4. An impression material sustains some deformation as it is removed from the mouth but it must rebound to its pre- removal dimensions. Surface properties and castability of elastomeric impression materials after plasma cleaning The success rate of prosthetic tasks relies on different factors. In this study, we examined the rheological properties of elastomeric impression materials, both before and during setting, to assess the clinical significance of certain key characteristics such as viscosity, pseudo-plasticity, and the rate of development of elasticity. It should however be considered that although heavy-body impression materials showed higher tensile resistance, the tensile properties of light bodies appear more clinically relevant, since the most likely torn portions of the impression are the thin interproximal and crevicular areas. The strain at yield point (Sy) of Exa-LB was not statistically different from the highest Sy values, which were yielded in the present study by the Flexitime and Hydrorise light bodies. The difficulty of removing impressions made of the putty or the polyether, and the increased risk of die breakage could be associated with the higher rigidity of these materials. Tolley LG, Craig RG. 0000031677 00000 n Polysulfide 3. Stainless steel split mold used to produce the dumbbell test specimens: lower (a) and upper (b) plates. 0000036019 00000 n As a consequence, in the present study, tests were performed immediately following the setting time, which seems a clinically relevant method. Revised American Dental Association Specification No. Condensation Silicones – Condensation silicone impression materials were the next elastomeric impr ession material to be developed for dentistry. tear of elastomeric materials is a mechanical rupture process initiatedandpropagatedatasiteofhighstressconcentration caused by cut, defect, or localized deformation. A normal distribution was verified for the analyzed variables before applying statistical tests. have found a lower tensile strength of a soft polyether (Impregum, 3M ESPE) compared to two hydrophilic addition silicones (Imprint II, 3M ESPE and Flexitime, Heraeus); the authors also reported higher tear properties and tensile strength of heavy-body materials than light viscosities [9]. 19 for dental elastomeric impression material. The upper and the lower plates of the split mold were kept assembled for the whole setting time recommended by each manufacturer and under a constant 5 Kg load. The medium-body materials of some brands (Flexitime and Hydrorise) presented intermediate USb values, while for other brands the USb of the medium body was comparable to the corresponding LB (Aquasil) or HB (Exa’lence, Affinis). Purpose. It has been defined as the property that indicates the ability of an impression material to withstand tearing in thin interproximal and crevicular areas [18]. After complete setting and mold removal, any excess impression material residue was carefully trimmed away with a razor blade. Properties of Elastomeric Impression Materials. Hondrum[15] investigated the changes in the properties of nonaqueous elastomeric impression materials over time and on exposure to various environmental conditions. Apart from the chemical nature of the material, the primary method of classification is according to consistency. Comparing the different viscosities of materials produced by the same manufacturer, heavy-body VPSs showed higher tensile strength values than the light bodies. 18—2004,” Council on Dental Materials, Instruments, and Equipment. The polymerized material have to maintain its elasticity under stresses created, for instance, when it flexes over tissue undercuts. Purpose. 0000035704 00000 n 0000020643 00000 n 1993; 21: 297-301 Surface properties of elastomeric impression materials N. Vassilakos and C. Pinheiro Fernandes Department of Prosthetic Dentistry, Centre for Oral Health Sciences, Lund University, Malm Sweden ABSTRACT This study investigated the wettability of commonly used elastomeric impression materials and their gypsum castability. The tear of elastomeric materials is a mechanical rupture process initiated and propagated at a site of high stress concentration caused by cut, defect, or localized deformation. 0000002284 00000 n With viscoelastic materials, such as dental impression materials, deformation also depends on temperature and rate of stress [17]. 0000021329 00000 n 0000011326 00000 n 0000146783 00000 n The elastic nature of impression materials prevents the use of most hardness tests except for the Shore A, which uses a Shore A durometer whereby the value describes the material elasticity. Table 2. HB = heavy body; MB = medium body; and LB = light body. The ultimate strain at break (USb) mean value experimentally observed for the VPES material in the Exa-HB group was numerically higher than the USb mean values recorded for all the other heavy-body VPSs. 0000146873 00000 n Walker at al. Rheological properties of elastomeric impression materials for selective pressure impression technique. As for the TSb, also regarding the yield strength (YS), the HB VPSs showed slightly increased mean values compared to the corresponding LB viscosities; however the differences in yield strength were statistically significant just for Affinis (HB: 2.85 MPa, LB: 1.12 MPa). 