Objective　The purpose of this studywas to investigate the relationship between apoptosis and proliferation of oral mucosa in lesions of leukoplakia and the role of apoptosis in the pathogenesis of this common oral disease.Methods　The mucosa was obtained from the leukoplakia lesions from 6 patients, with average age of 57 years, and all the patients had not received any treatment before this investigation. The lesionswere located on the lip (1), gingiva (1), tongue (2) and buccal mucosa (2). All the patients did not have any systemic diseases. Otherthree normal oral mucosa tissueswere collected as the control. In situ terminal de- oxynucleotidyl transferase end-labeling (TUNEL) and avidin-biotin peroxidase complex (ABC) immunohistochemical assaywere used to detect single-strand DNA breaks and proliferating cell nuclear antigens (PCNA). The negative control slides were treated with the tris saline bufferto substitute the terminal deoxynucleotidyl transferase (TdT) and PCNA-Ab in the assay. Five consecutive high pow- er fieldswith the magnification of 400 were used to search for positive stained keratinocytes.Results　Comparedwith the normal mu- cosa, the keratinocytes in leukoplakia showed positive apoptotic signals in the nucleus of suprabasal epithelial layers, while PCNA- positive stain was present in the basal position. In the connective tissue, positive apoptotic signalswere found in lymphocytes and the endothelia of blood vessels.Conclusion　The results indicate that the death of cells in leukoplakia is partly due to apoptosis which may play an important role in the genesis of oral leukoplakia.

Objective　The aim of this study was to investigate the circadian rhythm of the proliferative index of mandibular osteoblasts of goats in a normal situation.Methods　Twenty four healthy goats were selected and randomly divided into six groups. They were killed, and a piece of bone tissue with 2 cm×2 cm×0.5 cmwas obtained from rightmandibularmental foramen region at 0∶00, 4∶00, 8∶00, 12∶00, 16∶00 and 20∶00 time points, after they had been fed for one week. The primary cell culture method was used to cultivate osteoblasts from the bone. The method of anti-5-bromodeoxyuridine monoclonal antibody and the flow cytometric analysis were used to detect the proliferative index of the mandibular osteoblasts at different time. The data were analyzed using the method of single cosine rhythmometry.Results　The proliferative indexes of the mandibular osteoblasts of goats were higher at the nighttime and lower in the daytime. The undulation of the proliferative indexes displayed a significant circadian rhythm (P<0.01). The peak value was obtained at about 19∶44, and the lowest value at about 7∶44.Conclusion　The proliferative indexes of the man- dibular osteoblasts of goats are not stablewithin 24 hours in a normal situation, butwith significant circadian rhythm. There are differ- ent proliferative indexes at different time points.

Objective　The aim of this studywas to investigate effects of immunodeficiency on the periodontal infection char- acters of the specific pathogens of juvenile periodontitis.Methods　A total of 36 immunodeficient guinea pigs produced by twice whole-body irradiation with60Co were divided randomly into four groups, in whichActinobacillus actinomycetemcomitans,Porphy- romonas gingivalis, andA.actinomycetemcomitanswithP.gingivaliswere inoculated into the gingival sulcus of two mandibular inci- sors respectively. The pigs in the control group did not receive any inoculation. At 2, 3 and 6 weeks after inoculation, three animals in each group were sacrificed successively. Clinical and histological examinationswere used to examine the changes in the periodontal tissues. The other36 normal guinea pigswere divided into fourgroups and treated in a similarway described above.Results　Signif- icant periodontal damages were noted in immunodeficient pigs inoculated withA.actinomycetemcomitans,P.gingivalisorA.acti- nomycetemcomitansandP.gingivalisin 2 and 3 weeks after bacterial inoculation. The damages were more severe than in the normal groups. The immunodeficient groups demonstrated larger numbers of osteoclasts than the normal groups (P<0.05).Conclusion　 The loss of periodontal tissue in immunodeficient hosts is much serious than those with normal defence system, after they are infected withA.actinomycetemcomitansandP.gingivalis. Abnormal defence system in hostsmay play an important role in onset and develop- ment of juvenile periodontitis.

