Anatomy of Local Anesthesia

Compare local infiltration with nerve block local anesthesia.
Local infiltration is only on terminal nerve endings and is used for soft tissue only; gingival surgery.

Nerve block anesthetize close to a nerve trunk

Compare the effectiveness of maxillary anesthesia with the effectiveness of mandibular anesthesia.
maxillary anesthesia is more effective because its the bone is thinner in the anterior portion and there is less anatomical variances in it.

How effective is local infiltration in the maxillary?
More effective then mandible

PSA block; Area anesthetized?
Pulpal anesthesia in the maxillary 1st, 2nd, and 3rd molars

Tissue Anesthetized:
Maxillary molars (exception of mesiobuccal root of the first molar in some cases):

Pulps & periodontal ligaments
Overlying buccal gingivae
Overlying alveolar bone

Maxillary sinus, posterior portion.

GP block may also be necessary.

PSA block; Target area and injection site?
Posterior superior alveolar (PSA) nerve as it exists the maxilla

Site of Injection:
In the height of the mucobuccal fold on a 45ยบ angle
at the apex of the 2nd maxillary molar
distal to the zygomatic process of the maxilla

PSA block; Symptoms and possible complications?
Symptoms of anesthesia: none
Complications: hematoma
Vascular penetration: the pterygoid plexus of veins and/or maxillary a.
Harmless anesthesia of branches of the mandibular nerve

PSA block; How do you avoid complications?
Aspirate

MSA block; Area anesthetized?
Indicated for:
Dental procedures on the maxillary premolars and mesiobuccal root of the maxillary 1st molar.
GP block may also be necessary.

MSA block; Target area and injection site?
Target area:
MSA nerve at the apex of the maxillary 2nd premolar

The injection site for the MSA block is the tissue at the height of the mucobuccal fold at the apex of the maxillary second premolar.

MSA block; Symptoms and possible complications?
Symptoms:
Harmless tingling or numbness of the upper lip

ASA block; Area anesthetized?
Tissue anesthetized
Pulp and periodontal ligaments of the
Maxillary incisors
Maxillary canine
Maxillary premolars*

(*) if MSA is not present

Other tissue anesthetized
Adjacent vestibular gingivae and alveolar mucosa
Upper lip – skin and mucous membrane
Lateral external nose
Lower eyelid – skin/conjunctivae
Maxillary sinus – anterior half

ASA block; Target area and injection site?
Landmarks:
Located in a depression below the infraorbital rim*
Medial to the pupil of the eye* – if patient is looking straight

Target area:
At the apex of the maxillary canine Site of Injection:
The injection site is directed to the apex of the maxillary canine – at the height of the mucobuccal fold

The injection site for the ASA block is the tissue at the height of the mucobuccal fold at the apex of the maxially canine, just anterior to and parallel with the canine eminence.

ASA block; Symptoms and possible complications?
Symptoms:
Tingling and numbness of lower eyelid, side of the nose, & upper lip

Complications are rare.
Hematoma across the lower eyelid that resolves in a few weeks
Vascular penetration: hematoma that resolves in a few weeks
Intraorbital injection: Temporary blindness and/or double vision

IO block; Area anesthetized?
Indicated for:
Dental procedures on the maxillary incisors, canine and usually premolar teeth.
Nasopalatine block may also be necessary.

IO block; Target area and injection site?
Landmarks:
Located in a depression below the infraorbital rim*
Medial to the pupil of the eye* – if patient is looking straight

The target area for the IO block is the ASA and MSA nerves as they ascend to join the infraorbital nerve after the infraorbital nerve enters the infraorbital foramen.

The approximate depth of needle penetration for the IO block may vary, but typically is approximately 16 mm. In a patient with a higher or deeper mucobuccal fold or more inferior infraorbital foramen, less tissue penetration will be required than in a patient with a much lower or shallower mucobuccal fold or more superior infraorbital foramen.

The injection site for the IO block is the tissue at the height of the mucobuccal fold at the apex of the maxillary first premolar.

