Impression procedures /certified fixed orthodontic courses by Indian dental academy


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Impression procedures /certified fixed orthodontic courses by Indian dental academy

  1. 1. IMPRESSIONS PROCEDURES INDIAN DENTAL ACADEMY Leader in continuing dental education 1
  2. 2. Principles of Impression making. • To cover the MAXIMUM possible denture supporting AREA. • To achieve the closest possible CONTACT with the underlying epithelium. • To establish a PERIPHERAL SEAL. 2
  3. 3. Operator position for maxillary impression • Correct Incorrect 3
  4. 4. Operator position for Mandibular Impression Correct Incorrect 4
  5. 5. Techniques. •Single stage • Open mouth – Mucocompres sive – Mucostatic – Selective pressure •Double stage • Closed mouth. 5
  6. 6. Conventional two stage procedure. 6
  7. 7. Primary impression • It records the useful anatomy of the edentulous mouth so that a model can be cast on which an accurately fitting special tray can be made. Materials used:Alginate Impression compound. 7
  8. 8. Primary Impression in alginate. 1.Selection of stock tray. 2. Position borders at hamular notches. 3. Lift the tray anteriorly, 3-5 4. Tray should be adjusted by mm space for impression bending . material. 8
  9. 9. 5. Border of ray should be short of tissue reflection. 6. Adequate clearance in frenal areas. 7. Tray should be smoothened. 9
  10. 10. 8. Deficient borders corrected by adding utility wax. 9. Tray extension in buccal space and tissue side of posterior border. 10. Tissue stop in central portion of tray. 10
  11. 11. 11. Location of hamular notches. 12. Mark the vibrating line. 13. Some alginate to be 14. Alginate to be placed placed in vestibule. in deepest part of palate. 11
  12. 12. 15. Tray to be rotated into the mouth and seated first at the back of the mouth. 16. Upper lip elevated. 18. Labial and buccal borders to be molded. 12 17. Tray is held in the mouth.
  13. 13. 19. Completed maxillary Primary Impression with rounded and molded peripheries. 13
  14. 14. Mandibular alginate impression. 1.Britania metal edentulous tray. 2. Retromolar pad should be identified 3 . Tray should cover retromolar pad and rest against external oblique ridge. 14
  15. 15. 4. Bending and cutting the tray for adjustment. 5. Adding utility was to extend lingual border. 15
  16. 16. 6. Patient told to raise the tongue and tray is rotated in the mouth. 7. Patient told to do tongue movements. 8. Gently mold the labial and buccal areas. 16
  17. 17. • Completed Mandibular Primary Impression. 17
  18. 18. Alternative Techique for primary impression Alginate impression in compund tray. 1. Modelling compund. 2. Softenend in water bath and kneaded. 3. Compound placed in the tray. 18
  19. 19. 4. Molded with fingers to ridge form. 5. Should cover mylohyoid ridge and external oblique ridge. 6. Gently warmed over a flame. 7. Before insertion, tempering in warm water bath. 19
  20. 20. 8. Tray should be gently seated. 9. Patient instructed for Tongue movements and to purse lips. 10. Impression should 11. Any short areas can be cover all denture bearing remolded. area. 20
  21. 21. 12. All bordrs reduced by 2-3 mm. 13. Inside surface reduced by 1-2 mm. 14. Thin mix of alginate loaded. 21
  22. 22. 15. Completed preliminary impression made with alginate using a compound tray. 22
  23. 23. Preperation for Secondary Impression • Denture outline marked on the primary impression. Completed preliminary casts. 23
  24. 24. Secondary impression 1. Denture outline accentuated. 2. Posterior border of tray marked.distal to denture border. 3. Wax added for relief. 4. Special tray. 24
  25. 25. 5.Borders should be beveled. 6. Vibrating line marked. 7. Tray inserted in mouth. 8. Overextensions trimmed. 25
  26. 26. 9. Tray should be short of 2 mm from base of sulcus 11. Extra clearence in frenal areas 10. Borders should be adjusted. 12. Softened compound added from hamular notch to buccal space. 26
  27. 27. 13. Compound molded with fingers. 14. Softened again with alcohol torch. 16. The tray rotated in mouth 15. Tempered in warm water and cheek gently massaged. bath. 27
