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Fundamentals of Local Anesthesia

1) What must be done before placing topical?

Gently wipe tissue of any potential barrier with 2x2 gauze2) Is more topical necessarily better?

No, it will cause extra salivation and go down the throat

3) How long should the topical be left in place before needle penetration?

Minimum of 1-2 minutes

4) How long is the short needle used at Pacific S.F. main clinic?

20 mm

5) How far should the needle penetrate in giving a PSA injection?

12-18mm (thus 2-8mm from the hub of the needle which visually is ~1-3 gradations of Pacifics periodontal probe)

6) What is the range in length of short needles?

20-25 mm (for testing just give me any numbers; the more outrageous the better for memory purposes). What I want for you to remember when you enter practice or go to a different clinic is that the needle length may be different from what you are used to. This is important because you have learned to do needle penetration on dental block infections (PSA, inferior alveolar and Gow-Gates) to a certain distance from the hub.

25 mm at Stockton clinic-always measure with endo ruler at any new clinic or site.

7) How long is the long needle used at Pacific S.F. main clinic?

32 mm

8) How far should the needle penetrate in giving a Gow-Gates or inferior alveolar injection?

25-30mm (thus 2-7 mm from the hub of the needle). Visualize 6 mm as two gradations on Pacifics periodontal probe).

9) What is the range in length of long needles?

29-41mm (for testing just give me any numbers; the more outrageous the better for memory purposes)

36 mm with Dr. Sachs in O.S. 25 gauge long needle.

40 mm at Stockton clinic-always measure with endo ruler at any new clinic or site.

10) List 3 reasons when the needle must be replaced for the same patient

a) After the third penetrationb) After an injection, if bone was contacted

c) Before the anterior palatine (greater palatine injection)

11) What is the maximum number of cartridges that can be given without instructor guidance and/or approval?2 cartridges of local anesthetic

12) List the components in a standard cartridge of local anesthetic and their

function.

Components

Function(s)

a) Local anesthetic

block neural pain message transmission to the brain (anesthesia)

b) Hydrochloric acid

adjust the pH downa) to make the local anesthetic soluble in water

(for diffusion)

b) to make the local anesthetic more stable (longer shelf-life)

c) more is added in cartridge with vasoconstrictor to inhibit oxidation of the

vasoconstrictor

c) Vasoconstrictor

allow local anesthetic to remain in region longer via peripheral vasoconstriction thus longer duration of anesthesia (duration)

d) Sodium bisulfite or metabisulfitepreserve vasoconstrictor from oxidation

(only in local anesthetics

(antioxidant)

with vasoconstrictor)

vasoconstrictor antioxidant)

e) Sodium chloride

to control osmotic balance so that it is the same

as the tissue (isotonic)

f) Distilled water

mixer

13)Convert local anesthetic percent (%) concentration into milligrams (mg.) per milliliter (ml.) of solution

.5%

=5 mg/ml

2.0%

=20 mg/ml

3.0%

=30 mg/ml

4.0%

=40 mg/ml

The easy way to remember this is to move the decimal one place to the right to convert from percent (%) concentration to milligram (mg) per milliliter (ml) concentration.

What is the mg/ml concentration of _____________________? _______________.14) How much local anesthetic solution is in a cartridge?

1.8ml15) Calculate the maximum dose of this local anesthetic for this healthy patient.

DrugLidocaine local anesthetic:

a) a 2% concentration

b) a maximum dosage of 2 mg/lb patient weight c) a maximum dose of 300mg regardless of patient

health and weightProblemWhat is the maximum number of cartridges of this local anesthetic that can be given to a patient weighing 105 pounds?CalculationsA. 2% = 20 mg/mlA cartridge contains 1.8 ml Number of milligrams in a cartridge of this local anesthetic is:

20 mg/ml x 1.8 cartridge = 36 mg/cartridge

B.Patient weight is 105 lbs.

Maximum does for this patient is: 2 mg x 105 lbs = 210 mg

C.Check maximum dose step to see if this is above the maximum allowable dose.

