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South African Dental Journal

versão On-line ISSN 0375-1562
versão impressa ISSN 0011-8516

S. Afr. dent. j. vol.72 no.3 Johannesburg Abr. 2017

 

COMMUNICATION

 

Local anaesthetics in dentistry - Part 2: Choice of local anaesthetic agent

 

 

DS Moodley

PhD, MSc, PDD Aesthet. BDS, FICD. Department of Restorative Dentistry, Faculty of Dentistry, University of the Western Cape, Cape town, South Africa. Private Bag X1, Tygerberg, 7505. tel: 021 9373090 E-mail: dmoodley@uwc.ac.za

 

 

Currently, in general dentistry the most commonly used local anaesthetic agents are 2% lignocaine (Xylotox, Adcock Ingram; Xylesthesin, 3M) with 1:80000 adrenaline content, 3% mepivicaine (Carbocaine) without a vasoconstrictor and 4% articaine (Ubistesin 3M) with either 1:100000 or 1:200000 adrenaline concentration.

The local anaesthetic molecule consists of three components: (a) lipophilic aromatic ring, (b) intermediate ester or amide chain, and (c) terminal amine.1 The aromatic ring improves lipid solubility.1-3 The nerve membrane consists of a double lipid layer and a protein layer and therefore the property of enhancing lipid solubility contributes to increased potency of the anaesthetic agent as more of the available drug can diffuse through the membrane. The benzene aromatic ring is replaced in articaine by a thiophene ring, which allows even greater lipid solubility and further penetration of an administered dose into the neurons. Local anaesthetics have protein-binding characteristics which determine the duration of anaesthesia. Affinity for plasma proteins corresponds to affinity for protein at the receptor site within sodium channels, prolonging the presence of the anaesthetic at the site of action. Agents that attach to the protein components of nerve membranes are also less likely to diffuse from the site of action and enter the systemic circulation, and therefore pose a lower systemic toxicity risk.2,5

The intermediate chain can be either an amide or ester group; in general ester -containing local anaesthetic solutions are no longer packaged in dental cartridges.3 However, articaine is unique in this regard. It is classified as an amide according to its intermediate linkage, but also contains an ester side chain on its aromatic ring.1,2,6 It is the only amide anaesthetic containing an ester group, allowing hydrolysis by blood cholinesterase (biotransformation in the plasma) as well as in the liver (by hepatic microsomal enzymes).1-3,6 As a result, articaine has a half-life of only 20 minutes compared with 90 minutes for lignocaine that requires total hepatic clearance.3 Hence, articaine presents less risk for systemic toxicity during lengthy appointments when additional doses of anaesthetic are administered.2,3

 

DOSAGE OF LOCAL ANAESTHETIC

Dental cartridges generally contain two drugs, namely, a local anaesthetic and a vasoconstrictor, each having its own dose limitations. Serum concentrations are related to the total dosage rather than the concentration of the solution, e.g. 2% or 4% local anaesthetic. Administering 20ml of 2% or 10ml of 4% (400mg) produces the same serum concen-tration.2,3 Thus it is important to consider the dosage (milligrams) administered and not the volume (milliliters or cartridges) of the local anaesthetic administered. One should consider anaesthetic cartridges as containing 2ml and not 1.8ml to simplify calculations, leading also to an overesti-mation of the dosage, thereby promoting safety in limiting administration of the drug. Lignocaine 2% contains 36mg and articaine 4% contains 72mg of the drug per cartridge.

Each local anaesthetic has its own maximum recommended dose (MDR), expressed in mg/kg. Unfortunately, the mg/kg MDR for each drug varies in the literature7 from 4.4mg/kg8 to 6.6mg/kg.9 Recommended maximum doses for healthy adults (Table 1) for lignocaine 2% is 4.4mg/kg, for articaine 7mg/kg and for mepivicaine 6mg/kg with a ceiling dose approximate to those for a 70kg person.8,10

Thus, the MDR of 2% lignocaine with adrenaline for a 15kg child = 15kg x 4.4mg/kg = 66mg maximum dose of lignocaine. Since a lignocaine/cartridge contains 36mg of the drug this equates to 1.5 cartridges.7 A general conservative "rule of 10" may be used as a general guideline for maximum dosages i.e. one cartridge per 10kg body weight (up to a maximum of 70kgs). Thus, the MDR for a 15kg child would be 1.5 cartridges lignocaine.

