Accuracy Of Impression Materials Research Articles

Accuracy of Impression Material During COVID-19 after Sterilization- In vitro Study

Aims: The goal of this research is to assess the effect of steam autoclave sterilization due to the impact of Covid-19 on the accuracy of the elastomer impression materials.
 Study Design: In vitro study.
 Place and Duration of Study: Department of oral and Maxillofacial Prosthodontics, King Abdul-Aziz University, Jeddah; Saudi Arabia, between June 2021 and November 2021.
 Methodology: The following materials were used in this study: fully dentate master cast, metal trays, elastomer impression material (addition silicon), type IV stone. Forte impressions made using the metal tray and elastomer impression materials. The impressions were separated equally into two groups: Control group (C.G), untreated impressions. Sterilized group (S.G): Impressions were sterilized by using the steam autoclave. To make stone castings for each group, they were poured with type IV stone. The traveling microscope was used to evaluate the impression material's dimensional accuracy and detail reproduction with and without autoclave sterilization.
 Results: The cross-arch distance (X) of the master model was measured (41.29 mm), While the cross arch distance (X) in the control group (C.G) of the untreated impressions had a mean and standard deviation of 41.492 ± 0.150 mm. In the tested group (S.G) : the sterilized impression, we found the cross-arch distance (X) had a mean and standard deviation of 41.628 ± 0.223 mm. The master model's Anteroposterior distance (A-P) was measured (21.12 mm). For the control group (C.G) : we found the mean and standard deviation value reading of the A-P distance were 20.899 ± 0.79 mm. For (S.G) group: we found the mean and standard deviation reading of the A-P distance were 19.992± 0.482 mm.
 Conclusion: Steam autoclave sterilization of the elastomer impression material should be considered carefully, especially when fabricating fixed partial dentures. If the impression material is to be used in making diagnostic castings, conventional steam autoclave sterilization of the elastomers impression material may be sufficient for patients.

Laboratory investigation of Accuracy of Impression Materials for Border Molding.

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. To determine the accuracy of different impression materials for border molding of individual impression trays. 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. 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. Good manipulative qualities and measured accuracy in laboratory tests define these materials as very good for border molding procedures.

Volumetric Change as a Parameter for the Accuracy of Impression Materials

In this paper we studied the behavior of some impression materials such as alginate, condensation and addition silicones, considering the following parameters: the reproductive capacity of morphological details - dimensional stability - the ability to reproduce with accuracy the ratio between morphological elements. The essential conditions that an impression material should fulfill are plasticity, fidelity, flexibility, good mechanical strength, dimensional stability, suitable setting time and compatibility with materials from which the models are manufactured.The study results indicated that condensation silicones present the highest volumetric changes, their contraction being the result of the evaporation of volatile byproducts.The dimensional stability of fingerprint materials is one of the variables that contribute to the accuracy or inaccuracy of dental prostheses, other factors being represented by the changes occurring during the preparation of the fingerprint material as well as the fingerprinting techniques.

Comparison of double-phase impression technique in 1 step and 2 steps by evaluating dimensional stability and accuracy of condensation silicones

The diverse viscosities of silicone impression materials are suited for their use in various impression techniques, intended to improve the precision of the cast impression in the form of a plaster model. The purpose of this research is to determine the dimensional stability and accuracy of the double-phase impression technique in 1 step and 2 steps by using a condensation silicone impression material. This research was carried out by using a precise stainless-steel master model and an individual aluminum tray. Comparing the abutments of the master model and the abutments of the double-phase impression technique in 2 steps, showed that they are wider on average 81 µm, while the abutments from the double-phase impression technique in 1 step are on average 281 µm wider in diameter. After analyzing the results obtained in relation to the diameter of the abutments, it can be concluded that the double-phase impression technique in 2 steps is dimensionally more stable and accurate compared to the double-phase impression technique in 1 step. This study shows that dimensional stability and accuracy of impression materials also depend on the selection of appropriate impression technique and proper performance in order to obtain a high quality dental impression that will be the basis for an accurate fixed-prosthodontic fabrication. Keywords: silicone impression material, impression technique, fixed partial dentures, dimensional stability and accuracy

Digital evaluation of the accuracy of impression techniques and materials in angulated implants

ObjectivesThe aim of this study was to investigate the accuracy of 2 different impression techniques and 3 different impression materials in models simulating parallel and angulated implants. MethodsThree master models simulating partial edentulous mandible with 2 implants at the sites of second premolars (parallel) and second molars with different angulations (parallel, 10° or 20° angulated) were fabricated. Two different impression techniques [splinted direct (D), indirect (I)] and 3 different monophase impression materials [polyether (PE), vinyl polysiloxane (VPS), vinyl polyether silicone (VPES)] were used for each master model and a total of 180 impressions were made (n=10). Master model and casts were scanned by a modified laser scanner and data were transferred to VRMesh software. Master model and duplicate cast scans were digitally aligned observing the superposition of anatomic markers. Angular and coronal deviations between master and duplicated copings were calculated and data were statistically analyzed. ResultsMean angular and coronal deviations were in a range of 0.205–0.359° and 22.56-33.33μm, respectively. Statistical analysis revealed that the angulation of implant affected both coronal and angular deviations of the impression copings (P<0.05). According to statistical analyses, for parallel implants, the accuracy of impression materials and techniques were ranging as VPS-D=PE-D>VPS-I=PE-I>VPES-D>VPES-I from most accurate to the least. For 10° and 20° angulated implants the most accurate material and technique was VPS-D whereas the least accurate combination was VPES-I (P<0.05). ConclusionAngulation, impression technique and material were found to be effective on the accuracy of implant impressions. Clinical significanceClinicians may prefer VPS impression material and splinted direct technique for impressions of both parallel and up to 20° angulated implants.

Accuracy of impression materials in a semi-clinical model

The accuracy of seven impression materials has been tested using a semi-clinical model. Impressions were taken on a CrCo-biteplane in which three premolars prepared for full crowns were mounted. The biteplane was placed in a test person's mouth. Stone dies poured from the impressions were measured in a measuring microscope. The results show that the semi-clinical test seems to give comparable data with laboratory tests and that all tested materials seem acceptable for clinical use in crown and short-span bridge work.

Effect of material bulk and undercuts on the accuracy of impression materials

A truncated cone-shaped chromium steel die was used to determine the influence of the bulk of elastomeric impression material and size of undercut on the dimension of stone dies. It was found that both conditions affect the accuracy of stone dies. The possible clinical implications of the inaccuracies were discussed.

A comparison of elastic impression materials

T ests for accuracy and other characteristics of elastic impression materials generally fall into one or more categories. These are: (1) Linear tests which measure the material itself (usually unidimensional) .le5 (2) Tests which depend upon the formation and measurement of gypsum dies made from the impression materials. In these tests, the dies are measured, not the impression material itself. The configurations of the test dies vary.6-g (3) Methods which employ the use of master dies and castings. Accuracy of the impression material in question is judged by trial of the master castings on the stone die replicas.*“-13 This is a report of an investigation of 14 elastic materials representative of those frequently used in dentistry for impression making. The purposes of the study were: ( 1) to develop and use a laboratory test method suitable for measuring the accuracy of impression materials; (2) to test the conformity of the impression materials to ADA Specification No. 19 (consistency and mixing and working times) ; (3) to compare, by indirect means, the accuracy of the impression materials 30 minutes after setting; (4) to demonstrate the dimensional changes that occurred in the impressions during the serial pouring of four sets of dies over a 24 hour period; and (5) to compare the accuracy of stone dies prepared promptly with the accuracy of those obtained after a 24 hour delay.