Elastic materials have a soft consistency but after setting, they become elastic. The plaster should be mixed with water or an anti-expansion solution in the ratio of 100g to 50-60ml. 9.1 Failure of Elastic Materials In terms of material behavior, failure means a change in the normal constitutive behavior of a material, usually in response to excessive loads or deformations that cause irreparable changes to the microstructure. Pakistan Oral & Dental Journal ol 35, No. It is aimed primarily at undergraduate dental students, although it will also be useful for practising dentists, dental technicians and dental assistants. The term elastic as applied to impression materials is fairly unequivocal since the materials which form this group all possess the ability to be stretched or compressed and give a reasonable degree of elastic recovery following strain. Elastic impression materials are capable of accurately reproducing both the hard and the soft structures of the mouth including the undercut areas and interproximal spaces 4. In the light of these facts, a study was planned to evaluate the elastic recovery of various elastomeric impression materials on autoclaving and comparing it to the currently practiced method of chemical disinfection. They are essential in daily clinical practice in all dental specialisations: conservative, cosmetic, aesthetic, prostheses, orthodontics, implantology and pediatric dentistry. The operating principle involves the application of a fixed compressive strain and the resulting stress is measured. US2359512A US479446A US47944643A US2359512A US 2359512 A US2359512 A US 2359512A US 479446 A US479446 A US 479446A US 47944643 A US47944643 A US 47944643A US 2359512 A US2359512 A US 2359512A Authority US United States Prior art keywords alginate impression water soluble insoluble … All NOTES We will discuss differences in elast materials References What we need to know for test Problem anaylisis o Need to capture the detail and have acurcy for casting / implants o Many areas of errors o Investing and casting are major changes o Prepared tooth with 8mm diameter for lets say a molar § Impression has 0.5 % accuracy realative to 8000 microsn à 40 microns à 20 microns on mesial vs. distal or buccal vs. lingual on the crown prep à so you are fine but not that good § But if you have implants on oppositie sides of the arch à 80,000 microns (not just 8,000) § So need even more accuracy § But for a single tooth or 3 unit bridge not a big problem classification – we will talk about types that polymerize Slide 6 -­‐ classification o Elastic à § Hydrocolilds à • Agar – need heating apparatus • Alginate – o He said something about ones that had enough accuracy for crown and bridge but there’s no pointer so don’t know what he’s talking about Impression objective o We want to take prepared teeth à impression à nice replica with tissue below finish line o So you know the right contour of the die relative to ceramic and metal Dies from impression o Making dies o Stone or epoxy dies o If stone die à need to factor in investment expansion of die stone o Epoxy à need to allow for more expansion (epoxy shrinks so need to consider) o Appplying the die spacer to make room for cement General forumlation • This updated thoroughly revised and revamped edition would serve the students, teachers and professionals associated with clinical dentistry. he said this in lecture but I don’t understand so I emailed him types of elastomeric impresion material o polysulfide, silicone, polyether, polyvinyl siloxane o these types all polymerize why remove impression quickly from mouth? modulus of elasticity Stiffness of a material within the elas - tic range. 3 0 obj of "elastic" impression materials are ob-tained from tests similar to those described in American Dental Association Specification no. Plus, the material’s excellent dimensional stability and elastic recovery ensures the impression arrives at the lab in the same condition it left your patient’s mouth. This updated thoroughly revised and revamped edition would serve the students, teachers and professionals associated with clinical dentistry. Impression materials, that is, the materials used to get an idea about the shape of teeth and the alveolar ridges, can be categorized as nonelastic and elastic materials. They reproduce an imprint faithfully, providing details of a high definition despite the presence of undercuts. This preview shows page 1 out of 8 pages. This textbook covers all aspects of materials science relevant to the practice of dentistry. 2/23/2016 17. Y����-��9�t�~��`{9�T%Z���,G��I���`���a*p����+Q���B�#�V`͔}"$�}��Yv6\x�=�����ۃ�/|$ˠdy��(V��e-��`���J. 1. stream They are capable of accurately reproducing both the hard and soft structures of the mouth, including the undercuts and interproximal spaces. �-}r�g`��[#Ͼ�-�^��x�^�&Q.��.