IANB AND ITS REASONS FOR FAILURE

1. DR. AISHWARYAARYA
POST GRADUATE
MM COLLEGE OF DENTAL SCIENCES, HARYANA
INFERIOR ALVEOLAR NERVE BLOCK
AND ITS COMPLICATIONS
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2. CONTENTS
 Introduction
 Indications and contraindications
 Nerves and regions anesthesize
 Landmarks
 Techniques
 Procedure
 Signs and symptoms
 Complications
 Reasons of failure
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3. Three large branches arise from trigeminal nerve V1-
Ophthalmic nerve, V2- Maxillary nerve, V3- Mandibular nerve
The third division V3- Mandibular nerve of the trigeminal nerve
gives off branches in three areas from the -
BRANCHES FROM UNDIVIDED NERVE BRANCHES FROM DIVIDED NERVE
• NERVUS SPINOSUS
• NERVE TO INTERNAL PTERYGOID MUSCLE
• ANTERIOR DIVISION
• POSTERIOR DIVISION
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TRIGEMINAL NERVE

4. The posterior division of
trigeminal nerve is primarily
sensory with a small motor
component.
It descends for a short
distance downward and
medial to the lateral pterygoid
muscle, at which point it
branches into the
• Auriculotemporal Nerve
• Lingual Nerve
• Inferior alveolar nerves.
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5. PATHWAY OF INFERIOR
ALVEOLAR NERVE
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6. It descends medial to the lateral pterygoid
muscle and lateroposterior to the lingual nerve,
to the region between the sphenomandibular
ligament and the medial surface of the
mandibular ramus, where it enters the
mandibular canal at the level of the mandibular
foramen.
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7. The nerve, artery, and vein travel anteriorly in the
mandibular canal as far forward as the mental
foramen, where the nerve divides into its
terminal branches near the apex of second
premolar into-
 the Incisive nerve
 the Mental nerve.
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8. The inferior alveolar nerve block (IANB), commonly referred to as the mandibular nerve block, is
the second most frequently used (after infiltration) and possibly the most important injection
technique in dentistry. Unfortunately, it also proves to be the most frustrating, with the highest
percentage of clinical failures even when properly administered.
INDICATIONS
 Procedures on multiple mandibular teeth in one quadrant
 Surgical procedures on mandibular teeth and supporting structures when supplemented by anesthesia of lingual
and long buccal nerve.
 When buccal soft tissue anesthesia (anterior to the mental foramen) is necessary
 When lingual soft tissue anesthesia is necessary
CONTRAINDICATIONS
 Infection or acute inflammation in the area of injection (rare)
 Patients who are more likely to bite their lip or tongue, for instance, a very young child or a physically or mentally
handicapped adult or child
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9. NERVES ANESTHETIZED
 Inferior alveolar nerve and its subdivisons
 Occasionally lingual and buccinator
nerves
AREAS ANESTHETIZED
 Mandibular teeth up to the midline
 Body of the mandible
 Inferior portion of the ramus
 Buccal mucoperiosteum
 Mucous membrane anterior to the mental
foramen (mental nerve)
 Anterior two thirds of the tongue and floor of
the oral cavity (lingual nerve)
 Lingual soft tissues and periosteum (lingual
nerve)
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10. LANDMARKS
 Muccobuccal fold
 Anterior border of ramus of mandible
 External oblique ridge
 Retromolar triangle
 Internal oblique ridge
 Pterygomandibular ligament
 Buccal sucking pad
 Pterygomandibular space
AREA OF INSERTION
Mucous membrane on the medial (lingual) side of the mandibular ramus, at the
intersection of two lines
One horizontal- representing the height of needle insertion,
Other vertical- representing the anteroposterior plane of injection
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11. TARGET AREA
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12. PROCEDURE
A long dental needle is recommended for the adult patient. A 25-gauge or a 27 gauge long needle is preferred.
a Assume the correct position.
(1)For a right IANB, a right-handed administrator should sit at the 8 o'clock position facing the patient
(2)For a left IANB, a right-handed administrator should sit at the 10 o'clock position facing in the same direction as the
patient
b Position the patient supine (recommended) or semisupine (if necessary).
The mouth should be opened wide to allow greater visibility of, and access to, the injection site.
c Locate the needle penetration (injection) site.
The posterior border of the mandibular ramus can be approximated intraorally by using the pterygomandibular raphe
as it turns superiorly toward the maxilla.
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13. NEEDLE INSERTION SITE
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14. Three parameters must be considered during administration of IANB
 The height of the injection
 The anteroposterior placement of the needle (which helps to locate a precise needle entry point)
 The depth of penetration (which determines the location of the inferior alveolar nerve)
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15. HEIGHT OF INJECTION
Place the index finger or the thumb of your left hand in the coronoid notch
(a) An imaginary line extends posteriorly from the fingertip in the coronoid notch to the deepest part of the pterygomandibular
raphe (as it turns vertically upward toward the maxilla), determining the height of injection.
(b) The finger on the coronoid notch is used to pull the tissues laterally, stretching them over the injection site,
(c) The needle insertion point lies three fourths of the anteroposterior distance from the coronoid notch back to the deepest part
of the pterygomandibular raphe .
t
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16. Site of needle insertion Verification of length of needle entry from the
anterior border of the ramus
Barrel of syringe brought to contralateral side and the needle
closeness to the bone is verified and solution deposited
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17. TECHNIQUE IN PEDIATRIC PATIENT
The mandibular foramen is situated at a level lower to
the occulusal plane of primary teeth in pediatric
patient.
Hence the injection is made slightly lower and more
posteriorly than adult patients.
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19. SIGNSAND SYMPTOMS
SUBJECTIVE SYMPTOMS
• Tingling and numbness of lower lip
• After the lingual nerve is affected numbness is felt on the tip of the tongue
OBJECTIVE SYMPTOMS
• Instrumentation necessary to demonstrate absence of pain sensation
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20. DISADVANTAGES
One injection provides a wide area
of anesthesia - useful for quadrant
dentistry.
 Wide area of anesthesia (not indicated for localized
procedures)
 Rate of inadequate anesthesia (31% to 81%)
 Intraoral landmarks not consistently reliable
 Positive aspiration (10% to 15%, highest of all intraoral
injection techniques)
 Lingual and lower lip anesthesia, discomfiting to many
patients and possibly dangerous (self-inflicted soft
tissue trauma) for certain individuals
 Partial anesthesia possible where a bifid inferior
alveolar nerve and bifid mandibular canals are present;
cross-innervation in lower anterior region
ADVANTAGES
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21. REASONS BEHIND FAILURE OF IANB
 It is commonly stated that the significantly higher failure rate
of 15-20% for mandibular anesthesia
 This is related to-
 The thickness of the cortical plate of bone in the adult
mandible.
 Difficulty with the is the absence of consistent landmarks.
Branching of the inferior alveolar nerve in edentulous
patients
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22. Variant branching
patterns of the
inferior alveolar
nerve
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23. Studies have shown the patients who are more anxious prior to the procedure; experience a
higher amount of pain.
The mandibular hard tissue and soft tissue is supplied by a plexus of nerves. This plexus,
may allow sensation even if primary inferior alveolar nerve is blocked. In 1020% of the
cases, Mylohyoid nerve provides accessory innervation to mandibular molars
TYPE OF ANESTHETIC SOLUTION USED- Cohen et al. showed that 3% mepivacaine
is as effective as 2% lidocaine with 1:100 000 epinepthrine in achieving pulpal anaesthesia
with IANB.
Pulpal inflammation and abscess is a major problem when introducing anesthesia.[11]
Studies have shown changes in the impulse generation of nerve fibres in presence of
inflammation and also suggest changes in peripheral sensory fibers in presence of
inflammation.
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24. Presence of a bifid mandibular canal
occurs at a rate of 0.35%.
This can lead to missing one of the canals
which may actually contain the nerve
leading to inadequate or no anesthesia
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25. ALTERNATIVES
 Mental nerve block, for buccal soft tissue anesthesia anterior to the first molar
 Incisive nerve block, for pulpal and buccal soft tissue anesthesia of teeth anterior to the mental foramen
(usually second premolar to central incisor)
 Supraperiosteal injection, for pulpal anesthesia of the central and lateral incisors, and sometimes the premolars
and molars (discussed fully in Chapter 20)
 Gow-Gates mandibular nerve block
 Vazirani-Akinosi mandibular nerve block
 PDL injection for pulpal anesthesia of any mandibular tooth
 IO injection for pulpal and soft tissue anesthesia of any mandibular tooth, but especially molars
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26. Failure of inferior alveolar nerve block Exploring the alternatives- GAUTAM A. MADAN, M.D.S.; SONAL G. MADAN, M.D.S.; ARJUN D. MADAN, M.D.S. 26

