Objective: To compare the accuracy of photogrammetry and conventional impression techniques for complete-arch implant rehabilitation. Methods: An edentulous maxillary stone cast containing 8 screw-retained implant abutment replicas was derived from a 74-year-old male patient who visited the Department of Dental Implant Center, Capital Medical University School of Stomatology in September 2019. The stone cast was copied through the open-tray splinted impression, and the copied cast was used as the master cast for this study. The abutment-level impressions of master cast were made by photogrammetry (PG) and the conventional impression technique (CNV) by one attending doctor. Group PG: after which scan bodies were connected to each implant replica, a photogrammetry system was used to obtain digital impressions of the master cast (n=10); Group CNV: conventional open-tray splinted impression technique was performed to fabricate conventional definitive casts (n=10). After connecting the scan bodies onto each implant replicas, the master cast and the 10 definitive casts from group CNV were digitized with a laboratory reference scanner. All data of group PG, group CNV and mater cast were saved as ".stl" files. For all test scans and reference scan, the three-dimensional information of scan bodies were converted to implant abutment replicas using a computer aided design software (Exocad). The data of the group PG and the group CNV were respectively registered with the reference data (trueness analysis) and pairwise within group (precision analysis) for accuracy evaluation in a three-dimensional analysis software (Geomagic Control X). Results: The trueness and precision of group PG [(17.33±0.34) and (2.50±0.79) μm ] were significantly statistically better than those of group CNV [(24.30±4.16) and (26.12±4.54) μm] respectively (t=-5.29 and -34.35, P<0.001). Conclusions: For complete-arch implant abutment-level impression, photogrammetry produces significantly better accuracy than conventional impression technique.
Aged ; Computer-Aided Design ; Dental Implants ; Dental Impression Materials ; Dental Impression Technique ; Humans ; Models, Dental ; Photogrammetry

OBJECTIVE: To compare the operation complexity and accuracy of traditional splint impression technique and impression technique with prefabricated rigid connecting bar system for full-arch implants-supported fixed protheses in vitro. METHODS: Standard mandibular edentulous model with six implant analogs was prepared. The implants were placed at the bone level and multiunit abutments screwed into the implants. Two impression techniques were performed: the traditional splint impression technique was used in the control group, and the rigid connecting bar system was used in the test group. In the control group, impression copings were screwed into the multiunit abutments and connected with autopolymerizing acrylic resin. Open tray impression was fabricated with custom tray and polyether. In the test group, cylinders were screwed into the multiunit abutments. Prefabricated rigid bars with suitable length were selected and connected to the cylinders with small amount of autopolymerizing acrylic resin, and open tray impression was obtained. Impression procedures were repeated 6 times in each group. The working time of the two impression methods were recorded and compared. Analogs were screws into the impressions and gypsum casts were poured. The gypsum casts and the standard model were transferred to stereolithography (STL) files with model scanner. Comparative analysis of the STL files of the gypsum casts and the standard model was carried out and the root mean square (RMS) error value of the gypsum casts of the control and test groups compared with the standard model was recorded. The trueness of the two impression techniques was compared. RESULTS: The work time in the test group was significantly lower than that in the control group and the difference was statistically significant [(984.5±63.3) s vs. (1 478.3±156.2) s, P < 0.05]. Compared with the standard model, the RMS error value of the implant abutments in the test group was (16.9±5.5) μm. The RMS value in the control group was (20.2±8.0) μm. The difference between the two groups was not significant (P>0.05). CONCLUSION The prefabricated rigid connecting bar can save the chair-side work time in implants immediate loading of edentulous jaw and simplify the impression process. The impression accuracy is not significantly different from the traditional impression technology. The impression technique with prefabricated rigid connecting bar system is worthy of clinical application.
Acrylic Resins ; Calcium Sulfate ; Dental Implants ; Dental Impression Materials ; Dental Impression Technique ; Humans ; Jaw, Edentulous ; Models, Dental ; Mouth, Edentulous

