-
Journal of Oral Science Dec 2017The aim of this study was to examine the effects of tray design and impression material on impression pressure in a clinical simulation model of an edentulous mandible....
The aim of this study was to examine the effects of tray design and impression material on impression pressure in a clinical simulation model of an edentulous mandible. Two types of polyvinylsiloxane elastomer, one type of polyether elastomer, and one type of alginate were used. The three tray types had no relief, 0.36 mm of relief, or 1.4 mm of relief, with or without escape holes. Impression pressure was measured at the median alveolar crest, the bilateral alveolar crests corresponding to molars, and the bilateral buccal shelves. Impression pressure significantly differed in relation to tray design and sensor position. In trays without escape holes, impression pressure was highest at the median alveolar crest and lowest at the buccal shelves, for all impression materials. However, impression material had no significant effects on impression pressure. Our results suggest that bite-pressure load on alveolar crests can be alleviated by making an impression with a tray that has relief and escape holes, while applying pressure to buccal shelves and almost no pressure to alveolar crests.
Topics: Alginates; Alveolar Process; Dental Impression Materials; Dental Impression Technique; Glucuronic Acid; Hexuronic Acids; Humans; Jaw, Edentulous; Mandible; Maxilla; Polyvinyls; Pressure; Siloxanes
PubMed: 28855443
DOI: 10.2334/josnusd.16-0731 -
Journal of Radiation Research Sep 2022We evaluated the basic characteristics and efficacy of our newly developed patient fixation system for head and neck radiotherapy that uses a dedicated mouthpiece and...
We evaluated the basic characteristics and efficacy of our newly developed patient fixation system for head and neck radiotherapy that uses a dedicated mouthpiece and dental impression materials. The present investigation demonstrated that with this system, the changes in the absorbed dose to water depending on the material of the mouthpiece were small, with a maximum of 0.32% for a 10-MV photon beam. For the dental impression material, we selected a silicone material with the lowest Hounsfield unit (HU) value that had little effect on the generation of artifacts and the quality of the X-ray beam. Multiphase magnetic resonance imaging (MRI) revealed that the head-up and -down motions in the thermoplastic shell without the mouthpiece were 5.76 ± 1.54 mm, whereas the motion with the mouthpiece decreased significantly to 1.72 ± 0.92 mm (P = 0.006). Similarly, the head-left and -right motion displacement decreased from 6.32 ± 1.86 mm without the mouthpiece to 1.80 ± 0.42 mm with the mouthpiece (P = 0.003). Regarding the tongue depressor function of the mouthpiece, the median distance from the hard palate to the surface of the tongue was 28.42 mm. The present results indicate that the new immobilization device developed herein that uses a mouthpiece and a thermoplastic shell is useful for suppressing patients' head motions and tongue positions.
Topics: Dental Impression Materials; Head and Neck Neoplasms; Humans; Neck; Radiotherapy Planning, Computer-Assisted; Silicones; Water
PubMed: 35818301
DOI: 10.1093/jrr/rrac044 -
Indian Journal of Dental Research :... 2023Impression making is one such important clinical step, which is critical in the accurate fitting of resulting prostheses. Impression making itself depends on the type of...
INTRODUCTION
Impression making is one such important clinical step, which is critical in the accurate fitting of resulting prostheses. Impression making itself depends on the type of material and the impression technique used to record the details. Various combinations of material and the technique have been described in the literature.
AIM
To evaluate the effect of three different impression techniques on the marginal fit of computer-aided designed/computer-aided manufactured (CAD/CAM) single unit composite fixed dental prostheses (FDP), different consistencies of addition silicone impression material and different tray design were utilized.
METHOD
Impression of prepared tooth on typodont was made using Matrix impression system, two-step putty wash technique, and individual tooth tray technique. Prosthesis was fabricated using CAD/CAM technology and marginal accuracy was evaluated using scanning electron microscopy (SEM).
RESULT
In the present study, the matrix impression system resulted in less microgap in both mid-buccal and mid-mesial region, whereas putty wash technique showed very high standard deviation in the interproximal region.
CONCLUSION
Matrix impression system had the best results at both mid-buccal and mid-mesial position with least marginal discrepancy.
