Local Anesthesia Midterm

***For the general technique of local anesthesia injections

--the needle is place on the syringe AFTER loading the cartridge -Used needles must be disposed of in designated sharps containers -Injections are best made slowly (about 1 cc/30 sec) -aspirate before you inject -inject a small amount of anesthetic in front of the needle before touching bone or periosteum -Underhand hold the syringe, use 4th finger for stabilization -Push and pull on ring with thumb w/o moving needle

Allergies to anesthetics

-Amide-based anesthetic allergy is rare -Esters is not rare -Allergies to amide-baed anesthetics are drug specific--no cross reactivity -Allergies to ester-based anesthetics are more common and there is cross-reactivity *most topical anesthetics are ester based, i.e. benzocaine, tetracaine

The Gate Control Theory of Pain Perception

-Basis for "pressure" pre-anesthesia -administered by holding a cotton-tipped applicator or smooth instrument handle against the tissue to minimize needle puncture discomfort -blanching = hemostasis, forcing the blood out of localized areas of tissue and preventing more blood from entering that particular site

Coumadin Therapy

-Competitive inhibition of synthesis of vitamin K dependent clotting factors (II, VII, IX, X) in liver -Coumadin affects the factor with the shortest half-life first -Therapeutic levels of INR range from 2-3.5 -Maintain Coumadin therapy if INR is 3 or less --can inject local and perform a limited number of extractions IF the other components of the hemostatic mechanism are intact

Palatal injection technique

-Deposite 1/3rd as fast as most other areas (SLOW) -pressure anesthesia -

The facial nerve

-Exits the cranial fossa via the stylomastoid foramen -Passes through the parotid gland -Does not enter the mid face through the infraorbital foramen -Provides motor control to the facial muscles

Liver failure considerations with LA

-Hep B and C, ETOH -Prolonged LA half life increasing risk of OD

What are reasonable strategies to follow if a patient has not achieved adequate anesthesia

-If there are no subjective signs of anesthesia, repeat injection -If there is soft tissue anesthesia, but not adequate dental anesthesia, consider alternative techniques such as the Gow-Gates or intraosseous injection -Switch to an anesthetic formulation with a vasoconstrictor

Problem with mandibular and lingual nerve blocks

-Lingual nerve is relatively easy to anesthetize -Mandibular nerve that is the problem

The greater palatine nerve block

-Needle generally contacts the bone

Dental Guidelines for patients with hypertension

-Routine care if systolic BP <140 and Diastolic BP <90mmHg -Caution with SBP >140-159 and/or DBP >90-94 -SBP 160-200: emergency or urgent dental care only -SBP >200 and/or DBP >115: no dental care and immediate medical consultation

Angina and MI ASA Ratings

-Stable angina (exertion): ASA III -Unstable angina (prinfarction): ASA IV -MI > 6 months: ASA III -MI <6 months: ASA IV

The infraorbital nerve block

-The foramen is located in line with the pupil when the patient is in a straight forward gaze -1-1.5 cc of solution is used -if the positioning is correct, when the needle contacts bone it should be below the infraorbital rim

Cocaine use today

-Used as topical anesthetic and vasoconstrictor -Addictive -esther -readily absorbed through mucosa

Methemoglobinemia

-condition in which cyanosis like state develops in the absence of cardiac or respiratory abnormalities -respiratory depression and syncope -induced by large doses of Articaine, Prilocaine, or Benzocaine (topical) -3-4 hours after large dose -Lethargy and respiratory distress -Gingival puncture--> brown blood -cyanosis -skin becomes pale gray -unresponsive to 100% O2 -Treat with methylene blue, repeat every 4 hours

Pregnancy considerations with LA

LA and vasopressors are not teratogens and can be used when necessary in pregnant patients

Posterior Superior Alveolar Nerve (PSA)

This branch of the maxillary (V2) nerve exits the pterygopalatine fossa through pterygomaxillary fissure before splitting into external branches which travel along the posterior surface of the maxilla and internal branches which enter the inferior-posterior maxilla area through PSA foramina. a) PSA nerve → innervates the dental pulp, facial gingiva, PDL, and alveolar bone of the maxillary first (except mesiobuccal root), second, and third molars.