D.210 mg

=5.8 cartridges

36 mg/cartridge

16) How much time should you take in administering a cartridge of local anesthetic?30-60 seconds/ml (approximately 1-2 min/cartridge).How much time should you take in administering _____ cartridge? ____________.

17) The amount of epinephrine in a local anesthetic having 1:100,000 epinephrine is 0.01 mg/ml. Since there is 1.8 ml of solutions per cartridge there is 0.018 mg/cartridge.

(1.8 ml X 0.01 mg/ml = 0.018 mg/cartridge).

Epinephrine concentrationEpinephrine per millimeter Epinephrine in cartridge

1:50,000

1:100,000

1:200,000

Levonordefrin concentration

1:20,000

18) How many milligrams of vasoconstrictor are in _____ cartridge of _____________________ (local anesthetic) with ______________ (vasoconstrictor)?

__________________________________________.19) What is the usual time for onset of anesthesia?

3-5 minutes.20) What must be done prior to placing a clamp on a tooth?

Tooth: mirror handle to percussion test the tooth and contralateral tooth.Tissue: use curve of #2 explorer to pressure test any tissue that my be impacted

by the clamp.21) What must be done before using a handpiece on a tooth?

Tooth: mirror handle to percussion test the tooth and contralateral tooth22) Does the patient with subjective tingling sensation to the midline of the lower lip have anesthesia to the quadrant of teeth on that side?

No.23) Will the patient with subjective tingling sensation to the midline of the lower lip later have profound anesthesia?

Many times they will not. There may not be enough local anesthetic solution at the nerve to surround it and diffuse to all the nerve fibers within the neurovascular bundle.24) Does the patient with subjective swollen sensation to the midline of the lower lip have profound anesthesia to the quadrant of teeth on that side?

Yes, in the majority of cases.25) What nerves must be anesthetized before a tooth can be extracted?

a) Nerve innervating tooth and bone (nerve to tooth will be severed, bony socket will be expanded, and surrounding periodontal ligament will be severed).b) Nerve to lingual or palatal soft tissue (lingual/palatal gingival attachment will be severed).c) Nerve to buccal soft tissue (buccal gingival attachment will be severed).

All maxillary teeth: (1) Nerve to tooth also innervates bone and buccal soft tissue

(2) need palatal injection for corresponding palatal gingival

innervation

Mandibular teeth: Teeth at/or posterior to the mental foramen (molars and usually 2nd bicuspid): need inferior alveolar, lingual and buccal injections. Teeth anterior to the mental foramen (1st bicuspid, cuspid, and incisors): need only the inferior alveolar and lingual injections because the mental branch of the inferior alveolar exits the mental foramen and innervates buccal soft tissues anterior to the foramen and the lower lip to the middling while the incisive branch inside the foramen continues to the bone and teeth up to the midline.

26) What nerves must be anesthetized before a segment/area/quadrant of root planing?a) Nerve innervating tooth since area below CEJ is sensitive to instrumentation.b) Nerve innervating lingual or palatal soft tissue since tissue will be impacted during the instrumentation.c) Nerve innervating buccal soft tissue since tissue will be impacted during

Instrumentation. 27) Does the tissue site sometimes look swollen after an injection due to the quantity of local anesthetic injected?

Yes.28) Will the penetration site sometimes bleed after the injection?

Yes.29) Describe the gauges of needles mainly used in dentistry.Gauge Sheath color Width Deflection Ability to aspirate

25

red

widest least

best

27

yellow mid mid

mid

30

blue

narrowest most least30) Describe the hub and tip of the dental needles.

Hub: metal or plastic

Plastic hub: threaded or self-threading

Tip: type of bevel, sharpness and barbs will impact ease of penetration and penetration pain. In 2006 the clinic got needles from a different company and all the students started complaining of patient pain on penetration.

31) Does everyone like the same needle?

No, Dr. Sachs in O.S. clinic likes a 25 gauge, metal-hub 36 mm. long needle.

