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The Journal of Prosthetic Dentistry Feb 2021Elastomeric impression materials have been marketed for optimizing direct digital acquisition without requiring a stone cast. The trueness and precision of the...
STATEMENT OF PROBLEM
Elastomeric impression materials have been marketed for optimizing direct digital acquisition without requiring a stone cast. The trueness and precision of the digitization of these new elastomeric impression materials are unclear.
PURPOSE
The purpose of this in vitro study was to compare the trueness and precision of digital dental casts obtained from the direct digitization of 2 types of vinylsiloxanether (VSXE) impression materials by using a laboratory laser scanner.
MATERIAL AND METHODS
Thirty-eight elastomeric impressions were made of a master die with a similar morphology to a premolar crown preparation. The impression materials were Identium (IDE) and Identium Scan (SCAN), designed for direct digitalization. Each impression was digitalized by using an optical scanner to create digital casts. A computer-aided design (CAD) reference model of trueness (CRM) was created and aligned to each digital cast for digital 3-dimensional discrepancy analysis.
RESULTS
The mean ±standard deviation global trueness of IDE was 53 ±16 μm and that of SCAN was 46 ±3 μm. SCAN digital casts showed higher precision (58 ±5 μm) than IDE (69 ±18 μm) (P<.05). At the margin of the preparation and at the axial surfaces, SCAN models showed higher trueness (3 ±6 μm and 1 ±5 μm) than IDE (15 ±10 μm and 2 ±37 μm), respectively.
CONCLUSIONS
Scannable impressions could be digitalized with higher global precision than conventional elastomeric materials. Higher trueness could be achieved in specific impression locations such as gingival areas or axial walls of preparations, where the light emitted by the scanner was not blocked.
Topics: Computer-Aided Design; Dental Impression Materials; Dental Impression Technique; Imaging, Three-Dimensional; Models, Dental
PubMed: 32089364
DOI: 10.1016/j.prosdent.2020.01.002 -
The Journal of Prosthetic Dentistry Apr 2022This article describes a dental implant impression technique using custom impression copings. The implant impression coping was designed by using a dental computer-aided...
This article describes a dental implant impression technique using custom impression copings. The implant impression coping was designed by using a dental computer-aided design software program and manufactured by using additive methods. The impression copings were cemented to stock abutments, and the assemblies were used to make the definitive pick-up impression.
Topics: Adaptation, Psychological; Computer-Aided Design; Dental Abutments; Dental Implants; Dental Impression Materials; Dental Impression Technique; Dental Prosthesis Design
PubMed: 33386139
DOI: 10.1016/j.prosdent.2020.09.054 -
Journal of Indian Prosthodontic Society 2023The aim of this study was to evaluate and compare the accuracy of hexed and nonhexed pickup impression copings with and without splinting using polyether (PE) and...
Comparison of accuracy of hexed and nonhexed pickup impression copings in a multiple variable impression setup for recording multiple straight and angulated implant positions: An study.
AIM
The aim of this study was to evaluate and compare the accuracy of hexed and nonhexed pickup impression copings with and without splinting using polyether (PE) and polyvinyl siloxane (PVS) impression materials in open-tray technique in recording multiple straight and angulated implant positions.
SETTINGS AND DESIGN
An accurate impression results in an accurate definitive cast, thus minimizing the incidence of prosthesis misfit. The critical aspect is to record the three-dimensional location of the implant in bone rather than reproducing fine surface details. Precise fit of a fixed implant-supported prosthesis depends on the accuracy of the implant analog location within the definitive cast. Factors which affect impression accuracy include implant angulation, impression material, impression copings, technique, and splinting.
MATERIALS AND METHODS
A sample size of 80 study models fabricated from the impression of different groups was included. A reference master model based on All-on-4 implant concept with two parallel (implants 1 and 2) and two angulated (implant 3 at 17° and implant 4 at 30°) was fabricated using implant angulation guide. All impressions were recorded using open-tray impression technique. The groups were divided into two main groups of 40 samples each. Group A used hexed open-tray impression copings and Group B used nonhexed open-tray impression copings. Both the groups involved impression recording using splinted (Subgroup I) and nonsplinted impression copings (Subgroup II). Further, impressions in each subgroup were made using PE (Subsubgroups a) and PVS (Subsubgroup b). A total of eight subsubgroups with ten samples each were included. Impressions were recorded for each group and poured into Type IV die stone for fabrication of study models. After 24 h, the study models and reference master model were fitted with implant abutments for measurement with coordinate measuring machine.
STATISTICAL ANALYSIS USED
The mean differences of the interimplant distance R1 (1-2), R2 (1-3), R3 (2-4), and R4 (3-4) between the reference model and sample models in different subsubgroups were calculated and three-way analysis of variance test was applied with Tukey's post hoc tests.
