Impressions in removable partial dentures/ implant dentistry course

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Impressions in removable partial dentures/ implant dentistry course

  1. 1. Impressions in removableImpressions in removable partial denturespartial dentures INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.comwww.indiandentalacademy.com
  2. 2. Impression : a negative likeness or copyImpression : a negative likeness or copy in reverse of the surface of an object; anin reverse of the surface of an object; an imprint of the teeth and adjacentimprint of the teeth and adjacent structures for use in dentistrystructures for use in dentistry www.indiandentalacademy.comwww.indiandentalacademy.com
  3. 3. Diagnostic impressionsDiagnostic impressions Permit analysis of contour of hard and softPermit analysis of contour of hard and soft tissuestissues Types of restorations on abutment teethTypes of restorations on abutment teeth Determination of need for surgicalDetermination of need for surgical correction of exostosis, frena, tuberositiescorrection of exostosis, frena, tuberosities and undercutsand undercuts Serve as blueprint for placement ofServe as blueprint for placement of restorations, recontouring of teeth and restrestorations, recontouring of teeth and rest seat preparationseat preparation www.indiandentalacademy.comwww.indiandentalacademy.com
  4. 4. Permit analysis of patients occlusionPermit analysis of patients occlusion Adequacy of interarch spaceAdequacy of interarch space Presence of overerupted, malposed teethPresence of overerupted, malposed teeth and tuberosity interference.and tuberosity interference. www.indiandentalacademy.comwww.indiandentalacademy.com
  5. 5. Material of choice for diagnosticMaterial of choice for diagnostic impressionimpression Irreversible hydrocolloid (alginate)Irreversible hydrocolloid (alginate) www.indiandentalacademy.comwww.indiandentalacademy.com
  6. 6. Technique for Making Diagnostic Impressions 1)Position of patient and Dentist1)Position of patient and Dentist 2)Impression Trays2)Impression Trays a) selectiona) selection b) Checking trays for Correct sizeb) Checking trays for Correct size c) Extending impression traysc) Extending impression trays 3)Control of Gagging3)Control of Gagging 4)Control of saliva4)Control of saliva www.indiandentalacademy.comwww.indiandentalacademy.com
  7. 7. Technique for Making Diagnostic Impressions Contd )Manipulation of the impression material)Manipulation of the impression material 6)Making the Impressions6)Making the Impressions 7)Removal of Impression from the mouth7)Removal of Impression from the mouth 8)Inspecting the Impression8)Inspecting the Impression 9)Cleaning the impression9)Cleaning the impression 10)Disinfecting the impression10)Disinfecting the impression 11)Poring the cast11)Poring the cast www.indiandentalacademy.comwww.indiandentalacademy.com
  8. 8. Tray Selection for Diagnostic Impressions  Tray of choice - Rim lock tray because it is rigidTray of choice - Rim lock tray because it is rigid - it confines the impression material, helping to- it confines the impression material, helping to force it into all the areas to be included in theforce it into all the areas to be included in the impression.impression.  Perforated trays are rigid, but do not confine thePerforated trays are rigid, but do not confine the material as well as the rim lock tray .material as well as the rim lock tray .  Disposable plastic trays - too flexible to ensureDisposable plastic trays - too flexible to ensure the accuracy of impression and cast that isthe accuracy of impression and cast that is needed for removable partial denturesneeded for removable partial dentures www.indiandentalacademy.comwww.indiandentalacademy.com
  9. 9. Extending an Impression Tray  The modeling plastic is softened in a 60°The modeling plastic is softened in a 60° CC (140° water(140° water bath, kneaded, and adapted to the tray partially removedbath, kneaded, and adapted to the tray partially removed several times to prevent the locking of the tray into theseveral times to prevent the locking of the tray into the undercuts.undercuts.  Frequently an impression tray that has a correct width isFrequently an impression tray that has a correct width is too short to cover the entire desired impression area.too short to cover the entire desired impression area. The impression tray can be lengthened by the use ofThe impression tray can be lengthened by the use of modeling plastic .modeling plastic .  After the modeling plastic has been chilled, it is relievedAfter the modeling plastic has been chilled, it is relieved to provide approximately 5 to 7 mm of clearance & thento provide approximately 5 to 7 mm of clearance & then coated with alginate adhesivecoated with alginate adhesive www.indiandentalacademy.comwww.indiandentalacademy.com