 

CLINICAL EFFICACY OF ARTICAINE VERSUS LIGNOCAINE

There seems to be conflicting research results regarding the advantage of 4% articaine over 2% lignocaine. It is difficult to demonstrate to a level of statistical significance (evidence-based medicine) in a clinical trial that 4% articaine is superior to any other amide local anaesthetic.11

However, anecdotal reports claim that articaine

1. works faster,

2. works better,

3. "I don't miss as often," and

4. "gets patients numb when other local anaesthetics fail."11

2% lignocaine and 4% articaine with 1:100000 adrenaline have similar properties for use in surgery and have demonstrated a good safety and tolerance profile.12

On the other hand, articaine with 1:100000 adrenaline showed a higher success rate than lignocaine with 1:100000 adrenaline for buccal infiltration of mandibular molars1314 but not when administered in the attempt to anaesthetize teeth with irreversible pulpitis.15 The efficacy of 4% articaine with 1:100,000 adrenaline was similar to 2% lignocaine with 1:100,000 adrenaline for intra-ligamentary injections.16 In a study on patients with irreversible pulpitis the anaesthetic efficacies of articaine and lignocaine were similar for inferior alveolar nerve blocks.17-19

However, other studies have shown that infiltrations of 4% articaine with adrenaline offer better clinical performance than 2% lignocaine in terms of latency and duration of the anaesthetic effect, but have not demonstrated any statistically significant differences in anaesthetic efficacy.13,20 When the success of inferior alveolar nerve blocks were compared, articaine and lignocaine performed similarly.21 For infiltration articaine produced shorter onset and longer duration of pulpal anaesthesia than the lignocaine solution.22 Supplemental buccal infiltration with articaine was more effective than lignocaine in mandibular molars with irreversible pulpitis.23 This may be the result of a concentration effect or a greater diffusion of articaine. There was a high statistically significant difference between the articaine and lignocaine solutions when their efficacy was compared in maxillary buccal infiltrations in patients with irreversible pulpitis.24 The success of articaine after infiltration may be attributable to high lipid solubility and more molecules/ml injected when compared with lignocaine.3 For patients undergoing periodontal surgery, 4% articaine anaesthetic with 1:100000 or 1:200000 adrenaline provides excellent surgical pain control.25

In a systematic review articaine was shown to be more effective than lignocaine in providing anaesthetic success in the first molar region. The drugs appear to have similar adverse effect profiles.26,27 Another meta-analysis study concluded that articaine had a probability of achieving anaesthetic success superior to that of lignocaine, with an odds ratio of 2.44 (95% confidence interval [CI], 1.59-3.76; P < 0.0001).28 The odds ratio for articaine increased to 3.81 (95 % CI, 2.71-5.36; P < 0.00001) when the authors analysed only the data for infiltration. There was weaker, but still significant, evidence of articaine being superior to lignocaine for mandibular block anaesthesia, with an odds ratio of 1.57 (95% CI, 1.12-2.21; P =0.009).28

 

SAFETY OF 4% LOCAL ANAESTHETIC

The apprehension that 4% articaine is related to adverse neurological effects like paraesthesia seem to stem from a retrospective study by Haas and Lennon.29,30 These authors reported that generally the incidence of paraesthe-sia is low but if paraesthesia does occur, it is significantly more likely to do so if either 4% articaine or prilocaine31,32 has been injected. Hence, it has been suggested that the use of these agents for infiltration be limited and to rather reserve their use in nerve blocks for failed attempts with other agents.2,3

