Mandibular Injections

What is the rationale behind slow deposition of LA drug?

increased comfort, higher safety (lower hydrostatic pressure), and more successful

Can we do supra-periosteal infiltrations in the mandible, similar to how we did them in the maxilla?

YES - but usually ONLY for the incisors (canines often require mandibular blocks)

How do you do a mandibular infiltration?

-Topical

-Retract, short needle is fine

-Deposit solution deep to apices of the teeth you want to numb

-Avoid scraping the periosteum with the needle

Can you do lingual infiltrations in the mandible?

YES - necessary to infiltrate the tissue OR block lingual nerve if the lingual soft tissue needs to be numbed (small and large areas)

Why would you opt to do a lingual nerve block rather than lingual infiltration?

The lingual nerve block requires LESS tongue management and are more comfortable to the pt

What are interpapillary injections?

Penetrate from the facial which should already be anesthetized, advance the needle through papilla, deposit for 5 seconds max

What will the modified halsted IA and lingual nerve blocks anesthetize?

-All teeth in a lower quadrent

-All periodontium

-Buccal mucosa from the premolars to the midline

-Floor of mouth

-1/2 tongue on the side of the ipsilateral quadrent

The _______ and _______ nerve blocks cam be accomplished with the same needle penetration (simultaneously).

IA ; lingual

what are the intraoral landmarks for the IA nerve block?

-pterygomandibular raphe

-coronoid notch

-occlusal plane of mandibular molars

-internal oblique ridge

The pterygomandibular raphe is the ______ extent of the IA block landmarks!!!!

MEDIAL (meaning, you do NOT want to penetrate medial to the raphe)

What muscle is medial to the raphe? Lateral?

-medial: superior constrictor

-lateral: buccinator

How do we find the height of injection for an IA nerve block?

Find the coronoid notch concavity (deepest point) + 2-3mm ABOVE the concavity !!!

The insertion point for an IA nerve block is typically _______ mm above the mandibular molar occlusal plane.

6-10 mm

How far to you insert the needle for an IA nerve block?

Advance needle 20-25 mm until bone is contacted near the mandibular foramen, where the IA nerve enters the mandible, withdraw 1mm, aspirate, and deposit!!

During an IA nerve block, we must stay ________ to the internal oblique ridge to help avoid premature bony resistance/

MEDIAL

(so medial to the internal oblique ridge, but lateral to the raphe)

T or F? The only difference in anesthetizing the IA nerve/Lingual nerve is a matter of depth

TRUE - same pathway

The angle from which you inject for an IA nerve block will vary between patients depending on ...?

the flair of the mandibular ramus!!

Compared to the IA nerve block, the LINGUAL nerve only requires a needle insertion depth of ________ mm.

5-8mm

(deposit 1/4-1/3 cart)

If you do not meet resistance during the IA nerve block, should you still deposit?

NO - do not deposit, redirect until you do meet resistance

What nerve transits the paratid gland, and is also in a location that might be anesthetized unintentionally?

FACIAL - paralysis may result from a penetration that was too deep

What should you do during an IA block injection if you do not meet resistance and are too deep?

-Withdraw needle half way

-Increase angulation (redirect)

-Repenetrate until you meet resistance

What should you do during an IA block injection if you meet resistance too EARLY before proper depth?

-Withdraw needle half way

-Decrease angulation (redirect)

-Repenetrate in a new pathway (barrel over the contralateral side premolars)

-If resistance is too quick, withdraw completely and re-assess anatomy

T or F? For an IA/Lingual nerve block, you must meet resistance at the right depth, or you will NOT be successful

TRUE

What is the appropriate depth of the needle for an IA/Lingual nerve block?

-20 to 25mm, long needle

-About 2/3 or 3/4 of the needle penetrated

-About 6-11mm of shank exposed

How do you do the long buccal injection?

-Aim needle between internal and external oblique ridge

-Nerve is just under the mucosa (shallow injection)

-Use 1/8 to 1/4 of the carpule

T or F? You CAN have a mental block without an incisive block. You CANNOT have an incisive block without a mental block.

TRUE!!!!! usually you want both anyways

What will a mental/incisive block anesthetize?

-Teeth: premolars to midline!

-Periodontium + Soft tissue: premolars to midline

T or F? When giving injections, you want to enter the foramen.

FALSE - you want to get close but NOT enter. risk of nerve damage

How do we give the mental/incisive nerve block

-Confirm foramen first, then place topical (near premolars)

-Deposit 1/2 cart (0.9ml) above the foramen

-Use pressure anesthesia to help diffuse solution into foramen

Why are mental/incisive nerve blocks difficult to achieve at times?

Solution will probably not penetrate the cortical plate in this area, so it must enter the foramen

When a patient presents to you stating something like "They've never been able to numb my lower jaw.", what question is very helpful for you to know?

Have you even been able to get numb on your UPPER jaw?

What is the success rate for an IA injection VS a Gow-Gates injection?

