Mandibular Injection Techniques

Mandibular Injections1) Mandible has dense cortical plate covering cancellous interior

2) Density of buccal alveolar plate precludes the use of supraperiosteals

3) Wide variation of anatomy exists with location of IAN

4) 1 in 5 patients will require reinjection when given the IANB (80%)

5) Mandibular molar anesthesia requires a successful IANB

6) Height of the mandibular foramen is unpredictable from patient to

patient

7) Mental and buccal injections anesthetize the soft tissues only

8) IANB, Gow-Gates, Vazirani-Akinosi and incisive blocks anesthetize

pulps

9) PDL, Intraosseous and Intraseptal injections are used in maxillary and

mandible

Inferior Alveolar Nerve BlockInferior Alveolar Nerve Block: (IANB)Highest percentage of clinical failures 80% succesful or

1 in 5 failuresUseful for quadrant dentistryBuccal injection only necessary if soft tissue will be

involved

Nerves Anesthetized:1) Inferior Alveolar Nerve2) Incisive Nerve3) Mental Nerve4) Lingual Nerve

Inferior Alveolar Nerve Block (IANB)

Areas Anesthetized

1) Mandibular teeth to the midline (beware of cross over fibers teeth #24, 25)2) Body of the mandible3) Inferior portion of the ramus4) Buccal mucoperiosteum, mucous membrane anterior to the mandibular 1st molar5) Anterior 2/3rds of the tongue and floor of the mouth (lingual nerve)6) Lingual soft tissues and periosteum (lingual nerve)

IANB Anesthetized Areas

notanesthetized

Alternatives To IANB1) Mental Nerve Block; buccal soft tissue anterior to the 1st molar2) Incisive Nerve Block; pulpal and soft tissue anesthesia to teeth anterior to the mental foramen3) Supraperiosteal (although rather unsuccessful)4) Gow-Gates5) Vazirani-Akinosi6) PDL injection for pulpal anesthesia of any mandibular tooth7) Intraosseous: osseous and soft tissue anesthesia8) Intraseptal: osseous and soft tissue anesthesia

IANB TECHNIQUE

3 IMPORTANT PARAMETERS TO CONSIDER:

1) Height of the injection

2) Anteroposterior placement of the needle tip

3) Depth of needle penetration

Technique of IANB

1) 25 gauge long needle

2) Insert needle into mucous membrane on the medial

side of the mandibular ramus

3) Target is the inferior alveolar nerve before it enters

the mandibular foramen

4) Use coronoid notch, pterygomandibular raphe and

occlusal plane of the mandibular teeth as

landmarks for proper injection

5) Ask the patient to open widely

Height of IANB Injection Place the index finger in the coronoid notch Imaginary line should be parallel with the occlusal plane 6-10 mm above the occlusal plane Finger on the coronoid notch pulls the tissues taut Needle insertion is 3/4th the distance from the coronoid

notch back to the deepest part of the pterygomandibular raphe

Needle tip gently touches the most distal aspect of the pterygomandibular raphe

Anteroposterior Site of Injection

Needle penetration occurs at intersection of 2 points:

Point 1: a horizontal line from the coronoid notch to the deepest part of the pterygomandibular raphe as it ascends

vertically toward the palate

Point 2: a vertical line through Point 1 about 3/4ths of the distance from the anterior border of the ramus

determines the AP site of the injection

IANB (Inferior Alveolar Nerve Block)

Penetration DepthBone must be contacted at this point of the injectionSlowly advance the needle until you meet boney resistanceAverage depth until boney contact is 20-25 mm; or 2/3rds to

3/4ths the length of the long dental needle (32 mm)Needle tip will be located slightly superior to the

mandibular foramen where the IAN enters the mandibular foramen which can not be palpated clinically; with bifid alveolar nerves, a 2nd injection will be necessary more inferiorly to block the 2nd portion of the nerve

The needle is inserted approximately 23 mm; rarely do you need to insert the needle to its hub

Common ProblemsIf Bone Contacted Too Soon

1) less than half of the dental needle penetrated until bone contact means the needle tip is located too far anteriorly on the ramus

