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Advanced Local Anaesthesia
“Tried & True and What’s New”
Toronto Crown & Bridge Study Club
Feb 7, 2014
David Isen BSc, DDS
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