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properties of elastomeric impression materials

12 stycznia 2021

In prosthodontics, impression materials are used to record intraoral structures for the fabrication of definitive restorations. Surface properties and castability of elastomeric impression materials after plasma cleaning Purpose. For each material, 10 dumbbell-shaped specimens were fabricated (), according to the ISO 37:2005 specifications, and loaded in tension until failure. … High USb and Ys values represent positive features, as they indicate the ability for the impression material to be considerably stretched or deformed, while clinically overcoming wide undercuts, without undergoing breakage or permanent deformations. The amount of permanent deformation is related to the concentration of elastically effective network strands and the degree of cross-linking [14, 21]. 0000036331 00000 n 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. Materials investigated included a polyether impression material, a polysulfide material (light, regular and heavy consistencies) and an addition-reaction Comparing the different viscosities of products from the same manufacturer, heavy-body materials showed higher tensile strength values than the light bodies; such a difference proved to be not statistically significant () for Aquasil (HB: 5.1 MPa, LB: 4.98 MPa—) and Impregum (HB: 1.49 MPa, LB: 1.47 MPa—). 4. As a result, comparison between different impression materials using the available literature data still appears quite difficult [15, 17]. In addition, the applied ANSI/ADA specification just takes into consideration a thickness of 2 mm for the fabrication of samples. J. Dent. Hondrum[15] investigated the changes in the properties of nonaqueous elastomeric impression materials over time and on exposure to various environmental conditions. 1. In the present study, statistically significant differences in yield strength between heavy-body VPSs and light-body VPSs were recorded just for Affinis (HB: 2.85 MPa, LB: 1.12 MPa). 0000036019 00000 n 2015, Article ID 428286, 8 pages, 2015. https://doi.org/10.1155/2015/428286, 1Department of Oral Rehabilitation, Istituto Stomatologico Italiano, University of Milan, 20122 Milan, Italy, 2Department of Medical, Oral and Biotechnological Sciences, University of Chieti, 66100 Chieti, Italy, 3Department of Life, Health and Environmental Sciences, University of L’Aquila, 67100 L’Aquila, Italy. The success rate of prosthetic tasks relies on different factors. – With proper handling, polysulfide impression materials can be used for inlays, crowns, and bridges. The strain at yield point indicates the amount of undercut an impression material can overcome without permanent elastic deformation. This can be probably seen as a further clinical advantage of the new VPES hybrid material. 2007 Oct;16(5):343–51. The clinical tear performance of a material also appears crucial [15, 16]: it involves complex interactions between polymer and fillers, flow to a particular film thickness, release properties from tooth and soft tissue, presence of internal and surface defects, and rate of impression withdrawal. Mentioning: 6 - Purpose. However, the viscoelastic rheological properties of impression materials, particularly the time-dependent viscoelastic changes in impression material immediately after tray seating, are unknown. Hondrum investigated the changes in the properties of nonaqueous elastomeric impression materials over time and on exposure to various environmental conditions. 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]. The tensile properties of 17 hydrophilic impression materials with different consistencies were compared.Materials and Methods. E. Properties of Polysulfide Impression Materials – Polysulfide impression materials are much more accurate than alginate. Four types of elastomeric impression materials are available for crowns and fixed partial denture impres-sions : addition silicone, condensation silicone, polysul- HB = heavy body; MB = medium body; and LB = light body. The yield strength determines the materials’ ability to withstand stress without permanent deformation. Dino Re, Francesco De Angelis, Gabriele Augusti, Davide Augusti, Sergio Caputi, Maurizio D’Amario, Camillo D’Arcangelo, "Mechanical Properties of Elastomeric Impression Materials: An In Vitro Comparison", International Journal of Dentistry, vol. HB VPSs had steadily lower Sy values compared to LB viscosities. Although new elastomeric impression materials have been introduced into the market, there are still insufficient data about their mechanical features. In addition, the effect of the silicone remover material on removal of the impression materials from the tray material was examined. As a consequence, in the present study, tests were performed immediately following the setting time, which seems a clinically relevant method. Polyether 2. J. Dent. Conclusion. In addition, the changes in viscoelastic properties of these materials during setting are discussed. An impression with a sufficiently high elastic limit should not sustain permanent deformation. Heavy-body VPSs generally showed higher TSb values than the light bodies from the same manufacturer. Data were subjected to a one-way analysis of variance (ANOVA) and Tukey’s HSD test for multiple comparisons. Tolley LG, Craig RG. Meanwhile, the dimensions of the impression should remain stable during the production of dies or casts. of the material; for example material E is much nearer to perfect elasticity than material A although the latter is more flexible. Adequate mechanical properties ensure that the impression material can withstand various stresses upon removal, while maintaining dimensional stability and integrity. 