Dr Arif Khan Dawar

Inferior Alveolar Nerve Block (IANB)

Definition

The Inferior Alveolar Nerve Block is a mandibular nerve block in which local anesthetic is deposited near the inferior alveolar nerve before it enters the mandibular foramen, producing pulpal anesthesia of all mandibular teeth on that side.

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Anatomy

Target Area

The anesthetic is deposited in the pterygomandibular space near the mandibular foramen on the medial surface of the ramus.

Boundaries of Pterygomandibular Space

* Lateral: Ramus of mandible
* Medial: Medial pterygoid muscle
* Superior: Lateral pterygoid muscle
* Posterior: Parotid gland

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Landmarks

Intraoral

1. Coronoid notch (most important landmark)
2. Pterygomandibular raphe
3. Occlusal plane of mandibular teeth

Needle Insertion Point

* Lateral to the pterygomandibular raphe
* Approximately 6–10 mm above the mandibular occlusal plane
* Three-quarters of the distance from the coronoid notch to the deepest part of the raphe

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Technique

Right IANB

1. Operator stands at 8 o’clock position.
2. Retract cheek and identify landmarks.
3. Syringe barrel is positioned over the contralateral premolars.
4. Insert needle until bone is contacted at 20–25 mm.
5. Withdraw 1 mm.
6. Aspirate in two planes.
7. Deposit 1.5–1.8 mL anesthetic slowly.
8. Withdraw halfway and deposit 0.2–0.3 mL for lingual nerve anesthesia.

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Nerves Anesthetized

Inferior Alveolar Nerve

* All mandibular teeth on injected side

Mental Nerve

* Lower lip
* Chin

Incisive Nerve

* Anterior mandibular teeth

Lingual Nerve

* Lingual gingiva
* Floor of mouth
* Anterior two-thirds of tongue

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Areas Not Anesthetized

The buccal gingiva of mandibular molars is supplied by the Long Buccal Nerve, which requires a separate buccal nerve block.

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Signs of Successful Anesthesia

Subjective

* Tingling of tongue
* Numbness of lower lip

Objective

* No response to pulp testing
* Pain-free dental procedure

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Causes of Failure

Most Common Cause

Needle placed too low or too anterior to the mandibular foramen.

Other causes:

* Anatomical variation of mandibular foramen
* Cross innervation
* Accessory innervation via mylohyoid nerve
* Inadequate volume of anesthetic
* Acute infection

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Complications

Positive Aspiration

* Most common complication
* Incidence: 10–15%

Hematoma

* Injury to blood vessels

Trismus

* Trauma to medial pterygoid muscle

Facial Nerve Paralysis

* Occurs when anesthetic is deposited into the parotid gland
* Results in temporary inability to close eyelid

Needle Breakage

* Rare
* Avoid bending the needle

Paresthesia

* Persistent altered sensation after injection

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High-Yield FCPS Exam Points

🔹 Target: Inferior alveolar nerve before entry into mandibular foramen

🔹 Needle pe*******on depth: 20–25 mm

🔹 Most reliable sign of success: Lower lip numbness

🔹 Most common complication: Positive aspiration

🔹 Lingual nerve is anesthetized during withdrawal of the needle

🔹 Long buccal nerve block is needed for buccal soft tissue anesthesia of mandibular molars

🔹 Failure is most commonly due to incorrect needle position relative to the mandibular foramen

Superior Alveolar Nerve Blocks (Maxillary Nerve Blocks)

The three Superior Alveolar Nerve Blocks are used to anesthetize different regions of the maxillary (upper) teeth and their supporting tissues.

1. Posterior Superior Alveolar (PSA) Nerve Block

Target Nerve: Posterior Superior Alveolar Nerve

Anatomical Landmark: Mucobuccal fold above the maxillary second molar.

Needle Direction: Insert into the mucobuccal fold and advance approximately 16–20 mm upward, inward, and backward toward the maxillary tuberosity.

Area Anesthetized:

* Maxillary second molar
* Maxillary third molar
* Distobuccal and palatal roots of the first molar
* Buccal alveolar bone and soft tissues

Clinical Use: Ideal for procedures involving the upper molars. The mesiobuccal root of the first molar may not be anesthetized because it is often supplied by the MSA nerve.