RESULTS
No significant difference was found in mean coronal deviations for distance R1, R2, and R3 (P > 0.05) between different study groups. P = 0.02 for R4 (distance between 17° and 30° implants) between impression materials subsubgroups suggested that significantly less distortion was created in location of highly angulated implants (>30°) using PVS impression material. Splinting and type of coping did not have a significant influence on impression accuracy. Increasing angulation decreased the accuracy.
CONCLUSION
PVS was found equivalent in accuracy to rigid PE for recording parallel or angulated implants. Impressions of implants with higher angulations were recorded more accurately with PVS. The study found no difference in accuracy with or without splinting. Furthermore, nonhexed impression copings facilitate easier and accurate recording of multiple angulated implant location in bone.
Topics: Dental Implants; Dental Impression Technique; Models, Dental; Dental Impression Materials
PubMed: 36588371
DOI: 10.4103/jips.jips_218_22 -
American Journal of Orthodontics and... May 2016The objective of this study was to evaluate the accuracy and reliability of measurements on digital models obtained by scanning impressions 5, 10, and 15 days after... (Comparative Study)
Comparative Study
INTRODUCTION
The objective of this study was to evaluate the accuracy and reliability of measurements on digital models obtained by scanning impressions 5, 10, and 15 days after they were made from 2 soft putty polyvinylsiloxane (PVS) materials.
METHODS
Thirty volunteers were selected for making impressions of their dentitions with alginate to create a plaster model and with PVS impression material to create a digital model by laser scanning. Three examiners made the plaster model measurements with digital calipers and repeated these measurements on the digital models made from the scanned PVS impressions. A total of 34 distances were evaluated. Paired t tests were used to evaluate intraexaminer error and the accuracy of the digital model measurements. Measurement reproducibility and reliability among examiners were tested.
RESULTS
Although statistically significant differences between measurements on plaster and digital models were found, these discrepancies were not clinically significant except for overbite. Both plaster and digital models had high intraclass correlation coefficient values.
CONCLUSIONS
Digital models acquired by laser scanning of 2 types of soft putty PVS material may be used with clinically acceptable accuracy, reliability, and reproducibility, even at a postscanning interval of 15 days.
Topics: Calcium Sulfate; Computer Simulation; Dental Impression Materials; Polyvinyls; Reproducibility of Results; Siloxanes
PubMed: 27131245
DOI: 10.1016/j.ajodo.2015.10.027 -
The Journal of Contemporary Dental... Aug 2021To analyze the clinical effectiveness of three new gingival retraction systems: knitted retraction cord, expanding polyvinyl siloxane, and aluminium chloride containing...
AIM
To analyze the clinical effectiveness of three new gingival retraction systems: knitted retraction cord, expanding polyvinyl siloxane, and aluminium chloride containing paste.
MATERIALS AND METHODS
Twenty patients were enrolled with age-group of more than 18 years and who required fixed prosthesis with minimum of two abutments. A preliminary impression of the arch was made with a stock metal tray and irreversible hydrocolloid impression material. Group WR-impression without retraction, Group A-impression after retraction with gingival retraction cord, Group B-impression after retraction with expanding polyvinyl siloxane, and Group C-impression after retraction with aluminium chloride containing paste. A total of four impressions were made for each abutment tooth. Each impression was given a label 1WR, 1A, 1B, 1C-20WR, 20A, 20B, 20C: where 1 denoted the sample number. Comparison of the stereomicroscopic images was done using image analysis software. Time required from start of placement of gingival displacement agents till completion was recorded in seconds with the help of a stop clock.
RESULTS
The mean gingival retraction was found to be the highest for subjects of Group C followed by Group A, Group B, and Group WR. This difference was found to be statistically significant. Highly significant mean difference in time of placement was observed between Group A and Group B, between Group B and Group C, and between Group C and Group A.
CONCLUSION
The aluminium chloride containing paste was found effective in almost all the variables considered.
CLINICAL SIGNIFICANCE
The choice of particular gingival retraction system/technique is dependent upon the clinical variables and on operator's preference.
Topics: Adolescent; Aluminum Chloride; Dental Impression Materials; Dental Impression Technique; Gingiva; Gingival Retraction Techniques; Humans
PubMed: 34753845
DOI: No ID Found -
The Journal of Prosthetic Dentistry Mar 2017Gingival displacement is recognized as a substantive and difficult procedure in fixed prosthodontics. However, a realistic simulation of gingival displacement is...
STATEMENT OF PROBLEM
Gingival displacement is recognized as a substantive and difficult procedure in fixed prosthodontics. However, a realistic simulation of gingival displacement is unavailable for preclinical dental students.