-IA: 85%

-GG: 97%

Which nerves are anesthetized via a Gow-Gates block?

-AKA the V3 block because you get them all....

-IA, lingual, buccal, auriculotemporal, mylohyoid, accessories...

What is an alternative to the IA, lingual, and buccal blocks?

Gow-Gates

Why is the Gow-Gates block potentially safer than an IA block?

-Less vascularity in this area

-Greater duration of anesthesia

-Less positive aspirations

-Usually more comfortable to the pt (fewer encounters with structures)

What challenge inspired Gow-Gates to develop his technique?

The failure rate of the Halsted IA block!!! Also he demonstrated that 6-10mm above the mand occlusal plane is TOO LOW

What are the landmarks for the following nerve blocks: Halsted, Modified Halsted, Gow-Gates?

-Halsted: bisect fingernail at the greatest coronoid notch concavity

-M. Halsted: top of the fingernail at greatest concavity

-GG: ML cusp of maxillary 2nd molar

What is the difference between the IA and Gow-Gates block in terms of angulation of the needle?

-There is an UPWARD angulation with GG that is enhanced with pts open widely

-The needle is angled HIGHER to reach neck of the condyle (V3)

-IA is parallel to mand occlusal plane

Why do we target the neck of the condyle in a Gow-Gates nerve block?

Because it is always above the mandibular foramen, which is where we want to diffuse our solution!!!

Why do we want our patients to open WIDE when giving Gow-Gates nerve blocks?

-This is the most anterior position of the condyle, so allows needle to reach neck of the condyle

-NO deposition unless you have contact with condyle!!

-The penetration site is not high enough but when theres a steep angulation (wide open) it allows us to go higher by angling upward

Where is the ACTUAL deposition site for the Gow-Gates block?

The neck of the condyle, inferior to the insertion of the lateral pterygoid muscle (penetrate lateral to ML cusp of 2nd max molar)

What is the suggested barrel location when giving the Gow-Gates block?

-Opposite side canine works about 60-70% of the time

-If NO contact with this angulation, move barrel slowly to mesial of 1st molar

In the IA technique, redirection occurs after moving 1-2 teeth in the _________ direction.

forward/anterior

In the GG block, because the target is much smaller, redirection requires moving 2-3 teeth ________ OR _________.

forwards or backwards

What do you need to do immediately after giving the Gow-Gates block?

-Upright the pt quickly!!

-Place bite block between the teeth so pt does not close

-Leave bite block in for no longer than 20 seconds

-ALLOWS FOR APPROPRIATE DIFFUSION PATH

How can we still administer a V3 block with the patient CLOSED?

Vazirani-Akinosi technique

How can we get the correct direction/pathway for the Vazirani-Akinosi technique?

Since deflection occurs AWAY from the bevel, orienting the bevel medially to face the tongue will deflect the needle laterally towards the ramus/mandibular foramen

What is the height of injection/depth for the Vazirani-Akinosi technique?

-Height: mucogingival junction of max molars

-Depth: no more than 25mm from MB aspect of max 2nd molar

T or F? Even if the Vazirani-Akinosi technique is NOT successful, it will usually be enough to where you can use a different technique afterwards.

TRUE

What are the guidelines for bending the needle?

-Bends should not enter tissue

-Bends should NOT be at the hub

-Bends should be avoided if possible

Can some nerve blocks be performed extraorally?

YES - V3, infraorbital/ASA

What are the reasons for avoiding short needles in traditional IA blocks?

-Hubbing the needle increases needle fx occurance

-Needle fx can result in neural/vascular injury

-Higher odds of litigation for this reason...

What gauge needles are most frequently involved in needle fractures?

30 Ga needles :( are inappropriate for any technique with significant penetration depths

The _____ and _____ nerves are BOTH anesthetized using 1 penetration, after reaching a single deposition site.

IA ; lingual

T or F? Traditional IA blocks rely on depositing NEAR or ABOVE the foramen, after making contact with the medial ramus.

TRUE - no contact/resistance when doing short needle injection

According to a study done using 25mm short needles on cadavers, what did researchers find regarding the distance from the penetration site to the IA nerve?

distance from penetration site to IA nerve was within limits of the short needle!!

depth was half the width of the ramus at its narrowest aspect

What is the difference in success rates when you deposit DEEP vs SHALLOW to the foramen in IA injections?

-DEEP to foramen: 50% success

-SHALLOW to foramen: 80% success

IF bony resistance occurs with the short needle technique, decrease the penetration depth to _____mm.

15mm (rarely is it less than 15mm)

(avg depth is like 16mm using 25mm needle)

Ideally for an IA injection, you want to be above the mandibular occlusal plane by _________mm.

15mm!!!

Due to the HIGHER and more MEDIAL penetration site for the modified IA injection, we add 2-3mm to the avg depth, which is ...?

16mm + 2-3mm = 18-19mm depth

Why not use a long needle for injection techniques?

A long needle (ex: 31mm) can penetrate too far posteriorly and the likelihood of going to deep or deviating is greater