SOLUTION-withdraw needle slightly; do not remove completely-bring the syringe barrel around to the front of the mouth over the canine or lateral incisor on the contralateral side

-needle tip is now located more posteriorly

2) If Bone is not contacted

1) needle tip is located too far posterior (medial)

SOLUTION

-withdraw the needle tip slightly so that 1/4th of the needle

tip still lies in tissue

-bring the syringe barrel more posterior over the mandibular

molars

-after bone contact, withdraw syringe 1 mm to avoid

subperiosteal injection; results in ballooning of tissue

After bone is contacted (IANB)

6) Withdraw syringe 1 mm to avoid subperiosteal injection7) Aspirate; slowly inject solution ~ 1.5 – 1.8 ml (1 cartridge)8) Wait 20 seconds and return the patient to the upright position to allow gravity to move the solution inferiorly; begin treatment in 3-5 minutes9) Lingual Nerve will be anesthetized with this injection on the ipsalateral side; patients will say that half of their tongue is numb; Lingual Nerve is in the posterior division of V3 and can be numb without having any other structures numb

So, having a numb tongue does not necessarily mean the patient will have numb teeth!

Bell’s Palsy

Do not inject solution if bone is not contacted; more than likely the needle tip will be

within the parotid gland;

Injection will cause a transient Bell’s Palsy which is anesthesia of CN VII

Accessory Innervation

Failure of the IANB is related to accessory innervation of mandibular molar teeth by branches of the

Mylohyoid Nerve

Gow-Gates injection will block the Mylohyoid Nerve but the IANB will not provide anesthesia of these

accessory nerves

Solutions To Inadequate Anesthesia After IANB

1) Provide anesthesia on the lingual surface

of the tooth posterior to the tooth in question

(apex of 2nd molar if problem tooth is 1st

molar) penetrate soft tissue until bone is

contacted; aspirate and deposit 1/3rd cartridge

to gain anesthesia of the mylohyoid accessory

nerves

Solutions To Inadequate Anesthesia After IANB

2) PDL or Intraosseous injection can be

administered to anesthetize the

individual tooth in question

Reason For Inadequate Anesthesia After IANB

1) Mylohyoid Innervation

2) Overlapping fibers of the contralateral IAN may be

innervating the central/lateral incisors which would

require supraperiosteal injection in this area

3) Bifid inferior alveolar nerve which would require IANB more

inferior to the normal location

4) Poor injection technique

Complications of IANB

1) Hematoma (rare)

2) Trismus (common)

3) Transient Facial Paralysis (Bell’s Palsy)

Trismus occurs because the needle

pierces the buccinator muscle when giving the IANB

Long Buccal Nerve

Buccal Nerve Anesthesia Buccal nerve is a branch of the anterior division of V3 and

consequently is not anesthetized via the IANB

Anesthesia of this nerve is not necessary for most dental procedures

Provides sensory information to the buccal soft tissues adjacent to the mandibular molars only; also called the Long Buccal Nerve Block

The sole indication is when manipulation of these tissues is considered

Buccal Nerve Anesthesia

USES: 1) Scaling and root planing

2) Deep seated rubber dam clamp

3) Removal of subgingival caries

4) Placement of gingival retraction cord

Buccal Nerve Block Technique

1) Insert needle into the mucous membrane distal and buccal to the most distal molar tooth in the arch

2) Target is the buccal nerve as it passes over the anterior border of the ramus

3) Using a Minnesota Retractor or Mouth Mirror, retract the buccal mucosa to obtain good visualization and pull the tissues taut

4) Penetrate the mucosa distal and buccal to the last molar

5) Advance the needle slowly until bone is contacted gently

6) Depth of penetration is approximately 2-4 mm (1-2 mm)

7) Aspirate; inject slowly

8) Like the PSA, patients rarely feel anesthetized

Gow-Gates Injection

Gow-Gates Block

• Discovered by George Gow-Gates in 1973

• Gow-Gates Block is a true complete mandibular block

• Australian general dentistry practitioner

• Onset is longer than IANB; 5 minutes with GG; 2-5 minutes with IANB

Nerves Blocked (Gow-Gates):