32) List the local anesthetics commonly used in dentistry.

Generic name (limpa bet) Brand names (XOPOCS M.D.)conventionalLidocaine

Xylocaine, others

Mepivacaine

Polocaine, others

Prilocaine

Citanest

Articaine

Septocaine

Longer

Bupivacaine

Marcaine

acting?

Etidocaine

Duranest

33) List and define terms used to describe nerve injuries from local anesthesia

Paresthesia duration of anesthesia well beyond normal. Nerve damage has blocked conduction thus numb sensation. Improvement in degree and extent of symptoms is good. No improvement over several months may be permanent. Lingual nerve 2x more likely than inferior alveolar.

Dysesthesia pain felt from the area the nerve innervated though damage is in the nerve trunk. Nerve damage is causing nerve transmission of pain.

Improvement in degree and extent of symptoms is good. No improvement over several months may be permanent.

Lingual nerve 2x more likely than inferior alveolar.

34) Which local anesthetics are associated with frequent nerve injuries?

4% local anesthetics, especially 4% articaine.

35) How are local anesthetic metabolized?

Esters (procaine-Novocain & others before amides up to the 1950s): blood plasma by plasma psuedocholinesterase.

Amides (all modern): liver by microsomal enzymes thus need adequate liver functioning.

Articaine has ester and amide linkage with ester breakdown in plasma and amide in liver.

36) What is the half-life of local anesthetics?

The time is takes for 50% of the anesthetic in the blood to be metabolized systemically (not the same as duration of anesthesia based on how long anesthetic engaged with neural tissue).Articaine: about 30 minute due to faster ester bond breakdown in blood.

Other amides: about 1.5 hours because breakdown only in the liver.37) How is the maximum dose determined?

Person weighing 154 lb (70 kg) and in good health: use the maximum in the LA chart

Person below 154 lb (70 kg) and in good health:

multiply mg/lb approved drug dose X weight

Person not in good health: usually still will have adequate liver function for metabolism

of local anesthetic and impact of vasoconstrictor is the main concern.

38) Can more than the maximum dose of local anesthetic be used by factoring in local anesthetic metabolism?

Although perhaps in pharmaceutical theory could be within maximum dose all authorities indicate the maximum dose is per appointment/day.

39) Can more than one local anesthetic be use on a patient during an appointment?

Yes, for safety, similar to the answer above, all authorities indicate that the maximum dose for the two local anesthetics together is the maximum dose for the local anesthetic having the lowest maximum dose. Ex. Local anesthetic A has max dose of 10 cartridges and local anesthetic B has max dose of 7 cartridges; when used together the maximum dose is 7 cartridges.40) How should local anesthetics be stored?

At about 59 86 degrees F. to keep vasoconstrictor from premature breakdown

Hotter the temperature and the more intense the light will >>vasoconstrictor breakdown.

41) What are the signs of vasoconstrictor breakdown?

All injections with incomplete anesthesia or shortened duration of anesthesia.

42) What are some of the issues regarding local anesthetics, duration of anesthesia and temperature control?

3% mepivacaine without vasoconstrictor: ~20 min max and ~40 min mand block duration if in a place where the local anesthetic cannot be protected against high temperature. 2% lidocaine without vasoconstrictor: ~ 5 min hard tissue anesthesia, thus worthless to purchase and worthless with vasoconstrictor with significant vasoconstrictor breakdown (however, 2% lidocaine with 1:100,000 epi is the best local anesthetic available).43) What is the biggest issue with an unhealthy patient and local anesthetics?

How the patients cardiovascular system will respond to the vasoconstrictor (epinephrine, levonordefrin).

Refer to handouts and lecture notes on medical considerations in local anesthesia.

44) What do you need to do prior to delivering a case presentation to faculty?

Be ready to know how the patients medical history impacts local anesthesia and dentistry and theoretical questions on how other medications or health issues would affect local anesthesia and patient care. You will want to know the answers to these anyway and you will want to shine when Drs. Levy, Fendler and others put you to the test.

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