Thursday, 9 February 2017

Inferior Alveolar Nerve Block



Inferior Alveolar Nerve Block

The inferior alveolar nerve block is the most common type of nerve block used for dental procedures. Knowledge of mouth and inferior alveolar nerve anatomy is required to perform the procedure. The mandibular nerve exits at the base of the skull through the foramen ovale. The first branch from the main trunk is the nervous spinosus, which runs superiorly through the foramen spinosum to supply the meninges. The second branch is the first motor nerve, which supplies the medial pterygoid muscle. Inferior to that branch, the mandibular nerve splits into an anterior trunk (both sensory and motor) and a posterior trunk.The motor component supplies the masseter, temporal, and lateral pterygoid muscles.



Injection in proper area of ramus to effect alveolar nerve block
 
The posterior trunk radiates from the auriculotemporal nerve that gives sensory perception to the side of the head and scalp and sends twigs to the external auditory meatus, the tympanic membrane, and the temporomandibular joint. The posterior trunk then almost immediately divides into the lingual nerve and the inferior alveolar nerve. The sensory trunk is the long buccal nerve that supplies the buccal soft tissue distal to the first molar. The lingual nerve supplies the anterior two thirds of the tongue and the lingual surface of the mandibular gingiva. The mandibular nerve sends a branch to the mylohyoid muscle and the anterior belly of the digastric muscle and then enters the mandibular canal. The mandibular nerve furnishes sensation to the following areas:
  • Mandible
  • Buccal gingiva anterior to the first molar
  • Lower lip and the pulps of all the mandibular teeth in that quadrant
The inferior alveolar nerve is the larger branch of the posterior division of the mandibular nerve. The inferior alveolar nerve enters the mandibular foramen in the ramus of the mandible (see the image below) to occupy the inferior alveolar canal in the body of the mandible.

Identifying mandibular ramus
When the inferior alveolar nerve approaches the apex of the second bicuspid, it divides into two terminal branches, the mental and the incisive.
A nerve block of the intraoral mandibular or inferior alveolar nerve anesthetizes the following:
  • The body of the mandible and the lower portion of the ramus
  • All mandibular teeth
  • The floor of the mouth
  • The anterior two thirds of the tongue
  • Gingivae on the lingual surface of the mandible
  • Gingivae on the labial surface of the mandible
  • Mucosa and skin of the lower lip and chin
Understanding the underlying anatomy of the pterygomandibular space helps increase the effectiveness of inferior alveolar nerve blocks. [1]

Indications

An inferior alveolar nerve block is required to work in the following areas of the mouth:
  • Mandibular teeth to the midline
  • The anterior two thirds of the tongue
  • The floor of the oral cavity

Contraindications

Absolute contraindication
  • Hypersensitivity to local anesthetic agents: This occurs in less than 1% of the general population.
  • Cervical botulinum toxin injection: When given with an inferior alveolar mandibular type nerve block, this has resulted in severe dysphagia. [2]
Relative contraindication
  • History of malignant hyperthermia

Anesthesia

Various types and quantities of local anesthetic agents have been suggested for an inferior alveolar nerve block.

Determining local anesthetic concentrations and dilutions

Concentrations: Drug concentration is expressed as a percentage (eg, bupivacaine 0.5%, lidocaine 1%).
  • Percentage is measured in grams per 100 mL (ie, 1% is 1 g/100 mL [1000 mg/100 mL], or 10 mg/mL)
    • Calculate the mg/mL concentration quickly from the percentage by moving the decimal point 1 place to the right, as follows:
      • Bupivacaine 0.5% = 5 mg/mL
      • Lidocaine 2% = 20 mg/mL
Dilutions: When epinephrine is combined in an anesthetic solution, the result is expressed as a dilution (eg, 1:100,000).
  • 1:100,000 means 1 mg per 100 mL (ie, 0.001%)
  • 1:200,000 means 1 mg per 200 mL (ie, 0.0005%)
Table. Epinephrine Content Examples(Open Table in a new window)
Solution Volume
1:100,000



(1 mg/100 mL)


1:200,000



(1 mg/200 mL)


1 mL
0.01 mg
0.005 mg
5 mL
0.05 mg
0.025 mg

 

 

