Local Anesthesia: Armanterium

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Anaesthesia & Exodontia
Third Year

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Local Anesthesia: Armanterium

  1. 1. Local Anestheisa Armamentarium 1.) The Syringe 2.) The Needle 3.) The Cartridge
  2. 2. Types of Syringes Nondisposable: Side and basal-loading, metallic, cartridge type, aspirating or nonaspirating.
  3. 3. Pressure syringe: used in IL injection techniques, especially in mandibular teeth (types: pistol-grip, pen-grip).
  4. 4. Jet Injector (Needless)
  5. 5. Jet Injector (Needless)
  6. 6. Specialized syringes Intraosseus syringe: narrow surgical drill needed
  7. 7. Syringe Components 1.) Needle adapter 2.) Piston with harpoon 3.) Syringe barrel 4.) Finger grip 5.) Thumb ring
  8. 8. American Dental Association (ADA) criteria for acceptance of LA syringes:      1-Durable and resterilzable or packaged in a sterile container (if disposable). 2-Accept a wide variety of cartridges and needles of different manufactures (universal use) 3-Inexpensive, light weight, and simple to use with one hand. 4-Provide effective aspiration and the blood be easily observed in the cartridge. The incidence of positive aspiration may be as high as 10%-15% in some injection techniques.
  9. 9. Assembling the syringe system      Ensure syringe has been sterilized Ensure the needle container seal is intact Break the seal by rotation Screw needle to hub Check the LA cartridge contents:       Expiry date Cloudiness Cracking Air bubbles Load the syringe with cartridge Ensure free flow of LA
  10. 10. Holding the syringe    Hold the barrel rest with the index and middle fingers of the dominant hand and the thumb rest with any part of your thumb. The syringe should be below the vision level The other hand (dental mirror) should reflect and stretch the mucosa and identify the landmarks
  11. 11. Dismantling the syringe system  Remove needle either by:       Needle forceps Finger protector Single-handed pick up Disposable syringe has a built-in needle guard Place the needle and the glass cartridge in labelled sharps container (Orange) Return the syringe for washing and autoclaving
  12. 12. The Needle Gauge: the larger the gauge the smaller the internal diameter of the needle Usual dental needle gauges are 25,27, & 30 Length: 1-Long(approximately 40 mm "32-40 mm"), for NB. 2-Short(20-25 mm). 3-Extra-short(approximately 15 mm), for PDL.
  13. 13. Components of the needle 1.) Bevel 2.) Shank (shaft) 3.) Hub 4.) Syringe adapter 5.) Syringe penetrating end
  14. 14. The Cartridge     Components: Cylinder, plunger, diaphragm Types: Standard – Self aspirating, plastic, Glass Contents: LA, VC, Vehicle, preservative. Volume: 1.8, 2.00 & 2.2 ML.
  15. 15. The Cartridge
  16. 16. The Cartridge     Should not be autoclaved Stored at room temperature (21°C to 22°C (70°F to 72°F) Should not soak in alcohol Should not be exposed to direct sunlight
  17. 17. Packaging
  18. 18. Contents of Cartridge Anesthetic Agent Vasoconstrictor Preservative for vasoconstrictor Sodium chloride Distilled water
  19. 19. Preparation of Armamentarium
  20. 20. Loading the Syringe
  21. 21. 1.) remove syringe from sterile bag 2.) attach needle 3.) retract piston fully 4.) insert cartridge 5.) engage the harpoon 6.) carefully remove colored cap
  22. 22. Other Armamentarium 1) Topical Anesthetic (strongly recommended) -ointments, gels, pastes, sprays 2) Applicator sticks 3) Cotton gauze
  23. 23. Topical Free nerve endings Terminal nerve endings Main trunk Infiltration Nerve block
  24. 24. DentiPatch (lidocaine transoral delivery system) Preinjection – 10-15 minutes exposure prior to injection  Root scaling/planing – apply 5-10 minutes prior to beginning procedure 
  25. 25. Contents of Cartridge Anesthetic Agent The Ideal Local Anesthetic: • Water soluble/stable in solution • Non-irritating to nerve • Low systemic toxicity • Short induction period • Adequate duration of action • No post anesthetic side effects • Vasoconstriction effect 
  26. 26. Percent Solution Different anesthetics come in various concentrations  These concentrations are given as a percentage • .5% = 5 mg/cc • 1% = 10 mg/cc • 2% = 20 mg/cc  Multiply by 1.8cc to determine how many mg are in a dental cartridge 
  27. 27. Chemical Configuration of Local Anesthetic Compounds in Dentistry   Amides Esters
  28. 28. Amides vs Esters Major difference is method of metabolism – Amides: majority of the drug is metabolized in the liver – Use with caution in patients with severe liver disease – Use lower dose to avoid toxicity – Esters: metabolized in the plasma by pseudocholinesterase PABA is a major metabolite of ester metabolism – Known allergen • Atypical pseudocholinesterase deficiency – Patients will not be able to metabolize; toxicity may ensue 