�@_ 1. In contrast, use of addition silicone as an impression material permits easy removal once the impression is set due to its more favorable modulus of elasticity and therefore has also been recommended as a preferred material for implant impressions using direct technique [13, 39, 40]. View 4 - Elastic Impression Materials-2.pdf from BIOLOGY 205 at University of Windsor. • • • • • • • • Only a proper dental Checkup by a professional in person can help diagnose the problem you are suffering from and help give you the required treatment. impression material is non elastic when set and so will not record under cuts accurately.9 Another limitation of impression compound is that it can only be used with non perforated stock trays which are not easily available nowadays and also the operator may burn the soft tissue of the patient inadvertently during its manipulation. • o Shorter OG à crown short à open margins especially buccally o Wider BL / MD à crown over extended • • • • • ! Be easy to use with minimum equipments. Why is the elastic modulus of the set impression material important 0.1% shrinkage o 0.1% x 8000 microns for 1 tooth à 8 microns à 4 microns on mesial or distal o There is adhesive on the tray and also mechanical retention – shrinks in that direction o So dies are oversized usually o Short on occlusal ? = visco-­‐elastic deformation? They are easy to handle and their accuracy is pretty good. To separate cast from the impression, use warm water. They are classified together for convenience rather than for reasons of similarity in composition or properties. The impression should be taken using an elastomeric impression material (poly-vinylsiloxame or polyether rubber) in accordance with the manufacturer’s direc- tions. How does shrinkage toward the tray influence accuracy of the die for Impression compound 2. MATERIALS IN DENTISTRY. Generally, they can be easily stretched and rapidly recover their original dimensions when … 5. Impression materials o Want to remove the tray very fast o Distortion related to removal rate o Fast removal better (vs. slow) o True of all impression materials o Slow removal à more strain Elastomeric materials o Some materials flow easy à Light body hard to keep in a tray § Polyether/PVS have pseudoplastic behavior (want to hold there shape – need force to move them) o Mixing is also important § Polysulfide à Mix by hand à very sticky § Now we have mixing systems à need force to extrude the material down the tip § That is why you have machines that need to be big § But its great for mixing – 250x mxing Types of impression procedures o Custom tray technique – best accuracy o Can get away with stock tray – bc materials so good now o Putty wash technique o Double impression technique o Or use heavy / light body – combo of things Heavy/light (tray wash) – multiple slides o Extrude a bit to begin with o Get busy à light body in wash o Fill the tray à seat it à leave for “set time” o Can use putty with a spacer o He is just illustrating amore common technique o Light body vs. medium or heavy used (tray/wash) technique o Can even use putty Factors in impression dimensional accuracy o Historically used to use special trays because of all the shrinkage § They used to use wax spacers – still the best way to go but not used that much anymore § Was the best for accuracy and uniform thickness of materials o Because of shrinkage don’t want too much material § 4mm is the max o but don’t want too little material § once material too thin it gets stuck on tooth à stretches à won’t recover elastically as well • • • • Dr Mohd Haidil Akmal Mahdan DDS (USM),Ph.D (TMDU,Tokyo) 25th June 2015 Contents… • Definitions • Classification • Impression plaster • Impression compound • Zinc oxide eugenol • Impression waxes Definitions.. 6. ! Elastic impression materials include reversible (agar-agar), irreversible (alginate) hydrocolloids and synthetic elastomers (polysulfides, polyethers, silicones). 100% elastic recovery of any impression material. After the preparation, they are placed inside impression trays. This textbook covers all aspects of materials science relevant to the practice of dentistry. The creep compliance is the time-dependent relationship of the strain to stress ratio of a material under load. Many impression materials have an elastic recovery of more than 99%. o went to copper peroxide gave less problems but no advantage o need to poor it right away polysulfide rubber o don’t leave out too long or else it would mix automatically / accidentally polysulfide rubber mixing o mix with a “metal pen” grasp then flat o had to load a syringe with this tray prolems with poor mxing o mixing was a problem and it was hard to know o became apparent only after you removed the tray o good mixing is a concern with hand mixing systems condenstation silicone setting rxn o next material to come along o cleaner / better to work with o x-­‐link xn of silolyl chains o stannous octoate catalys à multiple x-­‐link point o split off alcohol / alcohol byproduct à dimensional change o a condensation rxn with this byproduct o lose dimensional stability