OBJECTIVEThis study aims to evaluate the optical data of the different sites of the cobalt-chrome (Co-Cr) alloy abutments covered by four different all-ceramic crowns and the color difference between the crowns and target tab using a digital dental spectrophotometer.

METHODSTen Co-Cr alloy abutments were made and tried in four different groups of all-ceramic crowns, namely, Procera aluminia, Procera zirconia, Lava zirconia (Lava-Zir), and IPS E.max glass-ceramic lithium disilicate-reinforced monolithic. The color data of the cervical, body, and incisal sites of the samples were recorded and analyzed by dental spectrophotometer. The CIE L*, a*, b* values were again measured after veneering. The color difference between the abutments covered by all-ceramic crowns and A2 dentine shade tab was evaluated.

RESULTSThe L* and b* values of the abutments can be increased by all of the four groups of all-ceramic copings, but a* values were decreased in most groups. A statistical difference was observed among four groups. After being veneered, the L* values of all the copings declined slightly, and the values of a*, b* increased significantly. When compared with A2 dentine shade tab, the ΔE of the crowns was below 4.

CONCLUSIONFour ceramic copings were demonstrated to promote the lightness and hue of the alloy abutments effecttively. Though the colorimetric baseline of these copings was uneven, veneer porcelain can efficiently decrease the color difference between the samples and thee target.

Ceramics ; Chromium Alloys ; Cobalt ; Color ; Colorimetry ; Crowns ; Dental Materials ; Dental Porcelain ; Dental Prosthesis Design ; Humans ; Metal Ceramic Alloys ; Titanium ; Zirconium

ObjectiveThis?study?aims?to?evaluate?the?optical?data?of?the?different?sites?of?the?cobalt-chrome?(Co-Cr)?alloy?abutments?covered?by?four?different?all-ceramic?crowns?and?the?color?difference?between?the?crowns?and?target?tab?using?a?digital?dental?spectrophotometer.?Methods???Ten?Co-Cr?alloy?abutments?were?made?and?tried?in?four?different?groups?of?all-ceramic?crowns,?namely,?Procera?aluminia,?Procera?zirconia,?Lava?zirconia?(Lava-Zir),?and?IPS?E.max?glass-ceramic?lithium?disilicate-reinforced?monolithic.?The?color?data?of?the?cervical,?body,?and?incisal?sites?of?the?samples?were?recorded?and?analyzed?by?dental?spectrophotometer.?The?CIE?L*,?a*,?b*?values?were?again?measured?after?veneering.?The?color?difference?between?the?abutments?covered?by?all-ceramic?crowns?and?A2?dentine?shade?tab?was?evaluated.?Results???The?L*?and?b*?values?of?the?abut-ments?can?be?increased?by?all?of?the?four?groups?of?all-ceramic?copings,?but?a*?values?were?decreased?in?most?groups.?A?statistical?difference?was?observed?among?four?groups.?After?being?veneered,?the?L*?values?of?all?the?copings?declined?slightly,?and?the?values of a*, b* increased significantly. When compared with A2 dentine shade tab, the ΔΕ of the crowns was below 4. Conclusion???Four?ceramic?copings?were?demonstrated?to?promote?the?lightness?and?hue?of?the?alloy?abutments?effec-tively.?Though?the?colorimetric?baseline?of?these?copings?was?uneven,?veneer?porcelain?can?efficiently?decrease?the?color?difference?between?the?samples?and?thee?target.

Objective To investigate the differences and harmonization of immunoassay systems in detecting CA19-9 and to assess the possibility of mutual recognition in different laboratories.Methods Data were collected and analyzed from External Quality Assessments (EQA) of NCCL(Lots:200811-201215) and ZJCCL(Lots:080309-120211).120 fresh serum with different concentrations of CA19-9 were collected.The CA19-9 results of healthy people were also collected from September 2010 to March 2012.Four kinds of stable immunoassay systems were involved in our research,including Abbott Architect i2000,Beckman UniCel DxI 800,Roche E170 and Siemens ADVIA Centaur XP.The differences among four system groups were calculated with the EQA data.The fresh serum comparisons were also performed following the guideline of CLSI EP9-A2 The 95％ confidence interval of each immunoassay system was calculated.Comparisons were made by scatter diagrams and weighted regression.Results Both EQA of NCCL and ZJCCL showed better correlation coefficients and larger bias (bw ranged from 1.340 to 4.683) than in fresh serum comparisons.Although the correlation coefficients were all unsatisfactory,the bw were all close to 1 in fresh serum comparisons.When the recommended serum concentration of 27 U/ml was used,the biases were Abbott-Roche-6.41％,Beckman-Roche-5.07％,Siemens-Roche 13.15％,Beckman-Abbott 2.46％,Siemens-Abbott 22.52％ and Siemens-Beckman 39.66％,respectively.Differences of 95％ confidence intervals were statistically significant among parts of the immunoassay systems.Conclusions Only in the lower concentration can CA19-9 results be mutual recognized among four different immunoassay systems,there will be larger differences and risks in the higher concentration.