  10. 10. Extending an Impression Tray Extending an Impression Tray www.indiandentalacademy.comwww.indiandentalacademy.com
  11. 11. Working properties of AlginateWorking properties of Alginate Easy to use and inexpensiveEasy to use and inexpensive Available as bulk and preweightedAvailable as bulk and preweighted quantityquantity Deteriorates rapidly at high temperatureDeteriorates rapidly at high temperature and humidityand humidity Is contaminated by gypsumIs contaminated by gypsum Accuracy not affected by changes in waterAccuracy not affected by changes in water to powder ratioto powder ratio www.indiandentalacademy.comwww.indiandentalacademy.com
  12. 12. Cont.Cont. Ideal temp of water 22degreeCIdeal temp of water 22degreeC Cooler water will provide more workingCooler water will provide more working timetime www.indiandentalacademy.comwww.indiandentalacademy.com
  13. 13. Storage of impressionStorage of impression Measurable distortion if not poured withinMeasurable distortion if not poured within 12 minutes12 minutes www.indiandentalacademy.comwww.indiandentalacademy.com
  14. 14. Technique of making alginateTechnique of making alginate impressionsimpressions www.indiandentalacademy.comwww.indiandentalacademy.com
  15. 15. Position of patient and dentistPosition of patient and dentist Dentist position-standingDentist position-standing Patient position-uprightPatient position-upright Occlusal plane parallel to floorOcclusal plane parallel to floor Patients mouth is at same level as dentistsPatients mouth is at same level as dentists elbowelbow Stand behind the patient for maxillaryStand behind the patient for maxillary impressionimpression www.indiandentalacademy.comwww.indiandentalacademy.com
  16. 16. Checking trayChecking tray Clearance of 5-7mm between tray and theClearance of 5-7mm between tray and the ridgeridge Tray should cover all anatomic landmarksTray should cover all anatomic landmarks or can be modifiedor can be modified www.indiandentalacademy.comwww.indiandentalacademy.com
  17. 17. GaggingGagging www.indiandentalacademy.comwww.indiandentalacademy.com
  18. 18. Methods to prevent gaggingMethods to prevent gagging Seating patient in upright positionSeating patient in upright position Correcting palatal area with modellingCorrecting palatal area with modelling plasticplastic Not overfilling the tray with alginateNot overfilling the tray with alginate Seating the posterior part firstSeating the posterior part first Patient to keep eyes open duringPatient to keep eyes open during procedureprocedure Use of astringent mothwash and coldUse of astringent mothwash and cold waterwater www.indiandentalacademy.comwww.indiandentalacademy.com
  19. 19. Control of salivaControl of saliva Use of gauze packsUse of gauze packs Saliva ejectionSaliva ejection 15mg propantheline bromide 30min before15mg propantheline bromide 30min before procedureprocedure www.indiandentalacademy.comwww.indiandentalacademy.com
  20. 20. Mixing impression materialMixing impression material Hand spatulationHand spatulation Mechanical spatulationMechanical spatulation Mechanical spatulation under vacuumMechanical spatulation under vacuum www.indiandentalacademy.comwww.indiandentalacademy.com
  21. 21. Inspecting the impressionInspecting the impression Alginate sticking to teethAlginate sticking to teeth Alginate pulling away from trayAlginate pulling away from tray VoidsVoids Layered impressionLayered impression Granular impressionGranular impression Inadquate extensionInadquate extension Contact between teeth and trayContact between teeth and tray www.indiandentalacademy.comwww.indiandentalacademy.com