1) Inferior Alveolar Nerve 5) Incisive Nerve

2) Mylohyoid Nerve 6) Auriculotemporal

3) Lingual Nerve 7) Buccal Nerve

4) Mental Nerve

Gow-Gates advantages over IANB

Higher success rate due to less soft tissue penetration

Lower incidence of positive aspiration 2% as opposed to 15% with IANB

Absence of accessory nerve innervation because

GG is true mandibular block

Gow-Gates Areas Anesthetized 1) Mandibular teeth to the midline2) Buccal mucoperiosteum on the side of injection3) Anterior 2/3rds of the tongue and floor of the mouth4) Lingual soft tissues and periosteum5) Body of the mandible; inferior portion of the ramus6) Skin over the zygoma, posterior portion of the cheek and

temporal region

*Remember, when doing extractions, the buccal nerve block is needed in addition to the IANB, however, with GG, only one injection is required

Gow-Gates Technique

1) 25 gauge long needle2) Insertion point: mucous membrane of the mesial of the mandibular ramus, on a line from the intertragic notch to the corner of the mouth, just distal to the maxillary 2nd molar3) Target area: lateral side of the condylar neck, just below the insertion of the lateral pterygoid muscle4) Landmarks: corner of the mouth and lower border of the tragus5) Height of injection: place needle tip just below the mesiolingual cusp of the maxillary 2nd molar

6) Ask patient to open wide to allow the condyle to

assume a frontal position

7) Direct syringe from the corner of the mouth from the opposite side of mouth

8) Height of insertion is considerably greater than the

IANB by 10-25 mm

9) Average depth of penetration is 25 mm

(same as IANB)

10) Bone contacted is the head of the condyle

11) Medial deflection is the most common cause of

the needle missing the head of the condyle;

redirect the barrel of the syringe more distally

which will move the needle tip more anteriorly

12) Partial closure of the patient’s mouth will move

the condyle in a distal direction making boney

contact more difficult

13) Do not deposit solution unless bone is contacted

14) Withdraw the needle 1 mm, aspirate, deposit 1.8 ml of solution

15) Request that the patient keep their mouth open for 1-2 minutes to allow diffusion of the anesthetic solution

16) Return the patient to the upright position; wait 3-5 minutes to start

Why wait longer to begin?1) Thicker nerve trunk requires longer time for anesthetic

penetration

2) There is 5-10 mm between the solution deposition site and

the nerve trunk

Gow-Gates is given much higher toward the condyle; the IANB is given much lower toward the medial surface of the

ramus toward the lingula

Vazirani-Akinosi

Vazirani-Akinosi Closed Mouth Mandibular Block

Injection for a patient with considerable trismus Third division block (V3) will relieve trismus/muscle spasm The mandibular division of the trigeminal nerve provides

motor innervation to the muscles of mastication VA Block is an intraoral approach to providing anesthesia

in patients with severe trismus (inability to open the mouth) VA Block can be performed extraorally through the sigmoid

notch

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VA Block

Nerves Anesthetized

1) Inferior Alveolar Nerve

2) Incisive Nerve

3) Mental Nerve

4) Lingual Nerve

5) Mylohyoid Nerve

VA Block Areas Anesthetized

1) Mandibular teeth to the midline

2) Body of the mandible and inferior portion of the ramus

3) Buccal mucoperiosteum and mucous membrane in front of the mental foramen

4) Anterior 2/3rds of the tongue and floor of the mouth

5) Lingual soft tissues and periosteum

Disadvantages of VA Block

1) Difficult to visualize the path of the needle and depth of insertion

2) No boney contact (similar to PSA); depth of penetration is arbitrary

3) Traumatic other technique other than extraorally is available if needle scrapes across periosteum

4) No if this block can not be done due to a patient’s inability to open their mouth

VA Block Technique1) 25 gauge long needle

2) Area of insertion: soft tissue overlying the medial (lingual) border of the mandibular ramus directly adjacent to the maxillary tuberosity at the height of the mucogingival junction adjacent to the maxillary 3rd molar

3) Target area: soft tissue on the medial (lingual) border of the ramus as the inferior alveolar, lingual and mylohyoid nerves run inferiorly from the foramen ovale toward the mandibular foramen

