China ; Dental Prosthesis ; Humans ; Tooth Loss ; surgery

OBJECTIVETo prepare zirconia toughened nano-composite alumina ceramic powder for dental application. Physical and chemical property of the prepared material were tested, and the effect of development technology on composite powder was also studied in this study.

METHODSNano-composite alumina powder was prepared by surface-induced precipitation method. The effect of pH value and dispersing agent content on volume of alumina suspension sediment was recorded. The effect of ultrasonic time on agglomeration was measured also. X ray diffraction (XRD) was used to analyze powder phase before and after the stabilizer was added. Scanning electronic microscope (SEM) was applied for characterizing the specimen.

RESULTSThe dispersion was better at pH=9 and wt (dispersing agent) = 0.2% approximately 0.3%. Selecting proper ultrasonic time can decrease the agglomeration of powders and lower the average particle size. XRD analysis indicated that the phase composition of the prepared nano-composite ceramic powder was shown as alpha-Al2O3, t-ZrO2 and a small amount of m-ZrO2 after the addition of stabilizer. Through SEM observation, nanometer-sized ZrO2 particles (80 approximately 100 nm) were uniformly located on the surface of submicrometer alumina grains.

CONCLUSIONSBy choosing appropriate preparation method, weakly agglomerated powders with fine particle size can be obtained. The zirconia part of nano-composite powder was transmitted to partially stabled zirconia after the use of stabilizer.

Aluminum Oxide ; chemistry ; Dental Porcelain ; chemistry ; Hydrogen-Ion Concentration ; Powders ; Zirconium ; chemistry

OBJECTIVETo study the influence of manufacture technique on the translucency and color of dental porcelain.

METHODSSpecimens were made of VITA VMK 95 dentin porcelain and enamel porcelain and divided into 3 groups: Sintering times group (1, 2, 4, 6, 8 and 10 times), sintering temperature group (910, 920, 930, 940 and 950 degrees C), sintering vacuum group (95, 65, 35 and 0 kPa). Transmittance, Y, dominant wavelength and saturation were measured by PR-650 spectra scan spectrocolorimeter.

RESULTSTransmittance of dentin porcelain increased after 6 times repeated sintering. Transmittance of enamel porcelain increased first after the second sintering, and then became decreasing when sintering more than 2 times. Transmittance of enamel porcelain deceased when sintering temperature was lower than standard. Decrease of sintering vacuum caused the transmittance of dentin and enamel porcelain decreased. The changing of value was coordinated with transmittance. Dominant wavelength and saturation had negative correlation with sintering times and temperature, and positive correlation with vacuum.

CONCLUSIONSintering times, temperature and vacuum all had prominent effects on the translucency and color of dental porcelain. Comparing with dentin porcelain, enamel porcelain was more sensitive with the modification of manufacture technique.

Color ; Dental Alloys ; Dental Enamel ; Dental Porcelain ; Dentin ; Humans ; Temperature

OBJECTIVETo study the distribution of the chromatic value of gingival porcelains.

METHODSThe color change of Shofu VINTAGE and Vita VMK95 gingival porcelains on the black and white backings was determined with a spectrophotometer (PR-650).

RESULTSThe results showed that the chromatic value of gingival porcelains was different on varying backings. The color space of gingival porcelain was L*: 41.85 - 50.64, a*: 12.46 - 19.46, b*: 1.33 - 4.62.

CONCLUSIONThe chromatic value distribution cannot cover the color region of natural gingiva.

Color ; Dental Porcelain ; Gingiva ; Spectrophotometry

OBJECTIVEThe purpose of this study was to evaluate the color changes of gingival porcelain through varying thickness and shade of porcelain of ceramometal restorations.

METHODSIn this study a spectrophotometer (PR-650) was used for color analysis. The color changes of dentin porcelain and gingival porcelain with three varied thickness (0.3 mm, 0.6 mm and 0.9 mm) were investigated. In addition, the color variances of Shofu vintage porcelain shade A2, A3 and B2 were tested.

RESULTSThe results showed that decreased L * value of ceramometal restorations and increased a * value were due to the increase of the gingival porcelain thickness, color measurements showed the same trend as the increased dentin porcelain thickness and the opaque and dentin porcelain with different color affected the appearance of gingival porcelain.

CONCLUSIONThe color of gingival porcelain would be changed with the differences of thickness and shade of porcelain of ceramometal restorations.

Color ; Dental Porcelain ; Humans ; Prosthesis Coloring ; Spectrophotometry

OBJECTIVETo evaluate the effects of GLUMA desensitizing bonding system in desensitizing hypersensitivity of vital abutment.