Common local anesthetic agents for dental anesthesia

1. Articaine 4% (Septocaine) with epinephrine 1:100,000 is suitable for dental procedures in the mandible subsequent to anesthesia with inferior alveolar nerve block. [8]
  • Adult total dose ranges for submucosal injection
    • Infiltrative administration: 0.5-2.5 mL (20-100 mg)
    • Nerve block: 0.5-3.4 mL (20-136 mg)
    • Oral surgery: 1-5.1 mL (40-204 mg)
    • Not to exceed 7 mg/kg (0.175 mL/kg)
  • Decrease dose in pediatric patients (>4 y), elderly patients, or those with hepatic impairment; use in children younger than 4 y not recommended
2. Bupivacaine 0.5% (Sensorcaine)
  • Maxillary and mandibular area for oral surgery
  • Adult total dose range is 1.8 mL to a maximum of 18 mL (9-90 mg)
  • Not to exceed 18 mL (90 mg) per dental sitting
  • Reduce dose in pediatric or elderly patients, those with cardiac disease, those who are debilitated, or those with hepatic impairment
3. Lidocaine 2% (Xylocaine) with epinephrine 1:100,000 (or 1:50,000 when greater depth and hemostasis are required)
  • Maxillary and mandibular area for oral surgery
  • Adult total dose range for submucosal injection: 1-5 mL (20-100 mg)
  • Children younger than 10 years: 0.9-1 mL (18-20 mg)
  • Maximum dose for adult and pediatric patients
    • Not to exceed 7 mg/kg (with epinephrine)
    • Not to exceed 4.5 mg/kg (without epinephrine)
4. Mepivacaine 2-3% (Carbocaine, Polocaine)
  • Also available with epinephrine 1:200,000 or levonordefrin 1:20,000; each prolongs duration of action
  • Dental infiltration or nerve block
  • Adult dose range
    • 2% with levonordefrin: 1.8 mL (36 mg)
    • Not to exceed 3 mg/kg or 400 mg in adults
    • 3%: 1.8 mL (54 mg)
    • Not to exceed 3 mg/kg or 400 mg in adults
  • Pediatric dose: Not to exceed 9 mL (ie, 180 mg as the 2% solution or 270 mg as the 3% solution)

5. Prilocaine 4% (Citanest)
  • Adult dose range: 1-2 mL (40-80 mg)
  • Not to exceed 8 mg/kg or 600 mg within a 2-hour period
  • Not to exceed 1 mL (40 mg) in children younger than 10 years
A single prospective blinded comparison of 1.8 mL and 3.6 mL of 2% lidocaine with 1:200,000 epinephrine for inferior alveolar nerve block in patients with irreversible pulpitis found that increasing the volume of 2% lidocaine from 1.8 mL to 3.6 mL improved the success rate but was not 100% successful. [9]

Equipment

See the list below:
  • Standard dental equipment should be present.
  • The examination table or chair can be adjusted to accommodate the patient's height.
  • An overhead light of sufficient intensity should be present.
  • Sterile thumb-control syringe
  • Topical anesthetic (in the form of pastes or gels)
  • 2% lidocaine with epinephrine or 0.5% bupivacaine with epinephrine
  • Cotton-tipped applicators to administer topical anesthetic and control bleeding
  • Ultrasonographic visualization of the inferior alveolar nerve using a new 8- to 15-MHz transducer that is shaped like a hockey stick may allow for improved ultrasound-directed inferior alveolar nerve block injections. [10]
  • Small-gauge (ga) needles (The longer the needle, the easier the inferior alveolar nerve block is to accomplish.)
    • 1 5/8 inch, 23 ga
    • 1 3/8 inch, 25 ga; some recommend 1 1/8 inch, 27 ga needle
    • 1 3/8 inch, 25 ga (probably the most popular choice of needle)

Positioning

See the list below:
  • Patients should be placed in a dental chair.
  • The head should be tilted back.
  • The patient should open his or her mouth.

Technique

The technique is as follows, based on the description of Powell: [11]
  • Apply topical anesthetic to the target area, which is the mucosa lateral to the pterygomandibular raphe but medial to the anterior border of the mandibular ramus and about 6-10 mm above the occlusal plane of the maxillary teeth.
  • Place the thumb of the nondominant hand on the coronoid notch and the index finger just anterior to the ear to stretch the tissues over the injection site, maximizing visibility and minimizing the pain of the injection as depicted below.