27. REFERENCES
 Handbook of Local Anesthesia 6th ed. Stanley F. Malamed, DDS
 Monheims – local anesthesia and pain control in dental practice- C RICHARD BENNET
 Sicher and dubrul- Oral Anatomy
 Articles-
 A basic review on the inferior alveolar nerve block techniques Hesham Khalil- Department of
Maxillofacial Surgery, College of Dentistry, King Saud University, Riyadh, Saudi Arabia
 FAILURE OF INFERIOR ALVEOLAR NERVE BLOCK (IANB) AND TECHNIQUES TO AVOID
IT. - Dr. Harsh Rajvanshi, 2Dr. Sandra Ernest, 3Dr. Hafsa Effendi, 4Dr. Sarah Afridi, 5Dr. Madhur
Chhabra, 6Dr. Navneet Kaur
 Inferior alveolar nerve block: Alternative technique- K. Thangavelu, R. Kannan, and N. Senthil Kumar
 Failure of inferior alveolar nerve block Exploring the alternatives- GAUTAM A. MADAN, M.D.S.;
SONAL G. MADAN, M.D.S.; ARJUN D. MADAN, M.D.S.
 Variant Inferior Alveolar Nerves and Implications for Local Anesthesia Kevin T. Wolf, BS,* Everett J.
Brokaw, BA,* Andrea Bell, DMD, MS,† and Anita Joy, BDS, PhD‡
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