Impression techniques for rpd / implant dentistry course

9,284 views

Published on



Indian Dental Academy: will be one of the most relevant and exciting training

center with best faculty and flexible training programs for dental

professionals who wish to advance in their dental practice,Offers certified

courses in Dental implants,Orthodontics,Endodontics,Cosmetic Dentistry,

Prosthetic Dentistry, Periodontics and General Dentistry.

Published in: Education

Impression techniques for rpd / implant dentistry course

  1. 1. 11 IMPRESSION TECHNIQUESIMPRESSION TECHNIQUES FOR REMOVABLE PARTIALFOR REMOVABLE PARTIAL DENTURE PROSTHESISDENTURE PROSTHESIS www.indiandentalacademy.comwww.indiandentalacademy.com
  2. 2. 22 CONTENTSCONTENTS • INTRODUCTIONINTRODUCTION • DEFINITIONDEFINITION • IMPRESSION TRAYSIMPRESSION TRAYS • CLASSIFICATION OF IMPRESSION TECHNIQUESCLASSIFICATION OF IMPRESSION TECHNIQUES • DIFFERENT FUNCTIONAL IMPRESSION PROCEDURESDIFFERENT FUNCTIONAL IMPRESSION PROCEDURES • TECHNIQUES OF POURING THE ALTERED CASTTECHNIQUES OF POURING THE ALTERED CAST • REVIEW OF LITERATUREREVIEW OF LITERATURE • CONCLUSIONCONCLUSION • BIBLIOGRAPHYBIBLIOGRAPHY www.indiandentalacademy.comwww.indiandentalacademy.com
  3. 3. ImpressionImpression A negative likeness or copy in reverse of the surfaceA negative likeness or copy in reverse of the surface of an object ; an imprint of teeth and adjacentof an object ; an imprint of teeth and adjacent structures for use in dentistry.structures for use in dentistry. GPT – 8GPT – 8 Partial denture impressionPartial denture impression A negative likeness of a part or all of a partiallyA negative likeness of a part or all of a partially edentulous archedentulous arch -- GPT – 8GPT – 8 Definitions 33www.indiandentalacademy.comwww.indiandentalacademy.com
  4. 4. An impression of partially edentulous archAn impression of partially edentulous arch must record accurately the teeth inmust record accurately the teeth in anatomic formanatomic form and surrounding tissues in aand surrounding tissues in a functional formfunctional form 44www.indiandentalacademy.comwww.indiandentalacademy.com
  5. 5. A receptacleA receptacle in to which suitable impression material isin to which suitable impression material is placed to make negative likenessplaced to make negative likeness (or)(or) A device that is used toA device that is used to carry, confine and control impression material while makingcarry, confine and control impression material while making an impression.an impression. Impression traysImpression trays 55www.indiandentalacademy.comwww.indiandentalacademy.com
  6. 6. 66www.indiandentalacademy.comwww.indiandentalacademy.com
  7. 7. Impression traysImpression trays can be classified broadly in to stock trays andcan be classified broadly in to stock trays and custom trayscustom trays Stock TraysStock Trays Stock trays for partially edentulousStock trays for partially edentulous patients may bepatients may be perforatedperforated to retainto retain the impression material or they maythe impression material or they may be constructed with abe constructed with a rimlockrimlock forfor this purpose.this purpose. 77www.indiandentalacademy.comwww.indiandentalacademy.com
  8. 8. Another type of stock tray designed for theAnother type of stock tray designed for the reversible type of hydrocolloid isreversible type of hydrocolloid is water cooled trayswater cooled trays. It. It contains tubes through which water can be circulated forcontains tubes through which water can be circulated for purpose of cooling the tray.purpose of cooling the tray. 88www.indiandentalacademy.comwww.indiandentalacademy.com
  9. 9. When stock tray is used 0.25 inch of impressionWhen stock tray is used 0.25 inch of impression material is mandatory otherwise custom tray should be usedmaterial is mandatory otherwise custom tray should be used 99www.indiandentalacademy.comwww.indiandentalacademy.com
  10. 10. a. The peripheral borders may not bea. The peripheral borders may not be accuratelyaccurately recorded.recorded. b. Considerablyb. Considerably more bulkiermore bulkier than a custom tray.than a custom tray. Disadvantages: stock traysDisadvantages: stock trays 1010www.indiandentalacademy.comwww.indiandentalacademy.com
