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 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.

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.

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.

Mineral trioxide aggregate (MTA), which was originally developed for repair of root perforations, is a biocompatible material with numerous clinical applications in endodontics. MTA must be allowed to set in the presence of moisture to optimize the material's physical and chemical properties. In the clinic, occasionally unset MTA has been detected after application of MTA on the tooth, and the reason has been unclear. This case report presents MTA washed-out for several years after placement at the root apex as an apical plug, and discusses the reason and things to consider in clinics.
Aluminum Compounds ; Calcium Compounds ; Drug Combinations ; Endodontics ; Glutamates ; Guanine ; Oxides ; Silicates ; Tooth ; Pemetrexed

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

OBJECTIVES: This study was performed to evaluate the effect of blood contamination on the compressive strength (CS) of Root MTA (RMTA) modified with Calcium chloride (CaCl2) and Disodium hydrogen phosphate (Na2HPO4) as setting accelerators over time. MATERIALS AND METHODS: A total of 110 cylindrical specimens of RMTA were divided into 6 experimental groups as follows: Group1, RMTA; Group 2, RMTA modified with CaCl2 (RMTA-C); Group 3, RMTA modified with Na2HPO4 (RMTA-N); Group 4, RMTA contaminated with blood; Group 5, RMTA-C contaminated with blood; Group 6, RMTA-N contaminated with blood. The CS of specimens in all groups was evaluated after 3 hr, 24 hr, and 1 wk. In the modified groups (groups 2, 3, 5, and 6) the CS of five specimens per group was also evaluated after 1 hr. RESULTS: Blood contamination significantly reduced the CS of all materials at all time intervals (p < 0.05). After 3 hr, the CS of specimens in the RMTA groups (with and without blood contamination) was significantly lower than those in the RMTA-C and RMTA-N groups (p < 0.05). The CS values were not significantly different at the other time intervals. In all groups, the CS of specimens significantly increased over time (p < 0.05). CONCLUSIONS: Blood contamination decreased the CS of both original and accelerated RMTA.
Aluminum Compounds ; Calcium Chloride ; Calcium Compounds ; Compressive Strength ; Drug Combinations ; Glutamates ; Guanine ; Hydrogen ; Oxides ; Silicates ; Pemetrexed

Three types of new high-efficiency phosphate fertilizers were made when pillared clays at certain proportions were added into ground phosphate rock. Chemical analyses showed that their soluble phosphorus content decreased more than that of superphosphate. Pot experiment showed that, under equal weights, the new fertilizers increased their efficiency by a large margin over that of superphosphate. Researches on their structures by means of XRD, IR and EPR spectrum revealed that their crystal structures changed considerably, improving their activity and preventing the fixation of available phosphorus in the soil, and consequently, greatly improved the bioavailability and became the main cause of the increase of biomass.
Aluminum Silicates ; analysis ; chemistry ; Fertilizers ; analysis ; Molecular Conformation ; Phosphates ; analysis ; chemistry ; Soil ; analysis

OBJECTIVETo study the strengthening of fluorophlogopite-based dental machinable ceramic through developing a new type of calcium-mica-based ceramic.

METHODSBased on the analysis of the crystal structure of the fluorophlogopite ceramic of Dicor MGC, the structure of a new type of calcium-mica-based ceramic was designed and the corresponding composition of the new material was experimented. And the new glass-ceramic was obtained through the treatment of glass preparation and nucleation. Then crystal content of the glass ceramic was analyzed by X-ray diffraction analysis (XRD) and the 3-point bending strength of the new ceramic was recorded.

RESULTSA new type of calcium-mica-based glass ceramic was developed and had the 3-point bending strength of (210.2 +/- 14.7) MPa. Compared with the strength of fluorophlogopite-based dental machinable ceramic, such as Dicor MGC, which was reported in the range of 150 approximately 180 MPa within inclusive studies, the higher strength of the new ceramic was recorded.

CONCLUSIONSThe fluorophlogopite-based dental machinable ceramic could be reinforced through internal strengthening.