Holding back cheek
  1. With the anterior ramus technique, palpate the anterior border of the ramus with the thumb and find the greatest concavity, which is the coronoid notch. [7]
  2. Orient the syringe so that the barrel is in the opposite corner of the mouth, resting on the premolars.
  3. With the anterior ramus technique, use the middle finger and thumb to determine the width of the ramus in its anterior-posterior dimension. Anatomically, the mandibular foramen lies in the middle of the ramus in this dimension. The average width of the ramus, including the thickness of the soft tissue in the coronoid notch, is approximately 35 mm, which is also the length of the needle. [7]
  4. Aim toward the index finger and slowly penetrate the mucosa until bone is contacted.
    1. Bone is usually contacted within about 2.5 cm.
    2. If the attempt does not result in contact with bone, reorient the syringe more laterally and repeat attempt.
  5. Withdraw slightly and aspirate.
    1. Rotate the bevel of the needle and re-aspirate; if no blood is returned, inject 1.5-2 mL of anesthetic.
    2. If aspiration is positive, pull back about 5 mm and redirect slightly, then repeat attempt at aspiration.
  6. If the injection fails to result in adequate analgesia, it may safely be repeated 2 additional times.
  7. Patients often report mild jaw muscle soreness for 2-3 days following this injection.

Complications

See the list below:
  • A failure rate of 15-20% is seen, even in experienced hands.
  • With an unsuccessful attempt, the patient experiences pain with no therapeutic benefit.
  • Inadequate anesthesia may also result from the formation of a blood clot due to the traumatized, lacerated, and bleeding vessel. The blood from the formation of a hematoma may dilute the local anesthetic solution. This may weaken the anesthetic effects.
  • Fracture of a dental needle while performing an inferior alveolar nerve block has been reported. [18]
  • Trismus and sensory deficit following resolution of trismus have been reported in 2 patients as delayed complications of inferior alveolar nerve block. [19]
  • Medial pterygoid trismus i.e. myospasm occurring after inferior alveolar nerve block has occurred. [20]


Reff



1. Khoury J, Mihailidis S, Ghabriel M, Townsend G. Applied anatomy of the pterygomandibular space: improving the success of inferior alveolar nerve blocks. Aust Dent J. Jun 2011. 56:112-21. [Medline].

2. Shahidi G, Poorsattar Bejeh Mir A, Khatib Shahidi R, Balmeh P. Severe Dysphagia after inferior alveolar nerve block preceded by cervical botolinum toxin injection: a case report. Iran Red Crescent Med J. 2013 Jul. 15(7):608-10. [Medline].

3. Monheim, L. Local Anesthesia and Pain Control in Dental Practice. 2nd ed. St. Louis, Mo: Mosby Elsevier, Inc.; 1961.

4. Articaine (Septocaine) [package insert]. Septodont. May 2006.

5. Lemay H, Albert G, Hélie P, Dufour L, Gagnon P, Payant L, et al. [Ultracaine in conventional operative dentistry]. J Can Dent Assoc. 1984 Sep. 50(9):703-8. [Medline].

6. Lidocaine (Lignospan) [package insert]. Septodont. Accessed: July 30, 2008.

7. Gaum LI, Moon AC. The "ART" mandibular nerve block: a new approach to accomplishing regional anesthesia. J Can Dent Assoc. 1997 Jun. 63(6):454-9. [Medline].

8. Kammerer PW, Palarie V, Daublander M, et al. Comparison of 4% articaine with epinephrine (1:100,000) and without epinephrine in inferior alveolar block for tooth extraction: double-blind randomized clinical trial of anesthetic efficacy. Oral Surg Oral Med Oral Pathol Oral Radiol. 2012 Apr. 113:495-9. [Medline].

9. Aggarwal V, Singla M, Miglani S, Kohli S, Singh S. Comparative Evaluation of 1.8 mL and 3.6 mL of 2% Lidocaine with 1:200,000 Epinephrine for Inferior Alveolar Nerve Block in Patients with Irreversible Pulpitis: A Prospective, Randomized Single-blind Study. J Endod. June 2012. 38:753. [Medline].

