Instruments broken in root canal is one of the frequent complications of endodontic therapy and fortunately, as the rapid development of microscope using in the root canal treatment, most of the broken instruments can be removed with the assistance of ultrasonic appliances. In the present study, we talked about the causes, the removing methods of broken instruments and troubles during the procedures. We put much emphasis on the creation of a traight pathway along the canal as well as some concerns in using the ultrasonic appliances, such as the water spray, the rotating actions and the assistance of microscope, all of which are supposed to offer great benefits for clinically avoiding as well as dealing with broken instruments.

Objective To investigate the early effects of the cyclic uniaxial compressive stress on Actin and Vimentin of the rat condylar chondrocyte. Methods The third- passage chondrocyte were harvested from the mandibular condyles of 2 - day - old rats, and a cellular compressive stress device was used to apply stress on cells at 4 000 μstrain for 15, 30, 60, 120, 240 min. The early effects of the cyclic uniaxial compressive stress on Actin and Vimentin of the rat mandibular condylar chondrocytes were examined by laser scanning confocal microscope（LSCM）, immunofluorescence technique and Western blot. Results The expression of fluorescent light of cys- toskeleton protein changed obviously with 4 000 μstrain compressive stress loading. The expression of Actin significantly decreased in 60 min, and the expression of Vimentin decreased in 30 min. Then the expression of these two protein recovered in 120 min. Conclusion There are time- responsiveness between the 4 000 μstrain compressive stress stimulate and Actin, Vimentin. It shows the expression of Actin and Vimentin down- regulated at first under the compressive stress, then increased by feedback. It hints that there are“self- regulate”mechanisms in the cell response to mechanics stimulate.

Objective To compare the wear between the enamel and two types of dental decoration porcelains for all- ceramic restorations（Vita- alpha, Vintage AL）. Methods Friction coefficients, wear scar width, element concentrations and wear surface evolution were considered relatively to the tribology of that in vivo situation. The wear scars of the samples were characterized by means of dynamic atomic force microscopy（DFM）. The different element concentrations of the surface before/after the wear test were determined with energy dispersion spectrometry（EDS）. Results The friction coefficient varied from time in each kind of material. The statistical differences between materials were observed in wear scar width and properties of materials（P<0.05）. DFM results showed wear surface of natural tooth full of abrasive particles and denaturation of dental texture. Wear surface of veneering ceramics consisted mainly of abrasive particles, plough and microcracking. EDS results showed that the element concentration of Fe was obviously found on the samples after wear. Conclusion The main underlying mechanisms of natural teeth wear are abrasive, and denaturation of dental texture. Abrasive wear, adhesion and fatigue of veneering ceramics characterize the wear patterns which plays different role in Vita - alpha and Vintage AL. The wear patterns of veneering ceramics can be described as mild wear.

Objective To investigate the stimulation of Cinnamaldehyde to the pulp tissue and the periapical tissue of rats′teeth, to provide evidence for developing Cinnamaldehyde as a pulp- cap of pulpotomy in primary teeth. Methods Using Cinnamaldehyde as pulp- cap in pulpotomy of rats′teeth, set up Cinnamaldehyde group, formaldehyde cresol formocresol group and blank group. After different treatment according to the empirical procedure, rats were killed in the 4th week and on the 12th week. Then the experiment teeth and the periodontal tissue were made into HE slides and observed using light microscope. Results The 4th week，internal absorption, external absorption, and calcification were of no significance among all the groups. Inflammation in blank group was far more severe than that in other two groups（P<0.05）, while the latter two were of no significance. The 12th week, internal absorption, external absorption, and inflammation between the former two groups were of no differences, but the indexes were significantly different from them of the blank group（P<0.005）. Calcify was not obvious in all the slides. Conclusion As a pulp- cap, Cinnamaldehyde stimulates the pulp tissue and the periapical tissue at a very low level. The research provides histopathology rationale for Cinnamaldehyde as pulp- cap of pulpotomy in primary teeth.

