Management of Local Anaesthesia in Endodontics - The ...

Management of Local Anaesthesia in Endodontics

Halton-Peel Dental AssociationAndrew Moncarz

BSc, DDS, Dip. An, MSc, FRCD(C)

March 22, 2007

Objectives Review of:

Reported rates of profound anaesthesia Anatomical variations Maximum doses of local anaesthetics Pulpal inflammation as a complicating

factor Adjunctive strategies for profound

mandibular LA

Reported Reasons for Mandibular Anaesthesia

Failure1. Operator Inexperience2. Armamentarium: Deflection of the needle

tip3. Patient factors:

1. Variations in anatomy2. Accessory innervation3. Unpredictable spread of LA4. Local infection5. Pulpal inflammation6. Psychological issues

What about experienced operators?

Effectiveness of Conventional IANB as

measured by EPT

Childers et al. 1997

lido 2% 1:100K 63%

Clark et al. 1999 lido 2% 1:100K 73%

Dunbar et al. 1996

lido 2% 1:100K 43%

Guglielmo et al. 1999

mepiv 2% 1:20K 80%

Reitz et al. 1998 lido 2% 1:100K 71%

Always use a long 25 gauge needle (the red one) 2 reasons:

1. Less deflection 2. Less false negative aspiration

Ultrasound Guidance Hannan et al. 1999: Repeated-measures design 40 subjects injected twice at separate

appointments—once with landmarks, once with ultrasound guidance

EPT after profound lip numbness reported Anaesthetic success 38%-92%, no

difference between the techniques Conclusion: accuracy of needle placement

is not the primary reason for failure of IANB

Nerve to mylohyoid

Berns et al. 1962: injected radiopaque material into pterygomandibular space

Spread is unpredictable Suggestion: inject more LA

Decrease in the pH locally Can influence the amount of LA

available in the lipophilic form to diffuse across the nerve membrane

Result is less drug interference of sodium channels

Less likely to influence mandibular block anaesthesia

Pulpal Inflammation Causes activation and sensitization of

peripheral nociceptors Causes sprouting of nerve terminals in

the pulp Causes expression of different sodium

channels: TTX-resistant class of sodium channels are 4 times as resistant to blockade by lidocaine and their expression is doubled in the presence of PGE2

Effectiveness of Conventional IANB: Irreversible Pulpitis

Reisman et al.1997

1.8 mL lido 2% 1:100K epi

25%

Nusstein et al. 1998

1.8 mL lido 2% 1:100K epi

19%

Cohen et al. 2000

1.8 mL lido 2%1:100K epi

50%

Claffey et al. 2004

1.8 mL lido 2% 1:100K epi 23%

100% lip anaesthesia

Adjunctive Strategies Additional Anaesthetic PDL Injection Intraosseous Injection Intrapulpal Injection Different anaesthetic

Retest using the CC

Adjunctive Strategies Additional Anaesthetic

Higher injection Gow Gates Akinosi Nerve to mylohyoid

PDL Injection Intraosseous Injection Intrapulpal Injection Different anaesthetic

Maximum Doses LA % means g/dL Example:

1% = 1 g/dL 1% = 10g/L 1% = 10 mg/mL

Therefore: 2% = 20 mg/mL

Maximum Doses LA A cartridge contains 1.8 mL Therefore a cartridge of 2% local

anaesthetic contains 20 mg/mL X 1.8 mL = 36 mg of local anaesthetic

Maximum Doses LA How much LA can you give? 193 lb 33 yo male Lidocaine 2% 1:100K Articaine 4% 1:200K

2.2 lbs = 1 kg 193 lbs = 88 kg

Maximum Doses LA Lidocaine 2% Max dose = 7

mg/kg 7mg/kg X 88=616

mg 36 mg/1.8 mL 616mg/36mg/

cart.= 17 cartridges **

Articaine 4% Max dose 7 mg/kg 7 X 88 = 616 mg 72 mg/1.8mL 616 mg/72 mg/cart.

= 9 cartridges

Maximum Doses Epi % = 1/100 = g/dL Therefore:

1/100 = 1% = 1g/dL = 10 mg/mL 1/1000 = 0.1% = 0.1 g/dL = 1 mg/mL 1/10000 = 0.01% = 0.01 g/dL = 0.1 mg/mL 1/100000 = 0.001% = 0.001 g/dL = 0.01mg/mL

A cartridge contains 1.8 mL Therefore a cartridge of 1:100 000 epi

contains 0.01 mg/mL X 1.8 mL = 0.018 mg(or about 0.02 mg)

Maximum Doses Epi Cardiovascular patient 0.04 mg Healthy patient 0.2 mg

Maximum Doses LA Lidocaine 2% Max dose = 7 mg/kg 7mg/kg X 88=616 mg 36 mg/1.8 mL 616mg/36mg/cart.= 17 cartridges ** 10-11 cartridges (epi)

Articaine 4% Max dose 7 mg/kg 7 X 88 = 616 mg 72 mg/1.8mL 616 mg/72 mg/cart.