CLINICAL IMPLICATION
The findings of this study could be used by clinicians to help them choose the viscosity of polyvinylsiloxane material and impression techniques for FDP that will result in high-accuracy impressions and well-fitting prostheses.
Topics: Computer-Aided Design; Dental Impression Materials; Microscopy, Electron, Scanning; Silicones
PubMed: 38197350
DOI: 10.4103/ijdr.ijdr_991_22 -
The International Journal of... 2020To evaluate the dimensional accuracy of impressions made using a new fast-setting polyether material.
PURPOSE
To evaluate the dimensional accuracy of impressions made using a new fast-setting polyether material.
MATERIALS AND METHODS
A metallic reference model with two crown preparations, one inlay preparation, and three stainless steel precision balls was digitized to create a digital reference model. Sixteen one-step impressions were made for each of the four study groups, differing in impression material (regular-setting polyether [RSP] vs fast-setting polyether [FSP]) and technique (monophase vs dualphase), for a total of 64 specimens. Plaster casts fabricated from these impressions were digitized using 3D scans. Global accuracy was studied by evaluating distance and angle deviations between the replica and the reference model. Local accuracy was described in terms of trueness and precision of the aligned individual abutment tooth surfaces.
RESULTS
For all impression materials and techniques, the local accuracy at the abutment tooth level was excellent. For surfaces prepared for crowns, mean trueness was < 10 μm, and mean precision < 12 μm. Inlay surfaces were associated with higher inaccuracies (mean trueness < 21 μm and mean precision < 37 μm). The greatest global inaccuracies were generally measured for the cross-arch span, with mean distance changes between -55 μm and -94 μm. For all aspects of studied accuracy, impressions with FSP were at least comparable to those fabricated with RSP.
CONCLUSION
Within the limitations of this study, all tested polyether materials would allow for clinically acceptable impression making. The new fast-setting material could be an alternative to regular-setting polyether materials, especially for single crowns and small fixed partial dentures.
Topics: Crowns; Dental Impression Materials; Dental Impression Technique; Inlays; Models, Dental
PubMed: 32639701
DOI: 10.11607/ijp.6419 -
The International Journal of... 2022To evaluate intraoral scanners, scannable impression materials, and conventional methods for impression-taking with regard to precision and accuracy.
PURPOSE
To evaluate intraoral scanners, scannable impression materials, and conventional methods for impression-taking with regard to precision and accuracy.
MATERIALS AND METHODS
Ten impressions per technique were initially taken from a cobalt-chromium (Co-Cr) master model (chamfer preparation for the maxillary right first molar) for fabricating Co-Cr crown copings. The test specimens, their respective metal master model, and the plaster casts from the conventional impressions were then digitized with the light-optical Atos Triple Scanner. The fit of the dental crown copings was measured in two and three dimensions using computer-aided design software. Global differences between the methods were determined using Kruskal-Wallis test, and pairwise comparisons were performed with Mann-Whitney U test. The significance level was set at .05.
RESULTS
The 2D analysis showed that the average absolute marginal distance of the crown copings was 0.026 mm when fabricated with the digital impression method and 0.038 mm when fabricated with the conventional method (P = .028). However, the 3D analysis revealed that the conventional group had a smaller marginal gap (0.028 mm) compared to the digital group (0.06 mm; P = .015).
CONCLUSION
This study showed that, in the field of single-crown prosthetics, digital impressions and the use of scannable impression material could serve as alternatives to conventional methods in the future.
Topics: Crowns; Dental Impression Technique; Dental Prosthesis Design; Dental Marginal Adaptation; Dental Impression Materials; Computer-Aided Design; Cobalt
PubMed: 36645864
DOI: 10.11607/ijp.7652 -
Clinical Oral Investigations Mar 2020To test if the partially digital workflow by digitalisation of the impression reveals a comparable accuracy as the indirect digitalisation of the gypsum cast for 4-unit...
OBJECTIVES
To test if the partially digital workflow by digitalisation of the impression reveals a comparable accuracy as the indirect digitalisation of the gypsum cast for 4-unit fixed dental prostheses (FDPs).
