OBJECTIVETo explore the manufacture and clinical application of IPS-Empress casting ceramic restorations.

METHODSThe problems in manufacture and clinical operation of 215 casting ceramic restorations were analyzed.

RESULTSIn 215 casting ceramic restorations, 12 (5.58%) casting ceramic restorations were affected by clinical design or application, 15 (6.98%) casting ceramic restorations were affected by some manufacture problems, and 14 (6.51%) casting ceramic restorations were affected by clinical try-in. Through 2-3 years' follow-up, the achievement ratio of 215 IPS-Empress casting ceramic restorations was 94.88%, and 11 casting ceramic restorations were affected by some problems.

CONCLUSIONBeauty and simultaneous enamel wear are the characteristics of casting ceramic restorations. But because of its brittle, the indications should be strictly selected.

Aluminum Silicates ; Ceramics ; Dental Enamel ; Dental Porcelain ; Humans

OBJECTIVETo evaluate the clinical prosthetic effect of IPS-Empress 2 pressahie ceramic crowns.

METHODS198 teeth of 70 patients were restored with IPS-Empress 2 pressahie ceramic crowns. The patients were asked to return in one week and every half year. The clinical prosthetic effect was evaluated.

RESULTSThrough follow-up of 3-38 months, the veneer porcelain crowns of 3 teeth were broken. 2 crowns fall off due to teeth fracture, gingivitis occurred in 2 teeth, pulpitis or periapical periodontitis occurred in 3 teeth. The shades of 3 crowns were darkening. The prosthetic effect of 185 teeth was satisfied. The rate of satisfaction was 93.4%.

CONCLUSIONIPS-Empress 2 pressable all-ceramic crown has the advantages of aesthetic effect, good hiocompatihility and simple fabrication. But its strength is not enough for posterior teeth and it can not cover the deep color of non-vital teeth and metal materials.

Aluminum Silicates ; Ceramics ; Crowns ; Dental Porcelain ; Humans ; Lithium Compounds

The phase constitution, microstructure and properties of a new type of machinable glass-ceramics containing fluorophlogopite-type (FPT) Ca-mica for used in restorative dentistry were investigated. According to the results of X-ray diffraction (XRD) and energy-dispersive spectrometry(EDS), its main crystalline phases were FPT Ca-mica and t-ZrO2, together with few KxCa(1-x)/2Mg2Si4O10F2, m-ZrO2. The flexible strength was 235 MPa, which was nearly two times larger than that of the present mica-based dental materials, and the highest fracture toughness was 2.17 MPa.m1/2. The microstructure had a great effect on properties, the glass-ceramics contained a large volume, and the fine crystals showed higher strength. The material possessed typical microstructure of machinable glass-ceramics and displayed excellent machinability during drilling test and CAD/CAM.
Aluminum Silicates ; Biomechanical Phenomena ; Ceramics ; Dental Materials ; Hardness ; Materials Testing

In order to develop tinted infiltration glass and its colorants, which can make the ceramic have good spectrum transmittance, color space, color stability and be suitable for clinical use, we selected the best prescription and confirm the ingredient and content of the colorants. Molten glass was prepared in Al2O3 crucible by heating the components to 1420 degrees C for 2 hours. The refractive index and thermal stability of the glass were investigated. The refractive index of the MIC infiltration glass was 1.5969(587.6 nm, nd). It was close to the index of aluminous matrix 1.759(546.07 nm, ne), which increased the spectrum transmittance of MIC. The thermal expansion coefficient of the glass was 7.565 microns/m/degree C, which was compatible with the thermal expansion coefficient of aluminous matrix(8.214 microns/m/degree C). This study proved that the tinted infiltration glass has good color stability, spectrum transmittance, and thermal expansion properties.
Aluminum Silicates ; Coloring Agents ; Crystallization ; Dental Porcelain ; Elasticity ; Glass ; Hardness

OBJECTIVETo compare the difference in strength degradation and morphology damage of two dental ceramic materials after Hertzian contact cyclic fatigue.

METHODSHertzian contact technique was used to investigate the response of Empress II glass ceramic and GI- II glass-infiltrated alumina ceramic to cyclic fatigue. Critical loads of specimens after different fatigue cycles were recorded.

RESULTSFor Empress II glass ceramic, critical load had significantly difference between specimens after 10(5) cycles loading. No significant difference of critical load was found in GI- II glass-infiltrated alumina ceramic after cycles loading.

CONCLUSIONGI- II glass-infiltrated alumina ceramic has better capability in resistance to cyclic loading. It may attribute to microstructure of material. Empress II glass ceramic shows a brittle damage model.

Aluminum Oxide ; Aluminum Silicates ; Ceramics ; Dental Porcelain ; Glass ; Humans ; Materials Testing

OBJECTIVETo detect the self-assembly morphology of sodium hyaluronate injection on mica using atomic force microscopy(AFM).

METHODSAtomic force microscopy with nanometer resolution was used to observe the self-assembly morphology of different concentrations of sodium hyaluronate injection on mica at room temperature.