Middle Superior Alveolar Nerve (MSA)

This is first branch of V2 in the infraorbital canal. The MSA exits the canal inferiorly to join the superior dental plexus, a term used to describe the aggregation of nerves in the maxilla, composed of the PSA, MSA, and ASA The MSA innervates the dental pulps, facial gingiva, PDL, and alveolar bone of the premolars and the mesiobuccal root of the first maxillary molar.

Anterior Superior Alveolar Nerve (ASA)

This is the second and final branch of V2 before it exits the infraorbital canal. The ASA exits the canal inferiorly to join the superior dental plexus. The ASA innervates the dental pulps, facial gingiva, PDL, and alveolar bone of the maxillary incisors and canines After branching into the MSA and ASA, V2 exits the infraorbital canal as the infraorbital nerve and divides into terminal branches to supply sensory innervation to the cheek area.

What nerve provides sensation for lateral border of tongue

lingual

The Gow-Gates technique

potential block of all branches of the mandibular nerve with one injection (V3; mandibular, lingual, long buccal, auriculotemporal) -longer lasting, the tissues are less vascular -long needle -3/4-1 carpule -Must touch condylar head: do not inject unless you do. Aspirate -Pt. must be able to open fully and hold for a few min

What is a PABA ester type local anesthetic

procaine

Inflammation as a result of infection in tissues

results in a lowered tissue pH (causes decrease in effectiveness of local anesthetics)

Palatal injection infiltration anatomical anesthetizations

teeth: at injection site peridontium: at injection site

Some of the landmarks used in the posterior superior alveolar nerve block

zygomatic strut of maxilla

Potential local complications to the injection of local anesthetics

1. muscle trismus 2. aphthous ulceration 3. prolonged paresthesia

Mandibular and lingual nerve blocks

-considered together bc they are accomplished with the same needle penetration -can be given separately but most of the time you want both -matter of depth -goal is to deposit solution at the mandibular foramen and the lingual nerve -angle varies depending on flair of ramus of mandible -allow finger to rest in area of greatest concavity of the anterior ramus Technique: 1/4-1/2 carpule at 4-5 mm in, the continue in until tip of needle contacts bone, back off 1 mm, aspirate carefully and inject rest of carpule -1.5 inch needle must touch bone at 20-25 mm in -2/3-3/4 of the long needle will be in tissue Landmarks: -external oblique ridge -internal oblique ridge -penetrate just lingual to the internal oblique ridge

Renal failure considerations with LA

-impaired excretion of LA -No risk at usual doses of LA

Stroke, history of CVA or TIA dental considerations

-monitor BP though the procedure -use minimal effective dose of LA -avoid intravascular injection -take into consideration anticoagulants

Lesser palatine foramen

-part of the palatal and lingual maxilla -exit point to the lesser and middle palatine arteries, veins, nerve which innervates the mucosa of the soft palate

Greater palatine foramen

-part of the palatal and lingual maxilla -site of exit of the greater palatine artery, vein and never which innervates the anterior lingual mucosa of the maxillary arch -commonly sits at the level of the 3rd max. molar

Management of Patients on aspirin

-platelet antagonist-->irreversibly acetylates platelet cyclo-oxygenase -bleeding time can be altered by a single dose of aspirin -1/2 life of platelets is about 10 days -surgery may be done with pts. taking some

The lingual nerve block

-provides anesthesia for 1/2 of the lateral/dorsal surface of the tongue

The long buccal nerve block

-provides anesthesia for the buccal gingiva in the posterior region -almost never results in bone contact during injection -Can extend buccal soft tissue anesthesia to the commissure of the mouth -Between the internal and external oblique ridges, where finger was for mandibular block, just under mucosa -1/4-1/2 carpule -mandibular nerve block for canines

Maximum recommended dose of epinephrine in an oral, healthy adult

0.20 mg

What volume of solution can be used in an adult in the posterior superior alveolar nerve block

1-1.5 cc of solution

Epinephrine interactions

1. Beta blockers: potential for increase BP 2. Tricyclic antidepressants: potential for HTN and arrhythmias 3. MAOi: potential for increased BP 4. Digoxin: potential for arrhythmias 5. Phenothiazines: postural hypotension Tx: limit doses of epic and monitor VS

