Advanced Local Anaesthesia

“Tried & True and What’s New”

Toronto Crown & Bridge Study Club

Feb 7, 2014

David Isen BSc, DDS

d.isen@rogers.com

416-498-8484

Reasons For Failure

1. Hot teeth and inflammation

2. Needle too short

3. Needle deflection

4. Inadequate volume

5. Anatomy (skeletal & neuro)

6. Molecular degradation

7. Patient cooperation

8. pKa and pH

1. IANB Failure Rates

• ~20%

• In endo, with irreversible pulpitis, ~55%

Claffey et al J of Endo Aug, 2004

Blocks and Inflammation

• Mediators of inflammation (eg histamine,

kinins, prostaglandins…) neuronal

excitability.

• ↑ prostaglandins in inflamed pulps.

• Inflammatory substances can move up nerve

tract.

• Acidic nature of infection/inflammation

• LA less effective

Hot Teeth

• Patients in pain:

– Are more apprehensive

– Have lower pain thresholds

This ↓ the effectiveness of LA

Take a PA radiograph

Study: Premed With NSAID

• 150 patients with irreversible pulpitis

mandibular molars

• Divided into 3 groups of 50

1: 75 mg indomethacin

2: 600 mg ibuprofen

3: Placebo

• 1 hr before tx

• All given IANB 1.7 ml lidocaine 1:100,000

Patriokh et al, 2010

Results

Group Success (%) Failure (%)

Placebo 16 (32) 34 (68)

Ibuprofen 39 (78) 11 (22)

Indomethacin 31 (62) 19 (38)

-Statistically significant for both NSAIDS compared to placebo

Parirokh et at, J Endo, 36:1450-1454, 2010

2. Needle Length

30 gauge deflecting 4 mm

27 gauge deflecting 2 mm

Aspiration

• 97% failure with 30 gauge

• 89% failure with 27 gauge

• 2% failure with 25 gauge

Foldes, Dent Clin North Am 5:257-278, 1961

What hurts when we inject?

Gauge of the needle?

• Irrelevant*

• Needle tip blunts even if bone not touched

• pain with used needles+

*Carr et al J Dent Res, 80:128, 2001

+Meechan et al, Anes Prog, 52:91-94, 2005

25 vs. 30 Gauge in Kids

• Compared pain from IANB in kids*

• 25 vs 30 gauge

• No difference

*Brownbill et al Anes Prog 34:215-219, 1987

and…

• In the US, ~30 needles break / yr.

• ~99% of needles that break are 30 ga.

• Break occurs at hub

Requires surgery for recovery

Malamed & Reed, Dent Clin North Am., 54:745-56, 2010

Factors Related to Broken Needles

• 30 gauge

• Injecting to the hub

• Bending needles

• Hitting bone during IANB

• Kids

• Sudden movement with pain

Needle Sales, 2006

Gauge Schein Septodont

25 Short < 1% 0.6%

25 Long 1% 2.3%

27 Short 10% 13%

27 Long 32% 25%

30 Short 50% 51%

30 Xtra Short 6% 8%

Malamed et al, Dent Clin NA, 54: 745-56, 2010

1% 3%

42% 38%

56% 59%

Choosing A Needle

• Length

• Gauge

• Quality

• Price

• Expiry date

Septoject XL 27 ga.

-Triple bevel

-43% wider

-1.8X less pressure to inject

Standard 27 ga

Septoject Evolution

• Patented scalpel design

• Sizes:

– 27 and 30 ga short (25 mm)

– 30 ga extra short (9 mm)

• No 35 mm lengths

• Bevel indicator

Septoject Evolution

• Smoother and easier penetration

– 29% less force needed for insertion

– 4th insertion still less force needed as

compared to standard needle

• Less tissue displacement

• Reduced needle deflection

Steele et al, submitted for publication

Meechan et al, submitted for publication

Temperature of the LA?

• No difference in reported pain from

warmed LA vs. room temp LA

•Rogers et al, Gen Dent , 37:496-499, 1989

•Oikarinen et al, Int J Oral Surg, 4:151-156, 1975

pH of the LA?

• What causes acidity?