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2. Middle Superior Alveolar (MSA) Nerve Block

Target Nerve: Middle Superior Alveolar Nerve

Anatomical Landmark: Mucobuccal fold above the maxillary second premolar.

Needle Direction: Insert at the height of the mucobuccal fold over the second premolar.

Area Anesthetized:

* Maxillary first and second premolars
* Mesiobuccal root of the maxillary first molar
* Buccal periodontal tissues and alveolar bone

Clinical Use: Used for restorative and surgical procedures involving the premolars and the mesiobuccal root of the first molar.

Note: The MSA nerve is absent in many individuals; in such cases, innervation is supplied by the ASA and PSA nerves.

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3. Anterior Superior Alveolar (ASA) Nerve Block

Target Nerve: Anterior Superior Alveolar Nerve

Anatomical Landmark: Mucobuccal fold above the canine fossa, just anterior to the canine tooth.

Needle Direction: Insert into the mucobuccal fold and advance toward the apex of the canine.

Area Anesthetized:

* Maxillary central incisors
* Lateral incisors
* Canines
* Labial alveolar bone and soft tissues

Clinical Use: Used for procedures involving the upper anterior teeth and surrounding labial tissues.

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Quick Summary

Nerve Block Teeth Anesthetized
PSA Maxillary molars
MSA Premolars + MB root of 1st molar
ASA Incisors and canines

Mnemonic:
P → Posterior → Molars
M → Middle → Premolars
A → Anterior → Anterior teeth (Incisors & Canines)

Root Canal Treatment of Lower 1st Molar #36

• Canals: MB, ML (mesial root) + 1 distal canal
• LA + rubber dam
• Access cavity → triangular
• Working length (apex locator + X-ray)
• Cleaning & shaping + irrigation (NaOCl, EDTA)
• Obturation (gutta-percha + sealer)

Surgical Extraction of Mandibular 3rd Molar with Curved Root 🦷

Primary (Baby) Teeth Eruption Timeline

Baby teeth, also called primary teeth, usually start appearing when a child is about 6 months old. By the age of 2½–3 years, most children have a full set of 20 primary teeth (10 in the upper jaw and 10 in the lower jaw).

These teeth erupt in a predictable order, although the exact timing can vary from child to child.

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1. Incisors (Front Teeth)

These are usually the first teeth to appear and help babies bite soft foods.
• Lower central incisors: erupt around 6–10 months (usually the first teeth).
• Upper central incisors: erupt around 8–12 months.
• Upper lateral incisors: erupt around 9–13 months.
• Lower lateral incisors: erupt around 10–16 months.

By about 1 year of age, most babies have several front teeth visible.

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2. First Molars

Molars are larger teeth used for grinding food.
• Upper first molars: erupt around 13–19 months.
• Lower first molars: erupt around 14–18 months.

These teeth help children start chewing more solid foods.

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3. Canines (Cuspids)

Canines are pointed teeth located between incisors and molars. They help in tearing food.
• Upper canines: erupt around 16–22 months.
• Lower canines: erupt around 17–23 months.

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4. Second Molars

These are the last primary teeth to appear.
• Lower second molars: erupt around 23–31 months.
• Upper second molars: erupt around 25–33 months.

By this stage, the child usually has all 20 primary teeth.

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Importance of Baby Teeth

Primary teeth are very important because they:
• Help chewing and proper nutrition
• Assist in speech development
• Maintain space for permanent teeth
• Guide the correct eruption of adult teeth

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Important Note

Every child develops differently. A delay or early eruption of a few months is usually normal and not a cause for concern.

🦷

𝗥𝗲𝗮𝗱𝗶𝗻𝗴 𝗢𝗰𝗰𝗹𝘂𝘀𝗶𝗼𝗻 𝘁𝗵𝗲 𝗥𝗶𝗴𝗵𝘁 𝗪𝗮𝘆: 𝗣𝗿𝗲𝘀𝘀𝘂𝗿𝗲 𝗢𝘃𝗲𝗿 𝗣𝗮𝗶𝗻𝘁

𝗕𝗹𝘂𝗲 𝗠𝗮𝗿𝗸𝘀 𝗟𝗶𝗲. 𝗣𝗿𝗲𝘀𝘀𝘂𝗿𝗲 𝗗𝗼𝗲𝘀𝗻’𝘁.
𝗛𝗲𝗿𝗲’𝘀 𝗛𝗼𝘄 𝗜 𝗥𝗲𝗮𝗱 𝗢𝗰𝗰𝗹𝘂𝘀𝗶𝗼𝗻 𝗪𝗶𝘁𝗵𝗼𝘂𝘁 𝗚𝘂𝗲𝘀𝘀𝘄𝗼𝗿𝗸.