10.         Chanpong B, Tang R, Sawka A, Krebs C, Vaghadia H. Real-time ultrasonographic visualization for guided inferior alveolar nerve injection. Oral Surg Oral Med Oral Pathol Oral Radiol. 2013 Feb. 115:272-6. [Medline].

11.         Powell SL, Robertson L, Doty BJ. Dental nerve blocks. Toothache remedies for the acute-care setting. Postgrad Med. 2000 Jan. 107(1):229-30, 233-4, 239-40 passim. [Medline].

12.         Shahi S, Mokhtari H, Rahimi S, Yavari HR, Narimani S, Abdolrahimi M, et al. Effect of premedication with Ibuprofen and dexamethasone on success rate of inferior alveolar nerve block for teeth with asymptomatic irreversible pulpitis: a randomized clinical trial. J Endod. 2013 Feb. 39:160-2. [Medline].

13.         Parirokh M, Sadr S, Nakhaee N, Abbott PV, Askarifard S. Efficacy of supplementary buccal infiltrations and intra-ligamentary injections to inferior alveolar nerve blocks in mandibular first molars with asymptomatic irreversible pulpitis: A randomised controlled trial. Int Endod J. 2013 Dec 21. [Medline].

14.         Nogami S, Yamauchi K, Shiiba S, Kataoka Y, Hirayama B, Takahashi T. Evaluation of the Treatment Modalities for Neurosensory Disturbances of the Inferior Alveolar Nerve Following Retromolar Bone Harvesting for Bone Augmentation. Pain Med. 2014 Dec 22. [Medline].

15.         Saatchi M, Khademi A, Baghaei B, Noormohammadi H. Effect of Sodium Bicarbonate-buffered Lidocaine on the Success of Inferior Alveolar Nerve Block for Teeth with Symptomatic Irreversible Pulpitis: A Prospective, Randomized Double-blind Study. J Endod. 2015 Jan. 41(1):33-5. [Medline].

16.         Araújo GM, Barbalho JC, Dias TG, Santos Tde S, Vasconcellos RJ, Morais HH. Comparative Analysis Between Computed and Conventional Inferior Alveolar Nerve Block Techniques. J Craniofac Surg. 2015 Nov. 26(8):e733-6. [Medline].

17.         Aggarwal V, Singla M, Subbiya A, Vivekanandhan P, Sharma V, Sharma R, et al. The amount of preoperative pain can affect the anesthetic success rates of IANB in patients with symptomatic irreversible pulpitis. Effect of Preoperative Pain on Inferior Alveolar Nerve Block. Anesth Prog. 2015 Winter. 62(4):135-139. [Medline].

18.         Shah A, Mehta N, Von Arx DP. Fracture of a dental needle during administration of an inferior alveolar nerve block. Dent Update. 2009 Jan-Feb. 1:20-2, 25. [Medline].

19.         Smyth J, Marley J. An unusual delayed complication of inferior alveolar nerve block. Br J Oral Maxillofac Surg. 2009 Mar. [Medline].

20.         Wright EF. Medial pterygoid trismus (myospasm) following inferior alveolar nerve block:Case report and literature review. Gen Dent. 2011 Jan-Feb. 1:64-7. [Medline].

21.         Aggarwal V, Jain A, Kabi D. Anesthetic efficacy of supplemental buccal and lingual infiltrations of articaine and lidocaine after an inferior alveolar nerve block in patients with irreversible pulpitis. J Endod. 2009 Jul. 7:925-9. [Medline].

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23.         Aminabadi NA, Farahani RM. The effect of pre-cooling the injection site on pediatric pain perception during the administration of local anesthesia. J Contemp Dent Pract. 2009 May. 3:43-50. [Medline].

24.         Aminabadi NA, Farahani RM, Oskouei SG. Site-specificity of pain sensitivity to intraoral anesthetic injections in children. J Oral Sci. 2009 Jun. 2:239-43. [Medline].

25.         Choi EH, Seo JY, Jung BY, Park W. Diplopia after inferior alveolar nerve block anesthesia: report of 2 cases and literature review. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2009 Jun. 6:e21-4. [Medline].

26.         Gow-Gates GA. Mandibular conduction anesthesia: a new technique using extraoral landmarks. Oral Surg Oral Med Oral Pathol. 1973 Sep. 36(3):321-8. [Medline].

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29.         http://emedicine.medscape.com/article/82622-overview#showall


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