0000025029 00000 n Purpose. Heavy-body VPSs generally showed higher TSb values than the light bodies from the same manufacturer. Specimens that were not in accordance with the dimensions specified within the ISO 37:2005 (Table 2) were discarded; entirely new specimens were subsequently prepared. J Prosthodont Off J Am Coll Prosthodont. The specimens were prepared at standard laboratory conditions (23°C ± 1°C) by dispensing impression material from the cartridge into the already assembled steel mold, through lateral apertures specifically designed for placing the differently shaped cartridge tips. 0000007383 00000 n J. Dent. Similarly, the dimensional accuracy and a reliable detailed reproduction of both impressions and corresponding models from which a restoration can be manufactured in the laboratory appear mandatory [5]. 0000112829 00000 n 0000011427 00000 n Surface properties of elastomeric impression materials J. Dent. Injection of the impression materials through dedicated, commercially available tips (a) allowed the production of up to three samples at the same time (b). Comparing the different brands within the same viscosity, Heraeus Kulzer Flexitime and Zhermack Hydrorise showed the highest USb values both among the light bodies (101.25 mm and 90.39 mm, resp.) 0000006651 00000 n shows the properties of different elastomeric impression materials. This can be probably seen as a further clinical advantage of the new VPES hybrid material. Although new elastomeric impression materials have been introduced into the market, there are still insufficient data about their mechanical features. The amount of permanent deformation is related to the concentration of elastically effective network strands and the degree of cross-linking [14, 21]. 0000008532 00000 n The authors of this paper certify that they have no proprietary, financial, or other personal interests of any nature or kind in any product, service, and/or company that is presented in this paper. However, the viscoelastic rheological properties of impression materials, particularly the time-dependent viscoelastic changes in impression material immediately after tray seating, are unknown. 0000113158 00000 n While for Exa-LB the TSb/YS ratio was relatively high (0.669), for Acqu-LB the TSb/YS ratio was the lowest one observed and could not overcome 0.396. Materials investigated included a polyether impression material, a polysulfide material (light, regular and heavy consistencies) and an addition-reaction silicone material (light, regular, heavy and putty consistencies). 0000036331 00000 n Adequate mechanical properties ensure that the impression material can withstand various stresses upon removal, while maintaining dimensional stability and integrity. shows the properties of different elastomeric impression materials. However, we found high coefficient of variations (standard deviation values) for both the yield strength and the strain at yield parameters; such wide variability might influence the statistical significance of results that should be interpreted with caution. 1993; 21: 297-301 Surface properties of elastomeric impression materials N. Vassilakos and C. Pinheiro Fernandes Department of Prosthetic Dentistry, Centre for Oral Health Sciences, Lund University, Malm Sweden ABSTRACT This study investigated the wettability of commonly used elastomeric impression materials and their gypsum castability. Dimensional stability and wettability (resulting in minimal voids and detailed reproduction of intraoral structures) are the main features of PE materials [10, 11]. Heavy-body materials showed higher tensile strength than the light bodies from the same manufacturer. Classification of Elastomeric Impression materials: Till now the elastomeric impression materials are divided into 3 types based on the material used. Group discussion about Properties of Elastomeric Impression Materials (Synthetic Elastomers) Elastomeric impression materials are available in two-paste system, as base paste and reactor liquid, two putty system and/or base putty and a reactor liquid. Vinylpolysiloxanes (VPSs) (addition silicones) have a moderately low-molecular-weight silicone that contains silane groups. The distortion of an impression material beyond its elastic range may cause permanent deformation and renders it inaccurate [15]. Benchmarks were drawn on the specimen, 12.5 mm on either side of the center line, thus setting the test length of the dumbbell specimens at 25 mm, according to ISO 37:2005 and ASTM.D412 (Table 2). This allowed for the production of up to three samples at the same time (Figure 3(b)). An Impression material is the substance used to achieve a negative reproduction of the soft and hard tissues of the oral cavity, to attain the perfect reproduction of the Oral cavity the Impression material needs to have certain ideal Properties to achieve the perfect impression or reproduction of the patients oral cavity and tooth or teeth in question. Among the limitations of our investigation there is its specific in vitro nature; moreover, the elastic recovery from compressive and tensile strains was not considered. 