  11. 11. a. Peripheral borders can bea. Peripheral borders can be preciselyprecisely recorded in the impressionrecorded in the impression b.b. ThicknessThickness of impression materialof impression material can be controlled.can be controlled. c.c. Custom trays are sometimes neededCustom trays are sometimes needed for mouths that arefor mouths that are abnormally orabnormally or of unusualof unusual configuration.configuration. Custom impression trays:Custom impression trays: 1111www.indiandentalacademy.comwww.indiandentalacademy.com
  12. 12. Impression Materials Non-elastic Elastic Aqueous Hydrocolloids Non-aqueous Elastomers Polysulfide Silicones Polyether Condensation Addition Agar (reversible) Alginate (irreversible) Plaster Compound ZnO - Eugenol Waxes O’Brien Dental Materials & their Selection 1997 1212www.indiandentalacademy.comwww.indiandentalacademy.com
  13. 13. Removable partial denture impression need to record theRemovable partial denture impression need to record the teeth that are irregular in contour as well as varying in theirteeth that are irregular in contour as well as varying in their vertical relations to occlusal plane.vertical relations to occlusal plane. The chosen impression material must be capable of recordingThe chosen impression material must be capable of recording the tissue contours as accurately as possible without distortion,the tissue contours as accurately as possible without distortion, which occurs as impression is withdrawn.which occurs as impression is withdrawn. 1313www.indiandentalacademy.comwww.indiandentalacademy.com
  14. 14. 1414 EdeEdentulous ridges will notntulous ridges will not contribute to support of partialcontribute to support of partial denture, because teeth absorbdenture, because teeth absorb these forces before the forces arethese forces before the forces are transmitted to the residual ridgetransmitted to the residual ridge www.indiandentalacademy.comwww.indiandentalacademy.com
  15. 15. 1515 Since the denture base does not contribute to support ofSince the denture base does not contribute to support of the partial denture & the underlying mucosa and bone are notthe partial denture & the underlying mucosa and bone are not subjected to functional forces, a tooth-supported removablesubjected to functional forces, a tooth-supported removable partial denture can be constructed on a master cast made frompartial denture can be constructed on a master cast made from a single, pressure-free impression that records the teeth & thea single, pressure-free impression that records the teeth & the residual ridge in their anatomic formresidual ridge in their anatomic form www.indiandentalacademy.comwww.indiandentalacademy.com
  16. 16. 1616 when the design of a Removable partial denturewhen the design of a Removable partial denture includes unilateral or bilateral distal extension denture base,includes unilateral or bilateral distal extension denture base, no single impression procedure can record both the anatomicno single impression procedure can record both the anatomic form of the teeth and the functional form of the residual ridge.form of the teeth and the functional form of the residual ridge. Therefore some secondary or corrected impression methodTherefore some secondary or corrected impression method must be needed.must be needed. www.indiandentalacademy.comwww.indiandentalacademy.com
  17. 17. 1717 • Steiger and Boitel (1959), the resiliency of the tissue fittingSteiger and Boitel (1959), the resiliency of the tissue fitting surface of the denture base ranges from 0.4 to 2.0 mm,surface of the denture base ranges from 0.4 to 2.0 mm, compared with the resiliency of 0.l mm for healthy periodontalcompared with the resiliency of 0.l mm for healthy periodontal tissues.tissues. • Tissue resiliency is therefore four to twenty times more thanTissue resiliency is therefore four to twenty times more than the axial displace ability of the abutment tooth (Steiger andthe axial displace ability of the abutment tooth (Steiger and Boitel, 1959).Boitel, 1959). www.indiandentalacademy.comwww.indiandentalacademy.com
  18. 18. 1818 The problem of achieving successful function of aThe problem of achieving successful function of a Removable partial denture is equilibrating this resiliencyRemovable partial denture is equilibrating this resiliency differential between the relatively non-resilient periodontaldifferential between the relatively non-resilient periodontal ligament of the abutment tooth and the more resilient mucosaligament of the abutment tooth and the more resilient mucosa covering the residual ridge.covering the residual ridge. www.indiandentalacademy.comwww.indiandentalacademy.com