Injection into what anatomical structures can cause hematoma formation during a posterior superior alveolar nerve block

1. pterygoid venus plexus 2. maxillary artery

Possible complications to the injection of 2% lidocaine with epinephrine 1:100,000

1. tachycardia as a result from anxiety from the injection 2. intravascular injection bc aspiration was not completed when injecting 3. hematoma from needle trauma to blood vessels

History and Physical Examination (H&P)

1. Chief complaint (CC) 2. History of present illness (HPI) 3. Past medical history (PMH) i. comprehensive list of most all medical and surgical illnesses ii. medications iii. allergies and intolerances 4. Family and Social history

Epinephrine can result in what reactions

1. Fear, anxiety 2. restlessness 3. throbbing headache 4. tremor 5. perspiration/sweating 6. pallor 7. tenseness 8. weakness 9. dizziness 10. dyspnea 11. palpitations (tachycardia)

CHF Considerations

1. Higher risk of overdose--limit max. dose of vasoconstrictors and other drugs -in severe CHF, cerebral circulation represents up to 30% of the cardiac stroke volume (normal 15%) -decreased liver perfusion--> increase drug half life 2. Compromise patient positioning due to orthopnea 3. anxiety: do not ignore 4. Epinephrine: can be dangerous to compromised pt.

What drugs causes vasoconstriction?

1. Neo-cobe-frin 2. Cocaine

Mandibular Nerve (Sensory)

1. The skin anterior to the ear 2. The lower cheek 3. The lower lip 4. The lower part of the face 5. The buccal mucosa 6. Anterior 2/3 of the tongue 7. Mastoid air cells 8. Mandibular teeth and periodontal tissues 9. Bone of the mandible 10. TMJ 11. Parotid gland

Contraindications to the injection of local anesthetics with vasoconstrictors

1. Untreated Hyperthyroidism --> sensitivity to catecholamines 2. TCAs--limit epinephrine to smallest effective dose

Physiology of Coagulation

1. Vascular phase--vasoconstriction 2. Platelet phase--primary plug 3. coagulation phase--clotting cascade -Platelet count: 150,000-350,000 -Prothrombin time: 12-14 sec, INR=1 -Partial thromboplastin time: 24-30 sec -Bleed time, Ivy: 3-10 min

Some common reasons for reactions associated with local anesthetic injections

1. anxiety 2. vasovagal syncope 3. idiosyncrasy

Local anesthetics neurophysiology

1. are less effective at lower pH 2. are supplied as a salt of the local anesthetic 3. must diffuse into the intracellular fluid of the nerve to be effective 4. dissociate into a base and a cation

Systemic reactions to lidocaine

1. can result from overdosage 2. can manifest as seizures 3. are very uncommon 4. are not a result of allergy to lidocaine

Anatomical landmarks used in performing the inferior alveolar nerve block

1. coronoid notch 2. external oblique ridge 3. mandibular plane of occlusion

What are reasons why you failed to achieve adequate anesthesia in a particular block

1. the solution was injected intravascularly 2. the volume of solution injected was too small 3. the solution was deposited too far away from the nerve

Safe drugs and malignant hyperthermia

1. vasoconstrictors 2. barbiturates 3. benzodiazepines 4. etomidate 5. Ketamine 6. Nitrous Oxide 7. Opioids 8. Propofol 9. Nondepolarizing muscle relaxants

What volume of solution can be used in an adult in the inferior alveolar nerve block

1.8 cc

How many micrograms are in 5 cc of a 1:50,000 solution?

100 mg

How many mg are in 2 cc of a 1:1000 solution

2 mg

***Maximum adult dose of lidocaine in mg/kg

7 mg/kg max. 500 mg/appointment

Congestive Heart Failure (CHF) ASA ratings

ASA II: mild CHF--no disability ASA III: dyspnea, shortness of breath on exertion ASA IV: unable to complete normal functions w/o disability Orthopnea: shores of breath when lying down Paroxysmal nocturnal dyspnea: shortness of breath after sleeping 1-2 h

Innervation of pulpal tissue tooth #8

Anterior superioralveolar N

Main organ system initially affected by local anesthetic toxicity (overdose)

Central nervous system

Innervation of gingiva palatal to tooth #14

Greater palatine N

For the PDL (interligamentary) injection

High pressure is needed to inject solution

To perform a pulpectomy on the mandibular 2nd premolar, what nerve would you anesthetize

IA

Innervation of gingival palatal to tooth #10

Incisive branch of nasopalatine N.

innervation of pulpal tissue tooth #21

Inferior alveolar N.