PURPOSE
The purpose of this study was to evaluate whether practice-based preclinical instruction of gingival displacement with animal models could improve students' skill in patient care.
MATERIAL AND METHODS
Isolated bovine mandibles (calves were younger than 6 months of age) and isolated porcine hemimandibles were prepared for this study. Twenty-two general dental practitioners with at least 5 years of experience were randomly selected and assigned to perform gingival displacement on both bovine and porcine jaws. Those practitioners were then asked to assess the clinical similarity of gingival displacement between human teeth and animal teeth. The data were analyzed with the paired t test (α=.05). Upon confirmation that the animal jaw provided a similar gingival displacement environment to that of human teeth, 80 predoctoral dental students were enrolled and randomized into 2 groups. Half of them underwent the new practice-based instruction, while the others underwent traditional preclinical teaching only (lectures, online video, or live demonstration). After preclinical learning, clinical performance in gingival displacement was evaluated for all students in terms of the effect of gingival displacement and quality of impression. The data were analyzed with the chi-square test (α=.05).
RESULTS
The dentogingival environments of porcine and bovine jaws were similar to those of human jaws, and no significant difference was detected between these 2 animal models (P=.178). A significant increase occurred in the acceptable rate of the effect of gingival displacement (P<.001) and the quality of impression (P<.001) among students who received the practice-based instruction compared with those who received traditional teaching.
CONCLUSIONS
These findings suggest that this practice-based instruction of gingival displacement with animal models is an effective method of promoting dental students' learning of gingival displacement.
Topics: Animals; Cattle; Chi-Square Distribution; Dental Impression Materials; Education, Dental; Educational Measurement; Gingiva; Gingival Retraction Techniques; Humans; Mandible; Models, Animal; Patient Care; Prosthodontics; Students, Dental; Surveys and Questionnaires; Swine
PubMed: 27677218
DOI: 10.1016/j.prosdent.2016.07.020 -
Marine Drugs Jan 2022This study aimed to investigate the potential use of brown algae as irreversible hydrocolloid (alginate) impression material. Potassium alginate extracted from was...
This study aimed to investigate the potential use of brown algae as irreversible hydrocolloid (alginate) impression material. Potassium alginate extracted from was prepared in three different compositions (14%, 15%, and 16%) and mixed with other standard components to form an alginate impression material. Prior to that, the purity of potassium alginate was quantified with Fourier Transform Infrared Spectroscopy (FTIR) analysis. As a control material, the alginate impression material from a commercially available product was used. All alginate impression materials were then applied to a die stone model. Dimensional accuracy was measured by calculating the mesiodistal width of incisors in the generated dental cast using a digital caliper 0.01 accuracy (five replications). In addition, to evaluate the dimensional stability, the impression results were poured at four different periods (immediately, 5 min, 10 min, and 15 min). An independent -test was performed to compare the measurement results with < 0.05 considered significant. Analytical results confirm that the impression material containing 15% potassium alginate gives the best dimensional accuracy similar to control ( > 0.05). Meanwhile, the optimal dimensional stability was produced in the impression material containing 16% potassium alginate. Our study suggested that brown algae has a promising potential to be used as an alginate impression material in clinical application.
Topics: Animals; Aquatic Organisms; Colloids; Dental Impression Materials; Materials Testing; Sargassum
PubMed: 35049910
DOI: 10.3390/md20010055 -
Folia Medica Sep 2019Border molding of the edge of the individual impression tray is an important stage of prosthetic treatment of edentulous jaws, which often depends on the final result of...
INTRODUCTION
Border molding of the edge of the individual impression tray is an important stage of prosthetic treatment of edentulous jaws, which often depends on the final result of the treatment. Classical thermoplastic impression materials for border molding have positive qualities that make them preferable by clinicians for their hardness, unlimited manipulation time and high impression sharpness. Modern silicone impression materials for border molding have long manipulating time and appropriate viscosity to allow dentists to perform functional tests.
AIM
To determine the accuracy of different impression materials for border molding of individual impression trays.
MATERIALS AND METHODS
Four impression materials for border molding were laboratory tested: Kerr impression compound green sticks and thermoplastic GC Iso functional sticks, additive type silicone Detaseal function and condensation type silicone sta-seal f. A modified individual impression tray designed by authors was used, allowing for laboratory load and stability. Ten impressions were taken and their formed edges were measured at 10 points three times - immediately after hardening/elasification, and 24 hours and 48 hours after hardening/elasification.
RESULTS
The results were analysed using ANOVA repetition analysis, where a statistically insignificant difference in the accuracy of three of the impression materials for border molding was established, except the C-type of silicone.