Objective　The aim of this study was to investigate the expression of collagen in the process of masseter muscle reattachment to the cortical and cancellous bones ofmandible.Methods　Atotal of nine adult goatswere used in the study. Onewas the control. The other eight were treated with bilateral detachment of the masseter muscles. The biopsies of bone and muscle were taken at 2, 4, 8 and 12 weeks after the operation. The characteristics of the healing muscle-bone interfaceswere examined using im- munohistochemical techniques.Results　Immunohistochemical analysis illustrated that the locations of collagen typeⅠ,ⅡandⅢ were different during the healing process, but similar in the cortical and cancellous bones.Conclusion　This study demonstrates that the distribution of the three types of collagens at the muscle-bone interfaces is associated with time, but not related with their loca- tions.

Objective　The purpose of this study was to investigate methods and expression of the recombinant human inter- leukin-1 receptor antagonist gene transfected into chondrocytes of temporomandibular joints (TMJ).Methods　Chondrocytes derived from the TMJ of 5~7 months old human fetus were transfected by recombinant human interleukin-1 receptor antagonist gene via cat- ionic liposome (Lipefectine) as a medium. The expressing level of hIL-1ra protein was detected using immunocytochemistry and enz- yme-linked immunosorbent assay (ELISA).Results　The positive results of the immunocytochemistry were found. The positive ex- pression was detected in the cell plasma and the cell culture supernatant, and there was significant difference between the cells with and without gene transfection (P<0.01).Conclusion　This feasible method provides experimented evidence for the future gene therapy of temporomandibular joint osteoarthrosis.

Objective　The purpose of this study was to determine the effects of amino group implantation on the surface struc- tures of titanium.Methods　The amino groups were implanted into the surfaces of titanium using 100 keV amino group ions at ambient temperature (25℃) with the following three different doses: 5×1017, 1×1017and 5×1016ions per cm2. The current density of the ion-beam was (10μA/cm2. The modified surfaces were characterized using X-ray photoelectron spectroscopy (XPS) to determine the chemical components of the modified surfaces. A scanning electron microscope (SEM) was used to study the physical structure of the surfaces.Results　The wide XPS profiles, the binding energy data and the SEMphotoswere obtained. The XPS showed that the modi- fied surface contained Ti, O, C and N. The possible chemical states were speculated using Gauss matching analysis. There was no sig- nificant difference between the surfaces with and without implanted amino groups.Conclusion　The XPS data reveals that the structure of the modified surface layer of aminogroup-implanted titanium is TiN, comprising a complex structure of titanium and amino compound near the surface. The SEM Photos show that this technique has little effect on the surface structures of materials.

Objective　The aim of this study was to analyze the clinical characters, diagnosis and treatment of primary neo- plasms in the parapharyngeal regions.Methods　Atotal of 115 cases of primary neoplasms in the parapharyngeal regionswere includ- ed in this study.Results　Disorders of swallowing, breath or speakingwere the common symptoms of neoplasms in parapharyngeal re- gions. The majority of neoplasms parapharyngeal regionswere benign. 46 caseswere from the deep lobe of the parotid, and 42 cases were neurogenic. CT orMRI provides useful information such as their sizes, shapes and extents. The relationship between the tumor and vessel was shown using super-selective angiography. All the tumors were resected completely by extra-oral approach through the posteroinferior incision of the mandible. The follow-upwas carried out from1 to 10 years, and the data indicated that 2 patients died, 18 cases were lost, and others had no recurrence.Conclusion　CT and/or MRI are essentially useful for diagnosis and presurgical planning. Super-selective angiography can be used if the lesions involved carotid artery. Posteroinferior incision of the mandible is a simple, effective and safe approach for excision of neoplasms parapharyngeal regions.

Objective　The aim of this study was to investigate the effects of the tympanotomy and pressure equilibrium tube insertion during palatoplasty on the alleviation of otitis media with effusion.Methods　A total of 49 ears in 38 cases of patients with cleft palate and otitis media with effusion were only treated with palatoplasty. Other 39 ears in 24 patients with middle ear effusion were treatedwith the palatoplasty and insertion of pressure equilibriumtubes. The function of the middle ear in each patientwas eval- uated 6 months after the operation.Results　48.7% of ears with middle ear effusion were healed in the group of the palatoplasty combined with pressure equilibrium tube insertion, and the hearing level was raised about 17dB six months after operation.Conclu- sion　The pressure equilibrium tube insertion is helpful for the recovery of the middle ear function in patients with cleft palate and middle media effusion.