MATERIALS AND METHODS
A titanium model with a tapered full veneer preparation of a molar and premolar was used as analysis model. To receive a virtual three-dimensional reference dataset (REF), it was digitised by industrial computed tomography. Three impression materials were used with individual impression trays (N = 36, n/material = 12): (1) PE (Impregum Penta), (2) PVS-I (Imprint 4 Penta: Super Quick Heavy plus Super Quick Light), and (3) PVS-D (Dimension Penta: H Quick plus L). For partially digital workflow (group IMP), two desktop scanners were used: (1) D810 (3Shape D810) and (2) ZZ (Zirkonzahn S600ARTI). For indirect digitalisation (group CAST), gypsum master casts were manufactured and digitalised using the same desktop scanners. Virtual datasets were superimposed by best fit algorithm, and accuracy was analysed by calculating the Euclidean distances (ED) to the REF (Geomagic Qualify). Statistic was determined (Kruskal-Wallis H test, Mann-Whitney U post hoc analysis, two-sample Kolmogorov-Smirnov test, p < 0.05).
RESULTS
ZZ showed for positive deviations superior accuracy for IMP than for CAST. PE and PVS-I showed superior accuracy than PVS-D. D810 showed partially significant better performance with PVS-I and PVS-D than ZZ.
CONCLUSIONS
The partially digital workflow by digitalisation of the impression can be used for clinical indications of small-span fixed dental prostheses. However, for this indication, the impression material and the desktop scanner are more decisive for the accuracy of virtual model datasets.
CLINICAL RELEVANCE
Despite the rapid advancement of the computer-aided technology for dental therapy purposes, the implementation of this technique is not as fast as the technical development. In order to combine the well-established procedure to use elastomeric materials for a conventional impression and to avoid the drawbacks of casting it by gypsum, the digitalisation of the impression itself by a desktop scanner may be a logical procedure as an access point to the digital workflow. However, there is only limited information about the accuracy of this partially digital workflow by the digitalisation of modern impression materials in comparison to the well-known process of indirect digitalisation of gypsum casts.
Topics: Computer-Aided Design; Dental Impression Materials; Dental Impression Technique; Dental Prosthesis; Humans; Imaging, Three-Dimensional; Models, Dental; Tomography, X-Ray Computed; Workflow
PubMed: 31302771
DOI: 10.1007/s00784-019-02995-w -
The Journal of Prosthetic Dentistry Jan 2022Intraoral scanners have significantly improved over the last decade. Nevertheless, data comparing intraoral digital scans with conventional impressions are sparse. (Meta-Analysis)
Meta-Analysis Review
Comparative assessment of complete-coverage, fixed tooth-supported prostheses fabricated from digital scans or conventional impressions: A systematic review and meta-analysis.
STATEMENT OF PROBLEM
Intraoral scanners have significantly improved over the last decade. Nevertheless, data comparing intraoral digital scans with conventional impressions are sparse.
PURPOSE
The purpose of this systematic review and meta-analysis was to determine the impact of impression technique (digital scans versus conventional impressions) on the clinical time, patient comfort, and marginal fit of tooth-supported prostheses.
MATERIAL AND METHODS
The authors conducted a literature search based on the Population, Intervention, Comparison, and Outcome (PICO) framework in 3 databases to identify clinical trials with no language or date restrictions. The mean clinical time, patient comfort, and marginal fit values of each study were independently extracted by 2 review authors and categorized according to the scanning or impression method. The authors assessed the study-level risk of bias.
RESULTS
A total of 16 clinical studies met the inclusion criteria. The mean clinical time was statistically similar for digital scan procedures (784 ±252 seconds) and for conventional impression methods (1125 ±159 seconds) (P>.05). The digital scan techniques were more comfortable for patients than conventional impressions; the mean visual analog scale score was 67.8 ±21.7 for digital scans and 39.6 ±9.3 for conventional impressions (P<.05). The mean marginal fit was 80.9 ±31.9 μm and 92.1 ±35.4 μm for digital scan and conventional impressions, respectively, with no statistically significant difference (P>.05).
CONCLUSIONS
Digital scan techniques are comparable with conventional impressions in terms of clinical time and marginal fit but are more comfortable for patients than conventional impression techniques.
Topics: Computer-Aided Design; Databases, Factual; Dental Impression Materials; Dental Impression Technique; Dental Marginal Adaptation; Dental Prosthesis Design; Humans
PubMed: 33143901
DOI: 10.1016/j.prosdent.2020.09.017 -
The Journal of Prosthetic Dentistry Oct 2022Although studies have evaluated the accuracy of data obtained by intraoral scanners (IOSs), studies on the precision of interocclusal registrations made with IOSs are...