Every dentist has seen this.

An articulating paper full of blue marks.
Patient still feels “high”.
Restoration looks perfect on the cast.
Occlusion says otherwise.

Here’s the thing most of us were never explicitly taught:
Size of the mark means very little. Pressure means everything.

That’s exactly what the image above shows.

🔵 Heavy pressure = premature contact
🔵 Light pressure = normal contact

Not all blue marks are equal.

𝗪𝗵𝘆 𝗮𝗿𝘁𝗶𝗰𝘂𝗹𝗮𝘁𝗶𝗻𝗴 𝗽𝗮𝗽𝗲𝗿 𝗮𝗹𝗼𝗻𝗲 𝗰𝗮𝗻 𝗺𝗶𝘀𝗹𝗲𝗮𝗱 𝘆𝗼𝘂

Thick articulating papers (40–100 microns) are great for:
• Locating contacts
• Initial equilibration
• Full-arch assessment

But they exaggerate contact size. A broad, dark mark often looks alarming, yet it may not be the first tooth hitting.

What we really need to know is:
Which contact hits first and how hard.

𝗧𝗵𝗲 𝘀𝗺𝗮𝗿𝘁𝗲𝗿 𝘄𝗮𝘆: 𝗹𝗮𝘆𝗲𝗿 𝘆𝗼𝘂𝗿 𝗼𝗰𝗰𝗹𝘂𝘀𝗮𝗹 𝗮𝘀𝘀𝗲𝘀𝘀𝗺𝗲𝗻𝘁

Start thick. Finish thin.
Use thicker paper to map contacts.
Then switch to thin articulating paper (20–25 microns) to identify early hits.

Early contact shows up as:
• Darker
• Sharper
• More defined

That’s your premature contact.

𝗪𝗵𝗲𝗿𝗲 𝗠𝘆𝗹𝗮𝗿 𝘀𝘁𝗿𝗶𝗽𝘀 𝗾𝘂𝗶𝗲𝘁𝗹𝘆 𝗼𝘂𝘁𝗽𝗲𝗿𝗳𝗼𝗿𝗺 𝗽𝗮𝗽𝗲𝗿

This is where experience kicks in.

Mylar strips (8–12 microns) don’t mark. They test.

If the strip:
• Holds firm → heavy contact
• Pulls through smoothly → light or no contact

This is invaluable for:
• Implant prosthetics
• Single crown occlusion
• Post-endodontic restorations
• Patients with TMD symptoms

Especially on implants, where periodontal proprioception is absent, relying only on ink is risky.

𝗣𝗿𝗲𝘀𝘀𝘂𝗿𝗲 𝗮𝘄𝗮𝗿𝗲 𝗼𝗰𝗰𝗹𝘂𝘀𝗶𝗼𝗻 𝗶𝘀 𝗻𝗼𝘁 𝗼𝗽𝘁𝗶𝗼𝗻𝗮𝗹 𝗮𝗻𝘆𝗺𝗼𝗿𝗲

Digital workflows. Guided surgery. CAD-CAM crowns.

All of that still fails if occlusion is wrong.

What this really means is:
Occlusion is a tactile diagnosis, not a visual one.

Ink shows where.
Mylar tells you how much.
Your fingers confirm when.

𝗔 𝘀𝗶𝗺𝗽𝗹𝗲 𝗰𝗹𝗶𝗻𝗶𝗰𝗮𝗹 𝗿𝘂𝗹𝗲 𝗜 𝗳𝗼𝗹𝗹𝗼𝘄

• Ink to see
• Mylar to decide
• Adjust conservatively
• Recheck in centric and excursions

Occlusion doesn’t need more gadgets.
It needs better judgment.

And that starts by respecting pressure, not just color.