= 9 cartridges

Pregnant Patients Which Local Anaesthetic to use?

Articaine 4% 1:200 000 epi Lidocaine 2% 1:100 000 epi Mepivacaine 2% 1:20 000 levo Mepivacaine 3% plain

FDA categories (based on risk of fetal injury)

A: controlled studies in humans—no risk to fetus demonstrated

B: animal studies show no risk, no human studies; or animal studies have shown a risk but human studies have shown no risk

C: animal studies show risk, no human studies; or no animal or human studies

Pregnant Patients Which Local Anaesthetic to use?

Articaine 4% 1:200 000 FDA category C Lidocaine 2% 1:100 000 FDA category B Mepivacaine 2% 1:20 000 FDA

category C Mepivacaine 3% plain FDA category C

Advantages of Injecting “Higher”

Failure to achieve profound local anaesthesia attributed to being “too low” and “too far forward”

Injecting superiorly and more distally may block accessory innervation

3 nodes of Ranvier may not be true

Gow-Gates Technique Landmarks:

Corner of the mouth (contralateral side) Tragus of the ear Disto palatal cusp of the maxillary

second molar AIMING FOR THE NECK OF THE CONDYLE

Efficacy of the Gow-Gates Technique

Author Year GG (%) IANB (%)Watson and Gow-Gates

1976 98.4 85.4

Gow-Gates and Watson

1977 96.2 85.5

Levy 1981 96 65

Malamed 1981 97.5

Montagnese et al. 1984 35 38

Akinosi Technique Closed-mouth technique Does not rely on a hard-tissue

landmark Parallel to occlusal plane, height of

the mucogingival junction Advanced until hub is level with distal

surface of maxillary second molar Delayed onset of anaesthesia

Akinosi Technique Martinez Gonzalez et al. 2003

Pain to puncture less with Akinosi Onset slower 17.8% failure vs. 10.7% IAB/LB

BUT-incomplete LB considered failure Cruz et al. 1994

Gow Gates more effective, but Akinosi most acceptable to patients

Nerve to Mylohyoid Deposit ¼ cartridge of LA on lingual

surface of tooth in alveolar mucosa Goal is to bathe the nerve as

branches of it enter the lingual surface of the mandible

PDL Injection Technique:

needle inserted into the gingival sulcus at a 30 degree angle towards the tooth

bevel placed towards bone advanced until resistance felt anaesthetic injected with continuous

force for about 15 seconds. approx. 0.2 mL of solution 25 vs. 30 gauge needle

PDL Injection Conventional vs. specific PDL

syringes: Malamed (1982):

similar rates of success D’Souza et al (1987):

no sig. difference in anaesthesia achieved. using the pressure syringe resulted in more

spread of anaesthetic to adjacent teeth

PDL Injection: Primary Technique

Melamed 1982: 86% overall Faulkner 1983: 81% overall White 1988: variable, short duration

esp. md. molars Walton 1990: “In reviewing the clinical

and experimental literature…the periodontal ligament injection does not meet all of the necessary requirements for a primary technique.”

PDL Injection: Supplemental Technique

Walton and Abbott 1981: Inadequate pulpal anaesthesia following

IAB 92% overall included situations where multiple PDL

injections required most critical factor was to inject under

strong resistance Smith, Walton, Abbott 1983:

83% overall with high pressure syringe

PDL Injection: Anaesthetic Distribution

Garfunkel et al 1983, Smith and Walton 1983, Tagger et al 1994, Tagger et al 1994* spread along path of least resistance influenced by anatomical structures and

fascial planes through marrow spaces avoided PDL route appears to be a form of intraosseous injection

PDL Injection: Effects on the Periodontium

Animal histological studies Most studies: no long term evidence

of tissue disruption or inflammation Roahen and Marshall 1990: evidence

of localized external resorption

Intraosseous Injection Technique for mandibular infiltration Perforate the cortical plate to

introduce LA in medullary bone Bathes the periradicular region in LA 2 commercial systems available:

Stabident (Patterson) X-Tip (Tulsa Dentsply)

Stabident

Success of Conventional IANB + IO as Measured by

EPTDunbar et al.

2% lido 1:100K 90%

Gallatin et al.

3% mepivacaine plain

100%

Guglielmo et al.