• Literature disagrees

: JADA vol 132, Oct 2001, pp 1396-1401

: Anes Prog 49:44-48, 2002 pp 44-47

: JADA vol 133, Dec 2002, pp 1652-1656

pH of Local Anaesthetics

Anaesthetic pH

Articaine, 1:100,000 5.8

Articaine, 1:200,000 6.1

Bupivacaine, 1:200,000 5.8

Lidocaine 3.6 – 3.8

Mepivacaine 6 – 6.5

Prilocaine plain 6

Prilocaine 1:200,000 5.7

Onpharma Buffering System

Onset

• Theory is to add basic solution to LA

cartirdge

• Three components:

– Sodium bicarbonate (3 ml cartridges)

– Mixing pen

– Cartridge connecter

Equal amount of LA replaced by bicarbonate

Cartridge connector

Mixing pen

Sodium bicarbonate 3 ml cartridge

Buffering Rationale

• LA’s with vasoconstrictor are acidic

• This can cause:

– More pain on injection

– ↑ tissue damage

– ↑ post-op pain

– Slower onset

– Less efficacy in areas of infection

– ↑ pH from 3.5 to 7 will ↑ lipophilic molecule concentration by 6000X

Pressure and tissue distention?

• Infiltration mandibular cuspid area

• Wand: slow (160 s/ml) vs. fast (30 s/ml) speed

Significant pain & anxiety with fast speed

Kudo, Anes Prog, 52:95-101, 2005

Slow IANBs are more accurate!!

Slow IANB

(60 sec)

Fast IANB

(15 sec)

Molars 220 159

Premolars 253 216

Lateral incisors 119 99

# Of Negative Responses To Max. Pulp Test

Kanaa et al, J Endod 32:919-923, 2006

4. Volume of LA

• Amount

• Neuroanatomy (nerve diameter)

• Anatomical Factors

– sphenomandibular ligament

– intravascular injections

• Time

5.

The incidence of

mylohyoid innervation

to the mandibular

teeth is 60%

Blanton et al, JADA, 134, 753-60, 2003

Location of Mylohyoid Nerve

• On average, mylohyoid nerve leaves the

IAN 14.7 mm above the mandibular

foramen

• This is superior to the location of IANB

• The Gow-Gates block may be advantageous

Hargreaves KM, et al, Endo Topics, 1:26-39, 2002

Vertical wall

Unattached gingiva

0.5 ml

Lingual Infiltration

6. Molecular Degredation

• Do not repeatedly warm or autoclave cartridges

• Avoid light exposure (esp lidocaine)

• Do not stockpile

• Store between 59 – 86 º F

• Look for air or wax flakes

• Do not violate vacuum until needed (esp levo)

Hondrum et. al. Anes Pain Control in Dent 2:4 1993

Cartridge under fluorescent light for 2 weeks:

75% of local anaesthetic molecules degrade!!

8. pKa and pH: Pharmacology Local Anaesthetic Structure

C N

R

R

Aromatic

Ring

Ester

Terminal

Amine

N H O

C

R

Amide

O

C

O

R R

R

R

Anesthetic Mechanism of Action

Nerve

Membrane

B + H+ BH+

Axoplasm

B + H+ BH+

B + H+ BH+

BH+ B

B is 4000X more lipid soluble than BH+

•LA pKa = 7.4

•Tissue pH = 7.4

B

50% Lipid soluble

BH+

50% Water soluble

pKa of Local Anaesthetics

pKa % B at pH 7.4 Approx Onset

(min)

Mepivacaine 7.6 40 2 to 4

Articaine 7.8 29 2 to 4

Lidocaine 7.9 25 2 to 4

Prilocaine 7.9 25 2 to 4

Bupivacaine 8.1 18 5 to 8

Procaine 9.1 2 14 to 18

Factors Influencing Tissue pH:

• Infection

–Infected tissue pH ~5

• The local anaesthetic itself

Remember: ↑ pH from 3.5 to 7 will ↑ concentration

of lipophilic molecules by 6000X

Henderson-Hasselbalch

Equation

pKa – pH = log 10 Ionized (BH+) Unionized (B)

Example: Lidocaine & normal tissue

pKa – pH = log10 ionized (BH+)

unionized (B)

7.9 - 7.4 = log10 ionized (BH+)

unionized (B)

= 3

1

Example: Lidocaine & acidic tissue

pKa – pH = log10 ionized (BH+)

unionized (B)

7.9 - 6.4 = log10 ionized (BH+)

unionized (B)