  19. 19. The impression of residual ridge mustThe impression of residual ridge must 1.1. Record and relate the tissues under uniform loadingRecord and relate the tissues under uniform loading 2.2. Distribute the load over as large area as possibleDistribute the load over as large area as possible 3.3. Accurately delineate the peripheral extent of denture baseAccurately delineate the peripheral extent of denture base 1919www.indiandentalacademy.comwww.indiandentalacademy.com
  20. 20. 2020 Factors influencing support of the distalFactors influencing support of the distal extension baseextension base • Quality of soft tissue covering edentulous ridgeQuality of soft tissue covering edentulous ridge • Type of bone in the denture bearing areaType of bone in the denture bearing area • Design of the prosthesisDesign of the prosthesis • Amount of tissue coverage of denture baseAmount of tissue coverage of denture base • Anatomy of the denture bearing areaAnatomy of the denture bearing area • Fit of denture baseFit of denture base www.indiandentalacademy.comwww.indiandentalacademy.com
  21. 21. 2121 Objectives of dual impressionObjectives of dual impression 1) It records and relates the supporting tissues under uniform1) It records and relates the supporting tissues under uniform loading.loading. 2) It distributes the load over as large area as possible.2) It distributes the load over as large area as possible. 3) Accurately delineate the peripheral extent of the denture base3) Accurately delineate the peripheral extent of the denture base www.indiandentalacademy.comwww.indiandentalacademy.com
  22. 22. 2222 Indications of dual impression technique.Indications of dual impression technique. 1.1. the distal extension ridge.the distal extension ridge. 2.2. long span anterior edentulous ridge normally including atlong span anterior edentulous ridge normally including at least all the 6 anterior teeth.least all the 6 anterior teeth. 3.3. increased resiliency of the mucosaincreased resiliency of the mucosa Test for determining the need for dual impression technique www.indiandentalacademy.comwww.indiandentalacademy.com
  23. 23. 2323 Impression techniquesImpression techniques • Physiologic impression techniquePhysiologic impression technique - McLean and Hindels method- McLean and Hindels method - The functional relining method- The functional relining method - The fluid wax method- The fluid wax method • Selected pressure techniqueSelected pressure technique www.indiandentalacademy.comwww.indiandentalacademy.com
  24. 24. 1.The Physiologic Or Functional Impression Technique:1.The Physiologic Or Functional Impression Technique: This technique records the ridge position by placingThis technique records the ridge position by placing an occlusal load on the impression tray as the impression isan occlusal load on the impression tray as the impression is being made.being made.  these techniques produced a generalized displacement of thethese techniques produced a generalized displacement of the mucosa to a greater or lesser degree.mucosa to a greater or lesser degree.  This displacement was intended to record the tissue in theThis displacement was intended to record the tissue in the configuration it would assume when occlusal loading wasconfiguration it would assume when occlusal loading was applied to a partial denture in function.applied to a partial denture in function. 2424www.indiandentalacademy.comwww.indiandentalacademy.com
  25. 25. 2525 MCLEAN'S IMPRESSION TECHNIQUE:MCLEAN'S IMPRESSION TECHNIQUE: They realized the need of recording the tissues of theThey realized the need of recording the tissues of the residual ridge that would eventually support a distal extensionresidual ridge that would eventually support a distal extension denture base in the functional, or supporting form and thendenture base in the functional, or supporting form and then relating this functional impression to the remainder of the archrelating this functional impression to the remainder of the arch by means of a second impression.by means of a second impression. www.indiandentalacademy.comwww.indiandentalacademy.com
  26. 26. 2626www.indiandentalacademy.comwww.indiandentalacademy.com
