Objective:The aim of this study is to investigate the demineralization effects of several beverages on bovine enamel.Meth- ods:The concentration of calcium and phosphate in these beverageswere measured by using EL312e Micro-Plate after the bovine enamel was exposed to beveragesfor a period of 7 days.Results:The data indicated that almost all of these beverages could cause demineralization of bovine enamel, except mineral water, and the concentration of calcium and phosphate in these beverages changed after the bovine enamel was exposed to beverages. There were great significant differences in demineralization abilities a- mong different beverages (P<0101). The concentration of calcium and phosphate in beverages also changed with time (P< 0101).Conclusion:All these beverages, except mineral water have erosive effects on bovine enamel. Demineralization degree varied with kinds of beverages. The fruit juice has the highest erosive effect on the enamel, and the calcium milk has the lowest erosive effect on the bovine enamel, when comparing with other beverages.

Objective:The study is designed to compare the effects of Lanthanum (La), Calcium (Ca), Fluoride (F) on pHchanges of plaque, and to discuss the anti -cariogenic mechanisms of Lanthanum in terms of metabolism.Methods:Plaque pHvalues after sucrose solution (containing La3+, Ca2+, F-) rinse were measured contiguously usingmicro-touchmethod, and then the mini- mum pH, time of minimum pH, ranges of plaque pH($pH), and areas of the response curves below (AUC6.5) were analyzed using two-way analysis of variance (ANOVA).Results:No statistical difference was found in the above monitored parameters of 8 subjects. For the decreasing degree of plaque pH, the pHvalue in the control group fell down the mostobvious, and the second was thatin the Ca group. The pHvalue decreased the leastin the F and La group, and there was no significant difference between the F and La group. The time of minimum pHwas the same in each group.Conclusion:Ca, La, F can decrease the range of plaque pHdrop after sucrose solution rinse. The degree of Cawas the weakest, and F and Lawere same. All the above evidences prove that La may inhibit the acidogenicity of plaque.

Objective:The occurrence of oral precancerous lesion is related with not only carcinogenic environmental factors but also some self-regulating mechanisms. The genetic heredity factors determine individualcs DNA repair capacity. The study is attempted to investigate the change of DNA repair capacity of the patientswith the precancerous lesion.Methods:The study is conducted in 16 pairs of oral precancerous lesion and normal controls by using host cell reactivation assay, while some dangerous factors such as smoking, alcohol intaking and family history of cancers are also recorded.Results:The host cell reactivation in the patients with precancerous lesion is lower than that of normal controls (P<0.05) and is shown to be an independent risk factor in the occur- rence of oral precancerous lesion (OR: 3.25 95%CI=1.01~10.49 ).Conclusion:The host cell reactivation is likely to be a helpful indicator for predict prognosis of cancer for the individuals with highly genetic sensitivity to cancer.

Objective:This study is aim atinvestigating the relationship between the expression and activity ofMMP-2,9, TIMP-1,2 and the metastasis of oral squamous cell carcinoma to neck lymph node.Methods:The expression ofMMP-2,9, TIMP-1,2 in 30 oral squamous cell carcinoma, two oral squamous cell carcinoma cell lines GNM and TSCCa was detected by in situ hubridization; Zomography was performed to determined the activity of MMP-2,9 in cancer tissue and conditioned medium of GNM and TSCCa; Ability of invasion ofGNMand TSCCawasmeasuredwith in vitro invasion assays.Results:Both tumor cells and stroma expressed both MMP-2,9 and TIMP-1,2; Itwas found thatMMP-2,9, TIMP-1,2 had a higher expression in patientswith neck lymph node metastasis than those without metastasis (P<0105), positive percentage of MMP-2,9 in GNM was higher than that in TSCCa; The MMP-2,9 in node-positive patients was more active than in node-negative ones (P<0105); GNM had more active MMP-2, 9 and higher invasive potential thanTSCCa.Conclusion:MMP-2,9 may play an important role inmetastasis of oral squamous cell carcinoma; Elevation of TIMP-1,2 is likely to be the result of interaction of tumor and stroma.