= 30

1

Factors

• Duration

– Short, medium and long

• Concentration

– 2, 3, or 4%

• Vasoconstrictor vs. plain

• Difficulty obtaining anaesthesia

• My office stocks it

• Price

LA Use In Ontario, 2007

Gaffen AS, Haas DA, JCDA, Vol 75, No 9, 2009

Methemoglobinemia

• doses of prilocaine, articaine, benzocaine or inborn errors of metabolism

• Can occur following extreme exercise

• Methemoglobin cannot carry O2

– usually ~ 1%

– to > 20%

• Blood rust-brown, respiratory distress, cyanosis, lethargy, dizziness - occurs a few hours after Tx

• Hospital and methylene blue? (O2 not helpful)

Cartridge of Articaine

Component Amount

mg/ml

Purpose

Articaine HCl 40 Anaesthesia

Epi tartrate 0.018 Vasoconstriction

Sodium chloride 1.6 Isotonicity

Sodium

metabisulphite

0.5 Vasoconstrictor

antioxidant

Distilled water 1.0 ml Volume

Articaine

• 90% plasma esterase (pseudocholinesterase

deficiency no problem)

• 27 – 40 min half-life

• Has an ester link possible lipid solubility

• Molecular configuration

• Scientific studies

• 4% and neurotoxicity

LA Half-Lives

LA Half-Life (min)

Articaine 27 - 40

Prilocaine 90

Lidocaine 90

Mepivacaine 115

Bupivacaine 210

4% Articaine vs. 2% Lidocaine

• Study compared pulpal anaesthesia in

mandibular 1st molars after buccal

infiltration:

Effectiveness of articaine was greater

than lidocaine – statistically significant!!

Kanaa MD et al: J Endod 32:296-298, 2006

Similar Study:

Tooth P Value

Articaine Lidocaine

2nd Molar 75% (45/60) 45% (27/60) .0001

1st Molar 87% (52/60) 57% (34/60) .0001

2nd Premolar 92% (55/60) 67% (40/60) .0001

1st Premolar 86% (49/57) 61% (35/57) .0001

Robertson D et al, JADA Vol 138, Aug 2007

Articaine vs. Lidocaine:

Block + Infiltration Study

1. IANB 4% articaine 1:100,000

2. Then, buccal infiltration beside mandibular

1st molar with 4% articaine 1:100,000 OR

2% lidocaine 1:100,000

Tooth 4% Articaine 2% Lidocaine

Mandibular 1st molar 88% 71%

Haase et al, JADA Vol 139, 2008

Infiltrating Mandibular 1st

Molars: Summary of Studies Local Anaesthetic % Anaesthetized Study

4% Articaine 1:100

2% Lidocaine 1:100

64

39

Kanaa et al, 2006

4% Articaine 1:100

2% Lidocaine 1:100

87

57

Robertson et al, 2007

4% Articaine 1:100

2% Lidocaine 1:100

88

71

Haase et al, 2008

4% Articaine 1:100 64 - 70 Corbett et al, 2008

4% Articaine 1:100 54 Jung et al, 2008

4% Articaine 1:100 64 Lindsay et al, 2009

Mandibular Infiltration:

Enhancing Success

• Use articaine 1:100,000

• Choose smaller, thin cortex patients

• Females

• Supplement with IANB

• Supplement with lingual infiltration

Articaine vs. Lidocaine

Maxillary Infiltration

Irreversible pulpitis

• Buccal infiltration only

• Success of pupal anaesthesia

1st Premolar 1st Molar

Articiane 100% 100%

Lidocaine 30% 80%

Srinivasan et al Oral med, oral path…107(1), 2009

Meta-analysis:

Articaine vs. Lidocaine

• Articaine superior to lidocaine for infiltration

anaesthesia

• Articaine 3.81X more likely to provide pulpal

anaesthesia via infiltration vs. lidocaine

• “weak evidence” to suggest articaine is better

for blocks

Brandt et al, JADA 142(5), 2011

Paresthesia (1973 – 1993)

• Retrospective study – 143 cases in 20 yrs

LA # %

Articaine 50 33.6

Bupivacaine 0 0

Lidocaine 5 3.4

Mepivacaine 4 2.7

Prilocaine 43 28.9

Unknown 47 31.5

Total injections 149 100

Haas & Lennon, JCDA, V61, No 4, 1995

Conclusions:

• No record of duration of paresthesia

• Retrospective study

• Possibility of paresthesia

– 2.8/million injections prilocaine

– 2.05/million injections articaine

Paresthesia (1999 – 2008)

Cases of paresthesia (%)

Articaine 109 (59.9)

Bupivacaine 0

Lidocaine 23 (12.6)

Mepivacaine 6 (3.3)

Prilocaine 29 (15.9)

Multiple 15 (8.2)

n = 182

Gaffen AS, Haas DA, JCDA Vol 75, No 9, 2009

Conclusions from this study:

• Lingual nerve more than 2X affected as IAN.

• Approximately 1 in 609,000 injections lead to

paresthesia (non surgical cases)

• 4% solutions associated with paresthesia

more than expected based on %age of use

Denmark Nerve Injury Study

• University Oral Surgery Center

• Known national center for referral after

nerve injury

• 2001 - 2007

Results LA Used # of Events

(%)

LA Market

Share* (%)

Articaine 4% 49 (70.6) 41.2

Lidocaine 2% 7 (10.3) 27.7

Mepivacaine 3% 7 (10.3) 11.8

Prilocaine 3% 6 (8.8) 19.4

Total 69 (100) 100

Hillerup et al, JADA, 142(5), 2011

*Danish drug registry

Risk Management Advice

“Until more research is done…prudent

practitioners may wish to consider

scientific literature before using a 4%

solution for mandibular blocks”

RCDS Dispatch, Summer 2005

RCDS Dispatch

“Paresthesia following LA in nonsurgical cases

is so rare that dentists are not legally

required to warn patients of the possibility of

temporary or permanent paresthesia as part

of informed consent.”

DeFerrari v. Neville, Ontario Court of Justice – General

Division – No. G14777 / 05

Summary:

• LAs are neurotoxic

• Neurotoxicity is related to concentration

• Thicker nerves may be more resistant

The Dilemma:

• More LA molecules may = ↑ effectiveness

• Can’t study concentration, efficacy &

paresthesia

• Even if not statistically significant, ↑ efficacy

may be noticed clinically (eg 1 less failure/week)

LA in Pregnancy

• Safe in pregnant or nursing patient

• Avoid 1st trimester if possible

• Allows avoidance of prolonged antibiotic or analgesic use

• Lidocaine and prilocaine highest FDA ranking (Category B)

• Prilocaine most effective at crossing placenta

• Defer to lidocaine since 2%

ASPIRATE WITH 25 GAUGE!!

Septanest Product Monograph:

“Safe use of local anaesthetics during

pregnancy has not been established with

respect to adverse effects on fetal

development. Careful consideration

should be given before administering

these drugs to pregnant women.”

LA and Nursing

• LA is secreted in breast milk

• It is safe for infant

• Stays in breast milk for ~ 6X the half life:

• Lidocaine ½ life ~90 min. In milk for 9 hrs.

• Articaine ½ life ~27 min. In milk for 2 ½ hrs.

Example: 2% lidocaine

2% = 20 mg/ml

a cartridge has 1.8 ml X 20 mg of

drug

= 36 mg of drug

For healthy 70 kg adult. Must adjust for age and weight

Recommended Max. Dose (mg)

DRUG Vasoconstrictor No Vasoconstrictor

Articaine 500 -

Lidocaine 500 300

Mepivacaine 400 400

Prilocaine 500 500

Bupivacaine 90 -

Maximum Doses

Articaine 7 mg/kg (up to 500 mg) 7

Bupivacaine 1.3 mg/kg ( up to 90 mg) 10

Lidocaine 7 mg/kg (up to 500 mg) 13

Mepivacaine 6.6 mg/kg (up to 400 mg) 7 or 11*

Prilocaine 8 mg/kg (up to 500 mg) 7

Equivalent #

Drug Maximum Dose of cartridges

For healthy 70 kg adult

* 7 for 3% and 11 for 2%

SYSTEMIC EFFECTS

• Cardiovascular system

• Central nervous system

Mild Moderate Severe

Medical Factors In LA Toxicity

• Age

• Weight

• Tolerance – Bell Curve

• Liver function

Clinical Factors in LA Toxicity

• Speed of injection

• Inadvertent IV injection

• Intraosseous injection

• Too large a dose

• No vasocontrictor

• Complacency

Toxicity & the Elderly

• May have reduced liver function

– Reduced liver function of 50% by age 65

– Therefore reduce total dose

• May have compromised cardiac function

– Therefore reduce or eliminate vasoconstrictor

Severe

Supine

CAB’s

D

Mild

Position Comfortably

Reassure

CAB’s

D

D/C once recovered

LA Overdose Algorithm

O2

9-1-1 Protect Patient O2 iv anticonvulsant?