Objective To observe the growth and osteogenic property of cultured dog bone marrow stem cells （BMSCs） by investigating the effects of astragalus polysaccharides（APS） on the proliferation and ultrastructure of BMSCs into osteoblasts in vitro. Methods BMSCs osteogenic property was detected by improved Wright - Giemsa, Gomori and alizarin dyeing method. The proliferation and differentiation of the induced BMSCs with APS in different concentration and time were detected by MTT assay and the morphologic change of the induced BMSCs was observed by transmission electron microscope（TEM）. Results BMSCs osteogenic property was detected with Wright - Giemsa deep- bluing, Gomori method blacking and with more mineral nodules alizarin dyeing method carmining. APS with concentration of 0.005 mg/mL can promote the  proliferation of the induced BMSCs in short - term culture（1th, 3th day） and 50 mg/mL can decrease the effect through long- term culture（5th day）. Observed by TEM（5th day）, the number of mitochondria, rough endoplasmic reticulum increased and the extracellular matrix was excreted more in the  induced BMSCs by APS with concentration of 0.005 mg/mL. However, not only the number of mitochondria, rough endoplasmic reticulum reduced but also the structure was swollen, degenerative, membrance damaged in the induced BMSCs by APS with concentration of 50 mg/mL. Conclusion APS with lower concentration in short - term culture may promote BMSCs proliferation and differentiation.

Objective To investigate the effects of the static magnetic field（SMF） generated by dental magnetic attachments on osteoblastic proliferations, cell cycle distribution, and apoptosis ratio. Methods By simulating those of the closed- field, the closure process and the open- field Magnedisc 800 magnetic attachments respectively, the in vitro cultured rat osteoblasts were exposed continuously to 12.5, 125, 250 mT SMF. The effects of the SMF on the proliferation of the cells were examined. MTT colorimetry test was performed to detect the effect of the SMF on the vitalities of cells. Flow cytometry was utilized to analyze the cell cycles and cell apoptosis rates. Results The SMF exposure didn′t change the vital osteoblasts number, the cell cycle distribution and proliferation activities of osteoblasts. The cell apoptosis situation were not observed statistical differences. Conclusion No matter the closed- field, the closure process and the open- field magnetic attachments respectively, continuous simulating SMF- stimulation of magnetic attachments couldn′t change osteoblasts proliferation activity, cell cycle distribution, and apoptosis ratio.

Objective To study the influence of thermochemotherapy on the activity of cytotoxic T lymphocyte （CTL） in peripheral blood of patients with oral maxillofacial cancer. Methods Twenty - one subjects with oral maxillofacial cancer were treated by thermochemotherapy, and the activity of CTL in peripheral blood was analyzed. Results Thermochemotherapy can obviously enhance the activity of CTL（P<0.01）. Conclusion Thermochemotherapy can enhance the activity of CTL, thus enhance the patient′s immune function. Therefore, it can enhance the antitumor response in whole body.

Objective To determine the expression and possible function of ClC- 5 during the rat tooth germ development. Methods Isolated total mRNA and protein from the rat tooth germs which were at different stages of development. RT- PCR and Western blot were used to investigate the mRNA and protein expression of the ClC- 5 in the rat tooth germ. Results The mRNA and protein of ClC- 5 expressed in the late bell stage, but undetected in the early or middle bell stage. Conclusion These results showed the spatial temporal distribution of expression of ClC- 5 during the different stages of the rat tooth germ development and suggested that it might contribute to the rat tooth germ development.

