Infra-orbital nerve block using alar base approach: A novel landmark and technique

Abstract

The infra-orbital nerve block is given to anaesthetize the anterior part of maxilla by depositing the local anesthetic agent in proximity of the infra-orbital nerve foramen. The two intra-oral approaches well documented in the literature are the ‘central incisor approach’ or the ‘bicuspid approach’. In 2011, Infra-orbital nerve block with extended coverage using the intra-oral ‘molar approach’ was employed. However, infra-orbital nerve block can pose a challenge in patients with no teeth. We have devised a novel landmark and technique for infra-orbital nerve block using the anatomical landmark alar base.

Introduction

The infra-orbital nerve block is achieved by depositing the local anesthetic agent at the exit of the infra-orbital nerve from the infra-orbital foramen either by utilizing the percutaneous or the intra-oral approaches. The two intra-oral approaches well documented in the literature^1,2 are the ‘central incisor approach’ or the ‘bicuspid approach’ as shown in Fig. 1. In 2011, Infra-orbital nerve block with extended coverage using the intra-oral ‘molar approach’³ was employed with distinctive advantages as shown in Fig. 1. The palatal approach used to anesthetize the anterior middle superior alveolar nerve (AMSA) have also been described.

Fig. 1.

Demonstrates the different techniques for Infra-orbital nerve block.

1.Conventional bicuspid approach.

2.Central incisor approach

3.Molar approach

4.Alar base approach.

Indications for the infraorbital block include the need for complete anesthesia for surgical exploration or removal of lesions from the anterior part of the maxilla, endodontic or surgical therapy on maxillary anterior teeth, multiple extractions from anterior part of maxilla, failure of alternative infiltration techniques.⁴

Contraindications include the use of block involved in canine space infection, the need of local hemostasis requiring infiltration at the surgical site.

In the conventional approach, needle may be inserted into the height of mucobuccal fold over any tooth from second premolar anteriorly to central incisor to achieve infra-orbital nerve block.¹ Achieving infra-orbital nerve block with the conventional incisor or bicuspid approach in edentulous arches is challenging at times. Thus, we devised a novel and simplified technique to achieve infra-orbital nerve block as shown in Fig. 1.

25 patients were studied to device methodology of standardisation for the proposed landmarks. No complications were encountered using the proposed technique.

The nerves anesthetized are as following.

• 1.Infra-orbital nerve and its terminal branches.
• 2.Anterior Superior Alveolar nerve
• 3.Middle Superior Alveolar nerve

Terminal branches of Infra-orbital nerve are.

• a.Inferior palpebral branch
• b.Superior labial branch
• c.Lateral Nasal branch.

Areas anesthetized by Infra-orbital nerve block using alar base approach are ipsilateral lower eyelid, upper lip, ala of the nose, pulpal anesthesia provided to incisors, canine, premolars and mesio-buccal root of the first molar along with the soft tissue and periosteum overlying the mentioned teeth.

Technique

Intra-oral approach

The patient is seated comfortably on the dental chair with the maxillary occlusal plane at 45° to the floor. The right-hand operator stands or is seated at 7 to 9 O’ clock position. An imaginary line is drawn connecting the right alar base, infra-orbital depression and the lower edge of the lateral part of infra-orbital rim. Placing the index finger just below the right alar base and simultaneously retracting the upper lip in an upward and forward direction using the thumb. The penultimate step before insertion of the needle is to taut the tissues. Avoid retracting the tissues in a lateral direction as this may stretch alar base. A 27-gauge long 38 ​mm needle is inserted along the imaginary line from the position inferior to alar base intra-orally as shown in Fig. 2. It is advanced slowly in an upward, inward and backward direction so that it lies on the infra-orbital foramen. The bevel is kept facing the bone throughout and 3/4th length of the needle is inserted till you hit the bone. Once the needle hits the bone, retract and aspirate in multiple planes before injecting the local anesthetic agent. On negative aspiration, approximately 1.2–1.8 ​ml of the local anesthetic solution is slowly deposited at 1 ​ml/min.

Fig. 2.

Demonstrates the Intra-oral infra-orbital technique using the alar base approach.

Advantage

The conventional approach may pose a challenge in patients with missing teeth either due to extractions or congenital absence of teeth and in edentulous patients with bony spicules on the alveolar ridge. The alar base is a stable landmark and easier in approach.

Disadvantage

Mildly difficult learning curve.

Extra-oral approach

A 25-gauge 25 ​mm needle is inserted percutaneously below the infra-orbital depression. An imaginary line is drawn connecting the alar base to lower edge of lateral part of infra-orbital rim and another imaginary line passing from supra-orbital notch, center of the pupil and along the long axis of premolars. The intersection of these imaginary lines is the point of insertion of the needle. The bevel is kept facing the bone throughout, 1.2–1.8 ​ml of the local anesthetic solution is slowly deposited at 1 ​ml/min after negative aspiration.

Advantage

The extra-oral approach using the landmark alar base doesn’t have an additional advantage over the conventional extra-oral approach. However, the proposed landmark is novel.