Objective　The aim of this study was to investigate the association between clinical and pathological characteris- tics of primary oral mucosal malignant melanoma and the prognosis of this disease.Methods　Clinical and pathological characters of 73 cases primary oral mucosal malignant melanoma were investigated. The association between risk factors, such as black macule, lymph node metastases, invasive depth, clinic stages, pathologic types, and prognosis was analyzed using Kaplan-Meier survival analysis and Log rank test.Results　The age of the patients ranged from 24 to 80 years (Median age, 50). Among the patients, 43 were males and 30 were females. The most common locations of the tumorwere palate and gingiva. The clinic stages of these patients were as the following: StageⅠ(46/73), StageⅡ(24/73), StageⅢ(3/73). The most common pathological type was nodular (44/73), followed by lentiginose malignant melanoma (15/73) and superficial spreading (1/73). According to the configuration of tumor cells, the most common typewas the mixed cell type (37/73), followed bythe epitheloid cell type (27/73) and the spindle cell type (9/73). Among the 73 patients, 43 were followed up, the 3-year and 5-year survival rates were 19.86% and 11.91% respec- tively. Black macule, lymph node metastases, invasive depth, clinic stages, pathologic types and therapeutic methods were signifi- cantly associated with the prognosis (P<0.05).Conclusion　The prognosis of the primary oral mucosal malignant melanoma is as- sociated with black macule, lymph node metastases, invasive depth, clinic stages, pathologic types, and therapeutic methods.

Objective　The purpose of this studywas to retrospect the prognosis of simultaneous repair of cleft lip and closure of cleft hard palatewith vomerflaps in patientswith unilateral complete cleft lip and palate.Methods　Aretrospective studywas car- ried out in 47 patients with unilateral complete cleft lip and palate and, simultaneously received repair of cleft lip and closure of cleft hard palate with vomer flaps. The duration of operation, as well as the blood loss during the operation was recorded, and compared with those patients who only received cleft lip repair.Results　All the operations were successful, and the wound healed well. The procedure of simultaneous repair of cleft lip and closure of cleft hard palate with vomer flaps did not prolong the operating time, com- pared with simple cleft lip repair. No blood transfusionwas needed due to closure of cleft hard palateswith vomerflaps.Conclusion　 Simultaneous repairs of cleft lip and closure of cleft hard palate with vomer flaps are safe for patientswith unilateral complete cleft lip and palate.

Objective　The aim of this studywas to evaluate quantitativelythe effectiveness and feasibility of the modified su- pracrestal fiberotomy (MSF) and the contact point reproximation (CPR) in decreasing the relapse of anterior segments rotating and/ or crowding after orthodontic treatment.Methods　Atotal of 129 patientswith crowding and/or rotated anteriorteethwere selected for this study, and the average age was 13·07 years (54 males, 75 females). The modified supracrestal fiberotomywas performed on the anterior segments of patients in the experimental group (48 cases). After the anterior teethwere aligned, 23 of the 48 cases received a further treatment of the contact point reproximation on the anterior segments (the subgroup of MSF+CPR), and the other 25 sub- jects did not receive this treatment (the subgroup ofMSF). The control group consisted of 81 cases. All cases wore Hawley retainers for 1·8 to 2·3 years, and all the patientswere revisited 2·4years postretention. The maxillary and mandibular dental models of all the patients were taken before treatment (T1), at the end of the treatment (T2) and 2·4 years postretention (T3).Results　The relapse rate in the experimental group [(T3-T2)/T1×100%] was 21·6%, lowerthan that in the control group (P<0·001). The relapse rate of mandible in the subgroup ofMSF+CPRwas 6·56% lowerthan that of the subgroup ofMSF (P<0·05). But the relapse rate of maxillary in the subgroups ofMSF+CPRwas similar as that of the subgroup ofMSF (P>0·05).Conclusion　The modified su- pracrestal fiberotomy can effectively alleviate relapse after orthodontic treatment of the crowding and/or rotation of anterior teeth. The treatment combining MSF and CPR can help maintain the stability of post-retention of mandibular anterior teeth.

