New Anatomic Intraoral Reference for the Anesthetic Blocking of the Anterior and Middle Maxillary Alveolar Nerves (Infraorbital Block)
José Inácio Saadi SALOMÃO1
José Antônio Saadi SALOMÃO2
Rosângela Cecília Saadi SALOMÃO COSTA3
1Faculdade de Odontologia de Ribeirão Preto,
Universidade de São Paulo
2Faculdade de Odontologia de Ribeirão Preto,
Universidade de Ribeirão Preto
3Dental Surgeon Ribeirão Preto, SP, Brasil
Braz Dent J (1990) 1(1): 31-36 ISSN 0103-6440
| Introduction | Description
of technique | Conclusions | References
The superior lateral labial frenum is proposed as a new anatomic reference
for the intraoral blocking technique of anesthesia of the anterior and
middle superior alveolar nerves (infraorbital). The main advantage of this
technique is the constancy of the reference point, independent of the presence
or absence of teeth, which other techniques do not offer.
Key words: anesthesiology, infraorbital block.
In order to anesthetically block the anterior and middle superior alveolar
nerves, it is essential to localize the infraorbital foramen which, when
reached with a needle, permits the diffusion of the anesthetic solution
through the infraorbital canal.
The anatomical location of this foramen has been studied by numerous
authors. Martani and Stefani (1965), studying the position of this anatomic
accident within statistical, morphological and topographical aspects, provide
an extensive bibliographical review of this topic.
From a practical standpoint in anesthesiology, despite the fact that
the infraorbital, foramen is found easily by digital palpation, or by other
methods based on fines traced between craniometric points (Haglund and
Evers, 1972; Bennett, 1977), the establishment of a. constant reference
point for needle insertion is of great importance for successful intraoral
The relevant literature shows a tendency of a majority of the authors
to use the teeth as the reference for intraoral blocking techniques. Thus,
Archer (1955) and Schram (1964) cite the maxillary central incisor, Partsch
(1936) the maxillary lateral incisor, Maurel (1944) and Ries Centeno (19M)
the maxillary canine, Mead (1948), Nevin and Puterbaugh (1955), Archer
(1955) and Jorgensen and Hayden (1970) the maxillary second pre-molar,
and Graziani (1958) and Bennett (1977) the maxillary pre-molars.
These references are, however, annulled when these teeth are absent,
a fact frequently observed in dental practice. Thus, if there existed an
anatomic accident always constant and present in everyone, which would
ease the orientation of the needle in the direction of the infraorbital
foramen during its introduction into the tissues, this anesthetic technique
would be of great value for all patients, especially edentulous patients.
The objective of this study is to propose the superior lateral labial
frenum as the new anatomical reference to be observed for the locafization
of the needle insertion point in infraorbital intrabuccal blockage.
Description of technique
Anesthesia in the infraorbital foramen seeks to insensibilize part of the
branch of the II division of the trigeminal nerve. The II division - maxillary
branch - exits the skull through the foramen rotundum, passes the pterygomaxillar
fossa, enters the infraorbital canal, now being called the infraorbital
nerve, runs along the orbital floor and emerges at the anterior side of
the maxilla by the infraorbital foramen, ending in 3 terminal branches:
lateral nasal, superior labial and inferior palpebral.
About 5-6 mm before the foramen, the infraorbital nerve supplies the
anterior maxillary alveolar nerve whose branches descend by narrow canals
in the maxilla, running between the sinus mucosa and the bony wall, penetrating
through the radicular apices, to innervate the pulp of maxillary incisors
and canines. Its branches also go to the outer bone plate, periosteum and
other lining structures in the region of these teeth. It even gives sensibility
to the mucosa of the anterior part of the maxillary sinus. A prolongation
crosses the maxilla in direction of the floor and lateral wall of the anterior
The middle superior alveolar nerve separates from the infraorbital nerve
at the posterior part of the floor of the infraorbital canal and continues
in a downward frontal direction until the pre-molar apices. At other times,
it separates near the infraorbital foramen and descends by the anterior
wall or the anterolateral maxillary sinus until the superior pre-molars,
innervating the dental pulp, the external alveolar lamina, the periosteum
and the mucosa. Several authors maintain that the middle superior alveolar
nerve may be absent and that, in this case, the maxillary pre-molars are
innervated by the external superior plexus.
Infraorbital block anesthetizes the anterior and middle maxillary alveolar
nerves, inferior palpebral, lateral nasal and superior labial with insensibility
of the maxillary incisors, canines and pre-molars, including their vestibular
osseous support and the soft tissues which cover them, as well as the mesiovestibular
root of the maxillary first molar, part of the maxillary sinus, nose, superior
labial and inferior palpebral.