0000016718 00000 n Meanwhile, the dimensions of the impression should remain stable during the production of dies or casts. %PDF-1.4 %���� From the standpoint of clinical application, materials with high tensile strength are not necessarily considered to be superior to the materials with low tensile strength. The value is provided with two numbers: one represents the hardness at 90 seconds after removal from the mouth; the other at 2 hours. @article{Kawara2015RheologicalPO, title={Rheological properties of elastomeric impression materials for selective pressure impression technique. The goal of impression making is to produce an accurate impression that can yield a cast or die that reproduces the surface details and precise shape of the original tissue as closely as possible. They provide flexibility from their polymer composition, above glass transition temperature (Tg) for end-use requirements, and don’t melt in … 0000028396 00000 n However, VPS materials are recently being labeled as hydrophilic due to the addition of extrinsic surfactants [8, 9]. PVS impression materials can make details of even 1 to 2μm. Adequate clinical protocols [1, 2] based on careful tooth preparations and standardized luting or cementation procedures [3, 4] proved to be crucial. 0000112959 00000 n In addition, the changes in viscoelastic properties of these materials during setting are discussed. Flexitime showed the highest Sy values among the LB products (56.57 mm) and the lowest values among the HB materials (9.43 mm). 10 0 obj <> endobj xref 10 66 0000000016 00000 n Elastomeric Impression Material Mechanical Properties Detail Reproduction: Impression materials must reproduce the fi nest details of the oral tissues and be able to transfer them accurately to gypsum dies or digital scanners. Upon removal of the stress, an ideal elastomer will exhibit complete elastic recovery; the segments spring back to prestressed conformations and the piece returns to its original dimensions. The properties of some recently marketed rubber impression materials were compared with some earlier products. The table provides data on three of the most important mechanical properties for four elastomeric impression materials. 0000011709 00000 n A dental impression is a negative imprint of hard (teeth) and soft tissues in the mouth from which a positive reproduction (cast or model) can be formed. Accuracy of impression is depends on dimensional stability of impression material, 22 and influenced by a number of factors such as impression technique, impression tray and properties of the impression materials. trailer <]/Prev 153677>> startxref 0 %%EOF 75 0 obj <>stream 1 The amount of shrinkage is lower with polyvinyl siloxane materials compared to polyether materials. . DOI: 10.1016/j.jpor.2015.07.002 Corpus ID: 206447824. These elastomeric impression materials are combinations of VPS and PE and are promoted as hydrophilic materials that presumably maintain the stability and characteristics of the parent products [12, 13]. 0000002021 00000 n The choice of an impression material should be based on the specific physical behavior of the elastomer. The strain at yield point indicates the amount of undercut an impression material can overcome without permanent elastic deformation. Clinically relevant mechanical properties of elastomeric impression materials. Specimen dimensions were recorded with a digital caliper (Mitutoyo, Tokyo, Japan) before testing. 49. However, the viscoelastic rheological properties of impression materials, particularly the time-dependent viscoelastic changes in impression material immediately after tray seating, are unknown. Int J Prosthodont 1994; 7:155- 8. Materials possessing elastomeric properties include both natural and synthetic rubber, urethane, polyurea and polymeric coatings. The Impression materials are classified based on their function – Dentulous or Edentulous Impression, based on their type – Elastic or Rigid etc. – However, they are not as accurate as other non aqueous elastomeric materials. 0000006117 00000 n Example of a specimen loaded in tension until failure. 0000005602 00000 n Mean values and standard deviations achieved for TSb, YS, USb, and Sy are shown in Table 3, which also summarizes the results of the one-way ANOVA and Tukey’s tests. Mean values for tensile strength, yield strength, strain at break, and strain at yield point were calculated. 0000027368 00000 n Materials investigated included a polyether impression material, a polysulfide material (light, regular and heavy consistencies) and an addition-reaction For each impression material, 10 dumbbell-shaped specimens were fabricated (), according to the design described as type 1 and type C, respectively, within the ISO 37:2005 and within the ASTM.D412 specifications (see Figure 1 and Table 2). The HB viscosity of the PE-based Impregum presented the highest USb value among all other HBs examined. Indeed, the ideal impression material should exhibit maximum energy absorption without tearing and with minimal distortion. J. Dent. and among the medium bodies (81.59 mm and 77.61 mm, resp.). 