  27. 27. 2727 DisadvantageDisadvantage The greatest weakness of this technique was that fingerThe greatest weakness of this technique was that finger pressure could not produce the same functional displacementpressure could not produce the same functional displacement of the tissue that biting force produced.of the tissue that biting force produced. www.indiandentalacademy.comwww.indiandentalacademy.com
  28. 28. 2828 Hindel's modification ofHindel's modification of Mcleans Technique:Mcleans Technique: www.indiandentalacademy.comwww.indiandentalacademy.com
  29. 29. 2929 DisadvantagesDisadvantages a) If the action of the retentive clasps of the partial denturea) If the action of the retentive clasps of the partial denture isis sufficient tosufficient to maintainmaintain the denture base in relation to the softthe denture base in relation to the soft tissuestissues inin the displaced or functional form, interruption ofthe displaced or functional form, interruption of blood circulation would ensure with possible adverse softblood circulation would ensure with possible adverse soft tissue reactions and resorption of the underlying bone.tissue reactions and resorption of the underlying bone. www.indiandentalacademy.comwww.indiandentalacademy.com
  30. 30. 3030 b) If the action of the retentive clasps was not sufficient tob) If the action of the retentive clasps was not sufficient to maintain that functional relationship of the denture base tomaintain that functional relationship of the denture base to the soft tissue, the denture base will be occlusally positionedthe soft tissue, the denture base will be occlusally positioned when the soft tissues are at rest.when the soft tissues are at rest. this results in premature contact of the artificial teeth, whichthis results in premature contact of the artificial teeth, which may be objectionable to many patients.may be objectionable to many patients. www.indiandentalacademy.comwww.indiandentalacademy.com
  31. 31. 3131 Functional Relining MethodFunctional Relining Method • It consists of adding a new surface to the inner or tissue side ofIt consists of adding a new surface to the inner or tissue side of the denture base.the denture base. • The procedure may be accomplished before the insertion ofThe procedure may be accomplished before the insertion of the partial denture, or it may be done later if the denture basethe partial denture, or it may be done later if the denture base no longer fits the ridge adequately because of bone resorptionno longer fits the ridge adequately because of bone resorption www.indiandentalacademy.comwww.indiandentalacademy.com
  32. 32. 3232 procedureprocedure www.indiandentalacademy.comwww.indiandentalacademy.com
  33. 33. 3333www.indiandentalacademy.comwww.indiandentalacademy.com
  34. 34. 3434 • During border molding the patient must maintain the mouth inDuring border molding the patient must maintain the mouth in a partially open position while the border molding anda partially open position while the border molding and impression are being accomplished because:impression are being accomplished because: 1. The border tissues, cheek, and tongue are thus best controlled .1. The border tissues, cheek, and tongue are thus best controlled . 2. The relationship between the partial denture framework and2. The relationship between the partial denture framework and the teeth must be observed.the teeth must be observed. www.indiandentalacademy.comwww.indiandentalacademy.com
  35. 35. 3535 Making the final impressionMaking the final impression 1)Usually free flowing ZnO eugenol paste is used1)Usually free flowing ZnO eugenol paste is used 2)If undercuts are present on the ridge,light bodied2)If undercuts are present on the ridge,light bodied polysulphide or silicone rubber may be usedpolysulphide or silicone rubber may be used Functional reline method has the advantage that theFunctional reline method has the advantage that the amount of soft tissue displacement can be controlled byamount of soft tissue displacement can be controlled by amount of relief given to modeling plastic before makingamount of relief given to modeling plastic before making final impression. Greater the relief,less will be the tissuefinal impression. Greater the relief,less will be the tissue displacementdisplacement www.indiandentalacademy.comwww.indiandentalacademy.com