To execute this proposed technique, the patient ought to be seated comfortably,
with the mouth open, reclining backwards, so that the maxillary occusal
plane forms a 45° angle with the floor (Alonso Verri, 1964). The upper
lip is raised, revealing the marina lateral labial frenum (Figure 1).
With a long needle (about 42 mm) mounted on a syringe resting on the
lower lip, the needle is introduced vestibularly to the gingival sulcus,
about 1 cm from the mucosa of the alveolar process, touching lateral and
parallel to the superior labial frenum (Figure 2).
The needle ought to be oriented as if it would virtually encounter the
base of the superior lateral labial frenum on the infraorbital border (Figure
The penetration of the needle is stopped when the needle reaches the
infraorbital foramen, the patient generally complaining of an electrical
shock or burning. The anesthetic solution is injected slowly, maintaining
a finger applied to the foramen so that the anesthetic solution is driven
into the area of less resistance - the infraorbital canal - in this manner
reaching the anterior and middle maxillary alveolar branches.
The success of this procedure is the lack of sensibility to thermal,
painful and tactile stimuli in the region innervated by the anterior and
middle maxillary alveolar branches and by the drooping of the upper lip
on the anesthetized side, shoving that the terminal branch of the facial
nerve (temporofacial) was reached in the infraorbital foramen region (Figure
With the anesthetic solution reaching only the terminal branches of
the infraorbital nerve (in the region of the foramen), purely subjective
symptoms cannot be taken into consideration to evaluate the success of
the anesthetic block.
Two muscles may be affected by incorrect execution of this technique:
the canine muscle which fills the canine fossa, and the elevator muscle
of the upper lip which inserts at the lower border of the orbit. The infraorbital
foramen is between the insertion of these two muscles. If the needle is
maintained near the bone, the canine muscle will be affected; but if it
is too far from the bone, the proper elevator muscle of the upper lip will
One ought to avoid reaching the orbit so that the ocular-motor and optic
nerve branches are not affected, the consequences being double vision and
temporary blindness. These accidents, although transitory and rare, are
extremely disagreeable. Rarely do intravascular injections occur.
In cases near the midline, a complementary infiltration of the opposite
side is recommended so that eventual crossed nerve junctions are also anesthetized.
Previous research offers different points of intraoral reference for needle
insertion for the anesthetic block of the infraorbital nerve. Most of them
do not consider the edentulous patient. This could lead to insecurity in
those beginning anesthesiology and those less familiar with this technique.
The anatomic reference point presented here is constant in all patients
- with or without teeth.
The superior lateral labial frenum is a fold in the mucosa of the gingival
sulcus, inserting in the region of the maxillary canines and pre-molars.
It is generally not noted on superficial examination. To be evident, it
is necessary to raise the buccal mucosa, separating it from the gingival
mucosa causing its distension by the attempt of gingival sulcus planing.
The practical application, with complete success, of the anesthetic
block of the infraorbital nerve by the above technique recommends the superior
lateral labial frenum as the infraoral reference point in patients with
or without teeth. Clinical experience in the application of this technique
permits the proposal that the localization of the infraorbital foramen
corresponds to the superior lateral labial frenum and that this correspondence
is invariable and always present.
Alonso Verri R: Técnicas anesthesiológicas locais em odontologia.
Thesis, Faculdade de Farmácia e Odontologia, Ribeirão Preto
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Bennett CR: Monheim - Anestesia local e controle da dor na prática
dentária. 5th ed. Guanabara-Koogan, Rio de Janeiro 1977
Graziani M: Cirurgia buco-maxilar. 4th ed. Vol I. Ed. Cientifica, Rio
de Janeiro 1958
Haglund J, Evers H: Local anesthesia in dentistry. Astra Lakemeded AB,
Jorgensen NB, Hayden JR: Anestesia odontológica. Interamericana,
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e topográfico alto studio del fore infraorbitário in crani
umani. Mondo Odontostomatol 7: 367-378, 1965
Maurel G: Cirugia maxilo-facial. Alla, Buenos Aires 1944
Mead SV: Cirugia bucal. 3rd ed. Vol I. UTEHA, México 1948
Nevin M, Puterbaugh PG: Anestesia dentária. 11th ed. Ed. Cientifica,
Rio de Janeiro 1955
Partsch C: Enfermedades quirúrgicas de la boca, dientes y maxilares.
4th ed. Labor, Buenos Aires 1936
Ries Centeno GA: Cirugia bucal. 7th ed. El Atheneu, Buenos Aires 1964
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Correspondence: Dr. José Inácio Saadi Salomão,
Departamento de Cirurgia e Traumatologia Bucomaxilofacial, Faculdade de
Odontologia de Ribeirão Preto, USP, 14050 Ribeirão Preto,