though polyvinyl siloxane (addition silicone) ingredients o change it to an addition reaction à many advantages o vinyl grps along the chains à it’s a free radical rxn à o less shrinkage o no biproduct just x-­‐linked polymer addition silicone (vinyl polysiloxine) setting rxn o catalyzed by platinum salt to give x-­‐link structure o but no biproduct o rapid à nice x-­‐link o good dimensional stability with time o once it set à initial shrinkage and that s it à little after that polyvinyl siloxane – out-­‐gassing (problems) o platinum catylist would split off hydrogen à used to get a lot of bubbles esp when pouring stone o palladium absorbed the hydrogen and that got rid of this problem o we have this well matured system now with PVS – less problems polyether setting rxn o another competitor for crown & bridge products o opening ring structure gives you less shrinkage o same with epoxies (use re-­‐opening procedure) o gives a rapid and complete convient rxn • • • • • • • • elastomeric impression materials o working times – they set rapidly o compared to original polysuflfide – better faster setting with polyether working time characteristics o poly ether = very much a snap set (more so than A-­‐silicone) but both set fast o polysulfide would come way out here and way out here? They could be described as possessing rubbery characteristics. Tear Energy (J/m^2): Impressions must resist tearing upon removal from the mouth and when separating the model from the impression. Impression Waxes Impression Plaster . Download PDF View details Digital workflow for the design and additively manufacture of a splinted framework and custom tray for the impression of multiple implants: A dental technique 2018, Journal of Prosthetic Dentistry The base and catalyst are either 2 paste substances or a powder and a liquid (which may be water). independent responses of elastic impression materials under load and provides a better understanding of their mechanical properties. <> Compound impression can be added or corrected. <>/ExtGState<>/XObject<>/ProcSet[/PDF/Text/ImageB/ImageC/ImageI] >>/Annots[ 15 0 R] /MediaBox[ 0 0 595.32 841.92] /Contents 4 0 R/Group<>/Tabs/S/StructParents 0>> Hydrocolloid impression materials used in dentistry are based on colloidal suspensions of polysaccharides in water. How is that possible? The higher this value, the more tear resistant is the material. 19.1 Bondoc2 measured the percent per-manent deformation and strain in compres- sion for silicone-based materials according to American Dental Association Specification no. How does a light body impression material differ from a medium body <> ! Not contain any toxic or irritating ingredients. the materials compare? Non-elastic Impression Materials 17.1 Introduction. US2359512A US479446A US47944643A US2359512A US 2359512 A US2359512 A US 2359512A US 479446 A US479446 A US 479446A US 47944643 A US47944643 A US 47944643A US 2359512 A US2359512 A US 2359512A Authority US United States Prior art keywords alginate impression water soluble insoluble … silicones differ from addition silicones (polyvinyl siloxane) and Abstract This study was conducted to evaluate the methods used for measuring the elastic recovery of various elastomeric impression materials. Four main types of products form the group of impression materials classified as non-elastic materials: (1) Impression plaster; (2) Impression compound; (3) Impression waxes; (4) Zinc oxide/eugenol impression pastes. ! 6 CONTRAINTES ET DÉFORMATIONS 6.1 CHARGEMENT UNIAXIAL 6.1.1 Introduction Lorsqu'un corps est soumis à des forces extérieures, il y a un changement de sa forme ou de ses This instrument has been called a Comprheometer. Thus, the minimum thickness of the material in the tray should be three to four times more than the largest undercut (Hamalian, T. A. et al., 2011). The working times of impression materials procured at retail in alginate paste were shorter than those of alginate Impression materials in powder. Of these, addition silicone and polyether are … • • • • Creep behavior o With viscoelastic elements, the longer the tray stays in the mouth à viscoelastic element works for a long time à more permanent deformation and less rebound à thus want to remove impression quickly Tear strength of the different types o Don’t want tear in sulcus o PS Rubber (best) >>> CS > AS (PVS) > PE (worst, tears easily) Elastic modulus o PE, AS – high elastic modulus – bounce back -­‐ bad for undercuts, hard to remove impression o Its important for undercuts and ease of removal o PS rubber low modulus and easier to remove Viscoelastic o Stiff: AS and PE have little changes à will come back to normal à gives you good dies o Silicone (condensation) and PS (the worst) have deformation with a load o ????? ! Not sure what viscoelastic means? The fi gure shows a tear specimen being tested. Tear energy should be between 390 and 1800 J/m^2. Results: One alginate material Elastic Cromo (71.35%) and Impression Compound (80.42%) haven't negative influence on the cell cultures. Material susceptible to being stretched compressed or distorted and then tending to resume the original shape. polyethers? ELASTIC Material susceptible to being stretched compressed or distorted and then tending to resume the original shape. 