  28. 28. 17. Appropriate molding will have mat surface. 18. Compound added in buccal frenum area. 19. To record the frenum patient told to purse the lips. 28
  29. 29. 20. Molded buccal and labial borders. 22. Excess compound on tissue side trimmed. 21. Recording the frenum. 23. Compound placed on posterior border. 29
  30. 30. 24. Tray seated in mouth with firm pressure. 25. Junction of tray and compound smoothened. 26. Border molded maxillary custom tray. 30
  31. 31. 1. Tray outline marked 2-3 mm short of denture outline. 2. Custom tray fabricated. 3. Posterior border of tray 4. External oblique ridge should cover anterior half of the marked. pad. 31
  32. 32. 5. Pencil mark transferred to fitting surface. 7. Anterior border of the tray adjusted . 6. Tray border should be resting against the ridge. 8. Lingual border adjusted. 32
  33. 33. 9. Compound placed on posterior border 11. Compound added on buccal border 10. The tray gently seated in place. 12. The border should be smooth,round and convex. 33
  34. 34. 13. Border molding continued in labial borders. 14. Border molding the lingual areas. 34
  35. 35. 15. Genial tubercles should be covered. 16. Border molded mandibular tray 35
  36. 36. •Clearance provided for frenum. •Tray held gently in place. • Impression tray loaded with Zinc oxide eugenol. •Lips and cheek movements to be done as material sets. 36
  37. 37. • Completed maxillary final impression. Primary impression 37
  38. 38. • Completed mandibular final impression. Primary impression. 38
  39. 39. Closed mouth techniques. • The denture has more accurate fit during mastication. • Impression material coated at bases of the blocks and patient told to close in retruted contact position. • Patent given small amount of water to rinse.This captures the normal movements of the surrounding musculature. • Material : – thin zinc oxide eugenol, – light body silicone. 39
  40. 40. Closed mouth technique. • Drawbacks of – Maxillary Disto buccal space is not recorded in function. – Viscous impression material can lead to increase in vertical dimension. Advantages • Discrepancies in the jaw relations, . from points of premature contact resulting of the rims are eliminated. • Masseter muscle can be recorded in function. 40
  41. 41. Mucodisplasive • The impression material must be capable of viscous flow as it is extruded under pressure from between the tray and the tissue surface. • Materials used – Impression compound – High viscosity silicones – Stiff zinc oxide eugenol. 41
  42. 42. Mucostatic. • Use a very fluid impression material, and use minimal pressure while it sets. 42
  43. 43. Selective pressure technique. • It is a combination of extension for maximum coverage within tissue tolerance with light pressure or intimate contact with the movable,loosely attached tissues in the vestibules. • The impression is refined with a minimum of pressure. 43
  44. 44. Suggested impression techniques. Clinical finding Primary impressions Secondary impressions T echnique Good ridge form Impression compund Plaster of Paris, zinc oxide/eugenol, alginate or elastomer conventional As above but undercuts present Impression compound Alginate or elastomer; depends on degree of undercuts Impression technique conventional but plan path of insertion and removal of tray to match that of the proposed denture. Good ridge form Upper ridge displaceable alginate Use a two-stage impression technique Controlled mini~ally displacive impression techniques Ridge may look satisfactory but consists of fibrous tissue or has non-corticated (e.g. knifeedge) ridge-pain elicited when palpated Alginate or mediumbodied elastomer Zinc-oxide/eugenol or light-bodied elastomer Controlled pressure impression technique Very atrophic ridges or where optimum peripheral extension is indeterminate Impression compound Functional Modify denture appropriately impression method and add impression material Sound denture supporting tissues No undercuts which is mounded by functional movements 44
  45. 45. Leader in continuing dental education 45