METHODS69 central incisors with vital pulp from 69 patients were randomly divided into A, B and C group. After tooth preparation, group A coated with primer after etching, group B coated with primer after etching cervical dentin only, and group C was control group without special treatment. The cold sensitivity of abutments was tested after coating with primer, after cementation of crown and three months later. Two fresh extracted caries and restoration-free middle incisor were prepared in routine way. The surface of specimen 1 was etched with conditioner and the control specimen 2 was prepared without any special surface treatment. Scanning electron microscope (SEM) observation was used to examine the details on dentin surface.

RESULTSIn all three times of examination, the sensitivities of two experimental groups had been significantly reduced compared with the control group. Immediately after coating, group B were more sensitive than group A (P < 0.05). After cementation of crown and three months later, there was no statistically significant between group A and group B. SEM photomicrograph showed that the smear layer was removed from etched dentine surface with open dentinal tubules.

CONCLUSIONCoating with GLUMA desensitizing bonding system could prevent hypersensitivity of vital abutment.

Acid Etching, Dental ; Cementation ; Dental Pulp ; Dentin ; Dentin Sensitivity ; prevention & control ; Dentin-Bonding Agents ; Glutaral ; Humans ; Methacrylates ; Microscopy, Electron, Scanning ; Smear Layer

OBJECTIVETo investigate the effect of two different ring liner thickness on the deformation of resulted castings.

METHODSGC No.2 casting rings (50 mm in height and 39.5 mm in diameter) were lined with two dry ceramic fiber liners with thickness of 0.70 mm and 0.45 mm. Plate-like wax patterns with pre-marked points were invested with a gypsum-bonded investment and the rings were cast with a silver-based dental alloy. The difference between the castings and the wax patterns at corresponding points was calculated to represent the dimensional change of the investment in the rings at different directions.

RESULTSThe expansion of the investment in the ring was non-isotropic, with larger radial direction expansion than the axial direction expansion (P < 0.01). In the scope of this study, the effect of two different ring liner thickness on the casting precision was statistically non-significant (P > 0.05).

CONCLUSIONThe liners with two different thickness failed to eliminate non-isotropic deformation of the castings under the testing conditions of this study.

Calcium Sulfate ; Ceramics ; Crowns ; Dental Casting Investment ; Dental Casting Technique ; Humans ; Prostheses and Implants

OBJECTIVEAfter sinboneHT bone replacement (SBR) was implanted in animals, to evaluate the biocompatibility of SBR and compounded in autogenetic bone in the proportion of one to one in order to prepare for the clinical applications in the future.

METHODSBone defects of 10 mm x l0 mm x 2 mm was made at the mandibular of rabbits, then SBR with different granule diameter and autogenetic bone was compounded in the proportion of being applied in the left defects, while autogenetic bone was implanted in the right defects and nothing was used in the right reformed defects. Animals were sacrificed at 2, 4 and 8 weeks respectively. The biologic capacity was evaluated with anatomy, X-rays studies and histology.

RESULTSSBR has better biocompatibility, which can effectively accelerate the reconstruction of bone defects and help the new bone by being compounded with autogenetic bone. It provides the appropriate scaffold or template which would allow cellular infiltration, attachment and multiplication.

CONCLUSIONSBR is a kind of bone substitute material with good biocompatibility. SBR compounded with self-bone has a better regeneration function.

Animals ; Bone Regeneration ; Bone Substitutes ; Mandible ; Rabbits ; Reconstructive Surgical Procedures

OBJECTIVETo 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.

METHODSBefore 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.

RESULTSThe 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).

CONCLUSIONThe plasma magnetron reactive sputter deposition technique has a positive effect in improving the bonding strength of DA9-4 dental alloy and ceramic.

Ceramics ; Chromium Alloys ; Dental Alloys ; Dental Bonding ; Dental Porcelain ; Humans ; Materials Testing ; Metal Ceramic Alloys ; Surface Properties ; Vacuum

OBJECTIVETo investigate the effects of the static magnetic field (SMF) generated by dental magnetic attachments on osteoblastic proliferations, cell cycle distribution, and apoptosis ratio.

METHODSBy 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.

RESULTSThe 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.

CONCLUSIONNo 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.

Animals ; Apoptosis ; Cell Cycle ; Cell Proliferation ; Electromagnetic Fields ; Magnetic Fields ; Magnetic Phenomena ; Magnetics ; Osteoblasts ; Rats