Local anesthesia ppt

Department of periodontics

1. LOCAL ANESTHESIA T.HUDSON JONATHAN, Ist yr MDS

2. CONTENTS INTRODUCTION MODE AND SITE OF ACTION OF LOCAL ANESTHETICS EVOLUTION OF THEORIES MECHANISM OF ACTION COMPOSITION OF LA CLASSIFICATION VASOCONSTRICTORS MAXIMUM RECOMMENDED DOSES DOSING CONSIDERATIONS ARMAMENTARIUM

3. CONTENTS MAXILLARY INJECTION TECHNIQUES MANDIBULAR INJECTION TECHNIQUES SUPPLEMENTAL INJECTION TECHNIQUES COMPLICATIONS OF LA CONTRA INDICATIONS OF LA RECENT ADVANCES OF LA CONCLUSION REFERENCE

4. INTRODUCTION Local anesthesia has been defined as the loss of sensation in a circumscribed area of the body caused by depression of excitation in nerve endings or inhibition of conduction process in peripheral nerves. An important feature of local anesthesia is that it produces this loss of sensation without the loss of consciousness.

5. Mode and site of action of LA Local anesthetic agents alter the process of impulse generation and transmission in a nerve membrane in one or more of the following ways: Altering the basic resting potential of the nerve membrane. Altering the threshold potential. Decreasing the rate of depolarization. Increasing the rate of repolarization.

6. Evolution of theories Acetylcholine theory: Acetylcholine is involved in nerve conduction together with its role as a neurotransmitter at nerve synapses. But there is no evidence of involvement of acetylcholine in neural transmission along the body of the neuron

7. Calcium displacement theory : Displacement of calcium from certain membrane sites that controls the permeability to sodium . Altering the concentration of calcium ions has no effect on local anesthetic policy.

8. S urface charge theory: Local anesthetics bind to the nerve membrane and change the electrical potential at the membrane surface. LA molecules carring net positive charge make the electrical potential at the membrane surface more positive,thereby increasing the threshold potential. Recent evidence shows that there is no alteration in the resting potential by local anesthetics,and they act within the nerve membrane channels rather than at the surface.

9. Membrane expansion theory : Local anesthetic diffuses to hydrophobic regions and expands the membrane preventing the sodium permeability increase. Lipid soluble molecules alter the lipoprotein matrix of nerve membrane and decrease the diameter of sodium channels. There is no direct evidence to support this theory.

10. S pecific receptor hypothesis: It is the most favoured theory,Local anesthetics act by attaching themselves to specific receptors in the nerve membrane. The local anesthetic receptor is located at or near the sodium channel in the nerve membrane either on its external surface or on the internal axoplasmic surface. Once the receptor access is gained,sodium ion permeability is decreased or eliminated and nerve conduction interrupted.

11. Mechanism of action Local anesthesia primarily acts by decreasing the permeability of the nerve membrane to sodium ions. They have an insignificant effect on potassium conductance. Calcium ions present within the cell membrane control the conductance of the sodium ion across membranes. The release of calcium ion from this cell membrane results in an increased sodium permeability of the nerve membrane.

12. Displacement of calcium ions from nerve receptor site. ↓ Binding of local anesthetic molecule to this receptor site. ↓ Blockade of sodium channel. ↓ Decrease in sodium conductance. ↓ Depression of rate of electrical depolarization. ↓ Failure to achieve threshold potential level. ↓ L ack of development of propagated action potential. ↓ Conduction blockade.

13. Mechanism of action

14. C omposition of LA Component Function Local anesthetic drug Blockade of nerve conduction Sodium chloride Isotonicity of the solution Sterile water volume Vasopressor ↑depth and duration of anesthesia;↓absorption of local anesthetic and vasopressor Sodium(meta)bisulfite antioxidant Methylparaban Bacteriostatic agent

15. C lassification INJECTABLE: (Stanley .F.Malamed) a.Low potency,short duration -Procaine -Chloroprocaine b.Intermediate potency and duration -Lidocaine -Prilocaine c.High potency,long duration -Tetracaine -Bupivacaine -Ropivacaine -Dibucaine

16. 2. SURFACE ANESTHETIC: a.Soluble -Cocaine -Lidocaine -Tetracaine b.Insoluble -Benzocaine -Butylaminobenzoate -Oxethazine

17. 1.ESTERS Esters of benzoic acid -butacaine -cocaine -ethyl amino benzoate -hexylcaine -piperocaine - tetracaine Esters of para aminobenzoic acid - chloroprocaine -procaine - propoxycaine

18. AMIDES -articane -bupivacaine -etidocaine -lidocaine -mepivacaine -prilocaine - ropivacaine QUINOLINE - centbucridine

19. Vasoconstrictors Vasoconstrictors are drugs that constrict blood vessel and therby control tissue perfusion. They are added to the LA solution to oppose the inherent vasodilatory action of LA. They are an important addition to the local anesthetics for the following reasons. By constricting blood vessels,vasoconstrictors decrease blood flow to the site of drug administration.

