Finished complete denture impression presentation final modification


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Clinical Removable Prosthodontics
Forth Year

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Finished complete denture impression presentation final modification

  2. 2. DEFINITION o AN IMPRESSION is the negative form of the teeth and/or other tissues of the oral cavity made in a plastic material that becomes relatively hard or set while in contact with these Tissues. oA COMPLETE DENTURE IMPRESSION is a negative registration of the entire denture bearing, stabilizing and border seal area present in the edentulous mouth. (Heartwell 5th edn.)
  3. 3. IMPRESSION  TYPES PRELIMINARY (Primary) IMPRESSION PURPOSE •Diagnosis •Construction of tray FINAL (Secondary) IMPRESSION • Making master casts  used for making dentures
  4. 4. PRINCIPLES AND OBJECTIVES OF IMPRESSION MAKING The impression technique for CD must strive to accomplish the following five primary objectives:PRESERVATION: The preservation of remaining residual ridge is one of the important objectives of impression making. STABILITY: It refers to the resistance against horizontal movement and forces that tend to alter the relationship between the denture base and its supporting foundation in a horizontal/rotatory direction. Close adaptation to the undistorted mucosa is most important for stability. Stability decrease with the loss of vertical height of the ridges or with increases in flabby movable tissues
  5. 5. SUPPORT: It is the resistance of a denture to the vertical components of mastication and to occlusal or other forces applied in a direction towards basal seat. Maximum coverage provides the ‘SNOWSHOE’ effect which distributes applied forces over as wide an area as possible . This helps in:oPreservation oStability oRetention
  6. 6. ESTHETICS Border thickness should be varied with the needs of each patient in accordance with the extent of residual ridge loss. The vestibular fornix should be filled but not overfilled, to restore facial contour.
  7. 7. RETENTION Retention for a denture is its resistance to removal in a direction opposite that of its insertion or Resistance of a denture to vertical movements away from the tissues (Prosthetic Dent. Glossary 1995 Quintessence). The quality inherent in the prosthesis acting to resist the forces of dislodgment along the path of insertion. (GPT 1999 7th edn.)..
  8. 8. BASIC CONCEPTS TO ACHIEVE A SUCCESSFUL IMPRESSION The tissues of mouth must be healthy. Impression should extend to include all of the basal seat within the limits of the health and functions of the supporting and limiting tissues. Borders must be in harmony with the anatomical and physiological limitations of the oral structures.
  9. 9. Proper space for selected impression material should be provided within the impression tray. A physiologic type of border molding procedure should be performed by the dentist or by the patient under the guidance of the dentist. Selective pressure should be placed on the basal seat during the making of impression.
  10. 10. The impression should be removed from the mouth without damage to the mucous membrane of the residual ridges. A guiding mechanism should be provided for positioning of impression tray in mouth. The tray and impression material should be made of dimensionally stable materials. External surface of impression should be similar to the external surface of complete denture.
  11. 11. AIM OF PRIMARY IMPRESSION Record the denture bearing areas of each arch in stock metal trays. According to the guides to standards in prosthetic dentistry there are basic requirements required for primary impressions.
  12. 12. THE MINIMAL REQUIREMENTS OF AREAS TO BE RECORDED IN PRIMARY IMPRESSIONS FOR COMPLETE DENTURES MAXILLARY ARCH Residual ridge including full extent of the tuberosities and hamular notch. Functional depth of labial and buccal sulci, including fraenae and muscle attachments. The hard palate and its junction with soft palate.
  13. 13. MANDIBULAR ARCH Residual ridge, including the full extent of retro molar pads. Functional depth of labial and buccal sulci, including fraenae, muscle attachments and external oblique ridges. The lingual sulci, lingual frenum, mylohyoid ridges and retromylohyoid areas. (BDJ)
  14. 14. IMPRESSION TRAYS For primary impression we use stock metal/plastic trays of varying sizes that are available. -Trays are the most important part of impression making procedure Non perforated  impression compound Perforated  alginates, silicone putty
  15. 15. Too large a tray will:- Distort tissue around the border of impression. Pull soft tissues under the impression away from bone. Distorting dimensions of sulcus.