Objective To evaluate the effects of all- ceramic veneers in clinic fabricated by computer aided design/ computer aided manufacturing（CAD/CAM） system and veneered with Vita VM9. Methods 54 all- ceramic veneers were made for 12 patients. The patients were divided into three groups: Tetracycline staining group, fluorosis group and devitalization group. The color of patients′teeth was checked before and after laminates with Shade Eye. All- ceramic veneers was checked on the white background and abutment background. The value of L*, a* and b* were calculated to compare the color difference among 3 groups. The color, fitness and fracture of all - ceramic veneers were checked in clinic after restoration every 3 months. Results All- ceramic veneers as a replacement for discol- ored teeth showed good appearance. The substructures and veneers showed significant color difference between white background and abutment background in tetracycline staining group and devitalization group, but there was no significant color difference in fluorosis group. All veneers had good esthetic effect, excellent marginal fit, good gingival and adjacent condition. The fracture was not found in clinic. Conclusion The effects of all - ceramic veneers were perfect in color, fitness and stability to fracture. Fluorosis teeth is the best indication for all- ceramic veneers. To tetracycline teeth and devital teeth, the fundic porcelain with deep color should be chosen, or an opaquing material be applied as fundus in all- ceramic veneers repairing.

Objective To evaluate the influence of different types of posts and cores on the final color of the IPS- Emperss 2 crown. Methods Five types of posts and cores（Cerapost with Empress cosmo, Cerapost with composite resin, gilded Ni- Cr alloy, gold alloy and Ni- Cr alloy）were made. The shifts in color of three points of IPS- Empress 2 crown surface （cervical, middle and incisal）with different posts and cores was measured with a spectroradiometer （PR- 650）. Results The L* a* b* values of zirconium oxide and gilded Ni- Cr alloy posts and cores with ceramic crown were the highest. The L* a* values of zirconium oxide posts composite cores were higher while the b* values were lower. The L* a* b* values of Ni - Cr alloy were lower than that of gold alloy and were the lowest. Conclusion In combination with IPS- Empress 2 crown, zirconium oxide posts are suitable for routine use in the anterior dentition, and gilded Ni- Cr alloy and gold alloy posts and cores can be recommended for clinical practice. Ni- Cr alloy posts and cores can not be recommended for clinical practice.

Objective To compare the number of the Tannerella forsythensis（T. forsythensis）, total bacteria, and proportion of T. forsythensis in subgingival specimens in diseased sites of chronic periodontitis patients and in healthy sites of periodontally healthy subjects, and clarify the relationship between bacterial load and periodontal status. Methods Subgingival plaque samples from 61 chronic periodontitis patients and 12 healthy controls（positive for T. forsythensis by conventional PCR）were analyzed with TaqMan real- time polymerase chain reaction assay for T. forsythensis and total bacteria. Quantification was performed with species- specific primer/probe, universal primer/ probe and serial dilution of plasmid standards. Results Numbers of T. forsythensis and total bacteria（P<0.001）, the proportion of T. forsythensis in subgingival specimens（P<0.05）were significant higher in diseased sites of chronic periodontitis patients than in healthy sites of healthy subjects. In addition, a significant correlation was found between the number of bacteria and various probing depth（P <0.001）. There was no significantly difference between the proportion of T. forsythensis in subgingival plaque and probing depth. Conclusion Number of T. forsythensis are closely associated with periodontal status, and demonstrate the broad potential of real- time polymerase chain reaction application on periodontology.

Objective To explore the effect of myringotomy with insertion of tube and tympanocentesis on alleviating secretory otitis media（SOM） and hearing loss in cleft palate infants. Methods Nineteen cleft lip and palate infants with SOM and hearing loss （38 ears）were treated with myringotomy with insertion of ventilation tube at the same time of repair of the cleft lip, who were performed averagely at 6.9 months of age. Fifteen cleft lip and palate infants with SOM（30 ears） were treated with tympanocentesis at the same time of repair of the cleft lip averagely at 6.6 months of age. All cases were followed up from 1 week to 12 months and estimated by auditory brainstem response（ABR） and acoustic immitance audiometry. Results The average wave Ⅴ reacting thresholds of ABR were separately 55.41 dBnHL and 28.48 dBnHL, and 79.17% tympanogram B changed to tympanogram A in cleft palate infants with insertion of tube before and after operation. The average wave Ⅴ reacting thresholds of ABR were separately 40.63 dBnHL and 26.50 dBnHL, and 40.91% tympanogram B changed to tympanogram A in cleft palate infants with tympanocentesis preoperatively and in 1 week postoperatively, in whom the average hearing thresholds and tympanograms had no significant difference preoperatively and in 1 or 3 months postoperatively（P>0.05）. Conclusion The early myringotomy with insertion of tube is effective to restore the function of the middle ear in cleft palate infants with SOM, so to suggest to be performed at the same time of the repair of cleft lip within the first 1- year of life. The tympanocentesis should not be used as a regular management in the cleft palate infants with SOM.