20. Absorption of local anesthetic into the cardiovascular system is slowed,resulting in lower anesthetic blood vessels . Local anesthetic blood levels are lowered,therby decreasing the risk of local anesthetic toxicity. More local anesthetics enter into the nerve,where it remains for longer periods,therby increasing the duration of action of more local anesthetics.

21. Maximum recommended doses Drug Formulation MRD mg/lb (mg/kg) Articaine With epinephrine None listed 3.2 7.0 Lidocaine Plain With epinephrine 300 500 2.0 3.3 4.4 7.0 Mepivacaine Plain With levonordefrin 400 400 2.6 2.6 5.7 5.7 Prilocaine Plain With epinephrine 600 600 4.0 4.0 8.8 8.8

22. Dosing considerations Patient with cardiac history: Should limit dose of epinephrine to 0.04mg Most local anesthesia uses 1:100,000 epinephrine concentration (0.01mg/ml) Pediatric dosing: Clark’s rule: Maximum dose =(child weight in lbs(pounds)/150 ) X max adult dose(mg ) Simple method= 1.8cc of 2% lidocaine/20lbs

23. Armamentarium Anesthetic carpules Syringe Needle Mouth props Retractors Carpules : 1.7 or 1.8cc Pre-made in blister packs or canisters Contains preservatives for epinephrine andlocal anesthetics

24. Syringe: Aspirating type Non-aspirating type Needle: Multiple gauges used 25g,27g, 30g Length:Short- 26mm,Long- 36mm Monobeveled

25. Topical anesthetic: Used prior to local anesthetic injection to decrease discomfort in non-sedated patients Generally benzocaine(20 %)

26. Maxillary injection techniques Supraperiosteal injection Posterior superior alveolar nerve block Middle superior alveolar nerve block Anterior superior alveolar nerve block Infra orbital nerve block Greater palatine nerve block Nasoplalatine nerve block Anterior middle superior alveolar nerve block Maxillary nerve block

27. Local infiltration: It is defined as a technique in which the local anesthetic solution is deposited at or above the apex of the tooth to be treated . Small terminal nerve ending in the area of the dental treatment are flooded with local anesthetic solution. Incision is then made into the same area in which the local anesthesia has been deposited.

28. An example of local infiltration is the administration of a local anesthetic into a interproximal papilla before root planning . Field block: Local anesthesia is deposited near the larger terminal nerve branches. S o the anesthetized area will be circumscribed preventing, the passage of impulses from the tooth to the CNS. Incision is then made into the area away from the site of the anesthetic.

29. Nerve block: Local anesthetic is deposited close to main nerve trunk,usually at a distance from the site of operative intervention. Posterior superior alveolar,nasopalatine and inferior alveolar are some examples of nerve blocks.

30. Posterior superior alveolar nerve block : Used to anesthetize the pulpal tissue,corresponding alveolar bone, and buccal gingival tissue to the maxillary 1st, 2nd, and 3 rd molars .

31. Technique: Area of insertion- height of mucobuccal fold between 1st and 2nd molar Angle at 45° superiorly and medially Insert about 15-20mm Aspirate then inject if negative

32. Middle superior alveolar nerve block : Used to anesthetize the maxillary premolars, corresponding alveolus, and buccal gingival tissue Used if the infraorbital block fails to anesthetize premolars

33. Technique : Area of insertion is height of mucobuccal fold in area of 1st/2nd premolars Insert around 10-15mm Inject around 0.9-1.2cc

34. Anterior superior alveolar nerve block : Used to anesthetize the maxillary canine,lateral incisor, central incisor, alveolus, and buccal gingiva Technique : Area of insertion is height of mucobuccal fold in area of lateral incisor and canine Insert around 10-15mm Inject around 0.9-1.2cc

35. Infraorbital nerve block: Used to anesthetize the maxillary 1st and 2nd premolars , canine, lateral incisor, central incisor , corresponding alveolar bone, and buccal gingiva Combines MSA and ASA blocks Will also cause anesthesia to the lower eyelid, lateral aspect of nasal skin tissue, and skin of infraorbital region

36. Technique : Palpate infraorbital foramen extra-orally and place thumb or index finger on region Retract the upper lip and buccal mucosa Area of insertion is the mucobuccal fold of the 1 st premolar/canine area Contact bone in infraorbital region Inject 0.9-1.2cc of local anesthetic