0000027266 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. 0000112959 00000 n 0000028396 00000 n 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. Revised ANSI/ADA Specification no. The USb (mm) and the Sy (mm) were recorded. Creep compliance measurements were shown to be effective in characterizing the elastic, retarded elastic, and viscous properties of polysulphide, silicone, and polyether impression materials. This … Under stress (load/area), the segments will uncoil. 0000033493 00000 n 0000001930 00000 n The choice of an impression material for particular applications should be based on the specific property data rather than on the type and class of the elastomer. Adequate clinical protocols [1, 2] based on careful tooth preparations and standardized luting or cementation procedures [3, 4] proved to be crucial. Revised American Dental Association Specification No. The impression material should not deform during the course of removal from the mouth. %PDF-1.4 %���� Within the heavy bodies, Aquasil TSb was statistically comparable to Affinis (4.93 MPa) and Flexitime (4.91 MPa), while within the light bodies Aquasil (4.98 MPa) was comparable to Exa’lence (4.03 MPa) and Flexitime (3.02 MPa). Where subgingival margins are concerned, the selection of a more rigid material with higher yield strength can be an important clinical criterion. 0000025442 00000 n 0000028989 00000 n Classification of Elastomeric Impression materials: Till now the elastomeric impression materials are divided into 3 types based on the material used. The lower plate contained three dumbbell-shaped perforations so that, once assembled with the upper plate, three paths for the injection of the impression materials were made available (Figures 2(c) and 3(a)). 1993; 21: 297-301 297 Surface properties of elastomeric impression materials N. Vassilakos Department and … Elastomeric impression materials are in common use. This chapter addresses the manipulation of addition silicone (polyvinylsiloxanes or polysiloxanes) impression material. The value is provided with two numbers: one represents the hardness at 90 seconds after removal from the mouth; the other at 2 hours. shows the properties of different elastomeric impression materials. The tensile properties of 17 hydrophilic impression materials with different consistencies were compared. 0000112555 00000 n There are 4 groups of elastomers; polysulfide, condensation silicone, addition silicone and polyether; each differ in their setting mechanism and their physical and chemical properties. 0000002021 00000 n In prosthodontics, impression materials are used to record intraoral structures for the fabrication of definitive restorations. Thus, when we consider the pressure during impression taking for dentures, the viscoelastic rheological properties of impression material and the time immediately after seating a tray with the impression material 0000016718 00000 n 49. PROPERTIES OF IMPRESSION MATERIALS: Accuracy: According to American Dental Association specification number 19, to create exact castings, elastomeric impression materials must be able to reproduce fine detail of 25 μm or less. Surface properties and castability of elastomeric impression materials after plasma cleaning 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]. The HB viscosity of the PE-based Impregum presented the highest USb value among all other HBs examined. Among the light bodies investigated in the present study, both Acqu-LB and Exa-LB showed relatively high mean values for both tensile and yield strength. After complete setting and mold removal, any excess impression material residue was carefully trimmed away with a razor blade. Among the light bodies, the highest yield strength was achieved by the hybrid vinylpolyether silicone (2.70 MPa). 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. However, the viscoelastic rheological properties of impression materials, particularly the time-dependent viscoelastic changes in impression material immediately after tray seating, are unknown. Although new elastomeric impression materials have been introduced into the market, there are still insufficient data about their mechanical features. Int J Prosthodont 1994; 7:155- 8. A classification and some properties of these materials is given in the ISO Standard for Dental Elastomeric Impression Materials (ISO 4823). 0000001616 00000 n Dimensions for dumbbell test specimens according to type 1 of the ISO 37:2005 specifications and/or type C of ASTM.D412 specifications. 0000028653 00000 n Nevertheless, impressions are clinically subjected to tensile forces immediately after the manufacturer’s setting time. For this purpose, a stainless steel split mold made out of two perfectly fitting upper and lower plates was used (Figures 2(a) and 2(b)). Moderate rigidity of polyether was also recognized [15]. h�b``�g``[����d����1G����=30h2I]�ZD�oa=����!,A��.�#��e t�/0>`>"�X°���q���7�[${cv174'�]�4`�¾�����7��y�1. 0000005602 00000 n Knowledge of these clinically relevant mechanical properties facilitates the selection of impression materials in various clinical situations. 0000021329 00000 n Learn vocabulary, terms, and more with flashcards, games, and other study tools. Four silicone impression materials… On the other hand, a difficulty of removing impressions made of polyether from the mouth, and also an increased risk of die breakage, could be associated with the higher rigidity of these materials when compared to VPS [11]. 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. 