Objective To investigate effects of non- surgical treatment on temporal mandibular joint（TMJ）of adult low- angle subjects with severe skeletal Class Ⅲ deformity. Methods Thirteen low- angle patients with severe skeletal Class Ⅲ malocclusion（male 5, female 8）were included in the study. The average age was 21.3 years old. They were treated with OPA- K straight wire technique. Helkimo index evaluation was made before and after treatment. Lateral cephalometric films and corrected TMJ lateral cephalometric radiograghs were taken before and after treat - ment, and linear and area measurement were observed. All data were analyzed with SPSS 12.0 software. Results After non- surgical treatment, Helkimo indexes of all patients redistributed. The line distance and area of anterior space in TMJ increased while the posterior space decreased. Linear percent decreased from 20.81% to 8.04%, and area proportion decreased from 1.62 to 1.01. Anterior space was the same as the posterior. Condyles and mandibles were retruded. Conclusion After non- surgical therapy in adult low- angle subjects with severe skeletal Class Ⅲ malocclusion, condyles remove posteriorly from more anterior position to normal concentric position, and temporomandibular disorders symptom is relieved and cured effectively

Objective To explore the coagulation indexes and offer a valuable reference for clinic therapy and prognosis in patients with oral squamous cell carcinomas（OSCCs）. Methods The indexes of prothrombin time（PT）, activated partial thromboplastin time（APTT）, thrombin time（TT） and fibrinogen（Fib）were detected by using automatic blood coagulation testing machine in 65 healthy people and 351 patients with OSCCs. All patients with OSCCs were divided into three groups included primary tumor, neck metastasis of lymph nodes and recurrence. The data were analysed by SPSS 11.0. Results The index of PT in patients with OSCCs was longer than that of healthy people. There was a significance between the control group and the group with the neck metastasis of lymph node or the recurrence group（P <0.01）. The time of APTT was shortened. Except for the group with the neck metastasis of lymph node and the recurrence group the distinctive difference existed in other groups（P<0.05）. There was no significance between two groups in the indexes of TT and Fib（P>0.05）. Conclusion PT and APTT may be the useful indexes for clinic therapy and prognosis in patients with oral squamous cell carcinomas.

Objective To investigate the distribution of H. actinomycetemcomitans, P. gingivalis, P. intermedia, T. forsythensis and T. denticola in the subgingival plaque in the patients with chronic periodontitis. Methods 27 patients with chronic periodontitis were included. Two of the deepest pockets of each patient were selected as the study sites. Semi- quantification of subgingival microorganism samples was analyzed by multiplex polymerase chain reaction and reverse hybridization assay. Results P. gingivalis, P. intermedia, T. forsythensis and T. denticola were detected in a high proportion of examined sites（corresponding values were 98.15%, 92.59%, 100% and 98.15%）, however, the pro- portion of H. actinomycetemcomitans was low（20.37%）. The levels of P. gingivalis and T. forsythensis were higher than the other three microorganisms with statistical significance. Conclusion The simultaneous infection of P. gingivalis, T. forsythensis, P. intermedia and T. denticola is found in the patients with chronic periodontitis, in which the levels of P. gingivalis and T. forsythensis are higher than the other two microorganisms.

