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DH-Den Therap I - 2

DH-DTherap I/2-Local Anesthetics and Topical Anesthetics

QuestionAnswer
What are local anesthetics? Injected locally these agents penetrate tissue and inhibit the movement of nerve impulses along sensory fibers. They block the transmission of peripheral nerve conduction thus reduce or block pain sensation along sensory nerves.
Local Anesthetics was released Procaine (Novocain) was synthesized by Einhorn in 1905. Xylocaine (lidocaine) was released in 1952. The search for the perfect local anesthetic agent is still ongoing.
How Do Anesthetics Work? (1-3) Natural nerve impulse conduction (called an action potential) works by opening sodium channels allowing an inward flux of Na++ and an outward movement of K++.
How Do Anesthetics Work? (2-3) As a nerve impulse is initiated, there is a change in polarity along the entire length of the nerve. Local anesthetics bind to a receptor and decrease the permeability of the nerve membrane to Na++, thereby decreasing the rate of depolarization.
How Do Anesthetics Work? (3-3) Without depolarization of the membrane, the nerve impulse is prevented from occurring.
Ideal Properties of a Local Anesthetic (1-2) In general a local anesthetic should possess the following qualities: Be potent Be reversible Be absent of local reactions Be absent of allergic reactions
Ideal Properties of a Local Anesthetic (2-2) Have rapid onset Have satisfactory duration Have adequate tissue penetration Have low cost Have long stability or “shelf life” Be sterilizable by normal methods Be easily metabolized and excretable
Composition In addition to the anesthetic agent, there are several other chemicals in local anesthetics: Vasoconstrictor Antioxidants Sodium hydroxide Sodium chloride Preservatives
Vasoconstrictor -Prolong duration of the anesthetic -Increase depth of the anesthetic -Delay systemic absorption -Reduce hemorrhage at site of injection -keeps the anesthetic in the area longer, keeping the patient anesthetized for a longer period of time.
examples of vasoconstrictors used in local anesthetics Epinephrine & Neo-Cobefrin
Antioxidants -reduce the oxidation or breakdown of the epinephrine. -Sodium bisulfite or sodium meta-bisulfite. -if allergic to this component & it can be especially hazardous with asthmatic patients: it may cause wheezing, stridor or chest tightness.
if allergic to Antioxidants it can be especially hazardous with asthmatic patients and can cause wheezing, stridor or chest tightness
Sodium Hydroxide An alkylinizing agent. Adjust the pH to between 6.0 and 7.0. Prevents pain at site of injection.
Sodium Chloride Makes the injected solution Isotonic. Allows the solution to penetrate tissue better and work better.
Preservatives Methylparaben and Propylparaben. Added to multiple dose injectable (parenteral) drugs to prevent bacterial contamination. Commonly used in Medicine. NOT found in Dental anesthetic carpules. Dental carpules are single use only.
What is not NOT found in Dental anesthetic carpules Preservatives Methylparaben and Propylparaben.
What makes injected solution Isotonic. Sodium Chloride
Classification of anesthetics BQ! Two main chemical types of local anesthetics: Amides Esters
Two main chemical types of local anesthetics: BQ! Amides Esters
Esters Less commonly used in dentistry today. Have a higher allergenicity potential. Butacaine Cocaine Benzocaine Piperocaine Tetracaine Procaine- “novocaine” Propoxycaine
Not used in therapeutics drugs Cocaine Benzocaine
95% no allaregies are to Amides
Amides Most common types used today. Low allergenicity potential. Lidocaine- “xylocaine” Mepivacaine- “carbocaine” Bupivacaine- “marcaine” Prilocaine- “citaneste”
Topical Anesthetics in Dentistry Benzocaine (esther)- 20% topical gel Lidocaine (amide)- 2% viscous solution
Long lasting Amides "pinetocaine" - Septocaine (newest)
Epinephrine Vasoconstrictors in local anesthetics. Most common one used. Sympathomimetic or adrenergic agonist, will increase blood pressure. Available in three common concentrations: 1 in 50,000 1 in 100,000 1 in 200,000
Which is most concentrated? 1 in 50,000 1 in 100,000 1 in 200,000 BQ! 1 in 50,000 high 1 in 100,000 medium 1 in 200,000 low
Natural adrenaline is similar to Epinephrine
With this anesthetics will increase blood pressure Epinephrine
Not injection anesthetics Benzocaine (esther)- 20% topical gel Lidocaine (amide)- 2% viscous solution
Neo-Cobefrin Vasoconstrictors in local anesthetics. This is a synthetic vasoconstrictor. Chemical name is levonordefrin. Similar effects as epinephrine but to a much lesser extent. Safer to use compared to epinephrine in similar quantities.