Objective:In order to prevent rampant caries in children, the predominant pathogenic bacteria of rampant caries in children were defined.Methods:The pathogenic bacteria of rampant carieswere isolated and identified in 30 childrenwith rampant caries, aged from 2 to 5 years old. Sampleswere collected from the caries of labial surfaces of maxillary anterior deciduous teeth, includ- ing caries lesions and caries-free smooth enamel surfaces. Plaque were obtained from the cervical third areas of the maxillary labial anterior deciduous tooth surfaces in children without rampant caries and caries-free children and served as controls respectively. The isolates were identified by colony morphology, biochemical tests and DNA base contents (mol percent G+C).Results:The prevalence of Streptococcus mutans (S.mutans) and Streptococcus sobrinus (S. sobrinus) in the plaque of caries lesions and the proportions of S. mutans and S. sobrinus in the plaque of 2 sampling sites of children with rampant caries were all significantly higher than those of children without rampant caries and caries-free children (P<0.05).Conclusion:S.mutans and S.sobrinus are predominant pathogenic bacteria in rampant caries in children.

Objective:The objective of this study is to compare effects of formocresol, camphorated phenol and Ya Kan (metronedazole) on endotoxin levels in canals of chronic periapical periodontitis.Methods:Atotal of 30 patientswith chronic periacal periodontitis were selected from outpatients, and 10 cases eachwere randomly picked out to treat by sealingwith formoresol, camphorated phe- nol and Ya Kan respectively. All patientswere both sampled before and after sealing of these disinfectants, and chromogenic sub- strate method of limulus amebocyte lysate (LAL) testwas used to measure levels of endotoxin.Results:The effects of Ya Kan, formocresol and camphorated phenol on levels of endotoxin did not showed significant difference.Conclusion:Some anti-anaerobic bacterial drugs can be used to treat chronic periapical periodontitis.

Objective:The effect of unilateral cleft lip and palate prothesis on the development of maxillary and facial soft tissue was in- vestigated.Methods:The standard cephalometric measurement was used in patients with complete unilateral cleft lip and palate operated in different periods. We obtained data by measurement.Results:Hard tissue: ANS-X, PNS-X and N-ANS in the group of patientswere statistically differentfrom those of the normal control group, butinANS-PNS and N-PO, there is no statistical dif- ference in these two groups. Angles of hard tissue: There is statistical difference in

Objective:The aim of this study was to assess the isolated effects of lip repair on inhibition of maxillary growth in patients with complete unilateral cleft lip and palate.Methods:The lateral cephalometric analysiswere applied to 20 patientswith unilat- eral cleft lip and palate who only had lip repaired in childhood, 32 patientswith unilateral cleft lip and palate who had both lip and palate repaired in childhood, as well as 37 normal Chinese of the same age as controls.Results:Both complete unilateral cleft lip and palate groups had almost the same significant degree of maxillary retrusion compared with the normal control group.Conclu- sion:Lip repair is one of important factors that could inhibit maxillary growth in patients with complete unilateral cleft lip and palate.

Objective:Porphyromonas gingivalis (Pg) is one of the main putative pathogens of periodontal disease, especially of adult periodontitis. This in vitro study was aimed at observing the inhibitory activities of 7 commonly used antimicrobical drugs on 106 stains of Pg which isolated from subgingival plaques of siteswith adult periodontits.Methods:Kirby-Bauer paper diskmethodwas used in this study.Results:Pgwas highly susceptible to Clindamycin, Sulfamzthoxazole timethoprin, Tetracycline and Cefazolin, the susceptibility rates were 93.4%, 78.3%, 60.4% and 56.6% respectively.Conclusion:Majority of the strains of Pg was moderately susceptible to cefalexin and acetylspiramycin, while no strains of Pgwas susceptible to PenicillinG. The concentrations of Pg solutions (105CFU/ml, 106CFU/ml and 108CFU/ml) had notinfluence on the results. This data is helpful for clinically an- tibiotic selection of periodontal treatment.

Objective:The purpose of this study was to develop a practical CAD/CAM system with knowledge databases for complete denture.Methods:A three-dimensional coordinate measuringmachine (3DCMM) was used to collect three-dimensional information of edentulous models and bite plates and the mathematics model of complete denture was established using B-Spline method. This system was established by suing eightfunctional models: the measuring model, the converting data model, the constructing curve- surface model, the producing base and the editing model, the arranging artificial and the editing model, the outputting income model, the imitating dynamic model and the managingmodel.Results:(1) The soft and hard system of a computer aided complete denture design (CACDD) was established, including 3DCMM, 8 functional models and databases. (2) ACACDD system and the three-dimensional demonstration were completed.Conclusion:This system lay down the foundation for setting up the computer aided complete denture design/manufacturing system.