2% lido 1:100K 100%

Reitz et al. 2% lido 1:100K 94%

IANB + IO in Cases of Irreversible Pulpitis


Lido 2% 1:100K

91%

Parente et al. 1998

Lido 2% 1:100K

79%/ 91%

Reisman et al. 1997

Mepivacaine 3% plain

80%/ 98%


Lido 2% 1:100K

82% (X-Tip)

Bigby et al. 2006

Articaine 4% 1:100K

86%

Adjunctive Strategies Additional Block (higher injection) PDL Injection Intraosseous Injection Intrapulpal Injection Different anaesthetic

Intrapulpal Anaesthesia VanGheluwe and Walton 1997: under back-pressure, efficacy of

LA=saline injection Conclusion: back-pressure is the key

to intrapulpal anaesthetic success

Articaine Reputation for improved local

anaesthetic effect—short linear molecule Amide local, contains a thiophene ring

instead of a benzene ring Partial hydrolysis by plasma esterases 4% solution—concern with toxicity Potential for methemoglobinemia (like

prilocaine)

Articaine More effective than other local

anaesthetics? No difference found:

Haas et al. 1990 (vs. prilocaine) Vahatalo et al. 1993 (vs. lidocaine) Malamed et al. 2000 (vs. lidocaine) Donaldson et al. 2000 (vs. prilocaine) Claffey et al. 2004 (vs. lidocaine) Mikesell et al. 2005 (vs. lidocaine)

Articaine Claffey et al. 2004:

Articaine vs. lidocaine IANB for irreversible pulpitis of mandibular teeth

Articaine 9/37 (24%) Lidocaine 8/35 (23%) (all subjects had subjective lip

anaesthesia)

Articaine Paraesthesia?

Haas and Lennon 1995: higher incidence of paraesthesia associated with prilocaine and articaine. Attributed to the higher concentration of drug required for comparable clinical effect

14/11 000 000 injections Statistically higher Clinical relevance? Claffey et al 2004

“clinically rare event”

Articaine Paraesthesia?

Dower 2003 (Dentistry Today) Review article Paraesthesia rates up to 2-4% when

using articaine for lingual blocks or IANBs

RCDSO Dispatch Summer 2005 pg. 26

“Until more research is done, it is the College’s view that prudent practitioners may wish to consider the scientific literature before determining whether to use 4% local anaesthetic solutions for mandibular block injections.”

College Registrar RepliesDispatch Fall 2005 vol. 19,

#4 “This college received legal advice

from our general counsel, and from outside counsel, before publishing what we did…The advice we received was that it was certainly within our obligation to advise members to be aware of the literature…”

Articaine Hillerup and Jensen 2006:

Danish population—all cases in Denmark referred to authors for evaluation

54 injection injuries in 52 patients 54% of all nerve injuries associated with

articaine Substantial increase in number of

injection injuries following introduction of articaine to Danish market in 2000.

Articaine What about a mandibular infiltration? Recommended by Steve Buchanan Kanaa et al. 2006

Cross-over design comparing articaine and lidocaine for mandibular infiltration for first molars

Anaesthesia measured by maximal EPT X2 Lidocaine 38% effective Articaine 65% effective

Kleinknect and Bernstein 1978: positive correlation between anxiety and reported pain during dental treatment

Topical Anaesthetic Benzocaine or

Lidocaine Effectiveness?

Gill and Orr 1979: 15 second application no more effective than placebo

Stern and Giddon 1975: 2-3 minutes=profound soft tissue anaesthesia

Topical Anaesthetic Recommendations:

Dry mucous membranes first 2-3 minutes, but concern with tissue

sloughing Tip of the tongue

Topical Anaesthetic Benzocaine Spray RCDSO Dispatch 21, 1, Feb/Mar 2007

pp.28-29 Advice to Dentists Benzocaine Sprays and

Methemoglobinemia (MHb) Health Canada—9 suspected cases, none

fatal

Topical Anaesthetic Benzocaine spray/Methemoglobinemia Recommendations:

Avoid in patients with a history of MHb Consider lidocaine as an alternative Broken/inflamed tissue may promote uptake Use only amount deemed necessary If suspicious, send patient to hospital for

methylene blue tx O2 won’t help, but give it anyways

Methemoglobinemia Fe2+ ion of the heme group of the

hemoglobin molecule is oxidized to Fe3+

Hemoglobin converted to methemoglobin, a non-oxygen binding form of hemoglobin that binds a water molecule instead of oxygen.

Conclusions: 1. Consider topical anaesthetic 2. Re-test using patient’s chief complaint 2. Inject again

Higher More Local Anaesthetic Nerve to Mylohyoid

3. Consider PDL/Intraosseous Anaesthesia 4. Consider Intrapulpal Anaesthesia 5. If they say it hurts, it hurts

Thank you Questions? Please feel free to contact me:

416-223-1771 [email protected] www.endoasleep.ca

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