general instruments & instrumentation - Restorative Dentistry


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Introduction to Operative Dentistry
Third Year

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general instruments & instrumentation - Restorative Dentistry

  1. 1. General instruments & instrumentation
  2. 2. General classification 1. 2. 3. Diagnostic or exploring instruments Cutting instruments Isolating instruments 4.Condendsing instruments 5.Plastic instruments 6. Finishing& polishing instruments a-Hand b-Rotary 7.Miscellaneous instruments
  3. 3. Restoring teeth back to normal
  4. 4. Parts of hand cutting instrument
  5. 5. Black's formula Three figure instrument: 1. Width of blade in 1/10 mm 2. Length of blade in mm 3. Angle between long axis of blade &long axis of handle
  6. 6. Four figure instrument 1. 2. 3. 4. Width of blade in 1/10mm Cutting edge angle Length of blade in mm Angle between long axis of the blade & long axis of the handle
  7. 7. 3 Figure instrument
  8. 8. Hand cutting instruments are chisels or excavators
  9. 9. Chisel -Used in enamel -Cleavage of undermined enamel -Heavier in weight -Firm strokes - Include chisel, enamel hatchet, G.M.T, Angle former, weadelsteadt chisel Excavator -Used in dentin -Scooping or peeling off soft carious dentin -Lighter in weight -Gentle force - Include spoon, discoid, celoide, Hatchet
  10. 10.  Direct cutting instrument: direction of cutting is the same as direction of application of force  Lateral cutting instrument: direction of cutting is ┴ to direction of application of force  Single plane instrument: main parts of the instrument conform to one single plan  Double plane instrument: main parts are in two plans  Reverse beveled instrument. Left hatchet and mesial chisel indicated by a ring in the shaft
  11. 11.  Contra-angling: additional angle or angles added to the shank on the opposite side of the shaft in order to make the cutting edge within 2-3 mm from the long axis of the instrument→ balance, visibility, accessibility
  12. 12. 4 Figure instrument
  13. 13. Spoon and discoid excavator
  14. 14. Spoon excavator
  15. 15. Discoid excavator
  16. 16. Gingival marginal trimmer and enamel hatchet
  17. 17. Instrument maintenance, sharpness using Arkansas stones
  18. 18. Rotary Instruments  According to the attachment to the hand piece it is  1- Latch type→ conventional speed  2-friction grip→ conventional or high speed  Speed ranges -low 2000-5000 rpm -medium -high -ultra high
  19. 19. Latch and frictional grip
  20. 20.  Cutting efficiency: Ability of the cutting instrument to cut maximum amount of tooth structure in minimal time with minimal effort.  Factors affecting the cutting efficiency:  1- speed used  2- pressure  3- bur design & shape  4-use of a coolant  5-eccentricity or run out  6- Tissue to be cut
  21. 21. –Eccentricity or Run-out Maximum displacement of the bur head away from the central axis of rotation. The bur is said to be eccentric if this displacement is greater than 0.025mm. This leads to vibration and loss of controlled cutting.
  22. 22.  Heat generation: Not all the energy delivered at the cutting bur is dissipated in the form of actual cutting part of the energy is dissipated in the form of heat generation because of friction at the cutting site. Generated heat→ to the atmosphere- to the hand piece- to the tooth structure→ adverse effects on the pulp
  23. 23.     According to material of construction 1- steel bur 2-Tungestin carbide bur steel is less efficient, used for removal of hard caries and finishing of restorations  Tungsten Carbide bur harder, higher melting, better manufacturing
  24. 24. Bur Design
  25. 25. Rake Angle Increasing +ve rake angle increases the cutting efficiency but within limits +ve radial -ve
  26. 26. Cross Cutting( increasing number of blades without affecting clearance space)
  27. 27. Coolant Air-water spray, multi-directed, copious amount, 37̊ c so as to dissipate heat, lubricate, increase bur life, cleaning effects and reduce the need for local anesthesia
  28. 28. Burs versus Stones
  29. 29. Burs and Stones
  30. 30. Foot driven dental drilling