STATEMENT OF PROBLEM
Although studies have evaluated the accuracy of data obtained by intraoral scanners (IOSs), studies on the precision of interocclusal registrations made with IOSs are lacking.
PURPOSE
The purpose of this clinical study was to compare the precision of IOS interocclusal registration with that of conventional methods with a silicone impression material and a gypsum cast.
MATERIAL AND METHODS
Eight participants with complete natural dentitions were enrolled. Images of their maxillary and mandibular quadrant arches and their interocclusal relationship were scanned with 2 IOSs: the 3M True Definition Scanner and the TRIOS Scanner 3. In the conventional method, impressions of complete-arch dentition and quadrant-arch dentition were made with a silicone impression material, and gypsum casts were fabricated, mounted on a dental articulator related with a silicone interocclusal record, and scanned with a 3D laboratory scanner. These procedures were repeated 4 times, and 4 sets of interocclusal registration data in standard tessellation language (STL) format were generated for each condition. Interocclusal registration precision was evaluated by determining the discrepancy of the STL data between repeated measurements by using the best-fit-algorithm method.
RESULTS
The average discrepancies for all participants were 25 ±12 μm for the True Definition, 31 ±7 μm for the TRIOS 3, 154 ±59 μm for the complete arch, and 128 ±33 μm for the quadrant arch. The Kruskal-Wallis test revealed that the effect of the impression methods on the discrepancy was statistically significant (P<.001). The Steel-Dwass test showed that both digital scan methods exhibited significantly smaller discrepancies than the 2 conventional methods (P=.005).
CONCLUSIONS
These results suggest that the intermaxillary relationship captured by the digital scan method by using IOSs had better precision than that obtained by the conventional method.
Topics: Humans; Dental Impression Technique; Models, Dental; Dental Arch; Computer-Aided Design; Calcium Sulfate; Imaging, Three-Dimensional; Dental Impression Materials; Silicones
PubMed: 33775391
DOI: 10.1016/j.prosdent.2021.01.021 -
Clinical Oral Implants Research Oct 2018This systematic review and meta-analysis were conducted to assess and compare the accuracy of conventional and digital implant impressions. The review was registered on... (Meta-Analysis)
Meta-Analysis
AIM
This systematic review and meta-analysis were conducted to assess and compare the accuracy of conventional and digital implant impressions. The review was registered on the PROSPERO register (registration number: CRD42016050730).
MATERIAL AND METHODS
A systematic literature search was conducted adhering to PRISMA guidelines to identify studies on implant impressions published between 2012 and 2017. Experimental and clinical studies at all levels of evidence published in peer-reviewed journals were included, excluding expert opinions. Data extraction was performed along defined parameters for studied specimens, digital and conventional impression specifications and outcome assessment.
RESULTS
Seventy-nine studies were included for the systematic review, thereof 77 experimental studies, one RCT and one retrospective study. The study setting was in vitro for most of the included studies (75 studies) and in vivo for four studies. Accuracy of conventional impressions was examined in 59 studies, whereas digital impressions were examined in 11 studies. Nine studies compared the accuracy of conventional and digital implant impressions. Reported measurements for the accuracy include the following: (a) linear and angular deviations between reference models and test models fabricated with each impression technique; (b) three-dimensional deviations between impression posts and scan bodies respectively; and (c) fit of implant-supported frameworks, assessed by measuring marginal discrepancy along implant abutments.) Meta-analysis was performed of 62 studies. The results of conventional and digital implant impressions exhibited high values for heterogeneity.
CONCLUSIONS
The available data for accuracy of digital and conventional implant impressions have a low evidence level and do not include sufficient data on in vivo application to derive clinical recommendations.
Topics: Computer-Aided Design; Databases, Factual; Dental Implantation; Dental Implants; Dental Impression Materials; Dental Impression Technique; Dental Marginal Adaptation; Dental Prosthesis Design; Dental Prosthesis, Implant-Supported; Humans; Image Processing, Computer-Assisted; Imaging, Three-Dimensional; Models, Dental; Treatment Outcome
PubMed: 30328182
DOI: 10.1111/clr.13273 -
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