Surface preparation and topical agents
The initial stage of safe pain management is the elimination of pain at the site of the future soft tissue puncture. For this purpose, topical agents such as Aroma Paste are used. This multi-component agent is effective even on intact skin and mucous membranes.
The paste contains a combination of active ingredients: ethylaminobenzoate, dibucaine hydrochloride, tetracaine hydrochloride, and homosulfamine. This formula provides several advantages:
- Rapid onset: the effect develops within a few minutes and lasts for tens of minutes.
- Deep penetration: the anesthetic penetrates the oral mucosa to a depth of 5 mm or more.
- Low toxicity: the drug is safer than analogues (e.g., a 1:1 eutectic mixture of lidocaine and prilocaine).
- Convenient form: the paste reliably adheres to the target area and has a pleasant taste.
In addition to injection preparation, topical pastes and specialized self-adhesive films (such as Diplen-LHF) are used in minimally invasive procedures (closed curettage), treatment of the tooth socket in alveolitis, and for pain relief during dressing changes in the postoperative period.
Topographic anatomy of the maxilla
For predictable injection anesthesia, the clinician must have a thorough understanding of the structure of the maxilla (maxilla), the largest paired bone of the upper facial skeleton.
Its anterior surface is concave in shape. Superiorly, it is separated from the orbit by the infraorbital margin. Directly below it lies an important landmark — the infraorbital foramen (foramen infraorbitale), which is the exit point of the canal of the same name. Below this foramen lies the canine fossa (fossa canina). Laterally, this area is bounded by the zygomaticoalveolar crest (crista zigomaticoalveolaris), which extends from the first molar to the zygomatic process.
The infratemporal surface participates in the formation of the infratemporal and pterygopalatine fossae. Here also lies the maxillary tuberosity, which features openings of the alveolar canals transmitting nerves and blood vessels to the posterior teeth.
The alveolar process (processus alveolaris) is an arched plate containing sockets for eight teeth within its spongy bone. An important surgical feature: the tooth sockets are shifted toward the buccal surface, making the vestibular bone wall significantly thinner than the palatal (medial) wall.
Pterygopalatine fossa and nerve pathways
The pterygopalatine fossa (fossa pterygopalatina) is a crucial anatomical crossroads. The medial wall of the fossa is formed by the perpendicular plate of the palatine bone, while the lateral wall is absent, allowing the fossa to communicate directly with the infratemporal region.
It is critically important for the surgeon to know the five openings through which the fossa communicates with other regions (and through which nerve trunks pass):
- With the nasal cavity — via the sphenopalatine foramen.
- With the cranial cavity — via the foramen rotundum (through which the maxillary nerve descends from the cranial cavity).
- With the region of the lacerum foramen — via the pterygoid canal.
- With the oral cavity — via the greater palatine canal.
- With the orbit — via the inferior orbital fissure.
Innervation of maxillary structures
Tissue sensation is supplied by the maxillary nerve (n. maxillaris), which is the second branch of the trigeminal nerve. Having exited the skull through the foramen rotundum, it gives off several branches. Notably, the zygomatic nerve, which branches off first, does not participate in the innervation of the oral cavity.
The branches of the pterygopalatine ganglion are responsible for the sensation of the mucous membrane:
- The nasopalatine nerve (n. nasopalatinus) descends along the nasal septum and innervates the anterior hard palate via the incisive foramen.
- The greater and lesser palatine nerves (n. palatinus major et nn. palatini minores) emerge through the foramina of the same name, providing sensation to the rest of the hard and soft palate.
Special attention is paid to the posterior superior alveolar nerves. A smaller portion of their fibers descends along the outer surface of the tuberosity, anesthetizing the buccal mucosa and periosteum in the premolar and molar regions. The main trunk enters the alveolar canals, innervating the sinus mucosa and the tissues of all three maxillary molars. However, an important exception must be kept in mind: in some patients, this nerve does not cover the mesiobuccal root of the first molar.
Briefly: answers to topical questions
What branches does the maxillary nerve give off?
The maxillary nerve gives off several main branches that innervate the tissues of the maxillofacial region and the dura mater. These include:
- The zygomatic nerve — branches off directly at the foramen rotundum and does not participate in the innervation of oral tissues.
- The pterygopalatine nerves (nn. pterygopalatini) — branch off from the trunk and participate in the formation of the pterygopalatine ganglion.
- The posterior superior alveolar nerves (nn. alveolares superiores posteriores) — branch off in the pterygopalatine fossa after the nerve enters the infraorbital sulcus.
- The infraorbital nerve (n. infraorbitalis) — lies in the infraorbital sulcus.
- The meningeal branch (r. meningeus medius) — runs alongside the frontal branch of the middle meningeal artery.
What bony structures form the walls of the pterygopalatine fossa?
The walls of the pterygopalatine fossa are formed by the following bony structures:
- Anterior boundary — posterior surface of the body of the maxilla and the orbital process of the palatine bone.
- Posterior boundary — maxillary and orbital surfaces of the greater wing of the sphenoid bone.
- Superior boundary — inferior surface of the body and base of the greater wing of the sphenoid bone.
- Medial wall — perpendicular plate of the palatine bone, which participates in the formation of the greater palatine canal.
- Lateral wall — has no bony wall, communicates directly with the infratemporal fossa.
The inferior boundary is not fully described in the sources.
What anatomical landmarks bound the canine fossa?
The canine fossa (fossa canina) is located in the central part of the anterior surface of the maxilla, directly below the infraorbital foramen (foramen infraorbitale). Complete data on other boundaries of the canine fossa are not provided in the presented materials.
Which nerves form the superior dental plexus?
The superior dental plexus is formed by branches of the infraorbital and maxillary nerves. Its formation involves:
- Middle superior alveolar branches (rr. alveolares superiores medius) — branch off from the infraorbital nerve within the infraorbital canal.
- Anterior superior alveolar branches (rr. alveolares superiores anterior) — also branch off from the infraorbital nerve within the canal of the same name.
- Posterior superior alveolar nerves (nn. alveolares superiores posteriores) — branch off from the maxillary nerve in the pterygopalatine fossa.
Class and exam questions
Which drugs are optimal for topical anesthesia before injection?
Multi-component topical pastes (e.g., based on dibucaine and tetracaine) have proven to be highly effective. They penetrate soft tissues to a depth of over 5 mm, have a short latency period, and last for tens of minutes.
Why is it important for a surgeon to consider the wall thickness of the alveolar process?
Tooth sockets are shifted toward the lateral (outer) surface of the alveolar process. Consequently, the outer cortical plate is significantly thinner than the medial plate, which affects anesthetic diffusion and the choice of tooth extraction technique.
Which anatomical structure limits the canine fossa laterally?
On the lateral side, the canine fossa is bounded by the zygomaticoalveolar crest (crista zigomaticoalveolaris). This bony ridge originates in the region of the first molar and transitions into the zygomatic process.
Do the posterior superior alveolar nerves always fully innervate the first molars?
No, this is a clinically important exception. In many patients, these nerves do not supply sensation to the mesiobuccal root of the maxillary first molar.
What else to study on this topic
- Features and innervation zones of the infraorbital nerve
- Anatomy and physiology of mandibular innervation
- Methods of tuberal and infraorbital anesthesia
- Prevention of complications during anesthetic injection into the pterygopalatine fossa
- Physicochemical properties of self-adhesive films in surgical dentistry
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