RESULTSThe self-assembly morphology of 0.001, 0.01, and 0.1 mg/ml sodium hyaluronate injection on mica featured piebald, reticular and dendritic structures, respectively. At 1 and 5 mg/ml, sodium hyaluronate injection displayed bacilliform and spherical structures on mica, respectively; the diameter and height of the particles of 5 mg/ml sodium hyaluronate was 197.97±78.48 nm and 30.79±18.67 nm, significantly greater than those of 0.1 mg/ml sodium hyaluronate injection (49.52±11.93 nm and 5.37±1.59 nm, respectively, P<0.05).

CONCLUSIONThe self-assembly morphology of sodium hyaluronate injection on mica varies with its concentration. The piebald and reticular structure may facilitate the function of sodium hyaluronate, and the dendritic feature resembles the representative model of diffusion-limited aggregation (DLA).

Aluminum Silicates ; chemistry ; Hyaluronic Acid ; administration & dosage ; chemical synthesis ; chemistry ; Microscopy, Atomic Force ; Nanostructures ; Surface Properties

BACKGROUND/AIMS: Three-dimensional (3D) imaging is gaining popularity and has been partly adopted in laparoscopic surgery or robotic surgery but has not been applied to gastrointestinal endoscopy. As a first step, we conducted an experiment to evaluate whether images obtained by conventional gastrointestinal endoscopy could be used to acquire quantitative 3D information. METHODS: Two endoscopes (GIF-H260) were used in a Borrmann type I tumor model made of clay. The endoscopes were calibrated by correcting the barrel distortion and perspective distortion. Obtained images were converted to gray-level image, and the characteristics of the images were obtained by edge detection. Finally, data on 3D parameters were measured by using epipolar geometry, two view geometry, and pinhole camera model. RESULTS: The focal length (f) of endoscope at 30 mm was 258.49 pixels. Two endoscopes were fixed at predetermined distance, 12 mm (d12). After matching and calculating disparity (v2-v1), which was 106 pixels, the calculated length between the camera and object (L) was 29.26 mm. The height of the object projected onto the image (h) was then applied to the pinhole camera model, and the result of H (height and width) was 38.21 mm and 41.72 mm, respectively. Measurements were conducted from 2 different locations. The measurement errors ranged from 2.98% to 7.00% with the current Borrmann type I tumor model. CONCLUSIONS: It was feasible to obtain parameters necessary for 3D analysis and to apply the data to epipolar geometry with conventional gastrointestinal endoscope to calculate the size of an object.
Aluminum Silicates ; Endoscopes ; Endoscopes, Gastrointestinal ; Endoscopy, Gastrointestinal ; Laparoscopy ; Pilot Projects ; Resin Cements

OBJECTIVETo explore the thermal treatment schedule of leucite microcrystallization to reinforce dental glass ceramics.

METHODSAfter component analysis and selection, the raw material were treated by different temperature schedules. The products were analyzed by polaring microscope and X-ray diffractometer to determine the appropriate thermal treatment schedule.

RESULTSThe temperature of melting, nuclearing and crystalizing was 1,600 degrees C, 1,200 degrees C and 1,500 degrees C. Leucite microcrystals dispersed in the glass matrix evenly and the size of leucite particle was about 0.8 micro m.

CONCLUSIONLeucite can be microcrystalized according to an appropriate thermal treatment schedule.

Aluminum Silicates ; chemistry ; Crystallization ; Dental Porcelain ; chemistry ; Glass ; chemistry ; Hot Temperature

OBJECTIVEAn intrinsically colored machinable glass-ceramic containing tetrasilicic fluormica as the predominant crystal phase was studied, which was used in molar crown in dental CAD/CAM system.

METHODSOrthogonal design analysis was used to select appropriate base formula, coloration and heat treatment process.

RESULTSFactors influencing the color appearance of mica glass ceramic were nucleation agent and the ratio of Mg(2+) to K(+) in base formula; Cerium oxide (CeO(2)) was used as the main coloration; The preferred heat treatment was 650 degrees C for 1 h and 1,000 degrees C or 1,050 degrees C for 3 h - 4 h.

CONCLUSIONSThis mica glass-ceramic could provide 4 to 5 color appearance for dental use, it showed excellent machinability which was eminently suitable for use in dental CAD/CAM system.

Aluminum Silicates ; chemistry ; Color ; Computer-Aided Design ; Crowns ; Dental Porcelain ; chemistry ; Glass ; chemistry ; Molar

Since its introduction in 1993, Mineral Trioxide Aggregate (MTA) has been shown to be superior to others in sealing, biocompatibility, and many other aspects of clinical endodontics. MTA is primarily Portland cement with bismuth oxide as a radiopacitifier. Although some studies suggested that the reasonable-priced Portland cement could be used instead of MTA, but MTAs are different from Portland cement in its composition, especially in heavy metal contents. Therefore, clinicians should be meticulous adapting the Portland cement as a MTA substitute.
Aluminum Compounds ; Bismuth ; Calcium Compounds ; Drug Combinations ; Endodontics ; Glutamates ; Guanine ; Oxides ; Silicates ; Pemetrexed