Objective To study the color changes on brightness and hue in dental ceramic prothesis materials. Methods The different color mark of VINTAGE series was sintered on 15 pieces Ni - Cr alloy denture materials. The sample group and control group was given the sintering of color blending with equivalent volume. The order of color mark was of A1 and A2, A2 and A3, A3 and A4, B1 and B2, B2 and B3, B3 and B4 in sample group, and A1, A2, A3, A3.5, A4, B1, B2, B3 and B4 orderly in control group. The chromatic analysis on samples of VITA had been taken through applying PR 650 spectrum detector and adopted the statistic software of Photo Research and SPSS 12.0 for analysis. Results The statistical difference（P<0.05）of L*a*b* value was found in the different color mark of the same color serials. A non- linearity relation had been found in the chromatic parameters a*b*. It means the change of color was visible. Conclusion Set A has a bigger grading change of brightness than Set B. The change of red- green is obviously in Set A, as well as yellow- blue in Set B.

Objective To investigate the influence of different intensity and directions of ambient light and adjacent tooth in anterior tooth color measurement by using colorimeter. Methods Fiber lite MI- 150 was used as ambient illuminant and it irradiated from three or twelve o′clock direction through 45°angle above. The light magnitude 0, 50, 75, 100, 125, 150 W were applied in this experiment. The values of CIE L﹡ a ﹡ b﹡were measured by Minolta Chroma meter CR- 321 colorimeter on the center labial surface of ten extracted human maxillary central incisors with or without adjacent teeth, then those data were analyzed statistically by using SPSS 11.5. Results Neither different intensities nor different directions of ambient light could influence the results of color measurement by using Minolta Chroma meter CR- 321 colorimeter, so did the adjacent teeth whether those were exist or not. Conclusion There is no influence of ambient light and adjacent teeth in the color measurement of anterior teeth under this experiment condition, and Minolta Chroma meter CR- 321 colorimeter can be used to measure the color directly aside the chair with light.

Objective To evaluate the matching of the shade between beverage and modifying porcelain shade guide according to Munsell color order system, thus to provide the reference basis for selecting modifying porcelain to mimic the stain of natural tooth by technician. Methods The shade of Vita Akzent, Vita Interno, Shofu Vintage & Unibond and Noritake Super Porcelain EX- 3 shade tabs as well as 15 kinds of beverage were measured according to Munsell color order system on Color- Eye 7000A spectrophotometer. The difference of the frequency of approximate hue, value, and chroma between shade tabs and beverage were compared by calculating the Fisher exact probabilities. Results The frequency of approximate hue between 4 kinds of shade tabs and 15 kinds of bev- erage was significant different（P <0.05）, while the frequency of approximate value, and chroma was not significant different （P>0.05）. Conclusion Except the hue, the color distribution of 4 kinds of shade tabs was similar to that of 15 kinds of beverage. But the color of beverage also can be approximately matched by any kind of modifying porcelain by mixing porcelain powder of appropriate hue, value, and chroma.

Objective To evaluate the clinic effects of alginate impression and agar/alginate combined impression. Methods 237 patients of fixed partial denture were collected and divided into group A and group B. Group A was taken impression by aglinate impression, including 81 patients（207 abutments）. Group B was taken impression by agar/alginate combined impression, include 156 patients（392 abutments）. The impressions were observed by megaloscope, and the number of abutment, the types and number of defect were recorded. Results In the aglinate impressions, 57.0 percent of abutment had some defect. But in the agar/alginate combined impressions, 36.0 percent of abutment had some defect. There were significant difference between group A and group B in the abutment, air bubbles in cervical margin, unsharpness of the gingival sulcus and shoulders（P<0.05）. There were no significant difference between group A and group B in the split and defect of the impressions on the cervical margin. Conclusion There were less defects in the agar/alginate combined impression than in the alginate impression.

