Objective: To study the color reproduction ratio of metal ceramic restoration in clinic. Methods:The color of 150 maxillary incisors and its metal ceramic restorations was measured by MinoltCR 321 chromaticity instrument(D65 daylight simulator inside),the color reproduction ratio was calculated with CIE 1976 L*a*b* system. Results: The color reproduction ratio of metal ceramic restoration measured by clinical eye evaluation was 33.9%.Color error ratio was 66.1%. Conclusion: The color reproduction ratio measured by eye evaluation is low and the color error ratio is high.

Objective: To study the denture base adaptation in fl uenced by technical factors. Methods: Thirty six maxilla ry denture bases were fabricated by different conditions of monomer content ,res in stage, polymerization temperature, mixing and cooling temperature conditions respectively. The gap between stone cast and acrylic resin base was measured wi th a stereoscopic microscope with a precision of 0.01 mm at five referential pos itions in each section. The data were submitted to t test. Resul ts: There was statistical significant difference ( P

Objective: To obtain the data of the surfaces of stand ar d posterior teeth crowns with an improved measurement system, so as to lay the f oundation for fabrication of dental prosthesis with computer aided design and la ser solid forming technology. Methods: Standard posterior teeth models were measured with a numerical controlled miller and a new data col lection system by cutting and scanning layer by layer, and the 3 dimension (3 D) shape of the models was reconstructed by image processing with a special soft ware. Results: Data of image profile and 3D shape of sixte en posterior teeth crowns were obtained. Precise configuration was acquired.Conclusion: Data of image profile can be easily and clearly ob tained by the improved measurement system with no measuring blind spot.

Objective: To develop a polyvinylidene fluoride (PVDF)-based instrument which may be used to measure bite force in natural teeth as well as in denture. Methods: The PVDF film was used as transducer. Electricity amplifier, lowpass filter, secondary magnifier in metrical circuit, and collection with disposal system were employed to produce the instrument for bite force measurement. The demarcating system was MTS-858. The instrument was used to measure the dynamic force in laterotrusion in 9 volunteers with Angle I occlusion. Results: The instrument was produced.By the used of the instrument the peak value of bite force (N) in the 9 subjects was 277.3?78.4 on the main functional side (MFS) and 258.7?83.3 on the subfunctional side (SFS).The time(ms) needed in the four phases on MFS was 65.6?7.3,354.4?66.1,116.3?25.0 and 226.9?35.8;that on SFS 67.5?6.6,394.4?65.3,141.9?25.6 and 167.5?41.9,respectively.Conclusion: The new system is steady and sensitive for bite force measurement.

Objective: To reconstruct 3D shape of upper edentulous jaw f or the design of a digital model of palatal metal plate of upper complete dentur e. Methods: Standard edentulous jaw models were measured with a numerical controlled miller and a new data collection system by cutting and sca nning layer-by-layer, the 3D shape of the models was reconstructed by image pr ocessing with special software. Based on these data, a palatal metal plate of u pper complete denture was designed by using SURFACER softerware.Results: Data of upper edentulous jaw models and a palatal metal plate of upper c omplete denture were obtained.The error between basal surface of the plate base and uper endentulous jaw was 0.0245 ?0.0267 mm. Conclusion:E dentulous jaw can be reconstructed by three-dimensional measurement, the design ed palatal metal plate of upper complete denture will be helpful to the further Laser Solid Forming.

Objective: To study the potential of growth and mineralization of cultured osteoblasts on the indium tin oxide conductive(ITO) glass disk coated with polypyrrole film (Ppy) . Methods: Osteoblasts were seeded onto ITO glass or ITO glass coated with polypyrrole film of implant materials. The cells were stained by HE and Von Kossa, observed by light microscope and scanning electron microscope (SEM) on day 3, 7, 14 and 28 after seeding respectively. Results: The osteoblast cells attached well to both ITO surfaces and Ppy films, mineralized nodules was observed on Ppy film. Conclusion: The polypyrrole films have good bone biocompatibility and it can be used as the biomaterials for dental implant.

Objective: To study the relationship between the patient satisfaction with complete denture and the pain perception threshold (PPT) of alveolar ridge mucosa. Methods: Forty-five edentulous patients with complete denture were investigated with the questionnaire of patient satisfaction, PPT of alveolar ridge mucosa in the patients was measured with a pressure algometer. Results: No difference was found in the PPT of alveolar ridge mucosa between the left and the right side. The PPT was found to be higher in maxillary site than in mandibular side(P

Objective:To investigate the microstructure and mechanical property of titanium parts made by laser solid forming technology. Methods: Titanium parts were made by laser solid forming technology; microstructure and elements were observed by SEM and spectrum analysis. The mechanical property of laser formed titanium and TA2 titanium were measured by Omnipotent testing machine. Results: The microstructure of titanium parts fabricated by laser rapid forming has columnar crystals with regular and epitaxial growth. The inner structure is dense and acicular structure distributed uniform at all field with width about 3-4 ?m; No obvious impurity elements were observed; the tensile-strength and yield strength of titanium parts is obviously superior to the standard of TA2. Conclusion: The microstructure of titanium parts made by laser solid forming can be obviously improved and mechanics performance was greatly improved. Those titanium parts may be used for dental restoration.

Objective: To study the masticatory muscles activity in the cases with severe tooth wear(TW) and the damaged display of masticatory muscles in different types of occlusal wear. Methods: The electromyography(EMG) of bilateral anterior temporalis(TA), masseter muscle(MM) and anterior digastric(DA) was taken in 15 elder patients aged 49～69 years old with TW, the EMG of the patients was compared with that of 8 healthy subjects aged 49～55 years old. Results: TW patients showed higher activity of TA,MM and DA in mandibular postural position than the controls (P