  36. 36. 3636 DisadvantageDisadvantage 1.1. The main problems that arise are caused by failure toThe main problems that arise are caused by failure to maintain the correct relationship between the framework andmaintain the correct relationship between the framework and the abutment.the abutment. 2.2. Failure to achieve accurate occlusal contact followingFailure to achieve accurate occlusal contact following reline procedure.reline procedure. 3.3. As in all other reline procedures occlusal discrepancies mustAs in all other reline procedures occlusal discrepancies must be correctedbe corrected www.indiandentalacademy.comwww.indiandentalacademy.com
  37. 37. 3737 Fluid Wax Functional ImpressionFluid Wax Functional Impression TheThe objectivesobjectives of the technique are:-of the technique are:- 1.1. To obtain maximum extension of the peripheral borders of theTo obtain maximum extension of the peripheral borders of the denture base while not interfering with the function ofdenture base while not interfering with the function of movable border tissues.movable border tissues. 2.2. To record the stress-bearing areas of the ridge in theirTo record the stress-bearing areas of the ridge in their functional form.functional form. 3.3. To record non-pressure-bearing areas in their anatomic form.To record non-pressure-bearing areas in their anatomic form. www.indiandentalacademy.comwww.indiandentalacademy.com
  38. 38. 3838 The term fluid wax is used to denote waxes that areThe term fluid wax is used to denote waxes that are firm at room temperature and have the ability to flow at mouthfirm at room temperature and have the ability to flow at mouth temperature.temperature. • The most frequently used fluid waxes:The most frequently used fluid waxes: ‫٭‬‫٭‬ Iowa WaxIowa Wax , developed by, developed by Dr. SmithDr. Smith ‫٭‬‫٭‬ Korrecta WaxKorrecta Wax No.4, developed byNo.4, developed by Dr.O.CDr.O.C andand S.G.S.G. ApplegateApplegate • Korrecta Wax No.4 is slightly more fluid than Iowa Wax.Korrecta Wax No.4 is slightly more fluid than Iowa Wax. www.indiandentalacademy.comwww.indiandentalacademy.com
  39. 39. 3939 • The key to the use of fluid wax lies in two areas:The key to the use of fluid wax lies in two areas: -- spacespace - time- time www.indiandentalacademy.comwww.indiandentalacademy.com
  40. 40. 4040 • The borders must be short of all movable tissues, but not moreThe borders must be short of all movable tissues, but not more than 2 mm short because the fluid wax does not have sufficientthan 2 mm short because the fluid wax does not have sufficient strength to support itself beyond that distance.strength to support itself beyond that distance. www.indiandentalacademy.comwww.indiandentalacademy.com
  41. 41. Each time the tray is introduced into the mouth, it must remain inEach time the tray is introduced into the mouth, it must remain in place 5 to 7 minutes.place 5 to 7 minutes. - To allow the wax to flow and- To allow the wax to flow and - To prevent buildup of pressure under the tray with- To prevent buildup of pressure under the tray with resulting distortion or displacement of the tissue.resulting distortion or displacement of the tissue. 4141www.indiandentalacademy.comwww.indiandentalacademy.com
  42. 42. procedureprocedure 1.1. Try in of frame work doneTry in of frame work done 2.2. Spacer adopted with use of base plate wax on castSpacer adopted with use of base plate wax on cast 3.3. Auto polymerising resin adapted and contoured over frameAuto polymerising resin adapted and contoured over frame workwork 4.4. Excess material removedExcess material removed 5.5. Relief holes prepared along the crest of ridgeRelief holes prepared along the crest of ridge 4242www.indiandentalacademy.comwww.indiandentalacademy.com
  43. 43. 4343 • the fluid wax taken from a water bath maintained at 51˚c tothe fluid wax taken from a water bath maintained at 51˚c to 54°C (125˚ to 130˚ F)54°C (125˚ to 130˚ F) • At this temperature the wax becomes fluid.At this temperature the wax becomes fluid. • The wax is painted on the tissue side of the impression trayThe wax is painted on the tissue side of the impression tray with a brush.with a brush. www.indiandentalacademy.comwww.indiandentalacademy.com
  44. 44. 4444www.indiandentalacademy.comwww.indiandentalacademy.com