Objective　The aim of this study was to examine the levels of prostaglandin E2in periapical exudates before and after root canal treatment.Methods　Periapical exudates specimens were quantitatively sampled from root canals of 25 teeth at con- secutive treatment visits, and the concentration of prostaglandin E2in each sample was determined using a commercial kit.Results　 The mean prostaglandin E2levels significantly decreased after the endodontic therapy. Significant correlations between the levels of prostaglandin E2and the clinical features of periapical periodontitis were also found in this study.Conclusion　The results suggest that the level of prostaglandin E2in periapical exudates reflects the state of periapical periodontitis.

Objective　The aim of this study was to explore the expression of basic fibroblast growth factor (bFGF) and fi- bronectin during the healing process of allografttissue engineering skin.Methods　The tissue engineering skin thatwas obtained from neonatal SD rats was cultured in the lab. Afterwards, the skin was grafted into adult SD rats, and the expressions of bFGF and fi- bronectin were detected on the 7th, 10th,14th, 20th and 30th day after the allograft of the tissue engineering skin. The autografted skin in 15 adult Wistar rats and the normal skin in 15 Wistarwere treated as the control. HE staining and immunohistochemical stain- ing were used to examine the healing of grafted skin.Results　The expression of bFGF and fibronectin was the strongest on the 10th day aftergraft, andwasweaker before the 10th day and afterthe 14th day. The expression changes of bFGF and fibronectinwere sim- ilar as they were in the autograft group.Conclusion　The expression changes of bFGF and fibronectin in the tissue engineering skin during the process of wound healing were similar to those of autografted skin, and these can promote the repair of tissue engineering skin allograft.

Objective　The aim of this studywas to investigate the mRNA expression levels of human leukocyte antigen Class Ⅰat different progressive stages of human oral squamous cell carcinomas.Methods　The expression of mRNA of human leukocyte antigen-B/C was detected in 23 primary tumors, 10 metastatic focuses and 11 histological normal oral epithelia using in situ hybrid- ization method with a digoxigenin-labeled DNA probe. The probe was human leukocyte antigen-B/C locus specific.Results　The hybridization signals were present in the cytoplasm of either normal epithelia or tumor cells. The integrated optical density values of the hybridization signalswere detectedwith the aid of an image analysis system. The results showed that the average integrated optical density values of the primary tumors were statistically lower than the normal oral epithelia (P<0.05), but there was no significant difference between metastatic tumors and the primarytumors orthe normal epithelia. The integrated optical density valuesmeasured in the metastatic tumors also did not show statistically differences compared with the primary tumors of the same patients.Conclusion　 Impaired regulation of human leukocyte antigen-B/C transcription could occur but might not be directly associated with metastasis of oral squamous cell carcinomas.

Objective　The purpose of this studywas to investigate the transcription and expression levels of human leukocyte antigen-DR at different stages of oral squamous cell carcinomas.Methods　The specific monoclonal antibody andβ-locus specific oli- gonucleotide probes of human leukocyte antigen-DR were employed in this study. A total of 32 primary oral squamous cell carcino- mas, 15 metastatic focuses and 26 histologically normal oral epithelia, were detected forthe presence of the human leukocyte antigen- DR molecule by using immunohistochemistry and in situ hybridization.Results　The human leukocyte antigen-DR expression of the primary focuses was significantly higher than that of the normal epithelia (P<0.05), but their expression did not show statistically difference between the metastatic focuses and the normal epithelia. The immunohistochemistric results were identical with those of in situ hybridization.Conclusion　The abnormal higher expression of theHLA-DR is a common character of primary oral squamous cell carcinomas, but it may be not relevant to the metastasis of tumors.

