Anatomical rationale of the method
The mandibular torus (torus mandibulae) is located at the confluence of the bone ridges descending from the condylar and coronoid processes of the mandible.
The clinical significance of this area is that three nerve trunks pass just below and medial to the torus:
- Inferior alveolar nerve (n. alveolaris inferior);
- Lingual nerve (n. lingualis);
- Buccal nerve (n. buccalis).
By delivering the local anesthetic directly into this area, the clinician achieves a massive blockade of the entire corresponding half of the jaw without the need for multiple separate punctures.
Technique of torus anaesthesia
The success of the technique depends directly on correct positioning and precise identification of landmarks.
Action algorithm:
- The patient should open their mouth as wide as possible.
- Determination of the puncture point: look for the intersection of two lines. The first (horizontal) line runs 0.5 cm below the occlusal surface of the upper third molar. The second (vertical) line is the groove between the cheek and the lateral slope of the pterygomandibular fold (plica pterygomandibularis).
- Syringe position: the syringe is placed at the level of the molars on the opposite side of the jaw.
- Advancement of the needle: the puncture is made perpendicular to the buccal mucosa. The needle is advanced to a depth of 0.2–2.0 cm until a distinct contact with the bone tissue is achieved.
- Drug administration: after a mandatory aspiration test, the main portion of the anesthetic is injected.
- Lingual nerve blockade: to reliably anaesthetize the n. lingualis, the needle is withdrawn slightly backward (by a few millimeters) and an additional 0.5–0.8 ml of the solution is injected.
Zone of complete anaesthesia
When Vaisbrem's anaesthesia is performed correctly, the same areas are numbed as in classical mandibular anaesthesia, but with more reliable coverage of the buccal nerve.
Tissues losing sensitivity:
- All mandibular teeth on the injection side.
- Bone tissue of the alveolar process and partially the body of the mandible.
- Mucous membrane and skin of the cheek, as well as the skin of the chin and the mucosa of the lower lip.
- Mucous membrane of the sublingual region and the corresponding half of the tongue.
- Mucous membrane of the alveolar process (from the middle of the second premolar to the middle of the second molar).
Alternative: apodactyl mandibular anaesthesia
If the clinician does not use palpation of bony landmarks, the apodactyl method is used.
The puncture is made at the outer edge of the pterygomandibular fold (at the border of the upper and middle thirds). The direction of the needle is almost perpendicular to the mandibular ramus (the syringe rests on the premolars of the opposite side). The needle is inserted 1.5–2 cm to the bone, part of the anesthetic is injected, then the syringe is moved toward the incisors and the needle is advanced further by 2.0–2.5 cm parallel to the ramus. This also allows blockade of the classical mandibular anaesthesia zone with an effect in 5–8 minutes.
Briefly: answers to topical questions
Which nerves are blocked during mental anaesthesia?
During mental anaesthesia, the mental nerve is blocked. When the anesthetic is injected into the mental canal, the anaesthesia zone expands to include the premolars, canine, incisors, alveolar process, and oral mucosa from the vestibular side within the specified teeth.
Which teeth and soft tissues are anaesthetized during mental anaesthesia?
The anaesthesia zone during mental anaesthesia depends on the injection technique used.
- Without injection into the canal — anaesthesia is limited only to the soft tissues of the chin and lower lip.
- With injection into the mental canal — the premolars, canine, and incisors, as well as the alveolar process and oral mucosa from the vestibular side within these teeth, are additionally anaesthetized. In rare cases, the zone may extend to the level of the second molar.
The RULE OF THREE for torus anaesthesia: it blocks THREE nerves, the syringe rests in the area of the teeth of the opposite side, and the puncture point is 0.5 cm below the THIRD upper molar.
Class and exam questions
Where exactly is the puncture point located in torus anaesthesia?
The point is formed by the intersection of a horizontal line (0.5 cm below the occlusal surface of the upper 3rd molar) and the groove between the cheek and the lateral slope of the pterygomandibular fold.
Why is the needle withdrawn backward after bone contact in torus anaesthesia?
After bone contact, the needle is withdrawn a few millimeters backward in order to precisely inject 0.5–0.8 ml of the anesthetic into the region where the lingual nerve passes.
Is an aspiration test required for these techniques?
Yes, the administration of local anesthetic during torus and any mandibular anaesthesia is performed strictly under the control of an aspiration test to avoid intravascular injection.
What else to study on this topic
- Inferior alveolar nerve block according to P.M. Egorov
- Gow-Gates technique and its clinical advantages
- Anaesthesia in trismus: Vazirani-Akinosi technique
- Trigeminal nerve block at the foramen ovale (subzygomatic-pterygoid approach)
- Intraoral (palatal) approach for V2 nerve branch blockade
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Other topics in "Chapter 4. Anesthesia in Oral Surgery (S.A. Rabinovich, S.T. Sokhov)"
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