OBJECTIVES: This work aimed to synthesize a novel injectable alginate impression material and evaluate its accuracy. METHODS: Certain proportions of sodium alginate, trisodium phosphate dodecahydrate, potassium fluorotitanate, diatomaceous earth, and other ingredients were dissolved in water and mixed evenly with a planetary centrifugal mixer to obtain a certain viscosity base paste. Certain proportions of calcium sulfate hemihydrate, magnesium oxide, glycerin, and polyethylene glycol (PEG) 400 were mixed evenly with a planetary centrifugal mixer to obtain the reactor paste with the same viscosity as the base paste. The base and reactor pastes were poured into a two-cylinder cartridge at a 2∶1 volume ratio. A gun device was used to accomplish mixing by compressing materials into a mixing tip. The samples were divided into three groups: injectable alginate impression materials (IA group) as the experimental group, and Jeltrate alginate impression materials (JA group) and Silagum-putty/light addition silicone rubber impression materials (SI group) as the two control groups. RESULTS: Scanning electron microscopy (SEM) showed that the injectable alginate impression materials had a denser structure and fewer bubbles than the commercial alginate impression material. The accuracy of the three kinds of impression materials was evaluated by 3D image superposition. The deviations between the three test group models and the standard model (trueness) were 49.58 μm±1.453 μm (IA group), 54.75 μm±7.264 μm (JA group), and 30.92 μm±1.013 μm (SI group). The deviations of the models within each test group (precision) were 85.79 μm±8.191 μm (IA group), 97.65 μm±11.060 μm (JA group), and 56.51 μm±4.995 μm (SI group). Significant differences in trueness and precision were found among the three kinds of impression materials (P<0.05). CONCLUSIONS The accuracy of the new injectable alginate impression material was better than that of the traditional powder-type alginate impression material but worse than that of the addition silicone rubber impression materials. The novel injec-table alginate impression material demonstrated good operation performance and impression accuracy, showing broad application prospect.
Alginates/chemistry* ; Silicone Elastomers/chemistry* ; Dental Impression Materials/chemistry* ; Powders

OBJECTIVETo evaluate the accuracy of 3 impression materials in reproductions of simian dental arches using a 3-dimensional optical digitizer.

METHODSTwo simian dental arches were prepared as the master models. Impressions were made for stone casts using three impression materials, including alginate impression materials, C-silicone materials and Impregum-Penta polyether rubber. Five plaster replication models for each master model, as well as for each impression materials were made. The master models and the casts were digitized using a 3-dimensional optical scanner and digitizer. The images of each plaster cast and its original master model were superimposed to obtain the setting cross-section volume of the dental crown. The ratios of the plaster cast volume change and discrepancy distribution patterns were analyzed.

RESULTSCompared with the volume of the master models, the discrepancies of the plaster casts volume were -5.84%, -3.21%, and -0.63% for alginate impression materials, silicone materials and Impregum-Penta polyether rubber, respectively. The discrepancy between the master models and casts from alginate material was statistically significant (P<0.05), but not for silicone materials or Impregum-Penta polyether rubber. Maximal deviation of image fitting was located in the cervix and the gingival areas.

CONCLUSIONThe volumes of all the plaster casts from the 3 impression material are smaller than that of the master model. Impregum-Penta polyether rubber allows the most precise and silicone material the relatively accurate reproduction of the denture model, while alginate can not. The major error areas are in the dental cervix and gingival region.

Dental Casting Technique ; Dental Impression Materials ; chemistry ; Dental Impression Technique ; Dental Models ; Humans ; Imaging, Three-Dimensional ; methods

OBJECTIVETo evaluate the dimensional stability and detail reproduction of five additional silicone impression materials after autoclave sterilization.

METHODSImpressions were made on the ISO 4823 standard mold containing several marking lines, in five kinds of additional silicone. All the impressions were sterilized by high temperature and pressure (135 °C, 212.8 kPa) for 25 min. Linear measurements of pre-sterilization and post-sterilization were made with a measuring microscope. Statistical analysis utilized single-factor analysis with pair-wise comparison of mean values when appropriate. Hypothesis testing was conducted at alpha = 0.05.

RESULTSNo significant difference was found between the pre-sterilization and post-sterilization conditions for all locations, and all the absolute valuse of linear rate of change less than 8%. All the sterilization by the autoclave did not affect the surfuce detail reproduction of the 5 impression materials.

CONCLUSIONSThe dimensional stability and detail reproduction of the five additional silicone impression materials in the study was unaffected by autoclave sterilization.

Dental Impression Materials ; chemistry ; Dental Models ; Hot Temperature ; Materials Testing ; Microscopy ; Polyvinyls ; chemistry ; Silicone Elastomers ; chemistry ; Siloxanes ; chemistry ; Sterilization ; methods

OBJECTIVETo establish a three-dimensional digital dental model through scanning dental impression directly with micro-CT.

METHODSThe polyvinyl siloxane (PVS) impression of the plaster model was taken and scanned with micro-CT. VGStudio MAX and Imageware softwares were used to obtain the digital dental model.

RESULTSThe three-dimensional digital model was established successfully. The scanning layer was 90 µm.

CONCLUSIONSA new way of establishing the digital dental models could be achieved with micro-CT.

Computer-Aided Design ; Dental Impression Materials ; chemistry ; Dental Models ; Humans ; Image Processing, Computer-Assisted ; Imaging, Three-Dimensional ; Polyvinyls ; chemistry ; Siloxanes ; chemistry ; Software ; X-Ray Microtomography ; methods

OBJECTIVETo prepare dental ulcer powder by using particle design technology, and compare the effect on the micromeritic property of dental ulcer powder with regular grinding and ultrafine grinding methods.

METHODAbove three methods were respectively used to make dental ulcer powder, in order to evaluate their difference in appearance character, grain size distribution, specific surface area and porosity, contact angle, micro-morphological character and borneol's stability.

RESULTCompared with normal powder, ultrafine powder and particle design showed increase in color uniformity and decrease in sour taste, and the particle design powder smells almost no borneol. Their grain size distributions were significantly less that of normal powder (P < 0.01), with the same grain size distribution in ultrafine powder and particle design powder. Their specific surface areas and porosities were significantly more than that of normal powder (P < 0.01), with the highest figures in ultrafine powder. Their contact angles were significantly more than that of normal powder (P < 0.01), with the highest figure in particle design powder. The surface of normal powder was smooth, with a few of small particle adhered. The surface of ultrafine powder was partially coated with small particles, where as the surface of particle design powder was mostly coated with particles. There was difference in micro-morphological character and surface attachment among the three. The 10-day accelerate stability experiment showed that normal power, ultrafine powder and particle design powder lost borneol by 90. 13% , 66. 48% and 40.57%, respectively. Particle design powder showed the highest stability, followed by ultrafine powder and normal powder.

CONCLUSIONThe preparation process can affect the micromeritic properties, by changing microscopic structure of the powders. We can design the macroscopic property of powder by regulating the formation of the microscopic structure with particle design technology.

Dental Impression Materials ; chemistry ; Drug Stability ; Medicine, Chinese Traditional ; methods ; Microscopy, Electron, Scanning ; Oral Ulcer ; therapy ; Particle Size ; Powders ; Reproducibility of Results ; Silicones ; chemistry ; Surface Properties ; Technology, Pharmaceutical ; methods