Pediatric Deaths From LA

Overdose

• Occur every year

• Most common LA in pediatric deaths is 3%

mepivacaine

• It`s used more in children

– Try to be nice re numb lip

– Mistaken belief that it`s less toxic since no epi

Example: Pedo Consideration

• 15 kg child (~ 30 lbs)

• Pediatric dose for articaine 7 mg/kg

• 7 mg/kg x 15 kg = 105 mg toxic dose

• 68 mg of drug per cartridge (1.7 ml x 4%)

• Toxic dose = 1.54 cartridges

Toxicity Factors:

1. Good child

2. Size & physiology

3. Greed - $

4. L.A. is just “Water”

5. Sedation

6. Bell Curve

The Ideal Pediatric LA

Vasoconstrictor

2% Vasoconstrictor does not

significantly change duration of

soft tissue anaesthesia

Vasoconstrictor Use in Ontario

1:50,000

1:20,000

None

1:200,000

1:100,000

Haas D. Lennon D., J Can Dent Assoc 61(4) 1995

Functions of the Vasoconstrictor

• Delays absorption of LA

– toxicity

– duration

• (no advantage for block > 1:200,000)

• Surgical hemostasis

• ( concentration is advantageous)

↓ Toxicity of LA

• 1:200,000 epi (5 μg epi):

↓ systemic toxicity of 1 ml of LA by ~ ⅓

Bowdle T., et al, Reg Anes, 11:123-7, 1986

Study: Epi Concentration vs Clinical

Efficacy For 3rd Molar Removal

• Compared Articaine 1:100 vs 1:200 for

– Pain during surgery

– Bleeding

– Duration of anaesthesia

– Duration of post-op anaesthesia

Santos G. et al J Oral Maxillofac Surg 65:2445-2452, 2007

Conclusions:

• No difference in any of the parameters!!

Santos G. et al, J Oral Maxillofac Surg 65:2445-2452, 2007

1:100,000 vs. 1:200,000

• Study compared cardiac effects of articaine 1:100,000 vs. 1:200,000 10 min. after injection:

mean SBP

HR

Statistically significant for 1:100,000 vs. 1:200,000

Hersh et at: JADA vol 137, Nov 2006

Adrenergic Receptor Functions

Vasoconstriction

Vasodilation / Bronchodilation

1 Cardiotropic

2

Epinephrine Drug Interactions

• MAO Inhibitors

• Tricyclic Antidepressants

• Halothane

• Atomoxetine

• Cocaine

• BETA BLOCKERS

Strattera (Atomoxetine)

• Used for ADHD kids, teens and adults

• Associated with ↑ BP and HR

• Dry mouth

• ↑ endogenous NE

• Avoid levo and caution with epi

Cocaine

• Possible interaction btwn cocaine and epi

• Also additive interaction btwn cocaine and LA

• Cocaine & LA are potentially cardiac toxic

• Possible dysrhythmias and arrest

Beta Blockers

• Blood pressure

• Angina

• Migraines

• Glaucoma

• Panic disorders

Indications:

Beta Blockers

• Cardioselective:

– acebutolol Monitan, Rhotral, Sectral

– atenolol Tenormin

– metoprolol Betaloc, Lopressor

• Non-cardioselective:

– nadolol Corgard

– oxprenolol Trasicor

– pindolol Visken

– propranolol Inderol

– sotalol Sotacor

– timolol Blocadren, Timoptic

Epinephrine + ß-Blocker

Cardioselective

Non-cardioselective

1 Cardiotropic Cardiotropic

2 Vasodilation Vasodilation

Vasoconstriction Vasoconstriction

Vasoconstrictor Concentrations

1. Concentation = grams/ml

2. 1:100,000 = 0.01 mg/ml

a. 1:50,000 = twice the amount

b. 1:200,000 = half this amount

Maximum Dosages

mg/ml mg/1.8ml Healthy Cardiac

impared

1:20,000 Levo 0.5 0.09 11 2

1:50,000 Epi 0.02 0.036 5 1

1:100,000 Epi 0.01 0.018 11 2

1:200,000 Epi 0.005 0.009 20 4

# Of Cartridges

0.2 mg is max dose for healthy 70 kg adult

0.04 mg for patient with significant C.V. disease ASA III-IV

LA Reversal Agent: OraVerse

• By Septodont:

• Aim: Reverse soft tissue anaesthesia

• Phentolamine: a vasodilator -blocks receptors

• Phentolamine used IV for hypertensive emergencies, cocaine OD and pheochromocytoma

OraVerse Indications

• Special needs patients

• Children 6 yrs & older, weighing greater

than 33 lbs.

• Diabetics (can eat sooner)

• Can go back to work

OraVerse

• Comes in 1.7 ml cartridges - 0.4 mg of drug

• Reverses epi induced vasoconstriction

• This allows faster clearance of LA

Phentolamine (OraVerse)

• duration of soft tissue anaesthesia by ½

• Injected after completion of tx

• Ratio of 1:1 of oraverse to LA

• ~ $13 per injection

Median Recovery Time From Soft Tissue

Anaesthesia (min), Teens & Adults

Phentolamine Sham

Mandibular lip 70 155

Tongue 60 125

Maxillary lip 50 133

Hersh et al, JADA Vol 139, Aug 2008

Median Recovery Time From Soft Tissue

Anaesthesia (min), Children 6 -11

Phentolamine Sham

Lip anaesthesia 60 135

Tavares et al, JADA Vol 139, Aug 2008

-Children aged 4-5 tested for safety but not reliable to

answer subjective questions

QAQ

• Quaternary ammonium-azobenzene-

quaternary ammonium

• Light switch LA

• cis and trans form changed by certain

wavelength of light

• Only one form works to penetrate nerve ion

channel

Oraqix®

• Scaling and root planing for adults

• Onset 30 seconds

• Duration 17-20 min

• Hygienist

• Needle-free

Oraqix®

• 2.5% lidocaine, 2.5% prilocaine

• Fluid at room temp

• Gel at body temp

• Maximum dose 5 cartridges* (~1 cartridge/quad)

* Herdevall et al ACTA Odontol Scand 61, 2003

Oraqix Cartridge

• Unique colour marking

• Safety collar

Oraqix Dispenser

Efficacy Results

In all 3 placebo-controlled studies

• Oraqix statistically better than placebo

• Pain scores reduced by at least 50%

• Median dose required was 1 cartridge per

quadrant

Other Indications (Off-Label)

• Retraction cord

• Temp crown removal

• Rubber dam clamp

• M3+ extraction

• Removing implant healing cap

www.oraqix.com

Contraindications

• Allergy

• Liver disease

• Methemoglobinemia

• Children (< 18 yrs.)

• Precaution nursing and pregnancy

• Watch dosages with injectable LA

HurriPak (Beutlich Pharma)

• 20% benzocaine

• No thermosetting agent

• Onset 20 sec, duration 15 min

• Max dose 3 ml. (can do whole dentition)

• One quadrant at a time

• Flavour

• For ages > 12

• Precise volume control

Citacaine

• 14% Benzocaine

• 2% Butamben

• 2% Tetracaine

-Luer-lock connection

-Max. dose 0.4 ml.

-Precise volume control

Gow-Gates Advantages

• Perceptible end point

• Decreased vascularity

• Anaesthesia of accessory nerves

• Decreased nerve damage

• Long buccal nerve?

• Duration of anaesthesia

• Good vision

Gow-Gates Disadvantages

• Mouth open wide

• Long onset

• Extra-oral landmarks

• Post-injection remain open

• Hemostasis

Gow-Gates Technique Summary

• Chin up, mouth open wide

• Landmark

• Initial puncture

• Check side of face

• Gently touch bone

• Pull back 1 mm

• Aspirate

LA Delivery Systems

Types of Injections Used

Type of Injection %

Standard techniques 97%

IO injections 20%

Computerized

injections

10%

Electronic devices 2%

Other 5%

Other = lasers, oraqix, topicals

Dental Products Report Survey Nov 2006

2. Intraosseous Anaesthesia

Anaesthetizing a tooth by injecting LA

directly into surrounding cancellous

bone.