IO block; Symptoms and possible complications?
Watch your frenums;
insert needle more posterior with MSA block to avoid going through.
In some cases, adjustment can be made by retracting it more anterior.
Make sure to leave at least 5 to 10 mm on each side of frenum

GP block: Area anesthetized?
Tissue Anesthetized:
Posterior to the maxillary canines
Palatal mucosa
Lingual gingivae
Underlying bone of the palate
Posterior portion of the hard palate

GP block; Target area and injection site?
Target Area:
Greater palatine nerve as it enters the greater palatine foramen
Anterior to the greater palatine foramen
At the apex of the maxillary 2nd (children) or 3rd molar

Site of Injection:
Depression by the greater palatine foramen
Depression about midway between the median raphe & lingual gingival margin of the molar tooth

GP block; Discuss the use of pressure anesthesia on the hard tissues of the palate.
Pressure use creates dull ache that blocks pain from needle

GP block; Symptoms and possible complications?
Complications: None. Patient may gag if lesser palatine is anesthetized

NP block; Area anesthetized?
Tissue Anesthetized:
Palatal mucosa & lingual gingivae of the six anterior maxillary teeth
Corresponding lingual plate of alveolar bone
Mucoperiosteum of anterior 1/3 of the hard palate

NP block; Target area and injection site?
Site of Injection:
Lateral to the incisive papilla – never directly because is extremely painful.
Incisive foramen is located posterior to and between the central incisor teeth

NP block; Discuss the use of pressure anesthesia on the hard tissues of the palate.

NP block; Symptoms and possible complications?
Symptoms:
Numbness in the anterior portion of the palate

Complications:
Hematoma is rare
Avoid enter the incisive canal – it will enter into the nasal cavity.

AMSA block; Area anesthetized?
2nd premolar through central incisor.

AMSA block; Target area and injection site
Tissues of the hard palate. Injection: Midway between median palatal sutures and max premolars.

AMSA block; Discuss the use of pressure anesthesia on the hard tissues of the palate.
Pressure reduces pain

AMSA block; Symptoms and possible complications?
Blanching occurs after given injection can cause postoperative ischemia and sloughing. slow injection can stop that.

Compare the effectiveness of mandibular injections with the effectiveness of maxillary injections.
less effective because of more density in areas.

How effective is an infiltration in the mandible?
The mandible is denser than the maxilla over similar teeth, especially in the area of the mandibular posterior teeth, therefore nerve blocks are preferred to local infiltration in most parts of the mandible.

What portion of the mandible is more effective using
infiltration?

IA block; Area anesthetized?

IA block; Are bilateral injections advisable?

IA block; Target area and injection site?
Target Area for Traditional IA:
The inferior alveolar nerve on medial aspect of the ramus prior to its entry into the mandibular foramen
Within the pterygomandibular space (infratemporal fossa)
Lingual, mental and incisive nerves are also anesthetized.

injection site:
Identify the
coronoid notch (with associated temporalis tendon).
laterally and
the pterygomandibular raphe & anterior border of the medial pterygoid m medially.
Injection site varies. Most frequent recommendation is a little above the occlusal plane, 3/4th of the anteroposterior distance between the above landmarks.
Successful technique results in anesthesia of the mandibular teeth on the ipsilateral side to the midline, associated buccal and lingual soft tissue, ipsilateral -lateral aspect of the tongue and lower lip

IA block; Symptoms and possible complications?
Symptoms:
Numbness or tingling of lower lip
Numbness or tingling of the body of the tongue and floor of the mouth

Possible complications:
Lingual shock
Facial paralysis if the facial nerve is mistakenly anesthetized
Muscle soreness
Hematoma

IA block; How do you avoid complications?

IA block; Discuss troubleshooting the IA block depending on the contact of the needle with the bone.
If bone is contacted early, needle tip is located too far anterior on the ramus.
Correction: withdraw needle partially or completely and bring syringe barrel more
closely over the mandibular anterior teeth, moves needle tip more posteriorly. If bone is not contacted when inserting even with the usual depth of penetration by the needle, needle tip is located too far posterior on the ramus. Correction: withdraw needle partially
or completely and bring syringe barrel more closely over the mandibular molars, moves needle tip more anteriorly. If bone is not contacted, do not deposit the local anesthetic agent. The needle tip may be too posterior and located in the parotid salivary gland where CN VII innervates creating complications.