  22. 22. ProblemsProblems Error. Using irreversible hydrocolloid that has beenError. Using irreversible hydrocolloid that has been frozen, even when it is stored in its original,sealedfrozen, even when it is stored in its original,sealed container.container. Problem: Freezing may alter the setting time of theProblem: Freezing may alter the setting time of the material drastically.material drastically. Solution: In the winter, when temperatures in some partsSolution: In the winter, when temperatures in some parts of the country are considerably below freezing,of the country are considerably below freezing, irreversible hydrocolloid should be tested before use.irreversible hydrocolloid should be tested before use. www.indiandentalacademy.comwww.indiandentalacademy.com
  23. 23. .. Error: Using irreversible hydrocolloid that has beenError: Using irreversible hydrocolloid that has been stored in defective packaging or in an unsealed containerstored in defective packaging or in an unsealed container after being opened for first use.after being opened for first use. Problem: Moisture contamination due to water uptakeProblem: Moisture contamination due to water uptake from the atmosphere can accelerate or retard the settingfrom the atmosphere can accelerate or retard the setting time and cause rapid deterioration of phys­ical andtime and cause rapid deterioration of phys­ical and chemical properties of the irreversible hydro­colloid.chemical properties of the irreversible hydro­colloid.44 Solution: Test the irreversible hydrocolloid before using itSolution: Test the irreversible hydrocolloid before using it www.indiandentalacademy.comwww.indiandentalacademy.com
  24. 24. Solution: Use prepackaged irreversibleSolution: Use prepackaged irreversible hydrocolloid to eliminate this error, even thoughhydrocolloid to eliminate this error, even though it is more costly than a can of irreversibleit is more costly than a can of irreversible hydrocolloid or bulk irreversible hydro­colloid. Ifhydrocolloid or bulk irreversible hydro­colloid. If bulk irreversible hydrocolloid is used, separatebulk irreversible hydrocolloid is used, separate and weigh amounts for individual use; then sealand weigh amounts for individual use; then seal each portion in an airtight container such as aeach portion in an airtight container such as a specimen containers. In addition, use aspecimen containers. In addition, use a dedicated mixing bowl and spatula only fordedicated mixing bowl and spatula only for mixing irreversible hydro­colloid. When in doubtmixing irreversible hydro­colloid. When in doubt about the deterioration of the irreversibleabout the deterioration of the irreversible hydrocolloid, test it before usehydrocolloid, test it before use www.indiandentalacademy.comwww.indiandentalacademy.com
  25. 25. Error: Using a mix of irreversible hydrocolloidError: Using a mix of irreversible hydrocolloid that is too thick.that is too thick. Problem: A thick mix of irreversible hydrocolloidProblem: A thick mix of irreversible hydrocolloid may set before it is fully seated in the mouth.may set before it is fully seated in the mouth. When this happens, the irreversible hydrocolloidWhen this happens, the irreversible hydrocolloid will set under pressure. When irreversiblewill set under pressure. When irreversible hydrocolloid sets as pres­sure is applied, it ishydrocolloid sets as pres­sure is applied, it is always distorted.always distorted.66 www.indiandentalacademy.comwww.indiandentalacademy.com
  26. 26. The irreversible hydrocolloid may not flow into theThe irreversible hydrocolloid may not flow into the interproximal spaces between the teeth or pick up theinterproximal spaces between the teeth or pick up the anatomy of the soft tissues. This error may also result inanatomy of the soft tissues. This error may also result in the creation of drag marks in the impression and on thethe creation of drag marks in the impression and on the cast during seating of the impression. The marks will notcast during seating of the impression. The marks will not fill in because the material is too stiff to flow after it isfill in because the material is too stiff to flow after it is seated.seated. Solution: Follow the manufacturer's instructions forSolution: Follow the manufacturer's instructions for water/powder proportions by weight rather than bywater/powder proportions by weight rather than by volume.volume. www.indiandentalacademy.comwww.indiandentalacademy.com