Allegations that 4% local anaesthetics are associated with a greater risk of paraesthesia are based solely on anecdotal reports and have no scientific justification.6,11 Linking 4% local anaesthetic with an increased risk of neurotoxicity, and recommending that the use of articaine be avoided in mandibular nerve blocks is unjustified. Articaine is in fact a "safe and effective local anaesthetic" for Dentistry.11 To date, there has been no explanation that an inferior alveolar nerve block can, on a rare occasion, cause permanent nerve injury.33 Articaine is a safe and effective local anaesthetic drug to use in Dentistry.4,6

 

References

1. Malamed SF. Handbook of Local Anesthesia. 6th ed. Malamed SF, editor. Vol. 33, Elservier. St. Louis: Elsevier Mosby; 2013. 25-38 p.         [ Links ]

2. Becker DE, Reed KL. Local anesthetics: review of pharmacological considerations. Anesth Prog. 2012;59(2):90-101.         [ Links ]

3. Becker DE, Reed KL. Essentials of Local Anesthetic Pharmacology. Anesth Prog. 2006;53:98-109.         [ Links ]

4. Yapp KE, Hopcraft MS, Parashos P. Articaine: a review of the literature. Br Dent J [Internet]. 2011;210(7):323-9. Available from: http://dx.doi.org/10.1038/sj.bdj.2011.240        [ Links ]

5. Moore PA, Hersh E V. Local Anesthetics: Pharmacology and Toxicity. Vol. 54, Dental Clinics of North America. 2010. p. 587-99.         [ Links ]

6. Malamed SF, Gagnon S, Dominique L. Articaine hydrochloride: a study of the safety of a new amide local anesthetic. J Am Dent Assoc. 2001;132:177-85.         [ Links ]

7. Weaver JM. Calculating the maximum recommended dose of local anesthetic. J Calif Dent Assoc. 2007;35(1):61-3.         [ Links ]

8. Meechan JG. Why does local anaesthesia not work everytime? Dent Update. 2005;32(2):66-72.         [ Links ]

9. Bassett K, DiMarco A, Naughton D. Local Anesthesia for Dental Professionals. 2nd ed. DiMarco Arthur NDBK, editor. New Jersey: Pearson Education Inc; 2015. 1-418 p.         [ Links ]

10. Meechan JG. Local anaesthesia: risks and controversies. Dent Update. 2009 Jun;36(5):278-80, 282-3.         [ Links ]

11. Malamed SF. Local anesthetics: dentistry's most important drugs, clinical update 2006. J Calif Dent Assoc [Internet]. 2006;34(12):971-6. Available from: http://www.ncbi.nlm.nih.gov/pubmed/17260521        [ Links ]

12. Martínez-Rodríguez N, Barona-Dorado C, Martin-Ares M, Cortes-Breton-Brinkman J, Martinez-Gonzallez J-M. Evaluation of the anaesthetic properties and tolerance of 1:100,000 articaine versus 1:100,000 lidocaine. A comparative study in surgery of the lower third molar. Med Oral Patol Oral Cir Bucal. 2012;17(2):345-51.         [ Links ]

13. Robertson D, Nusstein J, Reader A, Beck M, McCartney M. The anesthetic efficacy of articaine in buccal infiltration of mandibular posterior teeth. J Am Dent Assoc. 2007;138(8):1104-12.         [ Links ]

14. Balto K. Administration of articaine anesthesia may lead to superior profound pulpal anesthesia compared with lidocaine in adult patients. Journal of Evidence-Based Dental Practice. 2011;11:183-4.         [ Links ]

15. Ashraf H, Kazem M, Dianat O, Noghrehkar F. Efficacy of articaine versus lidocaine in block and infiltration anesthesia administered in teeth with irreversible pulpitis: A prospective, randomized, double-blind study. J Endod. 2013;39(1):6-10.         [ Links ]

16. Berlin J, Nusstein J, Reader A, Beck M, Weaver J. Efficacy of articaine and lidocaine in a primary intraligamentary injection administered with a computer-controlled local anesthetic de livery system. Oral Surgery, Oral Med Oral Pathol Oral Radiol Endodontology. 2005;99(3):361-6.         [ Links ]