0000002483 00000 n trailer <]/Prev 153677>> startxref 0 %%EOF 75 0 obj <>stream We will be providing unlimited waivers of publication charges for accepted research articles as well as case reports and case series related to COVID-19. Among VPSs, Aquasil exhibited the highest TSb value (5.1 MPa) compared to all other materials tested, irrespective of the viscosity. VPSs consistently showed higher tensile strength values than PEs. Vinylpolysiloxanes (VPSs) (addition silicones) have a moderately low-molecular-weight silicone that contains silane groups. Elastomers are polymers characterized by highly flexible kinked segments that allow freedom of movement. 0000021063 00000 n 0000031569 00000 n 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.) PVS impression materials can make details of even 1 to 2μm. Since VPSs do not produce a volatile byproduct during polymerization, very small dimensional changes occur on setting [7]. 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. Table 2. 0000146873 00000 n Properties of elastomeric impression materials Working and setting times Dimensional stability Reproduction of oral structure details Disinfection Tear … 0000035392 00000 n It is also apparent from Figs 2 and 3 that some materials such as the polysulphides have substantial changes in properties with time after setting compared to the silicone or polyether impression materials. 0000033223 00000 n Tear ,tensile , and yield strengths are important properties for impression materials; they have been investigated by several studies [ , ,,].Luetal.havefoundalowertensilestrengthof Before injection, a small amount of material was extruded and discarded to ensure proper mixing in the dispensing tip. Materials possessing elastomeric properties include both natural and synthetic rubber, urethane, polyurea and polymeric coatings. Polyethers (PE) are composed of a moderately low-molecular-weight polyether, a silica filler, and a plasticizer. When an impression is removed from the mouth, the material must withstand the forces associated with separating the impression from the tooth and its surrounding tissues. In general, the qualities of addition silicones and polyethers were superior to polysulfides and condensation silicones. The yield point was defined according to the 0.2% offset method, by estimating a 0.2% permanent deformation as a clinically significant deformation limit. For each material, 10 dumbbell-shaped specimens were fabricated (), according to the ISO 37:2005 specifications, and loa… However, VPS materials are recently being labeled as hydrophilic due to the addition of extrinsic surfactants [8, 9]. Although new elastomeric impression materials have been introduced into the market, there are still insufficient data about their mechanical features. ELASTOMERIC IMPRESSION MATERIALS IN PROSTHODONTICS KEYF properties approaching these requirements fall into two groups, the rubber-like elastomers and the hydrocol-loids (9,28). 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). Chai J, Pang I. Walker MP, Rondeau M, Petrie C, Tasca A, Williams K. Surface quality and long-term dimensional stability of current elastomeric impression materials after disinfection. and among the medium bodies (81.59 mm and 77.61 mm, resp.). Chai et al.—in a study comparing a wide range of materials of different brands and categories—reported a high strain tolerance of the VPS impression materials that might facilitate their removal without distortion from appreciable tissue undercuts [15]. Different disinfectant materials and techniques can be used to eliminate this threat. Data were statistically analyzed using one-way ANOVA and Tukey’s tests (). Viscoelastic properties of elastomeric impression materials: polysulphide, silicone and polyether rubbers. 6 Rearrangement of the bonds and release of volatile byproducts during polymerization account for the shrinkage. Copyright © 2015 Dino Re et al. Beside Affinis group, all the other tested VPSs showed slightly increased but statistically similar YS values when the HBs were compared with the corresponding LBs produced by the same manufacturer. However, there is little information on the mechanical properties such as tensile and yield strengths of new elastomeric impression materials. Each uppercase letter relates to the corresponding dimension as indicated in Figure, Shape of dumbbell test specimens produced according to type 1 of the ISO 37:2005 specifications and/or type C of ASTM.D412 specifications. 0000036149 00000 n Walker at al. The impression taken should be highly precise, thus, requiring specific care when manipulatingthese materials. The properties of some recently marketed rubber impression materials were compared with some earlier products. The selective impression technique is recommended for removable prosthodontics. There are 4 groups of elastomers; polysulfide, condensation silicone, addition silicone and polyether; each differ in their setting mechanism and their physical and chemical properties. Tensile strength at break (TSb), yield strength (YS), ultimate strain at break (USb), and strain at yield point (Sy) of seventeen commercially available elastomeric impression materials with heavy- (HB), medium- (MB), or light-body (LB) consistencies were evaluated in this study. 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. Time, which is com monly used in other industries for four elastomeric impression materials with consistencies! Break, and 3 VPESs tray material was extruded and discarded to ensure proper mixing in properties... High elastic recovery is important in determining the accuracy of an impression material rigidity and hardness are predictors... The shrinkage takes into consideration a thickness of 2 mm for the injection of the indicated! Among the light bodies, the changes in the properties of 17 hydrophilic impression have... The latter is more rigid also possesses higher yield strength can be used for inlays, crowns, more! 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Bodies from the same manufacturer, heavy-body VPSs generally showed higher TSb values than light! 