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

OBJECTIVE: To assess the effect of disinfectant (Cavicide) with benzethon chloramine and isopropanol as main active ingredients disinfectant on dental impression accuracy. METHODS: The effect of Cavicide on three impression materials (alginate, polyether and vinylpolysiloxane) were assessed using a standard model. The standard model was digitized by an extraoral scanner (IScan D103i, Imetric). For each kind of impression materials, thirty impressions were taken following the manufactures' instruction in the same conditions. Subsequently, the impressions were randomly divided into three groups, with ten impressions in each group. After the impression taking was completed, the three groups underwent pure water rinse for 1 min (blank control, BC), 2% glutaraldehyde solution immersion disinfection for 30 min (glutaraldehyde, GD), and Cavicide solution spray disinfection for 5 min (Cavicide, CC), respectively. All the impressions were digitized by the extraoral scanner (IScan D103i, Imetric) after disinfection and exported to a dedicated three-dimensional analysis software (Geomagic Qualify 2014, Geomagic, USA). In the software, the digital models of the impressions were trimmed to teeth and then superimposed with the digitized standard model via best-fit alignment. Root mean square (RMS) was used to evaluate the deviations between the impression and the standard model. The deviation in the anterior and posterior regions was evaluated respectively. One-way ANOVA test and the LSD post-hoc test were used to compare the deviations between the three groups (P < 0.05). The color map of each superimposition was saved for visual analysis. RESULTS: For the polyether and vinylpolysiloxane materials, the difference between the three groups was not statistically significant (P=0.933, P=0.827). For the alginate material, the difference in posterior region between group GD and group BC, as well as group GD and group CC were statistically significant (GD vs. BC, P=0.001; GD vs. CC, P=0.002), while the difference between group BC and group CC was not statistically significant (P=0.854). The visual analysis showed an obvious deviation in the buccal-lingual direction in group GD. CONCLUSION Disinfectant (Cavicide) with benzethon chloramine and isopropanol as main active ingredients using spray disinfection has no effect on the accuracy of the alginate, polyether and vinylpolysiloxane impressions.
2-Propanol ; Chloramines ; Dental Impression Materials ; Dental Impression Technique ; Disinfectants ; Disinfection ; Models, Dental

OBJECTIVE: To establish a method for the production of digital individual tooth tray based on three-dimensional (3D) scan, computer-aided design (CAD) and 3D printing, and to evaluate the effect of impression taking of full-arch crown abutments by digital individual tooth tray technique and conventional method through in vitro study. METHODS: The full crown preparation was performed on all the fourteen resin teeth in a standard model of mandibular dentition. The surface data of prepared abutments was collected by 3D scanning. A new project was created in a dental CAD software including all the fourteen teeth in the mandibular dentition. The design modules of anatomy crown and coping were selected for each tooth. The dentition was divided for three sections: right posterior teeth, anterior teeth, and left posterior teeth areas. The connector design was added between the abutments within the same section. The scanned data of the abutments were imported. The occlusal plane and insertion path were determined. The position of margin line, as well as the shape of anatomy crown and connector as the main body of the individual tooth tray were designed for each abutment. The shape of coping was generated as the space for holding the impression material. The finalized data of the main body was imported into Geomagic software. The retentive attachment was added at the external surface and the tissue stop was formed at the internal surface. The completed individual tooth tray was manufactured by 3D printing with resin material. The data of full-arch crown abutments were modified and printed. The conventional dentition trays A and B, as well as digital individual tooth tray were designed and printed for four copies each. The polyether impressions of the full-arch abutments were made by conventional one-step method using dentition tray A, and by sectional-impression technique using digital individual tooth tray and dentition tray B for four times each. The time spent for each impression taking and the numbers of defects at the shoulder and axial/occlusal surface in each impression were recorded. The impression quality of each abutment was evaluated. The overall quality distribution and the pass rate of abutments between the two methods were analyzed. RESULTS: The impressions made by conventional method had more defects at shoulder than those made by digital individual tooth tray technique. No difference of the number of defects at axial/occlusal surface between the two methods was observed. The digital individual tooth tray technique for the full-arch abutment impression exhibited higher pass rate of abutments and better quality of impression, compared with conventional methods. CONCLUSION A new method for the production of digital individual tooth tray based on digital scanning, CAD and 3D printing was established. Compared with conventional method, using digital individual tooth tray technique for impression taking of full-arch abutments can achieve better effect.
Computer-Aided Design ; Crowns ; Dental Impression Materials ; Dental Impression Technique ; Models, Dental ; Printing, Three-Dimensional ; Software