*Height of injection of the VA is below that of the GG but above that of the IANB

Height of Injections

Gow-Gates Highest

Vazirani-Akinosi Middle

Inferior Alevolar Lowest

4) Landmarks are the mucogingival junction of the maxillary 3rd molar, maxillary tuberosity and the coronoid notch of the ramus

5) Bevel is directed away from the bone of the ramus (toward midline)

6) Reflect the tissue on the medial aspect of the ramus laterally with the Minnesota Retractor or mouth mirror

7) Ask the patient to occlude gently, if they are not already occluded, this will relax the cheek and muscles of mastication

8) Barrel of the syringe is held parallel to the maxillary occlusal plane with the needle at the level of the mucogingival junction of the maxillary 3rd molar

9) Direct the needle posterior and slightly laterally

10) Advance the needle 25 mm into tissue (same as GG and IANB) distance is measured from the maxillary tuberosity

11) Tip of the needle will lie in the midportion of the pterygomandibular space where the branches of V3 are located

12) Aspirate and deposit 1.8 ml of solution

13) Return patient to the upright position which speeds anesthesia

14) If motor nerve anesthesia is present but not sensory, the patient should be able to open therefore allowing the IANB or GG injection

If the there is tingling or numbness in the tongue, which is a branch of the posterior division of the mandibular

nerve then you can feel confident that your injection has reached its target

Reasons For Failure of VA Block

1) Most common is failure to appreciate the flaring nature of

the ramus; direct the needle tip parallel with the lateral flare of

the ramus; if the needle is directed medially it rests

medial to the sphenomandibular ligament in the

pterygomandibular space resulting in failure

2) Injection point too low; make sure the needle is inserted at

or slightly above the mucogingival junction of the last

maxillary molar and parallel the occlusal plane as it advances

through the soft tissue

3) No bone is contacted so under/overinsertion possible (25mm)

Mental Nerve Block

Mental Nerve BlockMental nerve is the terminal branch of the IA nerve

Provides sensory innervation to the buccal soft tissues lying anterior to the foramen and the soft tissues of the lower lip and chin

Mental nerve block is the least used of the mandibular blocks

Anesthetizes buccal mucous membranes anterior to the mental foramen and skin of the lower lip and chin

Used for suturing tissues, biopsies in this area

Mental Nerve Block Technique

1) 25 gauge short needle

2) Insertion: mucobuccal fold at or anterior to the mental foramen

3) Target area: mental nerve as it exits the mental foramen (usually located between the apices of the 1st and 2nd premolars)

4) Pull the tissue taut

5) With gentle finger pressure it is possible to

feel the mental nerve as it exits the foramen

(patient will complain of discomfort)

6) Penetrate needle 5-6 mm and inject 1/3rd

cartridge of anesthetic

7) No need to enter the foramen with the needle tip to gain anesthesia

Incisive nerve is the terminal branch of the inferior alveolar nerve

Incisive nerve is a direct continuation of the inferior alveolar nerve continuing anteriorly in the incisive canal, providing sensory innervation to those teeth located anterior to the mental foramen

No need to enter the mental foramen for this injection to be successful

No lingual anesthesia is noted with this injection; supraperiosteal is necessary through the papilla which is atraumatic to the patient

The incisive nerve is always blocked when an inferior alveolar nerve block is successful, therefore, you do not have to anesthetize this nerve in addition to the IANB

Incisive Nerve BlockAreas Anesthetized 1) Premolars2) Canine3) Lateral Incisor4) Central Incisor5) Buccal soft tissue and bone

The incisive nerve block is indicated when bilateral anterior teeth or premolars require restoration; try to avoid bilateral IANBs because it makes the entire tongue/lower lip numb

Incisive Nerve Block Technique:

Same technique used for mental nerve block except:

1) Apply pressure to area after injection either intra or

extraorally to facilitate movement of anesthetic

solution into the foramen

2) Apply pressure for at least 2 minutes

Reference

Malamed, Stanley: Handbook of Local Anesthesia. Mosby. 5th Edition. 2004