Impression taking for fix appliences, sectional models

Transcription

1 Impressio takig for fix applieces, sectioal models Dr. Judit Borbély 2018

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8 Impressio soft, semifluid material placed i the mouth ad allowig that material to set 1. It should be a exact duplicatio of the prepared tooth, icludig all of the preparatio, ad eough ucut tooth surface beyod the preparatio to allow the detist ad techicia to be certai of the locatio ad cofiguratio of the fiish lie. 2. Other teeth ad tissue adjacet to the prepared tooth must be accurately reproduct to permit accurate articulatio of the cast ad to allow proper cotourig of the restoratio. 3. The impressio of the preparatio must be bubble free, especially i the area of the fiish lie.

9 Die-cast impressio for FPD Impresso for die= impressio of the prepared surfaces ad fiishig lie Impressio for cast = approximal cotours ad correct occlusio

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12 It is essetial that impressio materials adhere firmly to the impressio trays. perforatios or by the use of adhesives.

13 GINGIVAL RETRACTION

14 Sigle cord techique poor access Two cord techique: Double cord techique good access A piece of fie retractio cord is placed i the gigival sulcus A thicker cord is placed over the first leavig a tag for removal The thicker cord is removed after washig (ote clearly defied sulcus)ad impressio The buccal tissues are relatively thi ad great care is eeded to avoid recessio. Sufficiet haemostasis ca usually be achieved with ferric sulphate solutio to allow the impressio to be recorded Crows ad other extra-coroal restoratios: Impressio materials ad techique R W Wassell, D Barker & A W G Walls British Detal Joural 192, (2002) Published olie: 29 Jue 2002

15 Gigival Retractio Pastes & Gels saliva tooth saliva tooth tooth paste used for gigival retractio opes the sulcus, physically displacig the tissue ad leavig the field dry, place it directly ito the sulcus, leave it for oe to two miutes, the rise.whe you use it before takig the fial impressio, little or o pressure required to apply, that miimizes the risk of rupturig the epithelial attachmet. bleedig ad crevicular seepage are cotrolled through the presece of alumium chloride.

16 For FPD: elastic impressio materials These materials ca be stretched ad bet to a fairly large degree without sufferig ay deformatio. Used for recordig the patiet's mouth where udercuts are preset. 1.Hydrocolloid: Algiate 2.Sythetic elastomers: Polysulphide Polyether Silicoe Rigid No udercut areas Impressio Plaster Compoud Zic-oxide eugeol paste Wax

17 Opposig arch impressio-algiate hydrocolloid impressio materials: poor dimesio stability ad low tear resistace

18 IMPRESSION TECHNIQUES SINGLE MIX Regular viscosity - itermediate flow moophase pastes/moophase techique Custom tray DOUBLE MIX Low viscositycorrectio material or wash High viscosityheavy-bodied or putty or tray material or preimpressio material Oe stage Two stage Crows ad other extra-coroal restoratios: Impressio materials ad techique R W Wassell, D Barker & A W G WallsBritish Detal Joural 192, (2002) Published olie: 29 Jue 2002

19 Slide from Dr. Peter Herma

20 Slide from Dr. Peter Herma

21 Slide from Dr. Peter Herma

22 IMPRESSION TECHNIQUES DOUBLE MIX SINGLE MIX Regular viscosity - itermediate flow moophase pastes Custom tray Low viscosity-correctio material or wash High viscosity-heavy-bodied or putty or tray material or preimpressio material Oe stage Two stage

23 Double mix TWO STAGE IMPRESSION techique A impressio is take with the heavy-bodied material. This is the removed from the mouth ad ispected. The light bodied material is the prepared ad squirted over heavy-bodied material ad the impressio relocated. Heavy- bodied putty serve as a custom tray for a thi wash of a less highly filled, lowviscosity silicoe.

24 Escape chaels Procedure: Cut back impressio material to the borders of the tray Remove udercuts Remove material betwee uprepared teeth Cut i grooves up to the occlusal level at uprepared teeth alteratig orally ad buccally/facially 2mm wide ud max. 1mm deep

25 Double mix ONE STAGE IMPRESSION techique Light bodied impressio material is placed i a syrige, ad placed over the areas where high detail is required (e.g. over a crow preparatio). Some is the squirted over the heavy-bodied impressio material which has bee loaded ito a impressio tray. The impressio is the take as ormal. This techique saves time, but it ca be very labour itesive because the two eed to mixed at the same time.

26 Visible flaws related to impressio techique which occur commoly iclude: Fiish lie ot visible Air bubbles i critical places Voids or drags Uset impressio material o surface of impressio ad cast Ivisible impressio flaws, resultig i a apparetly good fit of the restoratio o the die but a poor fit o the tooth, may also occur because of: Tray ad impressio recoil Detachmet of impressio from tray Permaet deformatio

27 laboratory ispectio is a importat part of quality cotrol, but may techicias fid it difficult to feed back to their detists for fear of the messeger beig shot Commuicatio! As oe of us ca achieve perfectio every time there is much to be said for ecouragig techicias to feed back

28 SECTIONAL MODEL CAST: the positive likeess of a patiet s upper or lower jaw DIE: small model of prepared teeth

29 The dies of the prepared teeth or roots ca be removed separately from the cast to make a very accurate or precise wax patter for makig a fixed detal appliace. Materials for preparig dies: 1.die stoe: most widely used 2. Acrylic 3. Polyuretha DIES Essetial fuctio of the die is to allow a restoratio to be costructed i the laboratory which has a accurate iteral or fittig surface.

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31 Methods of makig die casts the base of the die provides a meas of locatig the die withi a larger localizig model which icludes the other teeth o the arch adjacet to the prepared tooth. the die ca be removed ad replaced i its origial positio Several methods are used for makig sectioal casts: Pidex method Kiefer method Crystal method

32 Pidex-method Images from: Dr. Peter Herma, Zolta Hajdu: Sectioal casts

33 Images from: Dr. Peter Herma, Zolta Hajdu: Sectioal casts

34 Images from: Dr. Peter Herma, Zolta Hajdu: Sectioal casts

35 Images from: Dr. Peter Herma, Zolta Hajdu: Sectioal casts

36 Images from: Dr. Peter Herma, Zolta Hajdu: Sectioal casts

37 Images from: Dr. Peter Herma, Zolta Hajdu: Sectioal casts

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39 Thak You for Your attetio