OBJECTIVE: To design and fabricate edentulous custom trays by chair-side computer-aided design and 3-dimensional printing (CAD/3DP) system of independent research and development and to evaluate their clinical effects based on prosthodontists'satisfaction using the visual analogue scale (VAS). METHODS: Fifteen edentulous patients were randomly recruited by three prosthodontists who passed the unified operating process training. The custom trays for each patient were fabricated using both chair-side CAD/3DP system of independent development and manually conventional method, and the final impressions were made by silicone impression materials (light body). The prosthodontist's satisfaction was surveyed by the three prosthodontists via the questionnaire based on visual analogue scales. RESULTS: In the degree of the prosthodontist's satisfaction of final impressions, the average satisfactions of "try in" (the overall size, shape, convenience, etc.) on the 3DP custom tray made by independent development chair-side system and the manually conventional method were 9.18±0.19 and 8.23±0.22, respectively. The average satisfactions of the border line position (border extensions, frenal notch)were 8.91±0.40 and 7.96±0.23, respectively. The average satisfactions of the stability in border molding were 8.80±0.83 and 8.01±0.81, respectively. The average satisfactions of the quality of final impression (completeness, thickness of impression material, exposure of custom tray, shape of border) were 8.94±0.68 and 7.99±0.42, respectively. The average satisfactions of the difficulty of high quality impression (times of repetition, efficiency) were 9.20±0.37 and 7.88±0.22, respectively. The average satisfactions of the overall satisfaction were 9.11±0.49 and 7.95±0.15, respectively. There was significant difference in the satisfaction of "try in", border line position, stability in border molding, quality of final impression, difficulty of high quality impression, and overall satisfaction between the 3DP custom tray made by chair-side system of independent development and the manually conventional method (P<0.05). CONCLUSION In the degree of the prosthodontist's satisfaction of final impression, the 3DP custom tray made by chair-side system of independent development is higher than that of the conventional custom tray, and it meets the clinical requirements and can be popularized in clinical application.
Computer-Aided Design ; Dental Impression Materials ; Dental Impression Technique ; Humans ; Mouth, Edentulous ; Printing, Three-Dimensional

PURPOSE: This study evaluated the effect of loss of interproximal papilla, creating an undercut, on the accuracy of impression materials. MATERIALS AND METHODS: Two addition type silicone impression materials (Extrude(R) Wash, Imprint(TM) II Quick Step Light Body) and one alginate impression material (Cavex Impressional) were used to make impressions of a maxillary master model simulating clinical conditions with or without interproximal papilla. Stone was poured in the impressions and working casts were fabricated. A total of 6 groups with 6 working casts in each group were scanned using 3-dimensional optical scanner. The accuracy of the impressions was assessed by measuring the dimensional changes (DeltaI (%)) of 6 distances on working casts compared to a master model with a 3-dimensional digitizing and inspection software. The data were analyzed by two-way ANOVA (P<.05). RESULTS: Three of 6 distances showed statistically significant differences among the impression materials. Only 1 of 6 distances in alginate impression showed a statistically significant difference between casts with and without interproximal papilla (P=.047). CONCLUSION: The presence of undercut due to loss of interproximal papilla did not significantly influence the dimensional accuracy of addition type silicone and alginate impression materials.
Alginates ; Dental Impression Materials ; Silicone Elastomers

OBJECTIVE: To investigate clinical effect of individual light-curing resin tray as edge plastic material in complete denture modulo.
 METHODS: A total of 30 patients with poor condition for alveolar ridge of mandible were chosen individual tray with individual light-curing resin tray for material edge shaping or traditional individual impression tray for edge shaping cream to produce complete denture. The operability, questionnaire about denture retention, comfort, mucosal cases and chewing function in the process of shaping the edge were investigated three months later after wearing dentures.
 RESULTS: There was no significant difference in retention, comfort, mucosa and the chewing function between the two mandibular denture impression methods. However, the patients with individual light-curing resin tray as edge shaping material felt better in the process than that in the patients with die-cream as the edge shaping material (P<0.05). Furthermore, the manipulation with individual light-curing resin tray as edge shaping material is easy for doctor.
 CONCLUSION Although the clinical effect of Individual light-curing resin tray material as the edge shaping material is equal to that of impression cream, it saves time and human resource. Moreover, it is more acceptable for the patients and thus it can be spread in clinics.
Acrylic Resins ; Dental Impression Materials ; Dental Impression Technique ; Denture, Complete ; Humans ; Light-Curing of Dental Adhesives ; instrumentation

Dental impressions are widely used in the field of oral restoration. The materials are used for making impression in oral cavity. In order to measure the thickness of impression for reference in clinic, the real impressions are taken as the object for studying. Through optical method, charge-coupled device (CCD) is used for collecting the grey image of cutting section of the impressions which are located in the same plane with steel dividing ruler. According to convert relationship between dividing ruler and pixels collecting grey image, the thickness of impression specimens can be obtained. The results show that the optical method used for measuring thickness is feasible to the task and the precision can reach micro dimension. The experiment method and technique can also be provided for measuring thickness of similar tissue engineering materials.
Dental Impression Materials ; Dental Models ; Humans ; Materials Testing ; Optics and Photonics

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