elastic impression materials pdf

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. Elastic impression materials are capable of accurately reproducing both the hard and the soft structures of the mouth including the undercut areas and interproximal Find answers and explanations to over 1.2 million textbook exercises. Applied Dental Materials Ninth Edition John F. McCabe BSc, PhD, DSc Professor of Dental Materials Science Newcastle University Angus W.G. 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. ! Have adequate shelf life for storage and distribution. = visco-­‐elastic deformation? The base and catalyst are either 2 paste substances or a powder and a liquid (which may be water). ���n�:d����>$�>2&�\���IW����2�;��o5Ӻ���4�u��ؚxW���aw�g������b?�`�O �S��zd�Y���ʌ���V�xq��;���j��O�=];EZ5�w0"��{:˹yrc$;Ȏ%|���ؾ�Co9���缿�P�~j���Hs^��A|H��ħ5$��H�v�/l#�ZZ�\�eUפ]st�3{���U�߷�;���i�O߄��ۨ������V@k�eC}�&lϛ ��y����ً�0����4���u��U�}ў�����F_"XC�8�U��� ����04�d""�u%OVY t�\�������RF��МF�bh�8);څ��m����i�r>�v��y�xjZ_�sr_�wj_Q����%�紾�j�%�a�v%��70�,@ They all have a flexible matrix (the continuous phase) that is filled with extender or filler (the dispersed phase) to minimize the effects of polymerization shrinkage during setting on the overall accuracy and dimensional stability of the system. 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 … The impression taken should be highly precise, thus, requiring specific care when manipulatingthese materials. The operating principle involves the application of a fixed compressive strain and the resulting stress is measured. Reproduction of oral detail The rubber impression materials are capable of reproducing detail more accurately than can be transferred to the stone die or cast ELASTICITY Elastic properties of elastomeric impression materials improve with an increase in curing time in the mouth Permanent deformation following strain in compression increases in following order- addition silicone, … Why is it important to measure impression material creep behavior? o (fast/short set time > slow): Addition silicone (PVS) > polyether > condensation silicone > polysulfide rubber Working time problems o In lab it takes for ever to set o But in the mouth it all happens faster o May have various layers where they don’t mix / steps Impression concerns o Make sure all the materials get to the mouth and there is no delay o Don’t want material in the tray to start setting without u knowning o May be elastic and may still also be flowing o We may be compressing it but it may recover once you remove it o Set in elastic state à Remove tray à impression rebounds à Might have a short and distorted die o Lab, not a problem, mouth is a problem o Want material freshly mixed and “dead soft” Impression materials o All has to do with rxn conversion o At 50% conversion à they all get rubbery o With PE and PVS very much in a hurry o They all set at different rates factors affection impression / dimensional stability / accuracy o polymerization shrinkage is immediate but … § there is a potential for longterm shrinkage with biproduct o when u remove it gets distored à will it recover elastically? Be easy to use with minimum equipments. This paper describes the development of an instrument for determining consistency, working time and setting time of elastomeric impression materials. This classification is based on the capability of the material to withdraw over the undercuts it has set. 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 o Shorter OG à crown short à open margins especially buccally o Wider BL / MD à crown over extended • • • • •

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