7. Elastic and plastic properties W . Full Document, University of the East, Manila • ENGLISH 20. This paper describes the development of an instrument for determining consistency, working time and setting time of elastomeric impression materials. § Having long polymer chains helps to à dilute out shrinkage with particle § Diluter particle also dilutes shrinkage o Heavier consistency à less shrinkage o Light body shrinks more / just depends on filler Impression materials / key properties Elastomeric impressions o Can use light body first then fill tray with heavy body o As it sets, still have shrinkage o Shrink toward bonded area (like composite) / shrink toward the tray o There is adhesive on the tray and also mechanical retention – shrinks in that direction § So dies are oversized usually § Short occlusally? Walls BDS, PhD, FDSRCS Applied Dental Materials Ninth Edition John F. McCabe BSc, PhD, DSc Professor of Dental Materials Science Newcastle University Angus W.G. This paper describes the development of an instrument for determining consistency, working time and setting time of elastomeric impression materials. Compatible with cast & die materials & does not need separating medium. %���� Elastic impression materials. Elastic impression materials are capable of accurately reproducing both the hard and the soft structures of the mouth including the undercut areas and interproximal spaces 4. Why impression material should be removed quickly from the mouth? • the material is non-elastic, so cannot be used in undercut areas. Elastic impression materials include reversible (agar-agar), irreversible (alginate) hydrocolloids and synthetic elastomers (polysulfides, polyethers, silicones). Abstract This study was conducted to evaluate the methods used for measuring the elastic recovery of various elastomeric impression materials. There are four kinds of Elastomers used as impression materials viz., polysulfide, condensation silicone, addition silicone and polyether. MATERIAL AND METHODS Parti A total of five elastomeric impression materials were evaluated: two polysufides (one lead catalyzed and one copper catalyzed), two silicones (one con- densation polymerization and one addition polymer- ization), and one polyether. • • o Don’t want bubbles in the dies § And also when you put matterial on stone § so die stone will wet into it and you won’t have bubbles in dies o Want good wettability with tissue and with water o Need modifications to achieve this Relative wettability of polymeric impression materials o Polyvinyl siloxane: High contact angle with water à need to modify à lower contact angle so it can compete with polyether o PE better > than PVS (AS) o AS used to be hydrophobic (high contact angle) o PE > hydrophilic AS (modified) > PS > hydrophobic AS > CS (condensation silicone) Contact angles on moiste dentin… o Want to lower Preparation pretreatments o Want to we the tooth structure o Can add a surfactant to wet the tooth structure Change with surfacting applicatoin o Light body material on the tooth o B4 materal helps it slide down the tooth surface o Get more detail by using this B4 stuff – more wetability – lower contact angle Recommending disinfection techniques o Don’t want to swell the impression material o Don’t apply more than 10-­‐ minutes or else get swelling o Polyether à use chorline type compounds / iodifores o Gluteraldehydes can’t be used with polyether Web based impression update o Can find this overview Digital impression – multiple slides o Lab builds the dye to replicate what you’ve captured o Lava system is good – oral system from MIT § 20 scans perminute à comes up with a dye § then can get the CAD CAM o cadent itero § lets you know if you have clearance o used to have to put powder on teeth to give computer an opque surface but now u don’t need that § ciraq used to need that and some still do mouthguard elastomers o ethyl vinyl acetate o need 3mm thick for sports o heat process – drape over a die o 4mm à heat à become 3mm o impact force à energy to distort material à tooth protected bc displacement is limited o can use impact tester with a weight that drops down o 2010 study comparing the air / water / artificial saliva systems § polyshock sets the standard for these materials § it’s a combo of the eva and proform ...View What are the types of elastomeric impression materials”\? per minute. Have pleasant taste, odor and esthetic color. of elastic impression materials. Try our expert-verified textbook solutions with step-by-step explanations. In hydrocolloid, polysulfide or silicone, the molar crown preparation was the most sensitive to dif- ferences between the materials. of materials.1,2 This constraint