  45. 45. 4545 • The impression surface which contacts the tissue will beThe impression surface which contacts the tissue will be glossy and the surface which does not come in contact withglossy and the surface which does not come in contact with the tissue will be dullthe tissue will be dull • Wax is added on the dull surface and the impression is placedWax is added on the dull surface and the impression is placed back for 5 min in the mouth .back for 5 min in the mouth . • Procedure is repeated till the impression is completed.Procedure is repeated till the impression is completed. The finished impression must be handled carefully, and theThe finished impression must be handled carefully, and the new cast poured as soon as possible because the wax is fragilenew cast poured as soon as possible because the wax is fragile and subject to distortion.and subject to distortion. www.indiandentalacademy.comwww.indiandentalacademy.com
  46. 46. 4646 • The fluid wax impression is made with the open mouthThe fluid wax impression is made with the open mouth technique so that there is less danger of over-displacement oftechnique so that there is less danger of over-displacement of ridge tissue by occlusal or vertical forces.ridge tissue by occlusal or vertical forces. www.indiandentalacademy.comwww.indiandentalacademy.com
  47. 47. 4747 DisadvantagesDisadvantages • The procedure is time consuming.The procedure is time consuming. • If the time periods are not followed accurately, thanIf the time periods are not followed accurately, than impression with excessive tissue displacement will result.impression with excessive tissue displacement will result. www.indiandentalacademy.comwww.indiandentalacademy.com
  48. 48. 4848 Selected pressure impression techniqueSelected pressure impression technique TheThe objectivesobjectives of the technique are:-of the technique are:- 1.1. the equalization of support between the abutment teeth and thethe equalization of support between the abutment teeth and the soft tissuesoft tissue 2.2. To direct more force to those portions of the ridge which isTo direct more force to those portions of the ridge which is able to absorb the stress without adverse response.able to absorb the stress without adverse response. 3.3. Protect the areas of the ridge which is least able to absorbProtect the areas of the ridge which is least able to absorb force.force. www.indiandentalacademy.comwww.indiandentalacademy.com
  49. 49. 4949www.indiandentalacademy.comwww.indiandentalacademy.com
  50. 50. 5050 Areas where relief is provided will be least displacedAreas where relief is provided will be least displaced as the impression is recorded . In those areas of the tray whereas the impression is recorded . In those areas of the tray where relief is not provided greater displacement of the underlyingrelief is not provided greater displacement of the underlying mucosa will occurmucosa will occur Mandibular Arch Posterior regionMandibular Arch Posterior region 1) Crest of Arch1) Crest of Arch 2)Buccal Shelf2)Buccal Shelf 3)Lingual slope – Principally resists horizontal or rotational3)Lingual slope – Principally resists horizontal or rotational forces.forces. www.indiandentalacademy.comwww.indiandentalacademy.com
  51. 51. 5151 • The end result of this selected pressure impression is that theThe end result of this selected pressure impression is that the denture base made impression will be closely adapted to anddenture base made impression will be closely adapted to and in firm contact with the tissue covering the buccal shelf area ofin firm contact with the tissue covering the buccal shelf area of the edentulous ridge.the edentulous ridge. • The ridge crest on the other hand is lightly adapted to theThe ridge crest on the other hand is lightly adapted to the tissue and the effects of occlusal loading will be less in thistissue and the effects of occlusal loading will be less in this area.area. www.indiandentalacademy.comwww.indiandentalacademy.com
  52. 52. 5252 Techniques for pouring the corrected castTechniques for pouring the corrected cast impressionimpression www.indiandentalacademy.comwww.indiandentalacademy.com
  53. 53. 5353 Procedure 1.1. Impression is received in the laboratory. Remove excess impression material from the framework in areas that contact the teeth. www.indiandentalacademy.comwww.indiandentalacademy.com
