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 observe the consistence of the color and optical parameters of metal-ceramic, all-ceramic and composite resin with Vita Classical shade guides. Methods:Specimens of VITA VMK95 metal-ceramic, In-Ceram all-ceramic and Artglass composite resin according to the same area with Vita Classical shade guide were made respectively. ?E_ ab ,L,a,b between specimens and shade guide were calculated. Results:The mean ?E between shade guide and all-ceramic or composite resin was less than 3 NBS. The mean ?E between shade guide and metal-ceramic material was 13.78 NBS, the significant difference could be identified by visual determination (P

AIM: The relationship between muscle force (MF) and bone mass (BM)has become one of the pivotal aspects in research of cause, prevention and treatment of primary osteoporosis. This paper is to probe into the mechanism by which estrogen influences the relationship between MF and BM.METHODS: We searched for the relative papers on the relationship between muscle force and bone mass and the effect of estrogen on relationship between muscle force and bone mass. Combining the literatures with our previous results, we discussed the effects of estrogen on relationship between muscle force and bone mass.RESULTS: Muscle force, which determines bone structure and bone mass,makes bone strength adaptable to work load. Estrogen adjustes adaptability of muscle force and bone mass, mainly by the influence on threshold of bone strain. Estrogen therapy could maintain muscle force, partially by which estrogen exerts the beneficial effects on bone.CONCLUSION: Estrogen could influence the relationship between muscle force and bone mass, and estrogen therapy could have the beneficial effect on muscle force.

Objective: To detect whether the metal base of the metal-fused-to-ceramic restoration have the same color performance and can be tested as natural teeth, and to evaluate whether they have effect on the color value determination by means of the photoelectrometer. Methods:Two kinds of shade guides of metal ceramic restoration were measured by photoelectric colorimeter, and color difference are analyzed compared with natural teeth of the same color. Results:The empfindung (color difference) of the shade guides with or without metal base and natural teeth is significantly different (P

BACKGROUND: Reverse engineering modeling has been widely used in previous studies. However, there are a few studies on implantation modeling, especially in aspects of mandibular molar implantation. The mandibular molar has high miss rate in dentition. Thus, to establish three-dimensional finite element models of a jaw bones with mandibular molar implant denture using reverse engineering shows a great parameter value for research of mandibular molar implantation repair. OBJECTIVE: To establish a three-dimensional finite element model of a mandibular molar with dental implant inserted in mandibular molar area using reverse engineering, and to provide mathematical model basis for biomechanics researches of stomatology.METHODS: Establish three-dimensional model, divide mesh and calculate by Solidworks 2007 through scanning mandible by screw jaw using helix CT, obtaining data from images, separating data, rebuilding three-dimension using Mimics software,optimizing the design of mesh by Magics software, and dealing with solid model by Pro/E preprocessor.RESULTS AND CONCLUSION: A three-dimensional finite element model of mandibular first molar implant with regular depth was established, which has high geometrical similarity, good properties of mechanics and mesh, and can be easily modified. This can provide excellent model support for studying the stress analysis of different designs on restoring mandibular first molar implant.

Objective To analyze the clinical features of patients with cholelithiasis treated in our hospital in the recent 10 years to explore the changing tendency of the spectrum of cholelithiasis in the Jiaodong region. Methods The clinical data of 2899 patients receiving operation for cholelithiasis in this hospital between January 1998 and January 2008 were retrospectively analyzed. The clinical parameters of sex, age and the lesion sites were reviewed. Compared with the clinical data of cholelithiasis patients in 1991, the data of the 2899 patients were statistically analyzed by SPSS 12.0 package.Results Significant differences existed in sex, e peak morbidity, and lesion sites. The ratio of male patients and female patients with cholelithiasis in differents site had obvious diversity. The constituent ratio of the female was manifestly higher than that of the male. The peak morbidity age range of cholecystolithiasis was 40 to 69. The peak age of gallbladder stones combined with common bile duct stones was 70 to 79, which was the same as that of common bile duct stones. The peak age of intrahepatic bile duct stones was 40 to 59. The constituent ratio of cholecystolithiasis was obviously higher than cholelithiasis in other sites. The incidence of cholecystolithiasis increased with age. Conclusion In the recent 10 years, female's ratio of gallbladder stones and intrahepatic stones was higher than male's.The morbidity of cholelithiasis significantly increased in aged patients. The spectrum of cholelithiasis has changed significantly.

OBJECTIVETo investigate the effect of different length and diameters on the stability of mini implant and to select optimal length and diameter using continuous variation of parameters.

METHODSTo perform 3-dimensional finite element analysis, finite element models of a maxilla, and mini implants with length of 6-12 mm and diameters of 1.2-2.0 mm were generated. Load of two different forces were applied to the head of mini implant. One type was horizontal force (HF), the other was composite force (CF). The maximum equivalent stress (Max EQV) in maxilla and the maximum displacement (Max DM) of mini implant were evaluated.

RESULTSThe Max EQV in maxilla and Max DM of mini implant decreased as length and diameter increased. When length was more than 9 mm, the evaluation indexes were small and had a less change. Datas indicated that diameter played a more important role in reducing target, and was a more effective parameter in reducing Max EQV when CF was loaded.

CONCLUSIONFrom biomechanical point of view, the choice of the length should not be more than 9 mm. When CF is loaded using the mini implant, diameter exceeding 1.2 mm are optimal design for mini implant.

he activity of MMP-2 and MMP-9 via ERK1/2 signaling pathway.

Objective To investigate the effect of locking plate combined with cortical screw internal fixation on ankle function and quality of life in patients with ankle fracture with tibiofibular separation.Methods A total of 120 patients with ankle fracture and distal tibiofibular separation treated in our hospital from May 2020 to December 2021 were selected and divided into control group and observation group according to random number table method,with 60 patients/group.The control group was treated with cortical screw fixation alone,and the observation group was treated with locking plate combined with cortical screw internal fixation.Before surgery and 6 months after surgery,the recovery function of the two groups was compared.X-ray,operation duration,healing time,intraoperative blood loss,postoperative complications were compared,and the living ability of the two groups of patients was evaluated.Results Before treatment,there was no difference in joint function between the two groups(P＞0.05).After treatment,the longest walking of the control group(15.89±0.85),foot alignment(15.06±0.71),pain response(29.03±4.48)and ground walking(15.65±0.59).The longest walking distance(16.19±0.87),foot alignment(15.29±0.76),pain response(31.24±4.55)and ground walking(15.96±0.68)in the observation group,which were higher than those in control group(P＜0.05).Compared with the control group,the intraoperative blood loss and healing time in the observation group were lower(P＜0.05).BI index of the two groups before treatment had no difference(P＞0.05);After treatment,BI index of observation group was higher than that of control group(P＜0.05).There was no difference in the total complication rate between the two groups(P＞0.05).Conclusion Locking plate combined with cortical screw internal fixation has a good therapeutic effect on improving ankle function,reducing intraoperative blood loss,promoting healing and improving behavioral ability in the treatment of ankle fracture combined with hypotibiofibular syndesmosis injury.