37. Greater palatine nerve block: Can be used to anesthetize the palatal soft tissue of the teeth posterior to the maxillary canine and corresponding alveolus/hard palate Technique : Area of insertion is ~1cm medial from 1st/2 nd maxillary molar on the hard palate Palpate with needle to find greater palatine foramen Depth is usually less than 10mm

38. Utilize pressure with elevator/mirror handle to desensitize region at time of injection Inject 0.3-0.5cc of local anesthetic

39. Nasopalatine nerve block: Can be used to anesthetize the soft and hard tissue of the maxillary anterior palate from canine to canine. Technique : Area of insertion is incisive papilla into incisive foramen Depth of penetration is less than 10mm

40. Inject 0.3-0.5cc of local anesthetic Can use pressure over area at time of injection to decrease pain

41. Mandibular injection techniques Inferior alveolar nerve block Gow gates mandibular technique Vazirani akinosi (closed mouth technique) Buccal nerve block Mental nerve block 25 gauge

42. Inferior alveolar nerve block IANB commonly referred to as the mandibular nerve block is the second most frequently used and possibly the most important injection technique in dentistry. Nerves anesthetized: inferior alveolar,incisive,mental and lingual Areas anesthetized : mandibular teeth to midline body of mandible,inferior portion of ramus buccal mucoperiosteum mucous membrane anterior to mental foramen

43. V . anterior two-third of tongue and floor of oral cavity lingual soft tissue and periosteum Landmark: Coronoid notch Pterygomandibular raphe Occlusal plane of mandibular posterior teeth. Three parameters must be considered during administration of IANB. Height of the injection The anteroposterior placement of the needle The depth of penetration

44. Techniques: use a 25 gauge long needle,retract the tongue toward the midline with the mirror handle or tongue depressor to provide access and visibility to the lingual border of the body of the mandible. Approach area of injection from contra-lateral premolar region Use the non-dominant hand to retract the buccal soft tissue (thumb in coronoid notch of mandible; index finger on posterior border of extraoral mandible) Penetrate the soft tissue and advance the needle until bone is contacted.The depth of penetration to bone is 3-5mm.

45. Aspirate in two planes,if negative,slowly deposite approxi 1.5ml of anesthetic. Inject remaining anesthetic into coronoid notch region of the mandible in the mucous membrane distal and buccal to most distal molar to perform a long buccal nerve block. Indications: Procedures on multiple mandibular teeth in one quadrant When buccal and lingual soft tissue anesthesia is necessary

46. Gow-gates technique Gowgates technique is a true mandibular nerve block because it provides sensory anesthesia to virtually the entire distribution of mandibular nerve. Landmarks: Extra-oral- lower border of tragus,corner of the mouth Intra-oral: Height of injection established by placement of the needle tip just below the mesiolingual cusp of maxillary second molar. Penetration of soft tissue just distal to the maxillary second molar at the height established .

47. Nerves anesthetized: Inferior alveolar, mental, incisive, lingual, mylohyoid, auriculotemporal, buccal . Areas anesthetized: Mandibular teeth to midline buccal mucoperiosteum and mucous membrane on the side of injection anterior two third of the tongue and floor of the oral cavity lingual soft tissue and periosteum body of the mandible inferior portion of the ramus

48. skin over zygoma posterior portion of the cheek and temporal regions.

49. Vazirani- Akinosi technique In 1997,Dr.Joseph Akinosi reported a closed mouth approach for mandibular anesthesia. Although this technique can be used whenever mandibular anesthesia is desired,its primary indication remains those situations in restricted mouth opening. Landmarks: Mucogingival junction of the maxillary third molar or second molar. Maxillary tuberosity.

50. Nerves anesthetized : Inferior alveolar Incisive Mental Lingual Mylohyoid Areas anesthetized: Mandibular teeth to midline Body of mandible and inferior portion of ramus Buccal mucoperiosteum and mucous membrane anterior to the mental foramen Anterior two-third of tongue and floor of oral cavity Lingual soft tissue and periosteum

51. Precaution: Do not overinsert the needle (>25mm) Decrease the depth of penetration in smaller patients;the depth of penetration will vary with the anteroposterior size of patient’s ramus.