Objective　The aim of this studywas to observe the expression of ciliary neurotrophic factors (CNTFs) in the fa- cial motor neurons in rats during facial nerve regeneration.Methods　The expression amount of CNTFs in eight groupswas determined with immunohistochemical staining and image analysis.Results　The expression of CNTFs increased during the process of nerve re- generation, and reached the maximum one-week and one-month after nerve injury respectively. After one month, the intensity of CNTFs reduced gradually. The expression of recombinant human bone morphogenetic protein-2 (rhBMP-2) did not show distinct dif- ference comparingwith the control, but beta transforming growth factors (TGF-β) benefited the expression of CNTFs during nerve re- generation.Conclusion　The endogenous CNTFs promotes the axon outgrow during regeneration, andTGF-βpromotes the expression of CNTFs to rescue motoneuron during facial nerve regeneration.

Objective　The purposes of this study were to investigate effects of chloroqquine (CQ) on inhibiting the decom- position of hydrogen peroxides (HP), and to optimize composition of the tooth- bleaching agent.Methods　According to the princi- ple of the color-changing reaction between horse radish peroxidase and substrate, the tooth-bleaching agent made of HP was divided into fourgroupswith different amounts of CQ. The stability ofHPwas observed using ELISAfor3 months.Results　Withthe prolon- gation of store time, the absorbance of HP solutions containing different concentrations of CQ declined at different degrees, which showed a dependent relation between absorbance values and concentrations of CQ. Within the range of experiment concentrations of CQ, the higher the concentration of CQwas, the strongerthe stability ofHPwas. And the duration of tooth-bleaching effects in 150. 0 mg/ml of CQwas prolonged 4 to 6 times compared to thatwithout CQ.Conclusion　The data indicate that CQ can inhibit the de- composition of HP. The bleaching effect of the tooth-bleaching agent which is made of HP and proper amount of CQ is satisfactory.

Objective　The purpose of this studywas to investigate the effects of static tension-stress on proliferation of man- dibular condylar chondrocytes in rats.Methods　The fourth-passage chondrocytes were harvested from the mandibular condyles of 2- week-old SD rats. A continuous static tension-stresswas applied on the cells in vitro using a cellular static tension-stress device, and the proliferation of mandibular condylar chondrocytes were examined using a flow cytometry. The other 30 specimens in the control group were divided into six groups to examine the effects of calf serum on cellular static tension-stresswithout any stress. The experi- mental group consisted of 70 specimenswhichwere divided into seven groups under continuous static tension-stress (5kPa, 10kPa) for 0 to 12 hours. Multivariable analyseswere conducted to test the associations between proliferation of condylar chondrocytes and differ- ent continuous static tension stresses.Results　The results showed thatthe lower calf serum inhibited the proliferation of ratmandibu- lar condylar chondrocytes. There was little effect on the proliferation of chondrocytes under continuous static tension-stress (5kPa, 10kPa) for 2 hours. The proliferation of mandibular condylar chondrocytes was promoted as the application time of stress was pro- longed (0~10 hours in 5kPa groups and 0~8 hours in 10kPa groups). The maximal proliferation appeared, when the condylar chon- drocyteswere cultured under 5kPa continuous static tension-stress for 10 hours, and 8 hours under 10kPa stress (P<0.05). The proliferation of cells in the 5kPa groupwasmore obvious than in the 10kPa group (P<0.05).Conclusion　The data prove thatme- chanical stimulates in vitro can influence and regulate the growth of condylar chondrocytes. It provides experimental evidence for ad- vanced study on cellular mechanical research in functional orthopedics.