Objective:The aim of this study is to investigate effects ofmaxillary protraction on softtissue profile in operated operated uni- lateral cleft lip and palate (UCLP) patients.Methods:A total of 10 growing UCLP patients (male 7, female 3), age from 812 to 12 years old (Average: 1014 years old), were selected to be treatedwithmaxillary protraction using head gear-chin cap-long hook protraction appliance. The appliance was worn 12~14 hours per day, and the protraction force was 400~500g each side. The protraction directionwas forward and slightly downward. The treatment period was 417 months (Average: 518 months). Cephalo- metricswere taken before and after treatment. The changes of soft-tissue profile were studied using the computer-aid X-ray cephalometric analysis.Results:After protraction, the points of Prn, Sn and Ls moved forward significantly. The distance from points Ls to E plane changed significantly from 0146mm before treatment to 1118mm after treatment. The angle G-Prn-Pgcde- creased significantly, andG-Sn-Pgcchanged significantly from-0130 before treatmentto 61260 aftertreatment. The anterior-poste- rior position of mandible and lower lip did not change significantly, the changes of angles Cm-Sn-Ls, Acls/SiLi had no statistical significance. The results indicated thatmaxillary protraction could make maxilla and upper lip move forward, and the convexity of soft tissue profile improve significantly.Conclusion:Maxillary protraction is an effective way to improve the facial deformity of op- erated UCLP patients. UCLP patients should have early interrupted treatment.

Objective:The authors presented the shortterm and long term effects of the trigeminal neuralgia treated by RFTwith anterior- lateral facial, lateral facial and trans-subzygomatic approaches.Methods:320 primary patients with trigeminal neuralgia were se- lected for this study. All these patientswere followed up with the period of 1 to 6 years.Results:The first-time effective ratios of pain-relieve treated by using the anterior-lateral facial approach, and the lateral facial and the trans-subzygomatic, were 9313% and 7313% respectively.1Mostof the patients (9215%) achieved excellentorgood pain-relieve after treated by one of these three approaches. Compared with the lateral facial and trans-subzygomatic procedures, the anterior-lateral facial approach caused less recurrent rate in long term effects (P<0101). The late recurrence was found in 93 patients, but pain-relieve effect still could be obtained by retreatingwith the formermethod and without difficulty or hazard. One patient had serious Rollets syndrome.Conclu- sion:It is concluded that the anterior-lateral approach is a method with more effective pain-relieve and less pain recurrence rate, and the trans-subzygomatic method can be used as a substitutive approach in the treatmentof the second branch of trigminal neural- gia.

Objective:The aim of this study is to explore the influence of palatoplasty and tympanotomy onmiddle earfunction orhearing condition in cleft palate patients.Methods:A total of 22 ears with otitis media with effusion in cleft palate patients were inserted with PE tubes, and Pre-and post-operative hearing level and middle ear function in these patients were tested and compared re- spectively, in orderto demonstrate the action of tympanotomy and PEinsertion on hearing and middle earfunction. Another38 pa- tients with cleft palate were operated in their early age with the proper operation method, and pre- and post-operative middle ear function were examined and compared to showthe influence of the operation on the middle earfunction.Results:PETube insertion and tympanotomy changed the pressure condition of middle ear cavity and raised the hearing level about 17dB in the middle-ear- diseased cleft palate patients, and patientswith palatoplasty did not show obvious changes in middle ear function in the short-term trail.Conclusion:Early and active tympanotomy do help in improving the function of the middle ear, and it is suggested to im- prove patients.hearing and middle ear function as early as possible. Palatoplasty did not affect the function of middle ear.

Objective:The aim of this study is to explore the effectof hamulotome on the eustachian tube function and verify the function of the tensor veli palatili muscle on eustachian tube.Methods:Single-sided hamulotome were carried out in the rabbits under the direct visual. And the middle ear cavity mucosa of the rabbitswas collected atdifferentintervals and dyedwith PAS and PHto ob- serve the middle ear changes under microscope.Results:Middle ear function changed obviously after the hamulotome, with in- crease in globular cells, submucosal edema and inflammatory cells. And mucin was not found in several cavities.Conclusion: Hamulotome do affecton the middle earfunction and should notbe damaged in orderto protectthe middle earfunction in some pa- tients.