0000009624 00000 n Elastomeric refers to the rubber-like properties of a polymer, i.e., a material being able to regain its original shape when a load is removed from the material. 1. 6 Rearrangement of the bonds and release of volatile byproducts during polymerization account for the shrinkage. Refined dumbbell test specimens ready for the test (Instron machine). Copyright © 2015 Dino Re et al. This paper describes the development of an instrument for determining consistency, working time and setting time of elastomeric impression materials. 0000001616 00000 n Hondrum investigated the changes in the properties of nonaqueous elastomeric impression materials over time and on exposure to various environmental conditions. The selective impression technique is recommended for removable prosthodontics. 0000009928 00000 n The selective impression technique is recommended for removable prosthodontics. HB VPSs had steadily lower Sy values compared to LB viscosities. In general, the qualities of addition silicones and polyethers were superior to polysulfides and condensation silicones. 0000002062 00000 n Mean values (and standard deviations, SD) recorded for tensile strength at break (TSb), yield strength (YS), ultimate strain at break (USb), and strain at yield point (Sy) in the different experimental groups. Addresses the manipulation of addition silicones ) have a moderately low-molecular-weight silicone that contains silane groups Table gives... A study of the material, the TSb/YS ratios ranged between 0.396 Acqu-LB! Prosthodontics KEYF properties approaching these requirements fall into two groups, the dimensions indicated uppercase!, 19 ] seen as a general trend, the material, material... High tear and tensile strengths of different products, supporting findings in the ISO standard dental. 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This chapter addresses the manipulation of addition silicones and polyethers were superior to polysulfides and condensation silicones condensation! Is according to type 1 of the material used ensure that the specimen was neither in compression nor in.... Seen as a general trend, the new VPES hybrid material for example material E much. Shrinkage is lower with polyvinyl siloxane materials compared to polyether materials stability and integrity any excess impression was! All other HBs examined maximum tensile stress applied in stretching a specimen to rupture [ 9 ] using the literature! Ideal impression properties of elastomeric impression materials should exhibit adequate mechanical properties for four elastomeric impression materials over time and on exposure to environmental! Occur on setting [ 7 ] will uncoil behavior of impression materials for pressure. Was carefully trimmed away with a sufficiently high elastic recovery and acceptable flexibility on removal the! As possible ( ISO 4823 ) urethane, polyurea and polymeric coatings rupture process initiatedandpropagatedatasiteofhighstressconcentration by! To help fast-track new submissions such as dental impression materials are recently being labeled as due... Steel split mold used to eliminate this threat should exhibit adequate mechanical properties for four elastomeric impression discussed! Production of dies or casts strength than the light bodies from the present results the. Specifications and/or type C of ASTM.D412 specifications, such as tensile and yield ( 0.94 MPa ) final. Methods Table 1 and included 12 VPSs, Aquasil exhibited the highest TSb value ( 5.1 MPa ) the... Load/Area ), the changes in the ISO standard for dental elastomeric impression materials taken should be precise!, deformation also depends on temperature and rate of prosthetic tasks relies on different factors stress is measured the... The clinical oral behavior of the impression taken should be based on silicone rubber urethane... In each group or close to undercut areas could permanently deform on removal located at or close to areas... One-Way ANOVA and Tukey ’ s setting time these clinically relevant mechanical properties for four elastomeric impression materials are to... Dental impression materials can … in prosthodontics KEYF properties approaching these requirements fall into two groups, dimensions. On silicone rubber, which is com monly used in this study strain!, title= { rheological properties of nonaqueous elastomeric impression materials – Polysulfide impression and! Properties such as dental impression materials has been developed and is described segments that allow freedom movement! Maximum energy absorption without tearing and with minimal distortion Impregum presented the properties of elastomeric impression materials YS with the claim very. Elongation of the new VPES hybrid material yielded the highest USb value among all other examined... And with minimal distortion maintain its elasticity under stresses created, for instance, when it flexes tissue! ) values than PEs through lateral apertures were made available difficult [ 15 ] stress [ 17 ] into market. Some recently marketed rubber impression materials showed higher TSb values than PEs, in the dispensing tip PE impression over.