Objective: To evaluate the effect of pure titanium modified by bioadhesive RGD peptide on the early attachment, growth and proliferation of osteoblasts. Methods: The titanium samples were hydroxylated by alkali/hot water aging and sol-gel layer-by-layer deposition technique. Afterwards, the terminal -NH_2 group was introduced to the titanium surface by organosilane APTMS self-assembled monolayers and the functional group -NH_2 was further reacted with EDC/NHS by which RGD peptides was covalently immobilized to titanium. The efficiency of this bioreactive surface in promoting cell attachment and the competitive inhibition effect of RGD peptide with different concentrations were observed by calculating the amount of osteoblasts attached on the modified titanium. The growth and proliferation were observed by MTT method and scanning electronic microscopy. Results: The cell adhesion percentage of the RGD modified titanium group was much higher than that of the other groups. The RGD peptide solutions with higher concentration had stronger inhibitory impact on the cell adhesion onto the titanium surface. The cell growth, morphology and proliferation on the RGD peptide modified titanium were better than other groups. Conclusion: Bioadhesive peptide can be chemically grafted onto the titanium surface by means of self-assembled monolayers technique. The cells′ biological behaviors on the surface of RGD immobilized titanium are greatly improved in vitro.

Magnetic attachments have flux leakages, thus they will exert certain magnetic fields on the adjacent tissues when used in the patients' oral cavities. There are few research reports on the biological effects of the magnetic fields generated by magnetic attachments on human body. A cellular static magnetic field (SMF) loading system was developed in this study. By using this system, in vitro cultured human periodontal ligament cells (HPDLCs) were loaded with SMF simulating those of magnetic attachments. The cellular SMF loading system could produce constant SMF and the strength of the SMF is adjustable. The system is small and is able to exert SMF to cells cultured in different culture vessels such as culture dishes and culture plates, thus is suitable to researches in multiple biological items of cells. The results of the SMF loading experiment on HPDLCs showed that this cellular SMF loading system could effectively load cells with SMF of different strengths for different time in vitro. The development of this system has provided a useful tool for the researches on the cellular hiologioal effects of SMF.
Cells, Cultured ; Electromagnetic Fields ; adverse effects ; Humans ; Magnetics ; Periodontal Ligament ; cytology ; metabolism ; radiation effects

OBJECTIVETo evaluate the in vivo retentive forces of mandibular complete overdenture with Magfit attachments, as well as the relation between the location of magnetic attachments and the retentive forces of the denture.

METHODS5 patients were selected and treated with mandibular complete overdentures retained by Magfit EX600 and MD800 attachments. A strainometer was used to measure the retentive forces in anterior, central and posterior parts of the overdenture before and after magnets were set. The vertical and anterior-upper 60 degrees retentive forces of the overdenture were measured one month later.

RESULTSThe retentive forces of the overdentures after setting magnets were significantly greater than that before magnets were set (P < 0.05). There was no significant difference in retentive forces between the different parts (P > 0.05). The retentive force in vertical direction was greater than that in anterior-upper 60 degrees direction (P < 0.025).

CONCLUSIONMagnetic attachments can significantly improve the retention of mandibular complete overdenture. The location of magnetic attachments greatly influences the retentive force of the overdenture.

Aged ; Aged, 80 and over ; Dental Prosthesis Design ; methods ; Dental Prosthesis Retention ; instrumentation ; Dental Stress Analysis ; Denture Precision Attachment ; Denture, Complete, Lower ; Denture, Overlay ; Electromagnetic Fields ; Female ; Humans ; Magnetics ; instrumentation ; Male ; Materials Testing ; Stress, Mechanical

OBJECTIVEStandards for determining mandibular position, especially the centric relation (CR), are in controversy because of anatomical, neurophysiological factors and research methods or instrument. The purpose of this study was to reevaluate the reproducibility of centric relation of the patients with severe dental attrition for oral rehabilitation.

METHODSReproducibility of the centric relation of 6 patients with severe occlusal attrition was investigated by using D5A Denar fully adjustable articulator and the Pantronic recording system.

RESULTS1. In supine position, anterior-posterior(AP) displacement of centric relation (CR) was 0.14 mm and superior-inferior(SI) displacements of CR were between 0.11 mm-0.12 mm. 2. In upright position, anterior-posterior displacement of CR was 0.35 mm and superior-inferior changes of CR were between 0.13 mm-0.20 mm.

CONCLUSIONThe CR is the most stable and reproducible position of mandibule in normal stomatological system and is useful as a reference position in occlusal treatment and functional rehabilitation.

