） and titanium mesh to restore the profile of maxilla. Results  All flaps were alive with satisfactory function and aesthetic appearance. The uncovered  BFP and the facial muscle surface of TMF epithelialized within 4-6 weeks. Their degree of mouth opening ranged from 2.5 to 4.0 cm and without nasal foods return. All patients had a good voice quality. Conclusion  Making use of BFP, TMF and titanium mesh can restore the good contour and function of maxillary． It is an effective method of reconstruction of maxillary defects, and is easy to manipulate. It is worthy to popularization.

Objective  To investigate the effects of substance P on cultured rat osteoclasts. Methods  Neurokinin-1（NK1）receptor expression in osteoclasts was examined by immunohitochemical method, and changes of bone resorption activity caused by substance P and NK1 receptor antagonists were detected by pit formation assay. Results  Immunoreactivity for NK1 receptor was distributed in the cytoplasm of osteoclasts. The average of pit formation areas significantly increased with addition of  substance P （10-7-10-4 mol/L） （P<0.05）, but the number of pitformations did not change（P>0.05）. NK1 receptor antagonists inhibited the enhancement of the bone resorption by substance P addition. Conclusion  The findings suggested  that substance P may stimulate osteoclasts and result in bone resorption by the mediation of NK1 receptor.

Objective To investigate the effect of anterior disc displacement on the expression of urokinase plasminogen activator and its inhibitor-1(uPA/PAI-1) in synovial tissues. Methods Forty Japanese white rabbits were used in this study. The animals were killed at 4 days, 1, 2, 4, 8 and 12 weeks postoperatively, respectively. In situ hybridization technology was applied to detect the expression of uPA/PAI-1 mRNA in synovial membrane. Results In normal synovial tissues, synovial lining cells and a few fibrosblasts with mild positive staining were occasionally seen. More synovial lining cells and fibrosblasts with moderate postive signals were found 1 week after operation. Since then, the degree of staining for uPA/PAI-1 increased gradually. By the end of 12 weeks postoperatively, strong signals of uPA/PAI-1 mRNA were detected. Conclusion There is a harmonized uPA/PAI-1 system existing in synovial tissues. The high expression of uPA and PAI-1 mRNA in synovial tissues indicates that the uPA/PAI-1 system may play an important role in the process of synovitis resulted from anterior disc displacement.

bjective To investigate the role of c-Jun and c-Fos as transcriptional factors in regulation of dentin sialophosphoprotein（DSPP） gene by a promoter-luciferase reporter gene construct in odontoblast cell line MDPC-23. Methods Endogenous c-Jun or c-Fos protein was determined by immunocytochemistry. The role of c-Jun or c-Fos in transcription of DSPP was investigated in co-transfection experiments using promoter-luciferase reporter gene construct containing the sequence between -791 bp and +54 bp of mouse DSPP gene. Results c-Jun and c-Fos was expressed by MDPC-23 cells, and located in the nucleus of MDPC-23 cells. Overexpression of c-Jun or c-Fos significantly inhibited luciferase activity of DSPP promoter. Conclusion These findings suggest c-Jun and c-Fos downregulated the transcription of DSPP gene as a transcriptional factor in odontoblast.

Objective  It is reported that Streptococcus mutans luxS gene may have an important role in the interspecies quorum sensing system. To construct the S. mutans luxS gene knockout mutant, this research aim to construct the luxS gene allelic exchange plasmid. Methods  The upstream and downstream flank DNA fragments of S. mutans luxS gene（Xup, Xdn）and the E. coli kanamycin resistance gene（Kana） were enriched by pfu DNA polymerase with“nest PCR”methods. These fragments were ligated into pBluescript  SK（+）Phagemids vector with double endonuclease reaction sequentially. Results  With endonuclease reaction and DNA sequencing, it was proved that the objective plasmid, Xukd-pbsk, was constructed correctively and the kanamycin resistance gene could be expressed in vitro. Conclusion  The S. mutans luxS gene allelic exchange plasmid is constructed correctively in this research and can be used in the future research of S.mutans luxS gene knockout mutant.

Objective To explore the relationship between immunochemical level of salivary and caries in children aged 4—6 years old. Methods Two groups were assorted as patients with caries and without caries. Every group included 45 people. Measurements of salivary secretory immunoglobulin A（SIgA）were performed by using radio-immunoassay and single agar diffusion assay. The levels of lysozyme（LZ）, alkaline phosphatase（ALP）and lactic dehydrogenase（LDH）were studied with colorimetry and turbidimentry. Results The levels of LDH, SigA, ALP, LZ had significant difference between the two groups（P<0.05）. The level of LDH between patients and peoples without caries had little difference（P>0.05）. Conclusion The incidence of caries is associated with age, and it may have association with immunochemical levels of salivary.

Objective  To study the ultrastructure changes of PDLLA as GTR membrane of soft tissue defects in the palates of goats. Methods  To establish penetrating rectangle palate defects in 8 goats. PDLLA membranes were implanted into the defect areas to guide the regeneration of the soft tissue defects. In 1, 2, 4, 6 months after the operation, the membranes were observed with scanning electron microscope. Results  The surface of PDLLA membrane was regular network before implantation. 1 month after the implantation, the edge of network became blunt. 2 months after the implantation, the surface of PDLLA membrane became coarse and irregular. 4 months after the implantation, PDLLA membrane network collapsed. 6 months after the implantation, PDLLA degraded into scraggly accumulation. Conclusion  PDLLA membrane supplies good supporting function during concrescence of the soft tissue defects. PDLLA gradually loses mechanic intensity and is absorbed.

Objective  To evaluate the effects of a solitary megadose protocol of ionizing radiation（IR）to parotid gland on the structured and function changes of bilateral parotid glands in miniature pig. Methods  Fourteen minipigs were subjected to either 15 or 20 Gy to one parotid gland with a linear accelerator, while another four minipigs served as non-IR controls. Salivary flow rates and salivary chemistries were measured pre-IR, and 4 and 16 weeks post-IR. A quantitative assessment of gland weight and acinar area, and detailed serum chemistry and hematological analyses, were also performed. Results  Parotid gland weights were significantly decreased in the 15 and 20 Gy groups at 4 and 16 weeks post-IR. The acinar cell area in glands of both IR groups was significantly reduced. Parotid flow rates decreased by 60% with 15 Gy at 16 weeks post-IR. In the 20 Gy group, salivary flow rates were reduced by 80% at 16 weeks post-IR. Additionally, parotid flow rates significantly reduced in contralateral glands with 20 Gy at 16 weeks, while structure and weight did not changes in parotid glands. Conclusion  Structural changes in salivary gland parenchyma occurred relatively early after IR, while the alterations in salivary output were relatively delayed. Further, reductions in salivary flow were not proportional to acinar cell area loss. There isn't a significant structured change of contralateral glands, but significant reduction of parotid flow rate at this time.

Objective  To investigate the influences of bicortical anchorage on values of natural frequencies of dental implants utilizing the 3-dimensional finite element analysis. Methods  Using the commercial code of Solidworks, 3-D models of a screw-shaped dental implant and a mandibular bone segment were generated. After the 3-D implant-bone complex was meshed by ABAQUS software, effects of bicortical anchorage on the buccolingual and axial first-order natural frequencies of the implant were computed. Results  Bicortical anchorage increased both the buccolingual and axial natural frequencies remarkably. As the bicortical anchorage got deeper, the frequencies correspondingly got higher. Conclusion  Bicortical anchorage can increase the buccolingual and axial primary stability of dental implants.