目的克隆人骨形态发生蛋白- 2（hBMP2）基因片段，构建pcDNA3.1- hBMP2真核表达质粒。方法采用逆转录聚合酶链式反应（RT- PCR）技术，从人骨肉瘤中扩增出人骨形态发生蛋白- 2基因片段，通过DNA重组技术将该基因片段重组于pcDNA3.1真核表达载体上，构建pcDNA3.1- hBMP2重组质粒，通过用PCR扩增、酶切电泳分析及DNA测序的方法对重组DNA进行鉴定。结果经PCR扩增、酶切电泳分析和DNA测序证实，本实验构建的重组质粒目的基因片段为人BMP2- cDNA。结论本实验成功克隆了hBMP2基因并构建成其真核表达质粒。

Objective To investigate the effects of oral carcinoma - associated fibroblasts（CAFs） on extracellular signal- regulated kinases（ERK） pathway in a lingual carcinoma cell line. Methods The lingual carcinoma cell line. Tca8113 was stimulated by conditioned medium from oral CAFs, or cocultured with oral CAFs for definite time. Total ERK and pERK in Tca8113 lysate were detected by Western blotting, and the ratio between pERK and ERK were calculated. Results Both stimulation by conditioned medium and coculture induced prompt phosphorylation of ERK, and increased the ratio between pERK and ERK. Conclusion Oral CAFs can activate ERK pathway of carcinoma cells.

Objective To investigate the movement tendency of lower teeth using multiloop edgewise archwire （MEAW） with vertical elastics in anterior teeth area by three- dimensions photoelastic analysis. Methods The photoelastical model of full teeth as human body on physical parameter and dimension was established and loaded by MEAW with vertical elastics in anterior teeth area similar with clinic. Every freezing model- tooth was bladed by anteroposterior axes and vertical axes, the stress of every point of alveolar bone was calculated by three - dimensions shear- equation method. The stress distribution regularity of per- tooth was analyzed to describe their move tendency. Results The lower second molar was intrused and rotated to distal and inclined as negative torque. The lower first molar moved and rotated to distal, the mesial rotate to buccally and the distal rotate to lingually. The lower second pre- molar was extruded and inclined as crown to mesial and root to distal, inclined as negative torque. The lower canine was intrused slightly and inclined as positive torque. The lower lateral incisor was extruded and moved and inclined as positive torque. Conclusion Using MEAW with several“L”loop can control the movement of every tooth in three dimension.

Objective To explore certain principle of how osteoprotegerin（OPG） and osteoprotegerin ligand（OPGL） take part in the periodontal tissues remodeling under the combined influence of inflammation and orthodontic force. Methods The positive signals of OPG and OPGL mRNA were measured with in situ hybridzation after orthodontic tooth movement in the experimental periodontitis groups and control ones. Results The OPG and OPGL mRNA expression intensity in the experimental group showed difference from control. All their optical density index reached a peak in day 2, respectively. Conclusion OPG and OPGL play important roles in the periodontal reconstruction induced by inflammation irritation and orthodontic force, and complex interaction could exist between the two factors.

Objective To investigate the differently expressed Homeobox genes between lingual squmaous cell carcinoma and normal mucosa. Methods Seven paired specimens including lingual squmaous cell carcinoma and its surrounding normal tissue were obtained from 7 patients. Customized Oligo microarray which contains numerous probes of 232 human Homeobox genes was used to analyse the results. All datas were scanned by Agilent scanner and differentiately expressed genes were sorted out. Results Homeobox gene NANOG was found up- regulated in 5 samples. PHTF2 was found down- regulated in 7 samples, and CRX, PITX1, OTEX was found down- regulated in 5 samples. Conclusion As the key gene to cellular proliferation and differentiation, Homeobox genes is closely releverant to the oncogenesis of lingual squmaous cell carcinoma.

Objective To observe the ability of induced ectopic bone using skeletal muscles satellite cells（SMSCs） from newborn green fluorescence protein（GFP） transgenic mice mediated by Ad- BMP2. Methods Transplantation of SMSCs transduced with Ad- BMP2 into back lamb muscles of subfascia in wildtype 129sv mice with a complex of collagen scaffords, then the tissue histologic examination, X ray plain film, fluorescence microscopy were used. Results Transplantation of SMSCs transfected with Ad- BMP2 into back lamb muscles of subfascia generated ectopic bone formation involving GFP- positive osteoblasts and osteocytes 2 weeks and mature bone formation 4 weeks after transplantation. SMSCs non- transfected with Ad- BMP2 failed to induce ectopic bone formation. Conclusion SMSCs retain differentiation potentitality into osteoblasts in response to Ad- BMP2. They are useful tools for analyzing the process of osteoblast differentiation in vivo after transplantation.