Anatomical Limitations

Other Bony Limitations

• Thick coritcal plate

• Root proximity

• Midline

• Mental foramen

• Mixed dentition

Intraosseous Contraindications

• Long procedures

• Cardiac disease

• Infected areas

• Periodontal disease

3. PDL Injections

• Express ¾ of contents of cartridge

• Embed needle into PDL space

– 27 ga short, bevel to tooth

• Inject 0.2 ml per root

• Watch for blanching of tissues

• Wait to allow back-pressure to

• Begin dentistry immediately

Citoject by Athena

Paroject by Septodont

3 squeezes of lever per root

DentalVibe

• “Vibrations close pain gate”

• Cordless and rechargable

• Proprietary “vibraPulse” – (ultrasonic

vibrations)

• Different tips for different injections

• Also has audible distraction

• ~$300 - $350

Vibration

• Placed heat on arm to cause pain

• Some had vibration applied as well

• Those with vibration, had 40% ↓ in pain

European Journal of Pain, Feb, 2011

•Infiltration

•Palatal

•Block

Needless Injectors

• Syrijet

• MadaJet

• Injex

Needless Injectors

• Spring-loaded

• Audible click

– Must prepare patient

• Heavier than syringe

• Need to control recoil

Needless Injectors Indications

• Diabetics

• Growth hormone injections

• Global vaccination programs

• Botox

• Minor skin surgeries

• Dentistry?

Injex

• Invented in 1998

• Produced in Germany

• Sold by Marketing Medical Canada

Injex

• Mandible: only anterior teeth

• Maxilla: anterior and premolars

• Hold perpendicular to buccal plate

• Attached gingiva

• 0.3 ml per injection

• Spring lasts for 5000 injections

• ~ $499 + ~ $2.30 per injection for

disposables

Injex: Advantages

• No needle

• ↓ dose of LA

• ↓ area of soft tissue numbness

• ↓ onset of anaesthesia

• Reduced risk of needle-stick injury

• ↓ pain

Injex: Disadvantages

• Recoil

• Click

• Haematoma, bleeding and swelling

– Manufacture says same as needle/syringe

Ontario Occupational Health & Safety

Act:

Bill 168 – Needle Safety Regulations

• As of Jul 1, 2010, SENs are manditory

• For any action using a hollow-bore needle

• Enforced by Ministry of Labour

• Also, OHSA act # 527: A person must not

recap waste needles

Cost of Injury

• Disease transmission

– HBV, HCV, HIV

• Loss of work for health-care worker

• Emotional component

• In U.S., ~$2500 for medical care after injury

– Antiviral drugs and blood tests

Exceptions To Regulation

• Use of SEN poses greater risk of harm to

patient or worker

• After reasonable effort, no appropriate

SEN is available

• Emergency exists and SEN not available

Safety Plus XL

Set-up

Fully retract sheath until

it clicks and this will

crimp and lock

base to syringe

Ways To Avoid Needle Injuries

1. Dentists:

• Use mirror to retract lip, not finger

• Re-cap needle with scoop technique

• HBV vaccination

• Use a re-capping device

Ways To Avoid Needle Injuries

2. Assistants

• Never pass uncapped needle

• Use sharps containers

• Only remove needle from syringe if capped

• Do not allow sharps container to over-flow

• HBV vaccinations

The Future

• Intranasal local anaesthesia

• Topical anaesthetics providing pulpal

anaesthesia

• Pain fiber specific local anaesthesia

Intranasal Local Anaesthesia

A plume of anaesthesia into one or both nostrils

Intranasal Local Anaesthesia

• Anaesthetize middle & anterior superior

alveolar nerves

• Pulpal anaesthesia 2nd premolar to central

• 3% tetracaine + 0.05% oxymetazoline

• Established medical intranasal use with

cocaine and tetracaine

• Studies looking at lidocaine

10 Success-Enhancing Ideas

1. Minimize vasoconstrictor

2. Optimize volume

3. Try long 25 or 27 gauge needles

4. Wait

5. Try higher blocks

6. Remember lingual infiltrations

7. Landmark

8. Elicit patient co-operation

9. Do not re-inject same area within 10-14 days

10. Keep alternative techniques handy