  54. 54. 5454 2. Trim the master cast so that the functional impression can be poured in correct relationship to the remaining teeth. www.indiandentalacademy.comwww.indiandentalacademy.com
  55. 55. 5555 3. Seat the framework on the cast, and inspect it for contact between the functional impression and the cast. If contact is present, the cast must be trimmed until clearance is present. www.indiandentalacademy.comwww.indiandentalacademy.com
  56. 56. 5656 4. Cut retention grooves into the areas of the cast that will be corrected when the functional impression is poured www.indiandentalacademy.comwww.indiandentalacademy.com
  57. 57. 5757 5. Adapt and seal beading wax 2 to 3 mm above the borders of the functional impression www.indiandentalacademy.comwww.indiandentalacademy.com
  58. 58. 5858 6. Seat the framework on the cast, and secure it in position with sticky wax www.indiandentalacademy.comwww.indiandentalacademy.com
  59. 59. 5959 7.7. Seal the leading edge of the impression to the cast to prevent dental stone from flowing onto the teeth when the cast is poured. www.indiandentalacademy.comwww.indiandentalacademy.com
  60. 60. 6060 8. Use strips of base plate wax to complete the boxing of the impression on the buccal and lingual aspects www.indiandentalacademy.comwww.indiandentalacademy.com
  61. 61. 6161 9. A tight seal of beading and boxing wax is critical in this pouring method and is difficult to attain. Test the completeness of the seal by pouring clear slurry water into the boxed impression. A difficult area to seal is the relief area under the major connector. www.indiandentalacademy.comwww.indiandentalacademy.com
  62. 62. 6262 10. Place the cast and impression in clear slurry water to soak for 4 to 5 minutes in preparation for pouring the corrected cast. www.indiandentalacademy.comwww.indiandentalacademy.com
  63. 63. 6363 11. Measure and mix the improved dental stone. Pour the boxed impression by adding small increments of stone and using light vibration. Sufficient stone must be used to support the heel of the cast. www.indiandentalacademy.comwww.indiandentalacademy.com
  64. 64. 6464 12. Remove the boxing and luting materials from the corrected cast. Shape the cast on a model trimmer. www.indiandentalacademy.comwww.indiandentalacademy.com
  65. 65. 6565 13. Soften the impression material in warm water, and remove13. Soften the impression material in warm water, and remove the framework and impression tray from the corrected cast.the framework and impression tray from the corrected cast. www.indiandentalacademy.comwww.indiandentalacademy.com
  66. 66. 6666 14. Burn the impression tray off the framework and place it on the cast. Smooth the land area of the cast, and the corrected cast procedures is complete. www.indiandentalacademy.comwww.indiandentalacademy.com
  67. 67. 6767 Altered cast techniqueAltered cast technique • Master cast must beMaster cast must be modified in preparation formodified in preparation for altered cast procedure.altered cast procedure. Broken line indicatesBroken line indicates proposed cast modificationsproposed cast modifications for bilateral altered castfor bilateral altered cast procedureprocedure www.indiandentalacademy.comwww.indiandentalacademy.com
  68. 68. 6868 • Master cast afterMaster cast after modification, Dovetailsmodification, Dovetails have been prepared tohave been prepared to permit mechanicalpermit mechanical interlocking of castinterlocking of cast segmentssegments www.indiandentalacademy.comwww.indiandentalacademy.com
  69. 69. 6969 • Framework seated onFramework seated on modified master cast andmodified master cast and affixed using modellingaffixed using modelling plastic to minimizeplastic to minimize displacement and distortiondisplacement and distortion Assembly is inverted inAssembly is inverted in preparation for rimming andpreparation for rimming and boxing proceduresboxing procedures www.indiandentalacademy.comwww.indiandentalacademy.com
  70. 70. 7070 • Utility wax is used to rimUtility wax is used to rim the impression.it is locatedthe impression.it is located 2-3 mm from impression2-3 mm from impression and 3-4mm peripherally.and 3-4mm peripherally. Boxing wax added to form aBoxing wax added to form a watertight vertical wall .watertight vertical wall . Freshly mixed dental stoneFreshly mixed dental stone is then introducedis then introduced www.indiandentalacademy.comwww.indiandentalacademy.com