Aged ; Centric Relation ; Dental Occlusion, Centric ; Female ; Humans ; Jaw Relation Record ; instrumentation ; Male ; Mandibular Condyle ; physiopathology ; Middle Aged ; Movement ; Reproducibility of Results ; Tooth Attrition ; rehabilitation ; therapy

OBJECTIVEThe purposes of this study were to determine the spectral transmittance of GI-II glass/alumina composites and to explore the effects of different specimen thickness and fining arts of glass infiltration on the transmittance. Data were compared with those of Vita In-Ceram Alumina materials.

METHODSPlate-shaped specimens 12.5 mm in diameter, with 3 thickness (0.5, 1.0, 1.5 mm), 6 color groups for GI-II and 4 color groups for Vita In-Ceram Alumina were fabricated. Specimens of color AL2 for In-Ceram and IG2 for GI-II were selected in the study of relationship between different infiltration arts and transmittance. Five infiltration time duration and three temperatures were studied. A spectrophotometer with standard A light source paralleled light beam 5 mm in diameter and spectra range 380-780 nm was employed to measure the spectral transmittance.

RESULTSThe range of spectral transmittance were 2.7%-4.5% for GI-II and 2.4%-5.2% for Vita In-Ceram Alumina. Transmittance decreased with specimen thickness, but they were not linearly related. Transmittance of GI-II tended to increase and that of Vita In-Ceram Alumina decreased as the infiltration temperature elevated. The transmittance increased with infiltration time less than 4 hours and reduced with prolonged time over 6 hours for both materials.

CONCLUSIONGI-II glass/alumina composite has comparatively lower translucency. Influences of factors as color, thickness and infiltration arts on translucency of restorations should be considered in the clinical selection of the all-ceramic materials.

Aluminum Oxide ; chemistry ; Ceramics ; chemistry ; Dental Materials ; Dental Porcelain ; chemistry ; Glass ; chemistry ; Light ; Spectrophotometry ; Temperature ; Tensile Strength ; Transition Temperature

OBJECTIVEThe purpose of this study was to determine the thermal, mechanical properties and density of the composite infiltrated with GI-II tinted infiltration glass.

METHODSThe bar-shaped aluminum oxide and glass/alumina composite specimens with the size of 20 mm x 5 mm x 5 mm were prepared, with two free-end surfaces perpendicular to the long axis of the specimens and parallel to each other. The thermal expansion curves were obtained on a TMA2940 thermal analyzer with heating rate of 5 degrees C/min and temperature range of 25 degrees C to 1000 degrees C. The bar-shaped specimens with the size of 25 mm x 5 mm x 2 mm were fabricated and employed to test the density using Archmede's method. The flexural strength, elastic modulus were measured by means of 3-point bending test with the same specimens. The fractured specimens were indented with Vicker's diamond pyramid under load of 49 N for 15 seconds to determine the hardness and indentation fracture toughness.

RESULTSThe thermal expansion coefficient of the glass/alumina composite was 7.620 x 10(-6) degrees C-1 (25-500 degrees C), which was higher than that of Vitadur alpha veneering porcelain. The 3-poit flexural strength, elastic modulus, Vicker's hardness, indentation fracture toughness and density were 389.6 MPa, 92 GPa, 9.409 GPa, 3.2425 MNm-3/2 and 3.662 g/cm3 respectively.

CONCLUSIONThe thermal expansion of the GI-II glass/alumina composite is compatible with that of Vitadur alpha veneering porcelain, and the material could meet the strength demands for clinical use.

Aluminum Oxide ; chemistry ; Ceramics ; Dental Materials ; Dental Porcelain ; chemistry ; Glass ; chemistry ; Tensile Strength ; Transition Temperature

OBJECTIVEThis investigation was to analyze the mechanism of formation of porous structure by studying some characteristics of the alumina powder used for GI-II Infiltrate Ceramic.

METHODSThe alumina powder crystal type was analyzed with X-diffractometer, and its size distribution was obtained by powder size analysis device, and fracture surface of alumina adobe was observed under scanning electronic microscope.

RESULTSAlumina crystals were purely alpha type, with firmest structure and best stability. Fine powder whose size was smaller than 0.5 micron occupied 9 wt% (mass) and, coarse powder with sizes between 1 to 3.5 microns occupied 75 wt% (mass). The SEM graphs of adobe showed that fine powders were attached to the surface of coarse powders, dispersed evenly, and alumina powders contacted each other firmly.

CONCLUSIONThe crystal type, size distribution and even dispersion of the studied alumina powder contributed to the formation of porous structure of alumina sintered body (preform), which was the material prerequisite in forming porous preform and one of the key factors to the rise of strength of GI-II Infiltrated Ceramic.

Aluminum Oxide ; chemistry ; Ceramics ; chemistry ; Dental Materials ; Dental Porcelain ; chemistry ; Glass ; chemistry ; Particle Size ; Porosity ; Powders ; Tensile Strength