Objective　The purpose of this studywas to investigate effects of static tension-stress andTGF-β1on proliferation of mandibular condylar chondrocytes in vitro.Methods　The fourth-passage chondrocytes were harvested from the mandibular con- dyles of 2-week-old SD rats for this study, and a cellular static tension-stress device was used to apply stress on cells. The effects of continuous static tension-stress and/or transforming growth factor-β1(TGF-β1) on the proliferation of mandibular condylar chondrocytes were examined using flow cytometry. The experimentwas divided into two parts. The first part consisted of 100 specimenswhichwere divided into 20 groupswith differentTGF-β1dosage (0 ng/ml, 0.1 ng/ml, 1 ng/ml and 10 ng/ml) for 0, 6, 12, 18 and 24 hours re- spectively. The second part consisted of 30 specimens which were divided into six groups under continuous static tension-stress (5 kPa) and different TGF-β1doseage (0.1 ng/ml, 1 ng/ml, 10 ng/ml) for 0, 6 and 12 hours. Multivariable analyses were conducted to test for associations between proliferation of mandibular condylar chondrocytes and TGF-β1and/or different stresses.Results　The results showed that TGF-β1had a mitogenic effect on rat mandibular condyle at the concentrations of 0.1, 1 and 10 ng/ml, and the mitogenic effects of TGF-β1on condylar chondrocytes were demonstrated in 12 to 18 hours after application of stresses, and the peak of mitogenic effects appeared at 18 hour (P<0.05). The most active mitogenesis happened in the group with continuous static ten- sion-stress (5 kPa) combined with TGF-β1.Conclusion　These results prove mechanical stimulates and TGF-β1in vitro could influ- ence and regulate the growth of condylar chondrocytes.

Objective　The purpose of this study was to study the methods of how to puncture the temporomandibular joint (TMJ) cavity of rabbits and get the synovia.Methods　The anthors punctured joint cavity and withdrew the synovia from bilateral TMJ cavities of 12 NewZealand rabbitswith differentmethods, such as the traditional puncture method, improved puncture, puncture under X ray, puncture guided by ultrasonography and spiral CT, and withdrawing synovia by micropump.Results　Only one cavity was successfully punctured using the traditional puncture method. A total of 4 cases were successfully punctured using the improved method. X ray and ultrasonography did not locate the TMJ cavity precisely. The spiral CThelped observation and puncture. Howev- er, the above methods did notwork in collecting synovia. The method of micropumpwithdrewsynovia successfully.Conclusion　The improved method and spiral CT are efficient methods to precisely puncture TMJ cavity. The technique of micropump successfully re- solves the problem of withdrawing synovia.

Objective　The purpose of this studywas to studythe changes of available spaces of posterior arch segments inman- dible dentitions (ASPAS) from ages of 11 to 20 years, whichwould provide information on normal growth and development of the dental arches in teenagers in Chengdu area.Methods　The data were derived from systematically collected preorthodontic lateral cephalograms of 526 patients, including 232 males and 294 females from the Orthodontic Department of West China College of Stomatology, Sichuan University during the period of 1999~2000 (aged 11~20 years). The values of ANB angle, FH-MP, ASPAS were obtained using the cephalometric analysis. Afterwards, the growth changes of ASPAS from the subjects and their correlations with age, gender, angle mal- occlusion types and vertical skeletal patterns were analyzed.Results　ASPAS was related to age and classⅡangle malocclusion. Though gender was not associated with ASPAS, significant differences in curves of ASPAS were found between males and females. The growth changes of ASPAS in the patients with skeletal ClassⅢmalocclusion were more obvious than in patients with ClassⅠandⅡ malocclusion.Conclusion　Our results reveal that significant differences were demonstrated in growth change values in posterior avail- able spaces of patients with different races and angle malocclusion types.

Objective　The purpose of this study was to determine the effect of transient exposure to chemotherapeutic drugs on multidrug resistance of Tca8113 cells.Methods　The MDR1 and MRP gene expressions in Tca8113 and K562/ADM cells lines were analyzed using reverse transcription polymerase chain reaction (RT-PCR), after the cells were treated with different cytotoxic drugs. The function and expressions of P-glycoprotein 170 and multidrug resistant associated protein were studied using fluorescence photometric assays.Results　The inhibitive rate ofTca8113 cells was higher than that of K562/ADM, after exposure to chemothera- peutic drugs. The transient exposure to cytotoxic drugs weakly induced MDR1 and multidrug resistant associated protein expression in Tca8113 cells. The intracellular drug concentration in K562/ADMwas lower than that in Tca8113 cells.Conclusion　Induction of MDR1 and multidrug resistant associated protein gene expression response to cytotoxic drugs may be related with the increased multi- drug resistance in drug-treated human tumor cells.