52. Mental nerve block Mental and incisive nerves are the terminal branches for the inferior alveolar nerve Provides sensory input for the lower lip skin,mucous membrane, pulpal/alveolar tissue for the premolars, canine, and incisors on side blocked. Technique : Area of injection: mucobuccal fold at or anterior to the mental foramen. This lies between the mandibular premolars

53. Depth of injection ~ 5-6mm Inject 0.5-1.0cc of local anesthesia

54. Intraligamentary injection: Because of the thickness of the cortical plate of bone in most patients and in most areas of the mandible,it is not possible to achieve profound pulpal anesthesia on a solitary tooth in the adult mandible. The intraligamentary injection is also known as the periodontal injection,which was originally described as so. In clinical studies in which an inferior alveolar nerve block failed to provide adequate pulpal anesthesia to the first molar. Supplemental injection techniques

55. So the doctor inserted a needle along long axis of the mesial root as far apically as possible and deposited a small volume of local anesthetic solution under pressure. This technique invariably provided effective pain control.

56. Intraseptal injection : The intraseptal injection is similar in technique and design to the PDL injection. It is useful in providing osseous and soft tissue anesthesia and hemostasis for periodontal curretage and surgical flap procedures. In addition it may be effective when the condition of the PDL in the gingival sulcus rule out the possibility of using PDL injection.

57. Saadeun and Malamed have shown that the path of diffusion of the anesthetic solution is through medullary bone as in the PDL injection.

58. Intrapulpal injection: Obtaining profound anesthesia in the pulpally involved tooth was a significant problem before the rediscovery of IO anesthesia. It is seen especially in mandibular molars where the nerve block anesthesia, proved to be ineffective in the presence of infection and inflammation. Deposition of local anesthetic(0.2-0.3ml) directly into the coronal portion of the pulp chamber of a pulpally involved tooth provides effective anestheia

59. The intrapulpal injection provides pain control through both the pharmacologic action of the local anesthetic and applied pressure. This technique is used once the pulp chamber is exposed surgically or pathologically.

60. Intraosseous injection: Deposition of LA into interproximal bone between two teeth has been practiced in dentistry since 20 th century. Originally IO anesthesia necessitated the use of half –round bur to provide entry into interseptal bone that had been surgically exposed,by which LA is deposited. In recent years IO technique has been modified with introduction of Stabident system,intra flow,X-tip.

61. Some persons had difficulty in placing the needle for LA deposition in previously drilled hole. The X-tip eliminated this problem,where it is composed of a drill and guide sleeve. The drill leads the guide sleeve through cortical plate and the guide sleeve remains in the bone and easily accepts a 27 gauge needle.

62. Complications of LA Needle breakage Prolonged anesthesia Facial nerve paralysis Trismus Soft tissue injury Hematoma Pain on injection Burning on injection Edema Infection Slouging of tissues

63. Contraindications of LA Absolute contraindication Relative contraindication Absolute contraindications History of allergy to local anesthetic agents Local anesthetic agents belonging to same chemical group should not be used. LA of different chemical group can be used. Relative contraindications Fear and apprehension Presence of acute inflammation or suppurative infection .

64. Infants or small children Mentally retarded patients Restricted mouth openings Patients with cardiovascular diseases, hepatic dysfunction, renal dysfunction, clinical hyperthyroidism. Presence of developmental defects Presence of congenital methemoglobinemia

65. Recent advances of LA Eutectic mixture of local anesthesia(EMLA) It is developed to diffuse through intact skin and to reduce the pain during needle injection through skin. Composition- 5% cream contains 25microgram/gram lidocaine and prilocaine. It is applied to skin atleast 1 hr before injection. It is contraindicated in children below 6 years of age

66. DENTIPATCH These are controlled releasing devices . Topical agent is incorporated into a matrix, which will adhere to mucosa and allow slow release of anesthetic drug . Eg: lidocaine transoral delivery system in 10% and 20% concentrations. JET INJECTIONS Also called as needle less anesthesia . It can penetrate mucous membrane/ skin under pressure with out causing exceesive tissue trauma . Eg: syrijet, madjet

67. WAND : It is computer controlled injection system. Dosage is controlled by computer. Trans electronic nerve stimulation(TENS) Electronic stimulation of nerve endings is used for anesthetic effect. Indicated in needle phobic patients and where local anesthesia is ineffective.

68. C onclusion Ideal properties as listed by Bennett says: It should have potency sufficient to give complete anesthesia without the use of harmful concentraed solutions. It should be relatively free from producing Allergic reactions. It should be stable in solution and should readily undergo biotransformation in the body.

69. It should be sterile or capable of being sterilized by heat without deterioration. No local anesthesia in use today satisfies all of these criteria.However ,all anesthetics do meet a majority of them. Research is continuing in a effort to produce a newer drugs that possess a maximum of desirable factors and a minimum of negative ones.

70. References Textbook of oral and maxillofacial surgery-S.M.Balaji. Handbook of local anesthesia-Stanley .F. Malamed. Textbook of oral and maxillofacial surgery-Neelima Anil Malik.