17. Bigby J, Reader A, Nusstein J, Beck M. Anesthetic efficacy of lidocaine / meperidine for inferior alveolar nerve blocks in patients with irreversible pulpitis. J Endod. 2007;33:1-4.         [ Links ]

18. Argueta-Figueroa L, Arzate-Sosa G, Mendieta-Zeron H. Anesthetic efficacy of articaine for inferior alveolar nerve blocks in patients with symptomatic versus asymptomatic irreversible pulpitis. Gen Dent. 2012;60(1):e39-43.         [ Links ]

19. Claffey E, Reader A, Nusstein J, Beck M. Anesthetic efficacy of lidocaine / meperidine for inferior alveolar nerve blocks in patients with irreversible pulpitis. J Endod. 2004;30(8):568-71.         [ Links ]

20. Sierra Rebolledo A, Delgado Molina E, Berini Aytís L, Gay Escoda C. Comparative study of the anesthetic efficacy of 4% articaine versus 2% lidocaine in inferior alveolar nerve block during surgical extraction of impacted lower third molars. Med Oral Patol Oral Cir Bucal. 2007;12(2) e139-44        [ Links ]

21. Corbett IP, Kanaa MD, Whitworth JM, Meechan JG. Articaine infiltration for anesthesia of mandibular first molars. J Endod. 2008;34(5):514-8.         [ Links ]

22. Costa CG, Tortamano IP, Rocha RG, Francischone CE, Tortamano N. Onset and duration periods of articaine and lidocaine on maxillary infiltration. J Prosthet Dent. 2005;94(4):381.         [ Links ]

23. Rogers BS, Botero TM, McDonald NJ, Gardner RJ, Peters MC. Efficacy of articaine versus lidocaine as a supplemental buccal infiltration in mandibular molars with irreversible pulpitis: A prospective, randomized, double-blind study. J Endod. 2014;40(6):753-8.         [ Links ]

24. Srinivasan N, Kavitha M, Loganathan CS, Padmini G. Com parison of anesthetic efficacy of 4% articaine and 2% lidocaine for maxillary buccal infiltration in patients with irreversible pulpitis. Oral Surgery, Oral Med Oral Pathol Oral Radiol Endodontology. 2009;107(1):133-6.         [ Links ]

25. Moore P, Doll B, Delie R, Hersh E, Korostoff J, Johnson S, et al. Hemostatic and anesthetic efficacy of 4% articaine HCl with 1:200,000 epinephrine and 4% articaine HCl with 1:100,000 epinephrine when administered intraorally for periodontal surgery. J Periodontol [Internet]. 2007;78(2):247-53. Available from: http://www.ncbi.nlm.nih.gov/pubmed/17274713        [ Links ]

26. Katyal V. The efficacy and safety of articaine versus lignocaine in dental treatments: A meta-analysis. J Dent. 2010; 38(4):307-17.         [ Links ]

27. Powell V. Articaine is superior to lidocaine in providing pulpal anesthesia. J Am Dent Assoc. 2012;143(8):897-8.         [ Links ]

28. Brandt RG, Anderson PF, Mcdonald NJ, Sohn W, Peters MC. The pulpal anesthetic efficacy of articaine versus lidocaine in dentistry A meta-analysis. J Am Dent Assoc. 2011;142:493-504.         [ Links ]

29. Gaffen AS, Haas DA. Survey of local anesthetic use by Ontario dentists. J Can Dent Assoc (Tor). 2009;75(9):649-55.         [ Links ]

30. Gabriella A, Gaffen AS, Lawrence P, Tenenbaum HC, Haas A, Lawrence HP, et al. Updated information and services including high-resolution figures, can be found in the online version of this article at: J Am Dent Assoc. 2010;141:836-44.         [ Links ]

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33. Pogrel A, Schmidt B, Sambajon V, Jordan R. Lingual nerve damage due to inferior alveolar nerve blocks: A possible explanation. JADA. 2003;134:195-9.         [ Links ]

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