  16. 16. Too small a tray :– the border will collapse inward onto the residual ridge. Distort dimensions. Proper support of lips is lost
  17. 17. Preliminary impression should be as accurate as possible At times even a correctly selected stock tray will not fit the denture – bearing area perfectly. Therefore select a impression material that has relatively high viscosity thereby allowing the material to compensate more easily for the deficiencies of the tray.
  18. 18. Most suitable materials for primary impression are 1.Silicone putty -Addition difficult -High viscosity – poor surface details 2.Alginate Accurate detail Simplicity of equipment needed Ease of manipulation Little discomfort to patient Short chair time Dimensionally unstable
  19. 19. 3.Impression compound -Thermoplastic -High viscosity -Support itself -Additions possible -Poor surface details -Inelastic –hence undercuts not recorded 4.Impression plaster MATERIAL OF CHOICE FOR MOST DENTIST CURRENTLY IS HIGH VISCOSITY ALIGINATE IMPRESSION MATERIAL.
  20. 20. PRIMARY IMPRESSION •Position of patient -Seat patient in upright comfortable position with the occiput firmly resting in the head rest. -Allay’s fear of patient of being chocked by impression material -Head and neck should be line with trunk it Relaxes infra and suprahyoid muscles (swallowing movements easy) -Prevents easy fall of impression material fragment (if any) in throat -Cover the patient to protect patients clothing. -Warm, flavored mouth wash for rising.
  21. 21. Position of operator A.UPPER ARCH B.LOWER ARCH
  22. 22. TRAY SELECTION FOR MAXILLARY PRIMARY IMPRESSION An edentulous stock tray that is approximately 5-6 mm larger than the outside surface of residual ridge is selected. Place the tray in the mouth and position it by centering the labial notch of tray over the labial frenum. Posterior extent of tray relative to PPS is maintained and the handle is dropped downward the permit visual inspection. Examine the extension of tray flange at buccal and labial areas.
  23. 23. The fingers of one hand are shifted into the middle of tray and border molding is carried out. The labial and buccal vestibule are molded by asking the patient to suck down onto the tray. Move mandible from side to side to record the distobuccal area and influence of coronary process and shape of buccal vestibules
  24. 24. Open wide to record pterygomandibular raphe. Asked the patient to suck the finger of the operator – establishes impression of posterior aspect of upper impression
  25. 25. COMMON FAULTS IN UPPER IMPRESSION 1. A crevice in the midline of palatal posterior third. Causes Insufficient composition in palatal area when fitting the tray. Insufficient pressure 2. Excessive composition extending well beyond the posterior palatal border of tray Causes Excessive pressure or too prolonged pressure when seating the tray. Too much compound in palatal area
  26. 26. 3. An impression short in one or more regions of sulci, especially the areas of tuberosities or labial sulcus. Causes Insufficient material in tray Failure to mold Failure to pull upper lip out and upwards Insufficient pressure 4. Tray flange showing through composition Causes Poorly selected or adapted tray Incorrect centering of tray Most of these deficiencies can be corrected by addition of small amounts of composition.
  27. 27. FAULTS IN LOWER PRIMARY IMPRESSIONS 1. Insufficient depth, in the posterior lingual pouch Causes Flange of the tray short in this region Lack of composition in the tray To little force used in seating the tray Tongue trapped by the tray flanges because the patient failed to raise the tongue as the tray was seated In some cases it is necessary to push the compound into the lingual pouch area with the fore-finger just before the tray is finally seated.
  28. 28. 2. Insufficient depth in the lingual, labial and buccal sulci. Causes Lack of impression material Not seating the tray with sufficient pressure The presence of a smooth hollow in the buccal distal peripheral Causes The cheek was not released from beneath the composition border during functional trimming.
  29. 29. 3.Edge of the tray showing through the impression Causes Incorrect centering of the tray before seating. In the anterior lingual region. The forward thrust of the tongue not being countered by sufficient backward pressure on the tray Use of too large a tray for the mouth or failure to trim the flanges adequately.
  30. 30. Corrections to faults (1) and (2 may be made by adding small softened pieces of composition to the imperfect areas and then reseating and re-molding the impression. The error due to cheek folds, (3) should be corrected by reheating the impression in that area and re-adapting, whilst fault number (4) usually requires an entirely new impression.
  31. 31. THANK YOU