  27. 27. Error: Attempting to control the setting time ofError: Attempting to control the setting time of irreversible hydrocolloid by altering theirreversible hydrocolloid by altering the water/powder ratio.water/powder ratio.55 ''66 Problem: If the mixture is thin one time and thickProblem: If the mixture is thin one time and thick another time, a standardized procedure cannotanother time, a standardized procedure cannot be established for seating the impression tray.be established for seating the impression tray. The result­ing inconsistency can causeThe result­ing inconsistency can cause unreliable results, in addi­tion to other problemsunreliable results, in addi­tion to other problems (see errors 9 and 10).(see errors 9 and 10). www.indiandentalacademy.comwww.indiandentalacademy.com
  28. 28. Solution: Control the water temperature to varySolution: Control the water temperature to vary the setting time of irreversible hydrocolloidthe setting time of irreversible hydrocolloid mixes. Always use the manufacturer'smixes. Always use the manufacturer's recommended water­to­powder ratio. Use waterrecommended water­to­powder ratio. Use water heated to more than room temperature to makeheated to more than room temperature to make the irreversible hydrocolloid set faster; use waterthe irreversible hydrocolloid set faster; use water chilled to lower than room temperature tochilled to lower than room temperature to increase the working time.increase the working time.77 A 10°F increase orA 10°F increase or decrease in the water temperature will increasedecrease in the water temperature will increase or decrease the working time by approximatelyor decrease the working time by approximately 40 seconds.40 seconds. www.indiandentalacademy.comwww.indiandentalacademy.com
  29. 29. Error: Failing to adequately mix the irreversibleError: Failing to adequately mix the irreversible hydrocolloid.hydrocolloid. Problem: If irreversible hydrocolloid is not mixed long orProblem: If irreversible hydrocolloid is not mixed long or thoroughly enough to completely saturate all of thethoroughly enough to completely saturate all of the powder with water, pockets of dry or partially wetpowder with water, pockets of dry or partially wet irreversible hydrocolloid can cause distortions.irreversible hydrocolloid can cause distortions. Solution: Hand mix the irreversible hvdrocoll­oidSolution: Hand mix the irreversible hvdrocoll­oid thoroughly for 60 seconds. Alternately, vacuum mix thethoroughly for 60 seconds. Alternately, vacuum mix the irreversible hydrocolloid for 15 seconds with at least 25irreversible hydrocolloid for 15 seconds with at least 25 inches of vacuuminches of vacuum www.indiandentalacademy.comwww.indiandentalacademy.com
  30. 30. Error: Allowing partially mixed irreversible hydrocolloidError: Allowing partially mixed irreversible hydrocolloid from around the top of the mixing bowl to befrom around the top of the mixing bowl to be incorporated into the mix as the tray is loaded.incorporated into the mix as the tray is loaded. Problem: Dry irreversible hydrocolloid particles absorbProblem: Dry irreversible hydrocolloid particles absorb water when the impression is washed. The dry particleswater when the impression is washed. The dry particles expand as they get wet and set. If a pocket of dry orexpand as they get wet and set. If a pocket of dry or partially wet irreversible hydrocolloid is in contact with apartially wet irreversible hydrocolloid is in contact with a tooth or other critical area when the impression is made,tooth or other critical area when the impression is made, dry material will expand after impression is removeddry material will expand after impression is removed from mouth and washed, resulting in inaccuracies.from mouth and washed, resulting in inaccuracies.55 ''66 Solution: Make certain that partially mixed or drySolution: Make certain that partially mixed or dry irreversible hydrocolloid powder is not incorporated intoirreversible hydrocolloid powder is not incorporated into the mix for the impression.the mix for the impression. www.indiandentalacademy.comwww.indiandentalacademy.com
  31. 31. Thank you For more details please visit www.indiandentalacademy.com www.indiandentalacademy.comwww.indiandentalacademy.com

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