Possible cause for failure to achieve mandibular local anesthesia

Innervation from cervical or floor of mouth nerves

What LA related procedures require antibiotic prophylaxis

Intra-ligamentary local anesthetic injections (PDL?)

Nasopalatine palatal injection anatomical anesthetizations

Key landmarks: central incisors, incisive papilla Penetration: lateral to incisive papilla, deposit a few drops, wait several seconds, slowly to bony resistance, 3-5 mm infiltration; 6-10 mm nerve block Deposit: <0.4 ml (1/4 cart) over 40 sec *3 min per cartridge Syringe angulation: 45 degrees No teeth Periodontium: palatal to incisors and canines

Innervation of lingual gingiva tooth #18

Lingual N

Innervation of buccal gingiva tooth #18

Long buccal N

Greater Palatine palatal anatomical anesthetizations

Penetration site: palatal soft tissue, slightly anterior to the border of the GP foramen, in depth of the depression Teeth: none Peridontium: palatal soft tissues distal to canine (posterior teeth) -posterior portion of hard palate and overlying soft tissues -anteriorly as far as first premolar and medially to the midline

Innervation of pulpal tissue MB root tooth #14

Posterior superior alveolar N

Facial Nerve (VII)

Provides: 1. Motor innervation to the muscles of facial expression, posterior belly of the digastric, stylohyoid, stapedius, and occipitofrontalis muscle 2. Parasympathetic innervation to lacrimal, submandibular, and sublingual glands 3. Taste innervation to the anterior 2/3 of the tongue and palate

Anterior middle superior alveolar palatal anatomical anesthetizations

Teeth: central through second premolar Sensory: no facial, labial numbness -buccal gingiva -palatal (often through 2nd molar) Volume: 2% lidocaine, 1:100,000 epi ~1/2-1/3 carpule Duration: there's no room for solution in reserve; 60 min Periodontium: to affected teeth Technique: on the palate, locate the site that is midway between the free gingival margin of the premolars and the mid-palatine suture (directly below the contact area of the premolars or free gingival margin -select area that is spongiest in the vicinity of the ideal site -approach site at 45 degree angle from contralateral

Posterior Anterior Superior Alveolar palatal anatomical anesthetizations

Teeth: central, lateral, canine Periodontium: to affected teeth

In performing the intraosseous injection

The perforation should be made anterior (distal) to the intended area of anesthesia

Mental/incisive nerve block

To obtain anesthesia of the anterior teeth (incisive nerve block), the solution must enter the foramen -the foramen is generally located posterior to the canine root -You can have a mental block w/o an incisive block but not an incisive block w/o a mental block -usually want together -Short needle -deposit 1/2 carpule -probably won't penetrate the cortical plates in this area, they are too thick

What additive will provide longer duration of local anesthesia

Using an anesthetic with a vasoconstrictor (i.e. vasopressor, epinephrine)

Tachyphylaxis

acute rapid decrease in a response to a drug once administered -reason for failure to regain adequate anesthesia by reinfection anesthetic

What are the likely contents of a local anesthetic cartridge

a. LA (lidocaine) b. NaCl c. Vasoconstrictor d. Distrilled H2O e. Preservative (sodium bisulfite)

Mandibular Nerve (motor)

a. The muscles of mastication b. Mylohyoid c. Ant. belly of the digastric d. Tensor tympani e. Tensor veli palatini

***Branchs of the third division of the trigeminal nerve

a. long buccal nerve

The nerve membrane is

a. made up of protein the lipids b. is permeable to potassium and chloride ions in the resting state c. impulse transmission is quickened by a myelin sheath

The risk of needle breakage when performing local anesthesia is increased by

bending the needle

Local anesthetics act upon nerves to

cause them to remain polarized during an anesthetic block

Epinephrine is what type of stimulant

is both an a and B adrenergic stimulant