  29. 29. Amide Local Anesthetics       Articaine Bupivicaine Etidocaine Lidocaine Mepivacaine Prilocaine
  30. 30. Ester Local Anesthetics          Butacaine Benzocaine Cocaine Chloroprocaine Hexylcaine Piperocaine Procaine Propoxycaine Tetracaine
  31. 31. Nerve Conduction      Resting membrane potential -60 to -90 Stimulus Slow depolarization Threshold reached causing action potential Repolarization
  32. 32. Nerve conduction At resting potential – Axoplasm is negative (around -70mV) – Membrane is freely permeable to K+ and Cl– Membrane is only slightly permeable to Na+ 
  33. 33. Nerve conduction Nerve excitation causes – Increase in the permeability of the membrane to Na+ – The rapid influx of Na+ to the interior of the nerve cell causes the axoplasm to become more positive – The firing threshold is reached (-50 to -60mV) – An action potential is created 
  34. 34. Nerve conduction Repolarization – At the end of the action potential, the electric potential is positive (+40mV) – The nerve membrane becomes impermeable to Na+ – There is an efflux of K+ and there is a return to normal resting potential 
  35. 35. Mechanism of Action of Local Anesthetic Agents    There are different unproven theories to explain the exact mechanism of action of local anesthetics The basic fact is that sodium channels are blocked preventing sodium ions from crossing the membrane This causes blockage of the formation of an action potential
  36. 36. Henderson hasselbach equation Determines how much of a local anesthetic will be in a non-ionized vs ionized form  Based on tissue pH and anesthetic Pka 
  37. 37. Henderson Hasselbach cont    Injectable local anesthetics are weak bases (pka=7.5-9.5) When a local anesthetic is injected into tissue it is neutralized and part of the ionized form is converted to non-ionized The non-ionized base is what diffuses into the nerve
  38. 38. Henderson Hasselbach Hence • If the tissue is infected, the pH is lower (more acidic) and according to the HH equation; there will be less of the non-ionized form of the drug to cross into the nerve (rendering the LA less effective) • Once some of the drug does cross; the pH in the nerve will be normal and therefore the LA re-equilibrates to both the ionized and nonionized forms; but there are fewer cations which may cause incomplete anesthesia 
  39. 39. Factors affecting LA action Lower pKa = more rapid onset (more LA in non-ionized form to diffuse through) • Increased lipid solubility = increased potency • Increased protein binding = longer duration of action 
  40. 40. Maximum Recommended Doses of Local Anesthetics
  41. 41. Vasoconstrictors      Constrict vessels and decrease blood flow to the site of injection. Absorption of LA into bloodstream is slowed, producing lower levels in the blood. Lower blood levels lead to decreased risk of overdose (toxic) reaction. Higher LA concentration remains around the nerve increasing the LA's duration of action. Minimize bleeding at the site of administration.
  42. 42. Naturally Occurring Vasoconstrictors   Epinephrine Norepinephrine
  43. 43. Vasoconstrictors should be included unless contraindicated
  44. 44. Mode of Action    Attach to and directly stimulate adrenergic receptors Act indirectly by provoking the release of endogenous catecholamine from intraneuronal storage sites Combination of 1 and 2
  45. 45. Epinephrine (Adrenalin)   Most potent vasoconstrictor used in dentistry Concentrations of 1:50,000 to 1:200,000 in dental cartridges
  46. 46. Concentrations of Vasoconstrictor in Local Anesthetics    1:50,000 1:100,000 1:200,000    0.020mg/ml 0.010mg/ml 0.005 mg/ml
  47. 47. Calculation 1:50,000= 1gram/50,000ml= 1000mg/50,000ml= 1mg/50ml= 0.02mg/ml
  48. 48. Levonordefrin  One fifth as active as epinephrine
  49. 49. Vasoconstrictors - Unstable in Solution Sodium metabisulfite added Known allergen
  50. 50. Max dose of vasoconstrictors    Healthy patient approximately 0.2mg Patient with significant cardiovascular history: 0.04mg • How many carpules of 2% lidocaine with 1:100,000 is max dose for CV patient???
  51. 51. Max Dose for Vasoconstrictors (CV patient) 1 carpule = 1.8cc 1:100,000=.01mg/cc 0.01 X 1.8cc= 0.018mg 0.04/0.018=2.22 carpules
  52. 52. In a healthy adult patient  0.2/0.018=11.1 carpules
  53. 53. Please Remember !!!    Principle 1- No drug ever exerts a single action Principle 2- No clinically useful drug is entirely devoid of toxicity Principle 3- The potential toxicity of a drug rests in the hands of the user

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