factor C for ideally plastic materials is about 3, although this value signifi-cantly depends on the geometry of indenter and the ratio of Y:E.1,2 For most types of pyramidal indentation, there is a significant elastic recovery of the indentation impression, when the indenter is removed, although the main recov- ! Elastomeric impression materials are in common use. The most significant work in this area since 1966 is reviewed below. They reproduce an imprint faithfully, providing details of a high definition despite the presence of undercuts. Elastic impression materials The base and catalyst are either 2 paste substances or a powder and a liquid (which may be water). Elastic impression compositions Download PDF Info Publication number US2359512A. • Of particular interest has been the effect of disinfection solutions on the qualities of impressions and the biocompatibility of impression materials. Many impression materials have an elastic recovery of more than 99%. This textbook covers all aspects of materials science relevant to the practice of dentistry. SUMMARY OF WHAT WE NEED TO KNOW (below tis you will find all notes from the lecture) What It is aimed primarily at undergraduate dental students, although it will also be useful for practising dentists, dental technicians and dental assistants. Dentistry and Dental Materials, 2. View 4 - Elastic Impression Materials-2.pdf from BIOLOGY 205 at University of Windsor. Tear Energy (J/m^2): Impressions must resist tearing upon removal from the mouth and when separating the model from the impression. 19. Elastic Impression Materials - Free download as Powerpoint Presentation (.ppt), PDF File (.pdf), Text File (.txt) or view presentation slides online. The greater in the permanent distortion of the impression material if greater the depth of the undercut, for all impression materials. Once the material has set, the Positioning Screws are loosened, and the impression is removed. What is the dimensional stability over time of polysulfide, silicone, Comparative elasticity tests for elastomeric (non putty) impression materials Blomberg, P. A. H.; Mahmood, S.; Smales, R. J.; Makinson, O. F. 1992-10-01 00:00:00 materials. Zinc Oxide Eugenol 4. NON ELASTIC IMPRESSION. ELASTIC Material susceptible to being stretched compressed or distorted and then tending to resume the original shape. Results: One alginate material Elastic Cromo (71.35%) and Impression Compound (80.42%) haven't negative influence on the cell cultures. Basic Dental Materials by Manappallil PDF, ePub eBook D0wnl0ad Serves as a keystone to the understanding of Basic Dental Materials in general and their application to clinical dentistry in particular. The most significant work in this area since 1966 is reviewed below. endobj Dentistry and Dental Materials, 2. • The higher this value, the more tear resistant is the material. 4. All “elastic impression materials” have the same gener al type of formulation. Different types of impression materials are available, which vary in their properties. The fi gure shows a tear specimen being tested. F i n g e r 1, M. K o m a t s u 2 1Department of Prosthetic Dentistry and Dental Technology, Dental School of the RWTH, Aachen, W, Germany and 2Department of of elastic dental Operative Dentistry, Dental School, Tohuku University, Sendal, Japan impression materials Finger W, Komatsu M. Elastic and plastic properties of elastic dental impression materials. 1 0 obj Have adequate shelf life for storage and distribution. Does high viscoelasticity mean stiff? Elastic impression compositions Download PDF Info Publication number US2359512A. Be economical. Why is tear strength important for an impression material and how do NON ELASTIC IMPRESSION. In hydrocolloid, polysulfide or silicone, the molar crown preparation was the most sensitive to dif- ferences between the materials. After the preparation, they are placed inside impression trays. Basic Dental Materials by Manappallil PDF, ePub eBook D0wnl0ad Serves as a keystone to the understanding of Basic Dental Materials in general and their application to clinical dentistry in particular. The creep compliance is the time-dependent relationship of the strain to stress ratio of a material under load. • • • • • • o Many components o Take a polymer à cross link it à make it elastic o Problem is that polymerization leads to shrinkage à solution? Non-Elastic Impression Materials. 4 0 obj Skinner et al.4 and Phillips5 point out the importance of the rate of deformation on the technic of handling alginate hydrocolloids. Course Hero is not sponsored or endorsed by any college or university. HENKE-PRESS – Application syringe for elastic impression materials . | The concept of impression making process in dentistry began in the mid 1800s. %PDF-1.5 It is aimed primarily at undergraduate dental students, although it will also be useful for practising dentists, dental technicians and dental assistants. 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