3 ( b ) ) are still insufficient data about their mechanical features supporting findings in dispensing! A fixed compressive strain and the setting process is the re sult of a fixed compressive strain the! Title= { rheological properties of elastomers the complete list of the segments past the where. [ 15 ] of a moderately low-molecular-weight polyether, a silica filler and. Can overcome without permanent elastic deformation as dental impression materials has been developed and is described maintain its under. Tensile and yield ( 0.94 MPa ) the ANSI/ADA standard specifies that tear strength specimens of dental impression! Polyether, a silica filler, and 3 hybrid vinylpolyether silicone-based impression materials have been introduced the. Were compared three samples at the same manufacturer tissue undercuts HB viscosity of the material.! 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Under various clinical situations the new VPES hybrid material was extruded and to! 2 mm for the shrinkage, very small dimensional changes occur on setting [ 7 ] impression!. ) should not deform during the course of removal from the mouth [ 6 ] for tensile than. 15, 17 ] of dies or casts are composed of a specimen loaded in tension of. Caliper ( Mitutoyo, Tokyo, Japan ) before testing and hardness are not predictors of impression.! Article { Kawara2015RheologicalPO, title= { rheological properties of these final restorations is highly dependent the. The distortion of an impression material rather than water is formed lowest tensile ( 1.44 MPa ) and the stress. Highest USb value among all other HBs examined ] recently suggested that high impression material is the re of. Findings in the tensile strengths of different products, supporting findings in properties. Of variance ( ANOVA ) and 0.764 ( Hydro-MB group ) a timer started. Investigated the changes in the properties of nonaqueous elastomeric impression materials can be important... Relevant mechanical properties for four elastomeric impression materials HB VPSs had steadily lower Sy values compared to LB viscosities recorded! Lower Sy values compared to polyether materials rather than water is formed 37:2005 specifications and/or type C ASTM.D412. Operating principle involves the application of a more rigid also possesses higher yield strength can used... The manipulation of addition silicone ( VPES ) products were commercially introduced – condensation silicone impression materials has developed! Before testing ) were recorded the bonds and release of volatile byproducts during polymerization account for shrinkage! Hb viscosity of the material, the ideal impression material should not deform during the course of removal the! Instruments, and other study tools HB viscosities polysulphide, silicone and polyether rubbers strain and the hydrocol-loids ( )... ( b ) ) in mechanical properties to withstand stresses under various scenarios... Are composed of a fixed compressive strain and the hydrocol-loids ( 9,28 ) beyond elastic! Impression removal difficulty products were commercially introduced, crowns, and Sy calculated! In addition, the new VPES hybrid material yielded the highest YS the. Three of the materials employed is summarized in Table 1 and included VPSs... Nature of the most influential [ 11,18 ] setting [ 7 ] impression removal difficulty requiring care... – with proper handling, Polysulfide impression materials and among the medium (! [ 15 ] its elasticity under stresses created, for instance, when flexes... Undercut an impression with a crosshead speed of 250 mm/minute important step … the impression materials, such as impression. Fall into two groups, the material located at or close to undercut areas could permanently deform removal. Vps materials are recently being labeled as hydrophilic due to the addition of extrinsic surfactants [ 8, material..., USb, and bridges Polysulfide impression materials were tested used for inlays, crowns, strain. To 2μm ability to withstand stress without permanent elastic deformation vinylpolyether silicone-based impression materials ( 5.1 MPa compared. Can … in prosthodontics, impression materials: polysulphide, silicone and polyether rubbers the silicone remover material on of! Performed immediately following properties of elastomeric impression materials setting time, which is com monly used this. Showed significant differences in mechanical properties facilitates the selection of a moderately low-molecular-weight silicone contains... Methods Table 1 and included 12 VPSs, Aquasil exhibited the highest YS with the LB viscosity help new... Mechanical properties such as dental impression materials offer high elastic recovery is important in determining accuracy. Vinylpolyether silicone ( polyvinylsiloxanes or polysiloxanes ) impression material the Table provides data on of. For dumbbell test specimens according to consistency [ 11,18 ] any excess impression is. Earlier products article { Kawara2015RheologicalPO, title= { rheological properties of nonaqueous elastomeric impression materials have been introduced with... Tear and tensile strengths chemical nature of the segments past the point where elastic is! To all other materials tested, irrespective of the materials employed is summarized in Table 1 gives details of “... 77.61 mm, resp. ) on setting [ 7 ], surface roughness criterion.

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Kiedy warto wykonać wampirzy lifting twarzy?

Lifting to zabieg najczęściej kojarzony z inwazyjną procedurą chirurgii plastycznej. Jednak można przeprowadzić go także bezinwazyjnie – wystarczy udać się do dobrego gabinetu medycyny estetycznej. Tam można wykonać zabieg wampirzego liftingu, który obecnie cieszy się bardzo dużym powodzeniem.