IA block; What is the accessory innervation that can prevent a successful IA block?
Accessory
innervation of the mylohyoid.

Buccal block; Area anesthetized?
Tissue Anesthetized:
Tissue associated with Mandibular molars:
Buccal periodontium
Associated gingiva
Periodontal ligament
Alveolar bone
Skin & mucosa of the cheek

Buccal block; Target area and injection site?
Target:
Buccal nerve, also known as long buccal nerve, as it passes over the anterior border of the ramus, and through the buccinator
The tissue just distal and buccal to the last molar tooth is the target area for injection

Buccal block; Symptoms and possible complications?
Symptoms & Complications:
Numbness of Mandibular molars:
Buccal periodontium
Associated gingiva
Periodontal ligament
Alveolar bone
Rare complications
Hematoma are rare

Mental block; Area anesthetized?
For dental procedures on the mandibular incisors, canine, and variably first and second premolars

Mental block; Target area and injection site?
Target
Mental nerve at the mental foramen

Injection area:
AT the height of the mucobuccal fold over the mental foramen
Immediately below the apex of the mandibular second premolar *, or just anterior or posterior to it

Mental block; Symptoms and possible complications?
Symptoms and Complications:
Numbness of facial gingiva and mucosa of these teeth and lower lip to the midline
Harmless.
Rare complication.
Hematoma is rare

Incisive block; Area anesthetized?
The pulp and facial tissue of the mandibular premolars and anterior teeth.

Incisive block; Target area and injection site?
Same as the mental block: it is anterior to where the mental nerve enters the mental foramen to merge wit the incisive nerve to form the IA nerve.

Incisive block; Symptoms and possible complications?
Same as the symptoms of the mental block with harmless tingling and numbness of the lower lip, except that there is pulpal anesthesia of the involved teeth, and there is an absence of discomfort during dental procedures. As with a mental block, a hematoma rarely occurs. Injection site: anterior to the depression created by the mental foramen at the depth of the mucobuccal fold with the needle in a horizontal manner, the syringe barrel resting on the lower lip.

Gow-Gates mandibular block; Area anesthetized?
Nerves anesthetized are the inferior alveolar, mental, incisive, lingual, mylohyoid, and auriculotemporal, as well as the (long) buccal nerves in most cases. Considered a mandibular block because it anesthetizes almost the entire V3.

Gow-Gates mandibular block; Reasons for use?
Used in quadrant dentistry in which buccal soft tissue anesthesia from most distal mandibular molar to midline and lingual soft tissues is necessary, and in some cases when a conventional IA block is unsuccessful. Success rate is higher than that of an IA block even taking into account a slightly more complicated procedure. Injection lasts longer that the IA block due to injection area being less vascular, but does require more anesthetic.

Gow-Gates mandibular block; Target area and injection site?
The anteromedial border of the neck of the mandibular condyle, just inferior to the insertion of the lateral pterygoid muscle. Injection site: located intraorally on the oral mucosa on the mesial of the mandibular ramus, just distal to the height of the mesiolingual cusp of the maxillary second molar following an imaginary line extraorally from the ipsilateral intertragic notch of the ear to the ipsilateral labial commissure.

Gow-Gates mandibular block; Symptoms and possible complications?
Numbness of mandibular teeth to midline, buccal mucoperiosteum and mucous membranes, lingual soft tissue and periosteum, anterior 2/3 of the tongue, the floor of the mouth, and the body of the mandible and inferior ramus, as well as the skin over the zygomatic bone and the posterior buccal and temporal regions. Two disadvantages: numbness of lower lip and temporal region, and longer time necessary for the anesthetic to take effect. The injection is contraindicated in cases with limited ability o open mouth, but trismus is rarely involved.

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