Objective:Glucosyltransferase (GTF) of Streptococcus mutans is considered as a cariogenic virulence factor due to its ability to synthesize glucan, which facilitate sucrose-depended adherence and cell-to-cell accumulation of bacteria. In this study, gtfB, the target gene fragmentwhich encodes multiple catalytic sites and antigen epitopes of GTF, was recombined into eukaryotic ex- pression vector pcDNA3. The feasibility of the recombination plasmid pcDNA3-gtfB used as gene vaccine will be investigated in further study.Methods:The target gene fragment gtfB (904-4578bp) was obtained by standard PCR amplification while genome DNAof streptococcus mutans GS-5 was used as template. Then the PCR products were extracted and purified from low-melting temperature agarose. The gtfB and plasmid pcDNA3 were cut by KpnÑ, XhoÑ, and the digested products were extracted and purified again for recombination. The purified gtfB and plasmid pcDNA3 were recombined by T4 DNA ligase, ligation products were transformed into competent cell, Escherichia coli JM109.Transformed colonieswere screened by AmprLB plate, then recom- bined plasmidswere isolated and identified by restricted endonuclease cutting and Sangerdideoxy DNAsequencing.Results:Identi- fied by agarose gel electrophoresis, the target gene-gtfB obtained PCR amplification had the same molecular size (36kb) as pre- dicted. Itwas indicated that recombined plasmids contained inserted gtfB gene fragment by restricted endonuclease cut analysis, the sequencing data also indicated thatinserted gtfB gene had correctDNA sequence and orientation according to DNA sequence of Streptococcus mutans GS-5(gene bank M17361).Conclusion:Inserted gene-gtfB of recombined plasmid pcDNA3-gtfB encoded multiple catalytic sites and epitopes. Itwas proved that these epitopes had high immune antigenicity and that antiserum could significantly inhibit the synthesis of water-insoluble glucans and water-soluble glucan. In vitro adherence experiment also indicated that it could inhibit streptococcusmutans adherence to saliva-coated hydroxyapatite. Vector pcDNA3 was high expressing eukaryotic vector, and could stimulate antigen-representing cell. Itwas suggested that recombined plasmid pcDNA3-gtfB had high immune antigenicity and immune responsiveness, and this supported its use as gene vaccine candidates in the development of anti-caries vaccines.

Objective:The aims of this study were to reveal the relationship between Fos protein expression, the transcription of pre- proenkephalin (PENK) mRNA, and the change of enkephalin (ENK) level initiated by experimental dental pain, and to under- stand the central modulationmechanism of dental pain.Methods:The techniques of Immunohistochemistry in situ hybridization and radioimmunoassay were applied respectively to detect the expression of Fos, the transcription of PENKmRNA, and the change of ENK level in the experimental nucleus of the spinal tract of the trigeminal nerve, caudal part (sp5c) of rats.Results:Itwas found that Fos protein expression was in a time-dependant manner. Fos appeared half hour after the pain stimulation, and its peak oc- curred two hours after the pain stimulation, but disappeared slowly four hours later. The transcription of PENK mRNA was seen two hours after the pain stimulation, its peak appeared four hours later and it disappeared eight hours later. The level of ENK in- creased significantly (P<0.01) in the caudal part of the spinal tract of the trigeminal nerve four hours after pain stimulation. Conclusion:Fos protein may take a part in the central modulation of dental pain by initiating PENKmRNA transcriptionwhich led to the increment of ENK.

Objective:This study was designed to testwhat are the suitable drugs for sclerotherapy and investigate the formation mecha- nism of cavernous hemagiomas.Methods:A total of 84 rabbits were selected for this study, and divided into 6 groups, including one control group and five experimental groups. We selected auricular veins of rabbits as the location of injection. The rabbits of the control were injected with physiological saline, and the rabbits of the experimental groupswere injected respectively with vari- ous drugs, including 5% sodium morrhuate, 10% alum, pinyungmycin, leurocristine and the combination of pinyungmycin and dexamethasone. Histopathological changeswere analyzed after3, 7, 14, 21, 28, 35 days of sclerotherapy.Results:According to histopathological changes of tissue, 5% sodium morrhuate, 10% alum, and the combination of pinyungmycin and dexamethasone produced bettereutherapeutic effects, when comparingwith othermethods. However, 5% sodiummorrhuate caused tissue necrosis of the injection site.Conclusion:The combined therapy of pinyungmycin and dexamethasone produced excellent scleritic effects. Whatever drugs causing serious damage of HVEC may contribute to the therapy for cavernous hemagiomas.