Objective To approach the effects on induction of differentiation of Tca8113 cells affected by abscisic acid. Methods The changes of surface differentiation markers, cell configuration, restrain of cell growth and the expression of Caspase - 3 mRNA were examined by using inverted- phase contrast microscope, immunohistochemistry （IHC）and in situ hybridization in vitro. The dependablity between the surface differentiation markers and Caspase- 3 mRNA was analysed. Results The restraint of cell growth in ABA groups was higher than that of the control group （P<0.05）. There was a trend that the tumor cell had transformed the normal cell. Furthermore, the time - dosage dependent relationship existed in the inhibition rate of tumor cells. The results showed that the expressions of Involucrin protein, retinoic acid receptor β（RARβ） and Caspase- 3 mRNA in experimental group had been higher than that of control group. There was a significance between the different concentration experimental groups at 24 h （P<0.05）. Moreover, the positive correlation existed among the Involucrin, RARβ and Caspase- 3 mRNA at the time of 12 hour and 24 hour（P<0.05）. Conclusion The possible mechanism is that abscisic acid acted on the tumor cell and raised the level of RARβ gene through combining the correlative receptors so that increased the expression of Involucrin protein and promoted the activity of Caspase- 3 and resulted in apoptosis of tumor cell.

Objective To investigate the effect of a new engineering technique of vacuum deposition - plasma magnetron reactive sputter deposition technique on the metal- porcelain bond strength of a new type of Co- Cr ceramic and framework dental alloy. Methods Before porcelain painted on the specimens, the standardized metal strips made from DA9- 4 dental alloy were coated with a thin Al2O3 ceramic film by plasma magnetron reactive sputter deposition technique. The conformation, structure and thickness of the ceramic film were analyzed. The specimens for three- point bending test made from DA9- 4 alloy and VMK95 porcelain were used for metal- porcelain bond strength measurement, in the same time the interface of metal- porcelain and element distribution were also observed. Results The flexural bonding strength of metal- porcelain of sputtering group and control group were（180.55±16.45）MPa and （143.80±24.49）MPa. The flexural bonding strength of metal - porcelain of sputtering group was higher than control group significantly through statistical analysis（P<0.01）. Conclusion The plasma magnetron reactive sputter deposition technique has a positive effect in improving the bonding strength of DA9- 4 dental alloy and ceramic.

Letterer- Siwe disease（LSD） is a kind of a histiocytosis, rarely seen in clinic. However, its prognosis is poor. A case of LSD which complaints of the oral ulcer is reported in this article. The patient of the case was a boy, came to hospital on July 5, 2003 because of oral ulcers, teeth loosing and falling off for a month, and pus running over from both antra auris for two weeks. No familial history of genetic diseases and special infections were found. The case consisted of the following features after exam: Erythematous papules and petechia dotted in the skin, primarily on scalp and trunk，two ears suffering otitis media, oral proliferative ulcers appearing in palate and lower gingival accompanying with the lower teeth loosing in the lesion area, in the meantime, the destruction of madibula on the left side also found out by X- ray, hepatic dysfunction and poor cellular immunity coming along with pertinacious candidosis. The pathologic exam showed histioid cell infiltration, and the immunohistochemical exam showed CDla（+）, S- 100（+）. Diagnosis defined it LSD. According to the case′s character and literature review, the clinical features, diagnosis and therapy of LSD were discussed.

The patient visited for swell and ache of sublingual region. The patient′s two sides of sublingual glands were swelled. The mandibular central incisors were repaired by the ill fitting prosthesis, and there was an irregular oral ulcer under it. The area of the ulcer was about 2 mm×2 mm. The sublingual glands recovered in two days after the ill fitting prosthesis of mandibular central incisors was removed away, iodoglycerin was applied on the oral ulcer, vitamin B1, vitamin B2, prednisone and amoxicillin was taken.