CONCLUSIONS
Good manipulative qualities and measured accuracy in laboratory tests define these materials as very good for border molding procedures.
Topics: Dental Impression Materials; Dental Impression Technique; Humans; Jaw, Edentulous
PubMed: 32337931
DOI: 10.3897/folmed.61.e39351 -
Indian Journal of Dental Research :... Oct 20233D printing technology is replacing manual fabrication in all fields. 3D-printed impression trays should be assessed as they could replace conventional impression trays... (Comparative Study)
Comparative Study
BACKGROUND
3D printing technology is replacing manual fabrication in all fields. 3D-printed impression trays should be assessed as they could replace conventional impression trays in the future.
AIM
In-vitro comparison and evaluation of the dimensional stability and retention strength of impressions to custom impression trays fabricated using conventional method and additive technology.
MATERIALS AND METHODS
A maxillary edentulous auto-polymerizing acrylic resin model served as the master model. Two moulds were prepared from the master model in order to obtain 12 casts. One cast was scanned for 3D printing digital light processing (DLP) and fused deposition modelling (FDM) 24 impression trays using polylactic acid (PLA). Twelve casts were used to fabricate light cure impression trays. Polyvinyl-siloxane impressions were made on the master model using 36 impression trays and 18 trays each were used to assess dimensional stability and retention strength.
RESULTS
In dimensional stability analysis, one sample t-test revealed a statistically significant difference between each group and the master model followed by a one-way ANOVA. There were significant differences, but the difference was less with FDM trays (P < 0.05). In retention strength analysis, one-way Analysis of variance (ANOVA) revealed statistically significant difference between each group and post-hoc test revealed specific difference, the highest with FDM trays (P < 0.05).
CONCLUSION
Dimensional changes were observed at 30 minutes and 72 hours. Lesser dimensional changes were observed when impressions were made using FDM trays followed by DLP and light cure trays. The mean retention strength seen in descending order was FDM, followed by DLP and light cure trays. The best retention strength was noticed when impressions were made using FDM trays.
Topics: Dental Impression Technique; Dental Impression Materials; Printing, Three-Dimensional; Polyvinyls; Siloxanes; Humans; In Vitro Techniques; Models, Dental; Materials Testing
PubMed: 38739826
DOI: 10.4103/ijdr.ijdr_519_23 -
The Journal of Prosthetic Dentistry Dec 2022Quantitative 3D clinical analysis of the selective pressure impression technique directly measuring tissue displacement during impression making for complete maxillary...
STATEMENT OF PROBLEM
Quantitative 3D clinical analysis of the selective pressure impression technique directly measuring tissue displacement during impression making for complete maxillary dentures is lacking.
PURPOSE
The purpose of this clinical study was to digitally compare impressions made of the edentulous maxillary ridge by using the selective pressure impression technique with different amounts of relief incorporated into custom tray designs.
MATERIAL AND METHODS
Nine participants receiving maxillary complete dentures were enrolled in the study. An initial custom tray was fabricated in urethane dimethacrylate by using the alternative border molding technique without relief and scanned to create a standard tessellation language (STL) file from which 3 groups of custom trays were designed and 3D printed with 0.0-mm (no relief), 1.0-mm, and 3.0-mm relief over the anterior ridge and median palatal suture. Definitive impressions using each of the 4 custom trays were made with a consistent volume of light-body polyvinyl siloxane impression material. The definitive impressions were scanned, and the STL files were superimposed to investigate the topographical differences among the groups, each with respect to the no relief, 3D-printed custom tray definitive impression. Mean volumetric differences for all 3 groups were measured in areas where relief was used and statistically analyzed with the Friedman test (α=.05).
RESULTS
No significant difference was found among any of the 3 groups of superimposed impressions in areas of no relief, 1.0-mm, and 3.0-mm relief (P=.558). The mean difference ±standard deviation for each comparison in regions of the anterior ridge and median palatal suture were 0.07 ±0.06 mm for no relief, -0.03 ±0.07 mm for the 1.0-mm tray relief, and -0.04 ±0.09 mm for the 3.0-mm tray relief. The negative values in mean difference indicated less compression of underlying tissues compared with the reference border molded urethane dimethacrylate custom tray impression.
CONCLUSIONS
Although results showed less compression when compared with that of the control group, custom tray relief of 1.0 mm and 3.0 mm over the anterior residual alveolar ridge and median palatal suture did not significantly impact the resulting impression topography when compared with no relief custom trays.
Topics: Humans; Dental Impression Technique; Models, Dental; Dental Impression Materials; Computer-Aided Design
PubMed: 33992466
DOI: 10.1016/j.prosdent.2021.03.026