Duration of anesthesia Short acting plain anesthetics (no epinephrine or any vaconstrictor) 30 minutes pulpal anesthesia Lidocaine (xylocaine) plain Mepivacaine (carbocaine) plain Prilocaine (citaneste) plain
Pulpal and soft tissue Duration of anesthesia Lidocaine w/epi: 60 minutes pulpal, 3-5 hrs soft tissue Mepivacaine w/epi: 60-90 minutes pulpal, 3-5 hrs soft tissue Prilocaine w/epi: 60-90 minutes pulpal, 3-8 hrs soft tissue.
Contraindication for vasoconstrictors BQ! Uncontrolled hypertension Tricyclic antidepressants Cardiovascular disease Recent heart attack Angina Arrhythmia Hyperthyroidism (it self cause HBP) MAO (monoamineoxidase) inhibitors
Maximum Safe Dose of Epinephrine for Cardiac Patients 1 in 50,000 1 in 50,000 Healthy pt: 0.2 mg, 5 carpules Cardiac pt: 0.04mg, 1 carpule
Maximum Safe Dose of Epinephrine for Cardiac Patients 1 in 100,000 1 in 100,000 Healthy pt: 0.2mg, 11 carpules Cardiac pt: 0.04mg, 2 carpules
Maximum Safe Dose of Epinephrine for Cardiac Patients 1 in 100,000 1 in 200,000 Healthy pt: 0.2mg, 22 carpules Cardiac pt: 0.04mg, 4 carpules
Delivering Anesthetic Infiltration Depositing anesthetic solution in the area of dental treatment. Aimed at flooding the area of small terminal nerve endings with anesthetic.
Delivering Anesthetic Block Depositing anesthetic at the nerve trunk providing a blockage of sensory input from the entire nerve. The injection is usually at a separate site from where the treatment will be provided.
Components of the Syringe Anesthetic carpule Color coded All information printed on cartridge Always check expiration date prior to loading syringe Always check for problems with the carpule
Dental needles Dental needles are usually 27 gauge. Blue- 1.0 inch ( 27x1) Yellow- 1.5 inch (27x1.5)
Components of the Syringe What type to use? Must always be autoclaved. Always use an “aspirating” type syringe.
Syringe Assembly Always check for problems with the anesthetic carpule: Air bubbles trapped Cracks in the glass Discolored solution Stopper pushing out end of glass carpule Breakdown of stopper Expiration date
What may cause shatter Syringe exert force on the plunger. Never, ever hit!
Local Anesthetics Complications Lip biting Paresthesia Hematoma Trismus
Prolonged use of topical anesthetic can cause epithelial desquamation (sloughing)
Local Anesthetics Complications Systemic Complications Angioedema-type of allergy-(life threatening) Other allergies-rash ,itching, erythema etc. Toxicity-accidental intravascular injection Hypothermia
Local complications are managed by symptomatic treatment
Systemic complications are managed based on the severity and may need emergency intervention
Primary Prevention (1-3) In order to prevent complications, it is important to use excellent injection technique Use aspirating syringe and always aspirate before injecting Inject v-e-r-y…… s-l-o-w-l-y Be alert & watch patient reaction Be ready for any emergencies
Primary Prevention (2-3) When using topical anesthetic, know what agent is used Use lowest concentration. Use smallest volume possible Limit area of application Avoid sprays
Reason why you should Avoid sprays Oral mucosa is highly vascular and majority is NOT keratinized. Topically applied can be quickly absorbed from the nonkeratinized mucosa into the circulation. As more topical is used, more concentrates in the circulation and can build a “Toxic” amount
Primary Prevention (3-3) Get medical history and know allergies Give appropriate instructions to patient about lip biting and cheek biting & tongue biting (especially children) Instructions about hot beverages and foods
Paresthesia
Hematoma
Trismus
Allergy-Angioedema
Briefly describe the ionization factors
an ideal local anesthetic agent
List the composition of local anesthetic agent
Classify local anesthetic and give examples for each class
Name two methods of local anesthetic injection.
List the precautions before giving local anesthetic injections.
List the possible complications of local anesthetic injections.
List the adverse effects of these agents – including toxic effect.
Describe the role of vasoconstrictor in local anesthetics.
List the contraindications for the use of vasoconstrictor.
Describe the care of local anesthetic cartridges.
Define “Topical Anesthesia.”
List the agents used in topical anesthesia and classify these agents.
Discuss the role of topical anesthetics in dentistry and dental hygiene.
Created by: Reda Redabj Reda Redabj on 2011-10-03



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