  71. 71. 7171 • After the stone has gainedAfter the stone has gained sufficient strength ,thesufficient strength ,the corrected cast is recoveredcorrected cast is recovered and trimmedand trimmed www.indiandentalacademy.comwww.indiandentalacademy.com
  72. 72. Review of literatureReview of literature 7272www.indiandentalacademy.comwww.indiandentalacademy.com
  73. 73. The altered cast impression technique revisitedThe altered cast impression technique revisited JADA, vol. 130, october 1999; 14;77JADA, vol. 130, october 1999; 14;77 7373 Preoperative figure displaying knife-edge residual ridge with moderate-to-severe resorption. final impression made in a border molded acrylic resin tray that has been attached to the latticework of the cast framework. www.indiandentalacademy.comwww.indiandentalacademy.com
  74. 74. 7474 Complete seating of the framework on the cast is essential before it is fixed in place with sticky wax. Note the placement of saw cuts and retention slots Before being poured, the final impression is beaded and boxed in the usual manner www.indiandentalacademy.comwww.indiandentalacademy.com
  75. 75. 7575 The final working altered cast. Occlusal view of a well-fitting, properly adapted removable partial denture. www.indiandentalacademy.comwww.indiandentalacademy.com
  76. 76. Although there is some clinical evidence that the alteredAlthough there is some clinical evidence that the altered cast impression procedure decreases the load on thecast impression procedure decreases the load on the abutments. The altered cast impression procedure does notabutments. The altered cast impression procedure does not offer significant advantages over the one piece castoffer significant advantages over the one piece cast 7676www.indiandentalacademy.comwww.indiandentalacademy.com
  77. 77. SINGLE- TRAY DUAL- IMPRESSION TECHNIQUE FORSINGLE- TRAY DUAL- IMPRESSION TECHNIQUE FOR DISTAL EXTENSION PARTIAL DENTURESDISTAL EXTENSION PARTIAL DENTURES JOSEPH A. R- JPD 1970(24,1,41-46)JOSEPH A. R- JPD 1970(24,1,41-46) • This technique is basedThis technique is based philosophically onphilosophically on Hindel’s loadHindel’s load distribution principledistribution principle • Records the ridgesRecords the ridges dynamically anddynamically and remaining teethremaining teeth staticallystatically • This techniqueThis technique produces less bulkyproduces less bulky final impressionfinal impression 7777www.indiandentalacademy.comwww.indiandentalacademy.com
  78. 78. conclusionconclusion ““ Good technique pays off ” is not merely a motto to hang on a wall but these are words of wisdom. Good technique will indeed result in better treatment and improved patient care. 7878www.indiandentalacademy.comwww.indiandentalacademy.com
  79. 79. 7979 BIBLIOGRAPHYBIBLIOGRAPHY 1. Glossary of Prosthodontic Terms -8 th Edn, 2005.1. Glossary of Prosthodontic Terms -8 th Edn, 2005. 2. Stewart, Rudd, Kuebker : Clinical Removable Partial2. Stewart, Rudd, Kuebker : Clinical Removable Partial Prosthodontics.Prosthodontics. 3. Kenneth D Rudd, Morrow: Dental Lab, Procedure for3. Kenneth D Rudd, Morrow: Dental Lab, Procedure for Removable Partial Dentures.Removable Partial Dentures. 4. McCracken’s : Removable Partial Prosthodontics -4. McCracken’s : Removable Partial Prosthodontics - 11 edition11 edition www.indiandentalacademy.comwww.indiandentalacademy.com
  80. 80. 5. J c davenport ; A colour atlas of removable partial dentures.5. J c davenport ; A colour atlas of removable partial dentures. 6. James s brudwik : Advanced removable partial denture6. James s brudwik : Advanced removable partial denture 7. John Osborne : partial dentures, iv edition7. John Osborne : partial dentures, iv edition 8080www.indiandentalacademy.comwww.indiandentalacademy.com
  81. 81. 8181 8. The altered cast impression technique revisited JADA, vol. 130, october 1999; 14;77 9. An altered cast procedure to improve tissue support for removable partial dentures jpd 1994(15), 4, 672- 678 10.single- tray dual- impression technique for distal extension partial dentures. Journal of prosthet dent 1970(24,1,41-46) 11. Selective pressure single impression technique for removable partial denture Journal of prosthet dent 1998 ; 80; 2; 259 www.indiandentalacademy.comwww.indiandentalacademy.com
  82. 82. 8282 For more details please visit www.indiandentalacademy.com www.indiandentalacademy.comwww.indiandentalacademy.com

×